INTRODUCTION
This chapter begins with a brief review of previous examinations, in the long-term, of individuals who had cerebral commissurotomy. There are next presented, in detail, observations made on some of these patients in the short term. The chapter concludes with a brief discussion of possible implications of these findings for our understanding of the cerebral basis of language and speech.
One of the most interesting features of the human brain is the usual difference between the two cerebral hemispheres in regard to their participation in linguistic performance. This aspect of the brain-language relationship was for a century understood in terms of the results of lateralized lesions. Recently another kind of evidence has become available from studies of individuals having cerebral commissurotomy for epilepsy intractable to medical management (Bogen & Vogel, 1962; Bogen, Fisher, & Vogel, 1965; Bogen, Sperry, & Vogel, 1969). This operation includes division of the corpus callosum and of the anterior and hippocampal commissures. Interhemispheric spread of seizure activity can then occur only via the brain stem; and the same limitations apply to the transfer of other neuronal activity. If stimuli are presented to only one hemisphere at a time, very little interhemispheric transfer occurs; this is especially true of cognitive or discriminative information. It therefore becomes possible to test each hemisphere separately so that the respective hemispheric contributions can be ascertained directly, rather than inferred from the deficits consequent to lateralized damage.
More than 60 scientific papers have been published on the commissurotomy patients (as well as a plethora of "popularized" versions). For those unfamiliar with the basic findings, the best introduction is probably Sperry, Gazzaniga, and Bogen (1969). In the present chapter a previous acquaintance with some of the "split-brain" findings will be assumed.
In the following discussion 1 will use the letter R to mean "the respondent" which, unless otherwise qualified, will mean "a right handed individual who has had a complete cerebral commissurotomy and is participating in a testing situation." In referring to postoperative (p.o.) stages of recovery, "immediately postoperative" means the first 6-12 hours and "shortly p.o." means the first 6-7 days. The word "acute" refers to changes in status within the first 6-12 weeks, as contrasted with the later "chronic." By "short-term" is meant the first 6 months and by "long-term" the second through sixth years. The period from 6-12 months can be considered "intermediate." Beyond 6 years is the "very long-term." Previous reports on language function following cerebral commissurotomy have mainly concerned either the "long-term" (Sperry et al., 1969; Sperry & Gazzaniga, 1967; Gazzaniga & Sperry, 1967; Gazzaniga, 1970; Sperry, 1974) or the "very long-term" (Zaidel, 1973). Although the limits or boundaries indicated here are time-honored in most cases and in common usage, the reader will understand that changes in status are rarely abrupt, usually occurring in a gradual and continuous fashion.
In addition to permitting the testing of each hemisphere more or less independently, cerebral commissurotomy can be considered somewhat differently-that is, as an ablation procedure. From this perspective we suppose that if language arises in part from hemispheric interaction via the commissures, then, when the commissures are cut, any deficit in language behavior can be attributed to the loss of a specific integrating structure. This approach is subject to the usual limitations of the ablation approach including the important point that section of the commissures entails a shock or diaschisis (for each hemisphere) as well as a simple disconnection. Deficits observed shortly after operation will therefore reflect both diaschisis and deconnection.
Language function for the first few days after operation is also depressed by the circulatory changes consequent to manipulation of the brain. In particular, there is considerable swelling or edema which reaches a maximum around the fourth or fifth day and takes at least another week or so to subside. During this period there are various abnormalities, often including mutism. This mutism, to be discussed more fully further on, is partly attributable to the edema, which tends to complicate further any conclusions as to the relative contributions of diaschisis and disconnection.
If we wait for several months the edema will be long gone and, furthermore, there will have been substantial subsidence of the diaschisis. So we might suppose that we could then see the effects of disconnection alone. But there will have been in the meantime compensatory adjustments. In the younger patients, the effects of maturation must also be considered. Moreover, there will be an increase in competence attributable to learning, in addition to the reorganization, disinhibition, and other compensatory adjustments.
It is worth noting that some learning takes place every time that R is tested. This produces an uncertainty analogous to the uncertainty in particle physics, in which every observation perturbs the situation so that the measurement is slightly inaccurate by the time it has been made. The problem may be worse than this suggests. For example, some experiments require that the patient learn a complicated task before we can measure the effect, on the performance of this task, of some experimental maneuver or change in circumstance. We have often had the experience that the patient's learning is so steadily progressive that one can hardly say of any series of observations that it samples a specifiable state. Or, learning may continue to a plateau where the task is so overlearned that manipulation of a variable can no longer produce interesting effects which seemed to be present in earlier stages. Replication of preliminary results in such circumstances is particularly elusive.
Some estimate of the compensatory aspects can be had from repeated follow up as the learning and related adjustments accumulate over the years. But no matter when we examine R, the results will reflect a compound of a number of processes, some subsiding and some augmenting.
One point of the foregoing is, therefore, that the status of R shortly after the operation does have significance in spite of the complications attending its interpretation, since testing in the short-term avoids the compensatory and maturational aspects, even though it is confounded by edema and diaschisis.
How different symptoms can be differently affected by the appearance of new or compensatory capacity is well illustrated by two prominent features of the disconnection syndrome: These are an anomia, and an apraxia for verbal com mand, both of which invariably involve the left hand of the right-handed patient following cerebral commissurotomy.
When R is tested in the short-term (less than 6 months postoperatively) there is to varying degree a dyspraxia of the left hand, as described in an earlier publication (Bogen, 1969 I): [{ see also Bogen 1993 (#114) }] The essential feature of apraxia is that the patient does not carry out an act at a time when he indicates in some way his comprehension of what is required and his intent to do it, whereas he can perform the required motions under other circum stances. Such a situation obtains with particular clarity in the unilateral apraxia which appears after a transection of the cerebral commissures. Cerebral commissurotomy in the right-hander is followed by a period of apraxia for the left hand whose duration differs from one patient to the next. During this period, the patient is unable to follow a verbal instruction with the left hand, such as "Stick out your left little finger," although he quickly follows such instructions with the right hand; however, he can do the requested act with the left hand if he is shown by demonstration what is expected of him. Similarly, although unable to perform with his left hand an abstract action such as, "pretend you are using a pair of scissors" or "pretend you are turning a door knob," the patient readily executes the appropriate motions if the scissors is placed in his left hand, or if he is asked to go through a door while keeping his right hand in his pocket.
We believe that for this monomanual apraxia to appear after commissural section, R must have two concurrent deficits. First, the left hemisphere clearly comprehends the instruction since the right-hand execution is excellent, but it (the left hemisphere) exercises insufficient control over the left hand to afford an adequate execution with that hand.
Second, the right hemisphere exercises excellent control of the left hand as can be seen from the behavior in various situations, but it (the right hemisphere) has insufficient comprehension of the verbal description. It is worth emphasizing that the right hemisphere does comprehend many nonverbal instructions as shown by the excellent cooperation in the left hand in response to pictorial instructions tachistoscopically flashed to the left visual half-field.
The dyspraxia depends, therefore, upon two deficits: a deficit in left-hemi sphere execution with the left hand and a deficit in right-hemisphere verbal comprehension. When the dyspraxia of the left hand for verbal command subsides, as it does in the long-term, either or both of the two concurrent deficits must have been alleviated. To decide which of these is more important, it is necessary to test R by restricting input to one hemisphere at a time. What has been found is that commands presented in the right half-field can be followed by the left hand. But even in the long-term, this ipsilateral control of the left hand by the left hemisphere is never as good as the left-hemisphere control of the contralateral right hand. Ipsilateral control is generally best for movements of proximal parts and is least for the distal interphalangeal joints.
When commands are pictured in the left half-field, the right hemisphere not only shows good contralateral control (that is, of the left hand) but also fairly good ipsilateral control. When the command in the left half-field is verbal, the right hemisphere can follow such verbal commands to some extent; but the right hemisphere even when responding with its proper (left) hand never reaches a level of linguistic comprehension at all comparable with that of the left hemi sphere (Zaidel, 1973).
In sum, the subsidence of the left-handed dyspraxia to verbal command can be attributed to the emergence or improvement of two capacities, left-hemisphere ipsilateral control and right-hemisphere verbal comprehension. Of these two, which is the more important depends upon the particular task or testing situation. Mention must also be made of a third factor-namely, the progressive increase in interhemispheric cooperation which is a prominent feature of the long-term. Although a detailed discussion of the various compensatory strategies employed by R is not appropriate here, the result is important. That is, by sharing a task, the two hemispheres can work together in such a way that each compensates for the deficiencies of the other.
Perhaps the most dependable feature of the disconnection syndrome is an anomia of the left hand. When an everyday object, such as a pipe or a pair of glasses, is placed in R's left hand, the object will be manipulated appropriately, giving the unmistakable impression that it has been correctly identified or recognized. This recognition we attribute to the right hemisphere since, in spite of the appropriate handling, R cannot name the article nor can he retrieve it with his right hand from a set of similar articles. Correct recognition by the right hemisphere is evidenced not only by the appropriate manipulation by the left hand but also by correct retrieval, if the test object is placed among a set of similar objects. This very dependable same-hand retrieval, in the absence of cross-retrieval, thus not only provides evidence for a lack of interhemispheric transfer but makes quite clear the additional point that it must be the right hemisphere which is responsible for same-hand retrieval with the left hand. As a matter of fact, correct same-hand retrieval occurs with certain objects (such as jigsaw puzzle pieces) whose tactile discrimination is so difficult that it is beyond the capability of normal persons. This is because some R have had, over the years, considerable practice in the course of repeated testing. But in spite of the above-normal capacity for tactile recognition of objects, R cannot as a rule name the objects when they are placed in the left hand.
For completeness we point out that naming of objects in the left hand is possible under certain special circumstances. This depends upon some rudimentary ipsilateral sensory projections, such as pain and temperature. For example, R can usually distinguish hot from cold in the left hand (Levy & Sperry, 1970). If, therefore, R is given a metallic object in the left hand, the minimal temperature cue may be sufficient to afford a correct identification by the left hemisphere, particularly if R knows in advance the entire set of test objects and can therefore use knowledge of the temperature as the basis for some exclusionary rule.
With respect to pain, it is fairly common to see the left hand manipulate an object which has a sharp point (such as a pencil or toothpick) into a position so that the point will press into the palm or the ball of the thumb. As soon as this happens (occasionally with a simultaneous wince) R will promptly name the object if the known set of objects contains only one or two items capable of producing pain under these circumstances. But if R does not know in advance the range of test items (and if certain items used many times over the past.8-l0 years are avoided), an object in the left hand cannot be named.
In contrast to the left-handed dyspraxia, the left-handed anomia does not subside significantly even in the very long-term. This persistence is in spite of the appearance of a wide variety of compensatory adjustments, some of which have been mentioned previously.
Variation from one R to another with respect to various abilities is common. These differences depend upon many variables including the nature of the epileptogenic damage, the age at onset of the epilepsy, the age at operation, the preoperative mental capacities and motivational habits, and the intensity of postoperative rehabilitation. But for every R there is a left-handed anomia for objects; and in every R this deficit persists indefinitely over the years.
The status of R in the long-term, and in particular the language capability of certain selected patients, has been discussed at length in a number of papers cited previously as well as in Levy, Nebes, and Sperry (1971). The remainder of this chapter will be devoted to certain observations made in the short-term, particularly the transient mutism which appears in almost every case.
SUMMARY OF THE STATUS ACUTELY FOLLOWING COMMISSUROTOMY
In some instances, stupor was present shortly after operation. This was attributable to various aspects of the intracranial pressure problem; an analysis of the stupor contributes little if anything to our understanding of where the language is in the brain. In contrast, mutism without stupor seems quite relevant to certain linguistic issues.
In almost every case there was a time during which the patient was mute. The duration of this mutism was not precisely determinable; this is in part because the mutism neither began nor ended abruptly. The exact duration was also difficult to determine because the mutism was sometimes associated with a degree of aphasia (patient C.C.) or with stupor (W.J. and N.W., for example). The most informative data come from mutism present when such complicating problems were not in evidence.
By mutism is meant that the patient appeared alert in following verbal requests and cooperated well with various procedures, seeming to have no gross defect in understanding. Usually during this period the patient was able to write to some extent, although the writing was never as good as subsequently. The recovery from mutism was usually characterized by a stage during which whispering was possible before there was any phonation; this was followed by a stage during which hoarseness was prominent, followed in turn by the eventual reaquisition of a voice quality approximating the preoperative state. As the mutism lifted, language returned intact without an intervening stage of phonemic or mor phemic paraphasia, and without any intervening stage of syntactic or semantic confusion. There was none of the characteristic progression which one is accus tomed to see in the usual recovery from dysfluent aphasia. In particular, there was never any anomia for objects presented for visual identification.
To illustrate the short-term situation, the following representative cases are reported in some detail.
A REPRESENTATIVE CASE OF POSTCOMMISSUROTOMY MUTISM. DYSPRAXIA, AND ANOMIA
R.M. (born December 31, 1939, on a farm) was delivered by breech extraction. He spent most of his childhood in an orphan home where he had several head injuries and twice broke his right arm, so that he learned to write with his left hand. However, there has never been anything he could do better with his left hand than with his right hand. He was always backward in school (he performed at a third grade level when tested at age 15). Convulsions began at age 12 and persisted, to which fact he ascribed his never having had a job. He was supported by Social Security and was able to live by himself with help from neighbors and local police. His convulsions progressively worsened and medication was ineffective.
Before operation the EEG (electroencephalogram) was mildly abnormal and nonlocalizing. Skull X-ray, bilateral carotid angiogram, and pneumoencephalogram were unrevealing. Neurological examination was essentially normal. Before cerebral commissurotomy R.M. wrote legibly and copied well with either hand. Following the operation he largely but not entirely lost the ability to write to dictation with the left hand; copying with the right hand was distinctly inferior to copying with the left hand (Bogen, 1969). In this case, the only lateralizing evidence for the epileptogenic lesion comes from a series of EEG studies made at various times during the first 2 postoperative years. They showed some disorganization over both hemispheres, but the maximum abnor mality was usually in the left temporal region.
On March 14, 1966 (he was then 27 years old), he had a cerebral commissurotomy following which he had mutism for several weeks, and a verbal dyspraxia in the left hand, of some degree, for several months. anomia for the left hand has remained ever since. The patient's recovery from the operation is summarized in Figure 1 and is detailed in the following progress notes.
R. M. Progress Notes
R.M. was seen on March 15, the day after his commissurotomy, at which time he was altogether mute, but would protrude his tongue if requested. He would not smile or grimace but would close and open his eyes on request. He would not hold up individual fingers on the left hand, although he could readily hold up those on the right. He did close his hand to verbal request on the left side on two separate occasions. He would not move the left leg or toes when requested. Both toe signs were extensor, the left markedly and the right minimally. If the bottom (planta) of the foot is stroked properly, the big toe moves. An upward motion (dorsiflexion) is considered a "positive toe sign" or "Babinski sign" and is usually pathologic. My interpretation of this plantar reflex is discussed in Bogen (1974) #47.
Figure 1 Duration of motor symptoms in the patient R.M. following cerebral commissu rotomy. The solid line indicates that the symptom was prominent and the dashed line indicates that the symptom was mild. Where the line is thick vertically an observation was made by the author. Where the line is thin, the status of the patient is interpolated or inferred from observations by others. The letter "N" means the finding was not present. The data summarized here are discussed in the text. The principal points are three: first, the patient was wholly or partially mute for 3 weeks although able to write during most of this time; second, a dyspraxia for verbal command was present in the left arm for 6 weeks; third, an anomia in the left hand was strikingly present when first tested, and it has been present ever since.
MARCH 18, 1966 (FOURTH POSTOPERATIVE DAY)
Today he was lying in bed and seemed quite alert and stuck out his hand to shake mine when I said "hello." However, he did not talk at all and when I suggested that he say "hello" he could not do anything. I finally asked him if he could say "yes," and with considerable urging, he was able to say "yes";this was said in a hoarse voice, not a whisper. He was unable (or unwilling) to say anything else. With the left hand he could squeeze on request but he could not open if any pull was applied. (In other words, there was a strong proximal traction reaction.) The apraxia in the left hand was complete as far as the fingers were concerned although he was able to hold his arm up when requested. On one occasion when he was asked to stick out his little finger the finger was stuck out on both hands simultaneously. He could not repeat this when requested to do so and was completely unable to hold up an individual finger even when shown what to do. Both toe signs were definitely positive today. On March 22, the patient was transferred to the ward from ICU (intensive care unit). He was nodding his head and on occasion tried to talk but only whispered. He was feeding himself very slowly; according to his nurse, "he took an hour but ate everything." He was still mute.
MARCH 23, 1966 (NINTH POSTOPERATIVE DAY)
He was alert and readily shook hands when I extended mine. No grasp reflex could be elicited on the left side but there was a very strong PTR (proximal traction reaction); that is, when I asked him to squeeze he did it readily, but he was unable to let go so long as I kept pulling away. He extended the left thumb twice when asked to do so but on several other occasions could not do it. He opened and closed his left hand readily when asked to do so but he couldn't hold up any of the other fingers.
He stuck his tongue out and opened his eyes, closed his eyes, and opened his mouth whenever requested, but did not speak. Finally, I asked him, "Can you say,'yes'?" and with much urging, he then whispered the word "yes." On another occasion I asked him what his name was and he said "Robert," and this was not whispered. He has a very positive toe sign on the left side today and a questionable toe sign on the right side. With his right hand, he wrote numerical answers to several simple addition problems; but he could not speak the same answers.
MARCH 26, 1966 (TWELFTH POSTOPERATIVE DAY)
The patient seemed bright and alert today and shook hands readily. When asked, "How are you," he nodded. When asked, "Can you talk?," he smiled. When he was asked to say something, he raised his eyebrows. When he was asked, "Can you say 'yes'!," he said "yes." When he was asked if he could say his name he said, "Robert." When he was asked to say his last name he smiled. Then he was asked to say his name again and he said "Robert." He was then told that he could talk all right, and he smiled and nodded. He was then asked, "Can you count!" There was a long pause after which he started to count slowly and correctly and quite audibly until he was stopped.
He had a good left grip to verbal command and only a trace of PTR. He was asked to stick out his left thumb. He put out the little finger on his left hand. (There was no difficulty at all in following commands with the right hand.) He was then asked to put out both thumbs and he stuck out the right thumb but stuck out the left little finger. I then said, "Look at your hand!" and he looked down and his face showed surprise; he smiled but the left little finger remained extended. I then showed him with my hands what I wanted him to do and after much comparing of his hands and mine he finally was able to extend the thumbs on both hands. I then suggested that he make a fist of the left hand and he did this readily. I then said, "Stick out your thumb" and nothing happened. I then said, "Now do this," and stuck out my thumb and he did it. I then said, "Hold up both thumbs," and he was able to do that for the first time to a verbal request. He made a left fist to verbal request. I then asked him to stick out the left thumb again and this time he extended the left little finger.
The plantar reflex was questionable on the right but definitely abnormal on the left. He was able to wiggle his toes on both sides together but he was unable at this time to wiggle the toes on the left side alone.
MARCH 31, 1966 (17 DAYS AFTER OPERATION)
Today he had a left-toe sign but the right was definitely normal. When he was asked to grimace, and on several occasions when he smiled, his face was symmetrical. The left arm moved well to request but he was unable to hold up an individual finger when asked unless he did it with both hands at the same time. There was a definite phenomenon of perseveration with the left arm such that if he did do something with the left arm and then was asked to do something else he did the thing which the left arm had previously done. He was starting to converse, although his voice occasionally dropped to a whisper.
APRIL 7, 1966
The nurses said that he first helped to dress himself on 3/31/66 and on 4/2/66 he buttoned his shirt and pants by himself. On 4/3/66 he was put in a wheel chair with a restraint and he reached underneath the chair and untied the knot using both hands. On this day the nurses' notes indicated that he was talking quite readily. On 4/5/66 he again was tied into a chair and he reached around underneath the seat with both hands and untied it; he got up and went to the bathroom by himself.
The patient was examined today (24 days postoperative). His apraxia was less evident than previously and on several occasions when he was asked to stick out an individual finger he did it correctly. However, he occasionally perseverated; sometimes he would stick out a finger which he had previously been sticking out. There was only a trace of a toe sign on the left side today.
JUNE15, 1966
I talked with his friend Mrs. R. today. She has seen him a few times recently and states that he speaks much better than he did before surgery in that he no longer stammers or says, "uh, uh," as frequently as he did before. On the other hand, he does not think nearly as well. This is particularly evident in a loss of recent memory and he frequently does not recall what he had for the immediately preceding meal. He does not recall being transferred from one ward to another and he does not remember having surgery. She states that on at least three occasions he gave the exact same statement almost word for word; "I was having one too many spells, so I got on my bicycle and came over here to see the doctor. Somebody stole my bicycle but that won't happen again because 1 got insurance for it now."
JULY 13, 1966 (4 MONTHS AFTER OPERATION)
R.M. was delighted to see me and recognized who I was, although he could not recall my name. "How are you, you old cotton picker7," he exclaimed. He was asked the time and immediately read it correctly from a nearby wall clock. He did not know the day of the week, and he thought the month was June. When asked the year, he hesitated and slowly said, "1965?"
He has the usual anomia in the left hand with his eyes covered. When a pencil was placed in his hand he held it appropriately but could not name it. When an ash tray was put in his hand he struck the table with it and then told me what it was. When a pair of glasses was put in his hand, he could not name what he was holding until he tried to put them on. When a watch was put in his hand, he said it was a "pencil" even when he was holding the watch up to his ear. A paper clip was put in his hand and he could not tell what it was, but when he put it in his right hand he immediately identified it. A pipe in the left hand was put into his mouth in an appropriate way; but it was called a "pencil" even after the bit was between his teeth. A handkerchief was put in his left hand; his left hand immediately put it into his pocket but he could not say what it was. When he felt it with his right hand he immediately identified it.
When tested for apraxia in the left hand it appeared that he was using a variety of cues including visual ones. He was therefore tested for apraxia in the left hand with a pillow slip over his head and the following procedure was followed:
In order to eliminate proprioceptive cues from the right hand, it was held for the following:
DECEMBER 13, 1966 (9 MONTHS POSTOPERATIVE)
He was quite pleasant and carried on a conversation readily, but he did not know the day of the week, the month, or the year. He did not know what he had for lunch. On the other hand he was subsequently able to remember after a conversation the names of the doctors who were talking to him. He did confabulate occasionally when asked something he did not remember. He was able to perform any movement requested with the left hand such as, "Make a circle with your thumb and index finger."
APRIL 7, 1967 (13 MONTHS POSTOPERATIVE)
He was doing somewhat better according to the nurses in that he seemed to be improving with respect to his short-term memory problems.
He was pleasant and dressed himself without difficulty while I waited. He cooperated well on the tests. He did have a trace of apraxia in the left hand in that he occasionally stuck out the wrong finger. When he was asked to stick out his thumb on one occasion he extended his left middle finger and was somewhat embarrassed by this obscene gesture.
He continued with a complete anomia in the left hand; but he used or manipulated objects with the left hand very appropriately including glasses, pipe, wristwatch, and pen. When the same object was placed in his right hand he immediately named it correctly. When an object was placed in his left hand and his eyes were closed he could not name it; but he could retrieve it quickly with his left hand from a group of objects.
Most interesting was an ability for cross-retrieval from right to left not previously present. That is, when an object was placed in the right hand (his eyelids being held closed), he often could select this object from a group if he was allowed to look at the group while using his left hand. He could not do this when vision was excluded (by putting a pillow slip over his head). But in this circumstance he did succeed a few times when he was allowed to say out loud the name of the object in his right hand.
MUTISM AFTER COMPLETE COMMISSURAL SECTION: FURTHER EXAMPLES
The patient W.J. [{see Bogen, 1969 I; Bogen, 1998 #124}] spoke normally before operation. He had a complete cerebral commissurotomy on February 6, 1962. He remained essentially speechless for more than a month. But during this time he wrote fairly well as shown in Figure 2, which is one example from many obtained by the patient's wife. On this occasion she asked him to write something and he wrote, "I love you and miss you and Julia Ann how is Julie Annn." There was subsequently an undecipherable word and he then wrote, "I sure miss here" (presumably intending the word "her").
Figure 2. Sample of writing by W.J. on March 4, 1962; see text for description.
He also wrote "It lives me out" with some perseveration of the letter "m"; it is not recorded to what this was in reference. The patient's wife subsequently asked if she should do anything for him and he wrote, "Were you able to get hold of that fellow at the V. A. about the chair and bed." The final example shown in Figure 2 is in answer to his wife's question if there was anything that was bothering him. He wrote, "yeah how bad I have to go to the bathahrooooom-and it's Iso] bob [bad] my teeth are floating." In these examples the significance of the punctuation and spelling errors is not always clear, but the perseveration is often quite striking (as seen in the word "Annn" and the word "bathahrooooom").
When speech gradually returned to W.J., it was at first a mere whisper, and then was rather hoarse; and in fact his speech retained some faint hoarseness ever after. When asked during the stage of whispering why it was that he talked so little, he said, "It kind of hurts my throat to talk"; no lesion was seen on examination of the throat and larynx at that time, but no systematic studies were made of glottal movements.
The patient N.W. was bilingual before operation. On December 30, 1966, (18 days after cerebral commissurotomy) the patient would not or could not talk at all. She was handed a pencil and a pad and asked to, "write something." She wrote the two words shown at the top of Figure 3. She was told, "well, you can write!" and she then immediately wrote (but misspelled), "can't you?." When asked to write the year of her birth she quickly wrote "1930" (which is correct). When asked to write, "what year is it now?," she wrote "1966," with perservera tion of the final numeral.
On January 13, 1967 (41A weeks postoperative) she was repeatedly coaxed to say something, but in vain. She was asked on a number of occasions if she could say, "yes"-she could not. However, in subsequent tests for facial apraxia it appeared that she could speak; when she was asked to stick out her tongue, she abruptly said, "Shame on you." She would not say anything else. At no time would she stick out her tongue although she was subsequently seen to lick her lips, an observation reminiscent of the very first reported case of "nonprotrusion of the tongue" (Jackson). In contrast, when she was asked to write the word, "yes", she did so quite readily, as shown at the bottom of Figure 4. (This figure was patched together from several sheets in order to save space.) She was subsequently asked to write some other words including "today," "apple," "momma" and did these quite readily. She was subsequently asked, "write the Spanish word for bed"; she wrote what looks like the word "calma." When she was asked to write the Spanish word for "table," she wrote only "mes." Her signature has been pasted over in this illustration to preserve anonymity; but the "Mrs." is left uncovered to show the perseveration in the letter "m" and the letter "w."
Figure 3. Sample of writing by N.W. on December 30, 1966; see text for description.
A.M. Case Summary
Figure 4. Sample of writing by N.W. on January 13, 1967; see text for description.
A.M. (born June 26, 1933) was considered normal until the age of 15 when, coincident with a head injury, he fell into a swimming pool and was apparently anoxic for a time. He did not return to school but helped his father at glass polishing for a while. Within a year he began having convulsions, beginning with twitching of the right side of his face. As the convulsive disorder worsened, he gradually developed severe incoordination of the legs which progressed, so that by the age of 25 he was confined to a wheelchair.
When seen in June 1964, he appeared mentally retarded but alert and coopera tive; with either hand he could write legibly and could copy various geometric figures. There was a gross ataxia of the legs associated with normal reflexes but impaired position and vibratory sense. EEGs showed a severe generalized abnor mality. A pneumoencephalogram showed marked cerebral atrophy, most evident biparietally, more so on the right side. A bilateral carotid angiogram showed no abnormality.
A.M. was operated on July 7, 1964 (at age 31). He had a rather stormy postoperative course but gradually improved. However, he has had persistent apraxia of the left hand and some degree of mutism ever since. Since operation, his seizures have been less severe. Spells including unilateral stiffening of the right side, occasionally with unresponsiveness and rarely with incontinence, have continued in great profusion. Generalized convulsions have occurred on a few occasions when medication was decreased or omitted. EEGs have continued abnormal, but (unlike the preoperative records) they are quite asymmetrical with bursts of delta activity largely restricted to the left.
He was essentially speechless for several years after surgery, although he could then write short sentences: An example 1 year after the operation was previ ously published (Bogen, 1969). More recently, speech therapy has seemed somewhat helpful. He rarely speaks spontaneously, and when he does speak, it is in a hoarse voice with poor articulation. He remains affable and interested in watching TV which is his principal occupation. He remains confined to a wheelchair as before operation.
A.M. PROGRESS NOTE FOR MAY 8, 1967
When seen today he was attentive and cooperative and seems to have put on a fair amount of weight. Since January, he has done fairly well, although he has some mild spells every other day or so. He has had only two convulsions so far this year. The mild spells consist of some movement of the right hand and unresponsiveness. Sometimes the right hand shakes a little bit for a few seconds and sometimes, according to his mother, "You can hardly tell he has them." She is quite definite that these are much milder than those he used to have; in fact, the two convulsions which he has had are "mild" in her opinion.
Both convulsions were about the same and they occurred in quick succession the same day about 6:00 A.M. about a month ago. She stated that she heard a noise and went in to look and he was shaking on both sides, harder on the right side, and the right side kept shaking a little bit longer than the left. She afterwards found some pills on the floor and believes that the convulsions occurred because he dropped some of them instead of swallowing them. The medicines he is taking are Mysoline 250 mg. t.i.d., phenobarbital gr. Ih t.i.d., Dilantin 100 mg. q.i.d., and Benadryl 50 mg. t.i.d.
In December (1966), he had injection of hemorrhoids, evidently successfully. He has more recently been treated, apparently successfully, with Furadantin for nocturia, frequency, and dysuria.
The patient was told, "Write something-anything at all." He wrote his name. He was then asked, "Write something else-not your name," and he wrote the word "yes," as shown in Figure 5. He was then told, "Write the same thing larger, so I can read it better," and he did that. He was then asked, "Can you write, 'I am going home?'." He did this as shown. A pencil was then placed in his left hand and he was told, "Write anything." After he starred he was told, "Write some more-more of the same." This urging resulted only in a continuation of the original scrawl (upper left of Figure 5).
Figure 5. Sample of writing by A,M. from May 8, 1967; see text for description.
He was then asked to read what he had written; he just shook his head. I then read it to him and asked him to repeat out loud what I had said. He opened his mouth several times but uttered no sound.
He was then asked to copy the square (shown in the middle) with his right hand. He did it. When he was asked to copy a square with the left hand there was no response. With the left hand a new model was used, and in this case he was watching while the model was done; the model was retraced several times in order to suggest the motion with which it could be done, rather than relying entirely on its final appearance. His left hand, given the pencil, then traced over the square repeatedly. The tracing was not square but circular, as shown in the lower left-hand corner, and resembled the model only in that three revolutions were made, which was the same as I used to make the model. When a triangle was used to test the left hand (above the square on the left) the same thing was true; that is, a more or less circular movement was made directly on top of the model. When the patient was shown a Greek cross and asked to copy it with his right hand, he did very poorly as shown in the lower right-hand corner where only the upper right part of his figure is correct.
A.M. PROGRESS NOTE FOR JUNE 17, 1967
Figure 6. Sample of writing by A,M. from June 17, 1967; see text for description.
The patient's status was unchanged from last month. He was as speechless as ever. Some further samples of writing were obtained (see Figure 6).
When asked, to "write something," he wrote his first name, and then the words "yes" and "no." He also wrote the word "mesa" quite legibly when asked to write the Spanish word for "table." He was able to write almost anything to dictation including the date (which he was told since he did not know it). He was unable to copy with his right hand a Greek cross, although he did the square reasonably well. With the left hand he was unable to write anything either spontaneously or to dictation; and when he copied he merely traced over the model: as before, if the model was more complicated than a square his tracing degenerated into circling.
A.M. PROGRESS NOTE FOR MAY 6, 1968
The patient was seen today together with Dr.S. and Dr. H. The patient has been taking Dilantin q.i.d.; Celontin, one in the morning; Mysoline t.i.d. and Phenobarb Gr I in the morning and Gr. 44 at noon and bedtime. The patient was started on Celontin 3 months ago by a clinic doctor, according to his mother, because he had a seizure consisting of his right arm sticking up in the air and becoming stiff and this lasted for somewhat less than a minute. She states that this was the only seizure he has had this year, and furthermore that he has had no "big" spells for a year. This "big spell" to which she refers consisted of convulsive activity lasting for several minutes and involving mainly the right side of the body. At the time of this "big" spell, there was no involuntary voiding and she believes that he has not been involuntarily voiding with seizures since the operation, whereas it was very common before the operation.
The patient understands complicated instructions fairly well and follows any request with the right hand including holding up any number of fingers or making a circle with the right thumb and little finger and so forth. Furthermore, when given a pencil he was able to write to dictation including: "2 X 2." When asked "what does that equal7" he wrote down "4."
In contrast to his good responses with his right hand is a marked inability to follow any verbal request with his left hand. The left hand is fairly well coordinated for nonverbal behavior; and I was able to develop a short game of pattycake with the left hand, but he cannot carry out any verbal instruction with it.
This patient's most impressive symptom is his continued mutism. His mother says that when the children are playing and something funny happens there have been some occasions when he has laughed out loud. When his mother was asked by Dr. H. what tone of voice this laughter had, she replied that it was just like he used to have before the operation. Although it was not possible to persuade the patient to say anything or to hum, he readily blew out a match and would also make a blowing motion without a match. When asked to say "ah" his produc tion was in a whisper and not vocalized. When he was asked to count, just making the motions with his mouth, the 2 and 3 were clearly identifiable, although produced in a whisper without any vocalization. When asked to do this again, he refused or was unable to do it. This is a common occurrence in that after first doing something, he will not do it again the second time. Sometimes on the first occasion he will do just the opposite, as when asked to open his eyes he closed them tightly. After considerable effort it was possible to get him to open his mouth and Dr. S. and Dr. H. both noted that there seemed to be some accompanying involuntary motion of the tongue. It was difficult to get him to hold out his tongue for any length of time, but after multiple attempts it was finally possible to get him to keep him mouth open and his tongue protruding for almost 30 seconds. When he was asked to put his tongue behind his teeth, he smiled broadly and pointed with his right index finger to his upper gum to show that he had no teeth. The patient is said by his mother to cough without difficulty, but he would not cough voluntarily nor would he hiccough. He chewed a cookie and swallowed fairly well. It was not possible to persuade him to pretend to chew. The patient continues to be in a wheelchair; his legs are ataxic but fairly strong, and he readily elevated his right leg and pointed the toe at one of the doctors when requested. He has a slow nystagmus on lateral gaze to either side which may suggest some Dilantin toxicity, although if so it is not very severe. The patient and his mother, as well as the other doctors present, agreed that he would probably benefit from some intensive speech work and some further arrangements will be made along this line.
A.M. PROGRESS NOTE FOR APRIL 2, 1971
According to his mother he has been doing reasonable well. He is just having small spells and no major ones. We have never been able to free him completely from them. His medication has been the same for the past year except for recent use of pyridium and sulfa for his recurrent bladder infection. He is quite ataxic when walking and cannot walk alone. He is getting swollen ankles from sitting so much; some support hose were prescribed. His speech seems to be minimally better. He says: "hello," "yes," and "no"; the words emerge suddenly in a gust of hoarse, breathy sound. His writing is the same as previously.
THE ACUTE POSTOPERATIVE COURSE IN A PATIENT WITH PREVIOUS RIGHT TEMPORAL LOBECTOMY
The patient J.M. had a complete cerebral commissurotomy on February 2, 1968. She awoke from anesthesia several hours after operation. When examined at 10 P.M. on the day of the operation she was cooperating readily with the right hand in response to various instructions such as, "Hold out your little finger." Although the patient followed fairly complicated instructions, no vocalization could be elicited. Cooperation was entirely restricted to the right hand; there was no motion of the left arm to verbal request; however, it was noted that the left arm occasionally would pull in a coordinated fashion at the intravenous tubing or the urinary catheter. There appeared to be some limitation of gaze toward the right. The deep tendon reflexes were normal bilaterally but no superficial abdominal reflex could be elicited, and there was a definite Babinski sign bilaterally. The patient wiggled her right toes on command but did not move the left toes.
Twenty-four hours after operation the patient was definitely less alert than immediately after the operation. Although making a good grip with the right hand, and moving fingers individually in a spontaneous fashion, she would not release her right grip on request. The bilateral toes signs were even more positive than previously.
During the second postoperative day, she was moving both arms and both legs in coordinated fashion and had a good grip on both sides, but would not cooperate by following any instruction. The movements of the eyes seemed wandering although conjugate.
On the third postoperative day the patient was slightly better with some attentive movements of the eyes and a more active facial expression. On this day very little spontaneous motion was observed of the left hand; the left arm was hypotonic.
On the fourth postoperative day the patient showed a slight amount of improvement with good grip of the right hand but no release on command. The right hand spent a good deal of time patting the right thigh. In the left arm there was a little more tone than previously and some waxy flexibility was demon strable at this time. Toe signs were still positive.
On the fifth postoperative day the patient was looking about with some interest and seemed definitely more alert. Gripping and opening the right hand on request were now readily done but there continued to be a marked proximal traction reaction. No verbal command could be followed with the left arm which still seemed rather hypotonic. It was noted on several occasions that she used the left arm in a very well coordinated fashion to scratch her nose. Plantar reflexes were minimally upward bilaterally.
From the sixth to eighth postoperative days the patient was taking fluids fairly well by mouth but seemed otherwise the same.
On the ninth postoperative day she was quite alert, was taking fluids well, and was very attentive to persons moving about her, but no vocalization of any kind was observed. Individual movements of the right hand were performed on verbal command but there was still a definite proximal traction reaction. On this day, for the first time, the patient squeezed with the left hand on command, but would not release (this may have been a forced grasping response to fingers placed in the palm). The left arm still seemed slightly hypotonic although, as before, it was observed to move in a purposeful fashion. The patient was smiling readily on occasion, showing less activity on the left side of her face. Raising eyebrows on command resulted in a rise only of the right eyebrow. Plantar reflexes continued mildly abnormal.
On the tenth postoperative day the patient would open her mouth when this movement was demonstrated for her, but she did not do it when asked on several occasions. The same was true for protrusion of the tongue, which was done on visual demonstration but not to verbal request. On one occasion the patient said "ah" in a very low volume which was barely discernible. The patient would make marks on paper (such as an "X") but would not write words. No response to verbal request was obtainable with the left hand. The patient continued to take nourishment well by mouth including drinking through a straw.
On the twelfth postoperative day the patient was cooperating well and on one occasion appeared to move the left arm to verbal request; but this could not be repeated. All deep tendon reflexes were normal as before and plantar reflexes continued to be minimally abnormal. Attempts to elicit speech were still unsuccessful.
On the fourrteenth postoperative day (February 16, 1968) the patient would not say anything, although repeatedly urged in a variety of different ways. She would open her mouth about halfway on request and when asked to stick out her tongue she put it between her teeth. After some coaching, she said, "ah" in a barely perceptible whisper. When asked to repeat this she almost did it, but one could not be certain because the utterance was so quiet. In contrast to this speechlessness, the patient wrote quite legibly with the right hand. She was asked if she could write the word, "yes". She did so correctly (see Figure 7) except for some perseveration (she wrote, "yesss"). She was then asked to write the word "cat" and did so correctly, although she was unable to speak the same word. When she was asked to write the answer to "what is 2 + 2?" she wrote a very neat "4." When she was then asked to write "What is 2 + 3?" she scrawled the numeral 5.
On this same day, the patient was following verbal instructions well with the right hand including not only a good grip and good release but also making a circle with the thumb and ring finger, and holding up any of the named fingers of the right hand on command. A mildly positive Wartenberg sign was observed in the right hand.
With the left hand she could not make a fist on command and this was tried on three occasions separated by other tests. However, the left hand was observed to coordinate well in spontaneous movements, for example in reaching up to hold the clipboard on which she was asked to write with the pencil held in her right hand. On this day it was noted that she had a minimal, late Babinski sign on the right side and no definite response to plantar stimulation on the left side. In response to request, she wiggled her toes quite well on the right side but did not wiggle her toes on the left. She was continuing to eat well and had had no seizures since the operation.
On the nineteenth postoperative day it was still not possible to obtain a grip with the left hand in response to verbal command. Reflexes were as before. On the twenty-second postoperative day the patient was saying "yes" and "no" and was repeating her name when asked but would say nothing else. There was still no response of the left hand to verbal command; in fact, it was not possible at this time to obtain actions even with visual demonstration.
On the twenty-seventh day the patient first said, "hello" (in a rather low, hoarse and breathy voice) after she was greeted in a manner which had previ ously failed to elicit any response. She extended her right hand to shake; and when the examiner's left hand was extended she took it with her left hand and shook it also. When she was then asked to do various things with the right hand she did them quite readily. When she was asked to make a fist with the left hand she did not. Then she was shown a fist; instead of imitating this gesture her left hand reached out and readjusted her gown.
On March 5, 1968 (31 days after the commissurotomy) the patient was still speaking only one word at a time and in a rather faint and slightly hoarse whisper. However, she had no difficulty in naming a wide variety of objects. On March 7 she was ambulating well with assistance and could converse using short sentences. Plantar reflexes were equivocal.
On March 8 the patient was returned to the operating room where the bone plate was replaced. On the day after this second operation she was conversing sensibly with the nurses. For the next 3 weeks the patient was in the rehabilita tion program.
Figure 7. Sample of writing by J.M. on February 16, 1968; see text for description.
On March 29, 1968 (55 days after commissurotomy), the patient spoke quite readily. She was well oriented for place and year but did not know the month or the day of the week. With her left hand she readily copied the demonstration of a fist, thumb, little finger, fist, and index finger. When given a verbal instruction to close her fist, she did this the first time but she would not open it to verbal instruction. After her left hand had been opened up by assistance with her right hand, she would not again make a fist with the left hand in response to verbal command or even to combined verbal command and demonstration. She walked unaided, although a little unsteadily, and seemed to have some difficulty in making her left foot go in the direction which she had in mind. She wrote quite fluently with her right hand, but with her left could make only a scrawl (Figure 8). She was discharged the following day.
On April 19, 1968. the patient came to the office and the following progress note was dictated subsequently:
The patient has been home from the hospital for 3 weeks and her husband says that she has steadily improved in that time. She is now able to walk about without any help, eats without any help, and talks readily in conversation. She and her husband both agree that she "eats like a horse." She continues to take Dilantin 100 mg. q.i.d. and primidone 250 mg. q.i.d. Both she and her husband believe that she has had no spells of any kind, small or large. She has on three occasions in the past 3 weeks been incontinent in bed, perhaps because she has been sleeping so soundly, although her husband agrees she might have had some form of spell without other outward sign.
The patient has considerable memory trouble. Her husband says that she may converse at length on the telephone with a friend and then 10 or 15 minutes later she will tell her husband, "I think I will call so and so-I haven't talked with them in days." In the office, she was asked what day it was and said "Tuesday" (it was Friday). However, she did know that the month was "April" and that the year was "1968," and that next month will be "May," and that the name of the president is "Johnson." When she was asked who is the governor, she did not know the answer. When she was asked how Johnson got to be president she said, "the people elected him." When she was told that this was wrong and that he had been elected vice-president, she then said, "the existing president died and he advanced." When she was asked who the existing president had been, she could not remember. When she was told that it was John Kennedy and that he had been shot, she said, "Oh yes, in Texas-they shot him on my birthday." When she was asked what date her birthday is, she said (correctly), "September 2nd." She was unable to remember what she had for supper last night.
Her husband says that she often gets lost inside their home, especially when she is looking for the bathroom. This is particularly a problem at night even though he leaves the light on in the bathroom. In general, she gets more (spatially) confused in the evening. He also stated that she will frequently sit for a long time and do nothing. He says that he works quite hard to get her interested in playing cards but that she has a rather short interest span. She has no interest in reading. She watches the television 5 or 10 minutes and unless it is an extremely active program, she quickly loses interest. She has no interest in sex; but she and her husband both agree that before the operation she never cared one way or the other about this.
Her husband says, "It is very difficult to get the left hand to do anything. Sometimes when she wants to put her left hand some place she has to pick it up with her right hand and move it over. When she is thinking about it she has a lot of trouble with the hand-if she gets the left hand onto something like a door jam, you just can hardly get it off-if she has a hold of her underwear with her left hand you cannot get it off of her." In contrast to this he says, "If she is not thinking about it, she can unconsciously use the left hand. Last night she poured some coffee [holding the coffee pot with her right hand] into a cup which she was holding [by its handle] with her left hand."
During routine neurological examination, the patient walked with some hesitation but without obviously favoring one leg or the other. When asked to perform the finger-to-nose test she was unable to get her left arm to do what she wanted it to, although she quickly did it with her right hand. Supination pronation was done very well with the right hand and to some extent with the left hand when both hands were done together; but the left hand would not do this by itself.
The extraocular movements were full and the pupils normal in size and reactivity. Air conduction was excellent with each ear. There was a very dense left hemianopia, and it did not seem to matter whether she was allowed to use one hand or the other. That is, when not allowed to use her right hand, she would not point to a moving object with her left hand. The patient readily protruded her tongue and cooperated in all facial gestures.
Figure 8 Sample of writing of J.M. from April 19, 1968; res the text for dercription.
She quickly cooperated with a variety of requests regarding her right hand, but with the left hand again had a great deal of trouble. A verbal request to make a fist with the left hand was ineffective. She was then asked to make a fist of the left hand while simultaneously being given a demonstration-this was done several times with a lot of urging; finally the left hand made a fist. After the left hand had relaxed, she was again given a demonstration of a fist and this time the left hand made a fist. Then a demonstration was made of opening, and the left hand opened; then a demonstration of making a fist, and the left hand made a fist; and then a demonstration for extension of the thumb, and nothing hap pened.
The deep tendon reflexes of the left biceps and left knee were faintly more active than those on the right. Using Szapiro reinforcement, it was possible to demonstrate a mild toe sign on the left side, whereas there was an absence of response to plantar stimulation of the right.
The patient was completely unable to identify any object (of a half-dozen) placed in the left hand. When she was asked to reach over and pick up an object with her right hand (with hey eyes closed) she had difficulty finding her left hand with her right hand. When she finally had the object in her right hand she immediately named it (and all of the other objects) correctly. It should be pointed out that she had no difficulty reaching with the right hand to take an object from the left hand when her eyes were open. However, on two occasions when she tried to take something out of her left hand, the left hand would not let go of it.
The patient wrote quite readily with her right hand, but she was unable to write anything at all with the left hand except a single, short unintelligible scrawl. She said, "I have never been able to do anything with my left hand." Her husband laughed and said, "She has always been quite ambidextrous and wrote very well with her left hand before the operation." (The patient's preoperative writing with each hand is shown in Figure 9). When asked to copy geometric figures, she was able to copy the square quite well with either hand although the left moved in a painfully slow way. Beyond this, the left hand would do nothing. The right hand copied a Greek cross, but made an obviously incorrect copy of the solid cube.
In conclusion, the patient resembles the previous patients at this stage of recovery, although the right hemisphere seems to be much less cooperative than in some, possibly because of the previous right temporal lobectomy.
A CASE OF PARTIAL SECTION: E.F.L.
We have previously reported (Gordon, Bogen, & Sperry, 1971) that "frontal commissurotomy," that is a complete cerebral commissurotomy sparing only the splenium, is not followed by mutism. But even a lesser commissural section, involving only the body and part of the gem of the corpus callosum, can produce a short-lived (several weeks duration) mutism. We have seen this in three cases when this approach was used to biopsy thalamic tumors. The following is a representative case:
The 35-year-old patient E.F.L. was examined shortly after a transcallosal approach to a right thalamic tumor. At operation, most of the body and part of the genu of the corpus callosum were divided. The tumor was biopsied, a window was made in the septum pellucidum, and a ventriculojugular shunt was emplaced via a right frontal burrhole.
One week after the operation the patient was still not talking although cooperating fairly well (see Figure 10). When asked to write his name he showed marked perseveration with three "m"s and two "s"s(the first name was correct but has been covered over here). He was asked to write the product of 3 X 4 (correctly done) and "the result of subtracting 5 from that" (correctly done). He also wrote correctly the word "Saturday" and when asked, "are you trying to talk!," he nodded but could not speak.
In this case, the speechlessness was almost certainly not attributable to callosal section alone; but the callosotomy was probably contributory. This case further illustrates the previously emphasized point (Sperry st al., 1969; Gordon st al., 1971), that postcommissurotomy deficits depend in large part upon the nature and amount of preexisting, extracallosal damage.
Figure 9 Sample of preoperative writing by J.M.
DISCUSSION
Hughlings Jackson believed, in 1894 (Jackson, 1958), that writing is a more complicated integrative act than speaking: "If a person can express himself in writing he gives proof that he has not lost speech. We must speak internally before we write-before we express ourselves in writing." This seems a reason able point of view, considering that writing always appears, both ontogenetically and phylogenetically, subsequent to the establishment of speech. However reasonable this point of view may be, the present data contradict it.
Figure 10. Writing by E.F.L. See text for description.
Jackson tended to use the word "speech" to refer not only to intelligible, propositional vocalization but also to what he called "internal speech." And we might therefore suppose that the seeming error in his opinion was attributable to use of the word "speech" in a special fashion (more or less synonymous with what we would call "language"). However, he also said: "I know that cases of loss of speech have been recorded by eminent physicians, in which ability to write was not lost. The chronic cases of this kind that I have seen have been mostly cases of pretended loss of speech. Besides, how is it conceivable that a person who has lost speech should be able to express himself in writing." Indeed, Jackson went so far as to say: "It is a priori incredible that a person who cannot speak should be able to write.... When a patient does not utter a word and yet writes well and swallows well-we may be almost certain...that the defect is 'hysterical,' whatever that word may mean" (Vol. I, p. 20).
In the past 80 years, more cases of speech loss without agraphia have been reported (Leischner, 1969) but Jackson's belief in a greater sensitivity to brain injury of writing than of speech has generally been supported (Chedru & Geschwind, 1972; Smith, 1972).
A principal purpose of the present chapter has been to present data, from patients with hemispheric disconnection, showing that there is a time when writing can be produced by a nonspeaking single hemisphere. It can be inferred that speaking out loud ordinarily requires some degree of interhemispheric collaboration and that loss of the commissural contribution results in an in ability to speak which recedes as certain compensatory adjustments are made. In contrast to this inference about speaking, it appears that writing is largely unihemispheric. The evidence is presented here for this conclusion with respect to the left hemisphere in the short-term. This fits evidence that in the long-term, chronic condition, the nonspeaking right hemisphere can occasionally write at a time when it cannot speak (Levy ct al., 1971).
With respect to the short-term, cerebral commissurotomy was followed by a period of an inability to speak, during most of which time there was good comprehension of spoken language and some ability to write. This emissive deficit lasted, in milder form at least, in 11 right-handed patients, for 3 months, 3 days, 9 years, 4 weeks, 4 months, 2 days,' 4 weeks, 2 weeks, 3 weeks, none, and 4 weeks. In 1 left-hander (P.D.) mutism lasted 8 months. There was little if any paraphasia; when ability to talk returned there was no nominal amnesia; in most cases there was a definite lack of bodily spontaneity and motor initiative for a time, but only partially correlated in duration with the loss of speech.
To some extent, the speech defect might be considered an aspect of facial apraxia, since in the case of prolonged duration (A.M.) the lack of speech was associated with difficulties in control of the tongue and larynx, manifested by intermittent inability to protrude the tongue at will, sometimes an inability to open the mouth at will, aphonia in the severe stages, and persistent hoarseness. Cortical injury from the surgery is an unlikely explanation since all but one of the patients (C.C.) were operated upon from the right side and all but one (P.D.) were left-hemisphere dominant for language.
Alternatively, the lack of speech could be considered a mutism of the type often associated with akinesia of cingulate or subfrontal origin, a conclusion supported by the correlation in several cases between the duration of mutism and difficulties encountered in severing the anterior commissure. This would require that we think of the postcommissurotomy state as a sort of form furste of akinetic mutism, in which the mutism is much more evident than is the akinesia. The strongest argument against this is the absence of any postoperative mutism in three patients (D.M., N.F., D.B.) whose splenium was spared but having comparable molestation of the area about the anterior end of the third ventricle.
A diaschisis, secondary to deafferentation of speech areas, is an explanation which accounts for the deficit in terms of left-hemisphere dysfunction although the left hemisphere was unmolested. This interpretation is consistent with the occasional appearance of right Babinski (a sign of left-hemisphere malfunction) and it may help to explain why the patients whose splenium was spared had no mutism. This means that the diaschisis of the left hemisphere (from a complete section) must affect the speech "centers" or "circuits" more than it affects writing "centers" or "circuits." This implies, in turn, that the writing function is more robust or resistant in some sense than that for speech, in spite of having developed later in life, and in spite of the fact that writing is almost certainly an overlaid function of the brain, whereas supposing that speech is an overlaid function is open to considerably more doubt. [{By "overlaid" I mean that the function is not attributable to anatomical circuitry produced by evolutionary pressure. In other words, a novel function was assumed by previously existing structure.}]
A more speculative possibility is that speech requires interhemispheric integra tion of the control of larynx and other midline structures in the following sense: One can suppose that left-hemisphere speech (like some other output; Preilow ski, 1972) includes a corollary discharge (Sperry, 1950) to the other hemisphere. When the commissures are completely severed a downstream interhemispheric conflict occurs at the level of the motor nuclei for the larynx, which results in dysphonia. This explanation is consistent with most of the evidence. In particu lar, it fits the case of one patient (M.K.) who had no mutism at all-this was a patient with right-hemisphere atrophy from childhood. Also, mutism was most persistent in those patients whose preoperative brain damage (of either side) occurred in adulthood.
The cause for the transient mutism may be different from one case to the next, and in any given case there may be more than one factor operative. Factors which may interact include the following: (I) The commissural fibers may have been acting in a compensatory fashion because of previous brain injury. (2) Speech may require some absolute number of relevant brain connections and in a marginal case the callosotomy may be sufficient to bring the number of connections below the minimum required. (3) Trauma to the anterior third ventricle during division of the anterior commissure (particularly when the division is accomplished with suction) may result in local swelling with a transient "subfrontal syndrome" in which akinesia is accompanied by a paucity of speech. (4) The callosotomy may produce a diaschisis in the speaking hemisphere from which it only slowly recovers. (5) The callosum may carry a corollary discharge for speech output, whose sudden loss results in downstream interhemispheric conflict subsequently compensated. (6) Temporary circulatory alterations (particularly of the internal cerebral veins) may transiently derange the more sensitive functions of the basal ganglia. (7) Damage to one or the other fornix may be contributory.
SUMMARY
Complete cerebral commissurotomy in the adult is typically followed by a transient mutism during which there is good comprehension and some ability to write in spite of the inability to talk. The return of normal voice may require many weeks, particularly in those patients with above average amounts of extracallosal brain damage predating the operation. Some possible explanations of these observations are offered, emphasizing the apparently greater complexity of the neural basis for speech output as compared with that for writing.
ACKNOWLEDGMENTS
I am indebted to V. Fromkin, K. Hoppe, R. W. Sperry, and E. Zaidel for many thoughtful suggestions.