BRAIN AND LANGUAGE 10, 224-242 (1980) Central Deafness and Subcortical JONATHAN Motor Aphasia LEICESTER The Royal Prince Alfred Hospital Clinical and autopsy studies were made on a right-handed man who had central deafness and subcortical motor aphasia, and the literature on central deafness and on subcortical motor aphasia was analyzed. Central deafness is due to bilateral destruction of the primary auditory cortex. It is sometimes difkult to distinguish from word deafness and from auditory agnosia, which are due to pathology in other parts of the temporal lobes. There is almost always some preserved hearing in central deafness, possibly from some auditory pathway other than the classical pathway. In this patient the subcortical motor aphasia was due to bilateral destruction of the motor cortex for the mouth and throat. In some other cases subcortical motor aphasia was due to the same pathology that usually causes Broca’s aphasia; in these cases the unexpected preservation of writing was perhaps related to some difference in how language functions were organized in the brain. INTRODUCTION The opportunity is taken here to report the clinical and pathological findings in a patient who had central deafness and subcortical motor aphasia. Occasional patients who were deaf because of bilateral destruction of the auditory cortex or auditory radiations have been reported for many years (e.g., Bastian, 1897b; Mott, 1907a, 1907b). Many of these cases have been criticized, either because there was lack of proof that the deafness was real rather than apparent, or because peripheral deafness was not excluded. However, there is now strong clinical and electrophysiological evidence that such cases are genuine and that the condition of central deafness exists (Jerger, Weikers, Sharbrough, & Jerger, 1969). For some reason the deafness is nearly always only partial. This fact raises two questions. One concerns the relation of central deafness to two other cortical disorders of hearing, auditory agnosia and pure word deafness. The other concerns how some hearing is retained after the Address reprint requests to Jonathan Leicester, 2OAl127 Burwood Road, Burwood 2134, New South Wales. Australia. 224 0093-934X/80/040224-19$02.00/0 Copyrighi All rights @ 1980 by Academic Press, Inc. of reproduction in any form resewed. DEAFNESS 225 AND APHASIA auditory cortex is destroyed. An analysis of both questions is attempted in the Discussion. In most cases of motor aphasia the patient has difficulty producing language whether he tries to speak or to write. But it has been known since Broca’s time that occasional patients with motor aphasia could write fluently. The classical term for this condition is subcortical motor aphasia. The question naturally arose whether such patients had aphasia or dysarthria. The history of the long and rancorous argument on this point has been reviewed by Lecours and Lhermitte (1976). There have been three theories to account for subcortical motor aphasia. They are defined and the evidence bearing on them is analyzed in the discussion section of the paper. The theories of subcortical motor aphasia are based on the classical view of Broca’s aphasia, a view which has recently undergone an important revision (Mohr, 1976; Mohr, Pessin, Finkelstein, Funkenstein, Duncan, & Davis, 1978). This has led in turn to the necessity for a corresponding revision of subcortical motor aphasia, which is attempted in the discussion section here. CASE REPORT-CLINICAL FINDINGS Case Otto S., male, died December 25, 1973, aged 62. Otto S. was a right-handed Estonian who had worked as a law court secretary before he came to Australia in 1950. In Australia he became a car radiator mechanic. Before his illness he spoke Estonian, German, and English, although his English grammar was imperfect and he spoke with an accent. There was no sample of his writing before the illness. He had a past medical history of hypertension, angina, and an anterior myocardial infarct. First Stroke-December 1970-Left Hemiplegia with Recovery He fell helpless at work and was taken to Canberra Hospital. He had complete left hemiplegia, paralysis of the left side of his face, a defect of his left visual field, slow slurred speech, and “slight difficulty forming words without apparent difficulty forming concepts.” He wrote his name and address, and could add and subtract accurately but slowly. He made good progress. After 4 weeks his speech, writing, and sensation were normal, his visual field defect was improving and his muscle power was normal except for weakness of the left side of his face. He returned to work. Second Stroke-July 1971-Central Deafness He reported to Canberra Hospital with deafness of sudden onset. On admission he moved all limbs well. The next day, “there are no signs except those related to language function. He certainly does not hear 226 JONATHAN LEICESTER sounds. He is a little slow to follow written commands. When he writes ht leaves out small words and one ending.” During the next week the following clinical comments on his hearing were recorded: ‘ ‘ENT clear except complete bilateral perceptive deafness,” “partially deaf in both ears,” and “95 percent deaf in both ears.” The patient was initially reluctant or partially unable to speak. On admission “he will not speak,” and later that week “he speaks only if absolutely necessary,” “he is still communicating by writing on paper, although he can answer back,” and “he can read aloud.” He was recorded to have said ah, la-la-la, thumb, brown bread and butter, the President of the United States is elected every four years, and to have read aloud George Washington was the first President of our country. His comprehension of writing was good and during the first week he carried out the written commands “put your left thumb on your right ear” and “put your right middle finger on Dr. Cassan’s left little finger.” He did the written arithmetic 14 x 7 = 98 and 108 t 9 = 12. The reluctance or difficulty speaking was transient, but the deafness was permanent. His son commented “he spoke quite well after he lost his hearing,” “ he seemed completely deaf,” “you wouldn’t have known there was anything wrong with him except he couldn’t hear, extraordinary, fit as an ox.” The patient also regarded himself as deaf from this time. Third Stroke-January 1972-Subcortical Motor Aphasia He walked into Canberra Hospital after the sudden onset of dysphagia and anarthria. On examination his mouth and tongue lacked movement to command but had some movement at other times. A nasogastric tube was needed for 9 days, his dysphagia recovered in 14 days. There was paralysis of the right side of his face. He was orientated and rational. His comprehension of writing was good. He had speech therapy for 3 months, and said the word “good” several times. The speech therapist recorded that “his writing is very serviceable if not accurate syntactically.” The virtual mutism was permanent. The patient regarded himself as dumb. His son commented that “he would try to talk but was never successful, occasionally there was an understandable word but mostly just grunting and moving his lips.” He had more fruitless speech therapy in 1973. The therapist reported that his deficits were present in all three languages, and that he was doing some lip reading. Clinical State, April-November 1973 Otto S. moved to Sydney in April 1973, and was under the author’s care for the rest of his life. From April until November his neurological state was stable, although he developed heart failure. Communication was quite satisfactory with examiner and patient both writing. DEAFNESS AND APHASIA 227 Neurological examination. He was alert, rational, and able to outline his past history and present circumstances. He appeared rather slow and inexpressive and showed little emotion. There was a partial left homonymous hemianopia with consistent extinction of double simultaneous stimuli. Facial movements and tongue protrusion were satisfactory. Movements of his palate were symmetrical but poor. His arms had normal power and normal pain and touch sensation. His gait was normal. Comprehension of writing was good, although two errors were recorded. Once he initially touched his ear and his elbow in response to the command “touch your ear and my elbow,” and once his response to the question “are you dizzy, see the world moving around?” was, “I lived in Canberra 197bFeb. 1973 this time,” an answer related to “moving around.” He did written arithmetic (2047 + 988 + 1506) and block construction tasks (WAIS cards l-6) easily. He matched nine written color names to color choices. Hearing. His ear drums were normal. He heard a loud watch only when it was held directly against his ears. He carried out no auditory commands, which he apparently did not hear. He matched four dictated single letters to visual choices with the examiner’s mouth in view, but when the examiner’s mouth was concealed he could match none of six letters, even when the letters were shouted loudly. He did match three of nine dictated color names to color choices, possibly by chance. His pure tone audiogram showed similar hearing in each ear and by air and bone conduction. The losses were 25 db at 250 and 500 Hz, 30 db at 1000 Hz, 60 db at 2000 Hz, 80 db at 4000 Hz, and 100 db at 8000 Hz. A hearing aid was fitted without any appreciable difference, and he did not wear it. Speech. He could only grunt. The author never heard a word or a syllable. Writing. A lot of writing was seen. Sometimes the penmanship was careless, but he could write neatly. In English his spelling was poor, his grammar faulty, and his sentences condensed. His son thought it was possible that his writing was no worse nor more condensed than it had been before the illness. Much of the writing was simply answering questions. The following examples are preserved; they are all appropriate answers. “I am alone, does cooking and everything”; “we are separated, still married! !“; “I have son, but he are now an ambulance driver in Mugdee. 170 mile from Sydney”; “I am invalid pensioner”; “third time I got storke, than I got food to take thru nose. I did not drink alcohol never”; “I had coughing, and breathing, and Dr. Laycock said to have X-Ray first time 11.9.73 and now this morning got friend to call Dr. that is all.” He was also capable of initiating his own writing, and could make propositions. Thus he wrote this summary of his history-“first time I got storke 13 Dezember 1970, my left hand side and half face. Second I got storke 12.7.1971 and I lost hearing. Third time, 11.1.72 and lost 228 JONATHAN LEICESTER talking”-and the description of cardiac failure shown in Fig. l-“Being deaf and dumb I will write Report for you how I felt after I was discharged from Hospital 20.9.1973. Being at Home first week I was coughing lying on a bed sleepiness and very much sweating. I took my tablets strictly as directed. My temperature when I took I was most times 37.2 or .3. shortly I felt very bad and ill. Second, weeks from 27.9 to 3.10.73 I felt better not much coughing only at nights mostly and sleeping few hours at nights. No more sweating. I hope doctors will help me for further treatment.” There was also a letter of 1% words written in Estonian, which gave an appropriate account of daily matters, small talk, and greetings. Two translators were asked to comment on spelling, syntax, word use, and telegram style. One felt the letter was probably normal. The other thought the style was somewhat senile, and commented on two sentences run together without a break, one spelling error, and two failures of verb agreement. Thus there was a mild degree of defective comprehension of writing and minor agraphia with paraphasias and agrammatism. These defects were FIG. 1. Writing, after subcortical motor aphasia. DEAFNESS AND APHASIA 229 certainly partly, if not entirely, due to an imperfect premorbid mastery of English. It is not certain whether any additional defect, if present, was caused by the second or the third stroke. Fourth Stroke-November 1973-Right Hemiplegia This was a severe stroke with right hemiplegia and total aphasia. He made only minimal improvement, and died after 27 days. PATHOLOGICAL FINDINGS Methods The uncut brain was mounted whole in a single block. It was cut in the horizontal plane in gapless serial sections of 50-pm thickness. Sections numbered 25, 50, 75, and 100 were stained by Weigert’s method for myelin, sections 51 and 101 with cresyl violet, section 52 with PTAH, section 102 with H and E; and so on through the block. Through the left superior temporal gyrus every 10th section was stained with H and E. The stained sections were mounted whole in DPX under thick glass. The sections were examined by naked eye, dissecting microscope, and low power microscope. Areas of infarction were classified as recent or old. In the recent infarct the basic anatomy was still present, the structures had a crumbly appearance, an eosinophilic background, and many areas of intense cell infiltration. In the old infarcts some areas of brain had completely disappeared or had entirely lost their architecture. The remaining structures had decreased in size and had poorly cellular areas with lattice-like tissue strands and spaces, areas of gliosis, only occasional cellular areas, and prominent secondary pallor of the related white matter. There were some areas of severe partial damage with laminar necrosis of the cortex and marked pallor of the white matter. (See Plate 1.) The brain stem and cerebellum were normal. The cerebral hemispheres contained the following embolic infarcts. Right Hemisphere-Old Middle Cerebral Infarct This was a very large infarct. There was complete destruction of the horizontal (main) ramus of the Sylvian fissure, the upper surface of the first temporal gyrus, the frontoparietal operculum including Broca’s area, the putamen (except for the anterior third of its lower half which was spared), and the insula (although some ghost remnants of this cortex were recognizable) (Fig. 2). This predominantly deep infarction of the Sylvian fissure and putamen was in continuity with an extensive complete surface infarction of the lateral parieto-occipito-temporal region, the territory of the angular artery. There was more infarction in the walls of the superior precentral sulcus, more extensive in its upper two-thirds. Most of the white matter of the inferolateral frontal lobe and the lateral part of the 230 JONATHAN LEICESTER PLATE 1. (A) Right hemisphere-Sylvian, upper temporal plane region. Massive infarction (Fig. 2, second column, second from right) (Weigert). (B) Left hemispherefrontoparietal operculum. Recent infarction of banks of anterior part of circular sulcus, anterior limb of Sylvian fissure, and posterior part of third frontal gyrus including Broca’s area. Old infarction of Rolandic operculum, here at its maximum size (Fig. 3, second column, extreme right) (Weigert). (C) Left hemisphere, Sylvian fissure region. Recent infarction in Broca’s area. Old infarction of Rolandic operculum, its inferior end. Old infarct of isthmus of Heschl’s gyrus, and infarction with gliosis of cortex of Heschl’s gyrus, partly overlain by normal supramarginal cortex (Fig. 3, third column, second from left) (PTAH). (D) Left hemisphere. Old infarct of white matter beneath Heschl’s gyrus (Fig. 3, third column, third from left) (Weigert). DEAFNESS AND APHASIA 231 232 JONATHAN LEICESTER temporal and occipital lobes was severely pale in myelin stain. There were many well-myelinated fibers in the inferior longitudinal bundle forming a sharp medial edge to the pale zone, and many intact optic radiation fibers. The corpus callosum appeared intact, and there was only minor damage to the internal capsule. The right medial geniculate body measured 5 x 2 mm in the stained section of its greatest extent, and contained only occasional remaining neurones . Right Hemisphere-Old Posterior Cerebral Branch Infarct An infarct involved most of the walls of the posterior three-quarters of the collateral sulcus, and the posterolateral part of the inferior surface of the occipital lobe had disappeared (Fig. 2). Left Hemisphere-Old Auditory Cortex Znfarct There was infarction of the cortex of the outer three-quarters of the crown of Heschl’s gyrus, of both banks of the sulcus forming its posterior border, and of the groove forming its anterior wall (Figs. 3 and 4). There was severe myelin loss of the underlying white matter laterally, and complete infarction of the white matter medially. This extended from the cortical infarct to the medial end of Heschl’s gyrus and beyond, 2-3 mm into the stem of the temporal lobe. A tongue of infarction extended forward from the medial end of the cortical infarct to reach the descending part of the Sylvian fissure (the temporal wall of the circular sulcus), and extended down that border of the temporal lobe for a short distance. A small tongue of superficial infarction extended back to involve the cortex of a part of the outer half of the planum temporale. The left medial geniculate body measured 5.5 x 2.5 mm in the stained section of greatest size, and still contained a large number of neurones. In the posterior temporal and lateral occipital regions there were seven tiny cortical infarcts up to 3 mm across, and 10-20 minute cortical lesions that were easily seen in PTAH as lines of gliosis 0.1 mm wide perpendicular to the cortical surface and correlated with columns of absent neurones in the cresyl violet. These tiny lesions were not seen in any other region. Left Hemisphere-Old Motor Cortex Infarct There was old superficial infarction of the crown of the gyrus of the Rolandic operculum extending from the precentral sulcus in front to the Sylvian fissure behind (Figs. 3 and 4). A very short distance further up, this became an extensive and deep infarction of the lower end of the precentral gyrus at and just above the lower end of the central sulcus. At this level there was a lesser but moderate involvement of the posterior bank of the lower end of the central sulcus. Further up, there was a lesser, but still considerable infarct of the crown and central sulcus bank of the precentral gyrus throughout its lower two-thirds. DEAFNESS AND APHASIA 233 234 JONATHAN LEICESTER FIG. 4. Diagrams of surface extent of old infarctions of left hemisphere. Left, Lateral surface; right, superior temporal plane. Left Hemisphere-Recent Middle Cerebral Infarct This was a large infarct. There was infarction of most of the anterior bank of the precentral sulcus and the surfaces of the posterior thirds of the frontal gyri, including all of Broca’s area. The banks of the proximal ascending part of the Sylvian fissure, the anterior temporal pole, the cortex of the circular sulcus, and almost all the insula, a considerable part of the cortex of the parietal lobe, and some of the region of the angular gyrus were all infarcted. There was an extensive deep infarction involving virtually all the head of the caudate nucleus, all the putamen, the anterior limb of the internal capsule, and some damage to other deep white matter. DISCUSSION The Cortical Disorders of Hearing There are three conditions: central deafness, auditory agnosia, and pure word deafness. Theoretically, in central deafness the patient is deaf, and the cause is complete bilateral destruction of the primary auditory cortex or of the auditory radiations leading to the cortex. In auditory agnosia the patient is not deaf because some primary auditory cortex is still functioning, but he cannot discriminate or name nonspeech sounds because the pathways from the auditory cortex to the brain areas responsible for the discrimination of sounds are destroyed. In pure word deafness the patient is not deaf but he cannot discriminate speech because of a disconnection of the paths from the auditory cortex to Wemicke’s area. In fact, the conditions are not as distinct from each other as might be supposed. On one hand, the hearing loss in central deafness is nearly always partial, and on the other hand patients with auditory agnosia or pure word deafness often seem deaf on superficial observation and often regard themselves as deaf or partly deaf. Another problem has been a DEAFNESS AND APHASIA 235 common bias to assess for word deafness very carefully and for auditory agnosia haphazardly or not at all. The classification of some patients causes genuine difficulty. For example, Lemoyne and Mahoudeau (1959) classified their patient as having auditory agnosia with cortical deafness. Clinical features. The clinical features of central deafness are that the patient regards himself as deaf or nearly deaf. He pays no attention to even loud noises. He has little or no ability to recognize or name those sounds that he does hear. Simple bedside tests of hearing using speech and noises give an impression of deafness or near deafness, although a tuning fork may be heard surprisingly well. The patient may comment that those things that he does hear all sound similar and undifferentiated, e.g., like static humming. A number of patients have learned some lipreading. Some of the patients are reluctant to speak, but they can speak unless there is also another lesion that prevents speech. The patients with sound agnosia have little or no ability to recognize nonspeech sounds, but it is easy to demonstrate that they are not deaf, and that they do not fail because of such factors as dementia or aphasia. The patients are usually inattentive to loud sounds. They may say that noises sound distorted and unclear, and that different noises sound similar. They may regard themselves as deaf or nearly deaf. Severe sound agnosia is a rare condition. Some of the patients have also had word deafness, but other patients have not @preen, Benton, & Fincham, 1965; Albert, Sparks, von Stockert, & Sax, 1972). In one patient the disorder was transient (Wortis & Pfeffer, 1948). The patients with word deafness are unable properly to hear and comprehend speech, but bedside tests easily show that they are not deaf and that they do not have ordinary aphasia. These patients also often pay little attention to sounds, they may refer to themselves as deaf, and may blame this supposed deafness for their auditory incomprehension. Other patients, or even the same patient at other times, may stress that they are not deaf, and that they can hear soft sounds like a fly buzzing. They may be irritated with their neurologist when he shouts at them. Some of these cases also had sound agnosia (Schuster & Taterka, 1926, p. 501). Others did not (Kanshepolsky, Kelley, & Waggener, 1973). Formal audiology. It is characteristic of central deafness that the cases are not completely deaf. Probably some cases are temporarily totally deaf when the stroke occurs, but soon have some return of hearing which then improves for months (Lhermitte, Chain, Escourolle, Ducame, Pillon, & Chedru, 1971). The pure tone audiogram shows surprisingly good hearing. It can even be normal, although more often there is a moderate persistent loss, that tends to affect medium- and high-frequency tones. One patient with such an audiogram had no cortical auditory average evoked response (Jerger et al. 1969). Bekesy audiometry has shown a severe hearing loss, more consistent with the bedside impression (Jerger et al., 1969). Dis- 236 JONATHAN LEICESTER crimination of sound ,and of rhythm have been very poor, while short increment frequency and especially loudness discrimination have been better (Lhermitte et al., 1971). More cases need to be studied before it will be known whether these characteristics are consistent from case to case. There was one remarkable case of central deafness who achieved more auditory function than any other patient with similar pathology. This was the case reported by Landau, Goldstein, and Kleffner (l%O). It is probably no coincidence that the patient was a child. This boy with congenital heart disease evidently had bilateral middle cerebral emboli in infancy and did not develop any natural speech. At postmortem the Sylvian region on each side was replaced by a large cyst from an old infarction, and both medial geniculate bodies showed severe secondary degeneration. Yet he had normal or near-normal pure tone audiometry, monitored spoken voice audiometry, and white noise threshold. After special tuition he learned to comprehend slowly spoken speech, and to speak simple sentences. About modern audiology in patients with auditory agnosia and pure word deafness information is lacking. More clinicopathological correlations are needed to find out if audiology or cortical evoked auditory responses can differentiate auditory agnosia from central deafness in all cases. Pathological findings. In central deafness bilateral destruction of the auditory radiations or the primary auditory cortex has been a constant finding. Some of the cases have very extensive lesions, and there could hardly be even a vestige of functioning primary auditory cortex (Landau et al., 1960). The pathology of sound agnosia has been variable. It has occurred with unilateral lesions of the right, minor hemisphere (Spreen et al., 1965), with bilateral lesions (Albert et al., 1972), and with unilateral lesions of the left, major hemisphere (Schuster & Taterka, ‘1926). The lesion can be in efferent tracts from Heschl’s gyrus (Schuster & Taterka, 1926), but there is insufficient pathology to know if this is generally so. It is impossible to tell from the pathology whether the patient had sound agnosia or not. Thus one patient with an old small left temporal lobe lesion had sound agnosia (Schuster & Taterka, 1926), while another patient had the same area destroyed by much larger bilateral lesions without sound agnosia (Kanshepolsky et al., 1973). There must be many patients with large right temporal lobe lesions who do not have sound agnosia. There is a big factor of unpredictability. The pathology of pure word deafness has also been variable. In some cases there has been approximately the lesion theoretically expected; a white matter lesion in the left first temporal gyrus posterior to Heschl’s gyrus (Schuster & Taterka, 1926). A significant proportion of cases have had bilateral lesions affecting both superior temporal gyri. In some cases DEAFNESS AND APHASIA 237 the lesions have been extensive and have involved much of the temporal lobe speech area and have damaged the primary auditory cortex (Kanshepolsky et al., 1973). Sometimes the left, major hemisphere lesion caused only transient aphasia, and severe word deafness developed with the second, minor hemisphere lesion (Kanshepolsky et al., 1973; Mackenzie & Klamus, 1979). Mechanisms possibly underlying the cortical hearing disorders. Experience has confirmed the theoretical position that central deafness is due to loss of function of the primary auditory cortex bilaterally. The puzzle in central deafness is how some hearing is preserved. This is still obscure. It has been attributed to remaining primary auditory cortex, but in some cases the pathology has been so extensive that this explanation is hardly plausible. Another suggestion has been that some perception is possible in the medial geniculate bodies, but the hearing has been similar in cases where the medial geniculate bodies have undergone retrograde degeneration (Landau et al., 1960). Perhaps the hearing occurs in accessory auditory cortex. Until recently there has been little information about accessory auditory areas in man. Now Celesia (1976) has mapped these areas with electrodes on the exposed brain at craniotomy, using averaged evoked responses to click stimuli. He found constant responses of short latency from Heschl’s gyrus and labile, variable responses of longer latency from the posterior two-thirds of the lateral surface of the first temporal gyrus and from those parts of the Rolandic, postcentral, and supramarginal gyri adjacent to the Sylvian fissure. The suprasylvian responses were not affected by removing the primary auditory cortex on that side. In some cases of central deafness with hearing all these areas seem to be destroyed (Landau et al., 1960). The author tentatively favors the idea of an accessory auditory pathway which is able to adapt to achieve some hearing after the classical pathway is destroyed. The preserved hearing is probably acquired gradually over months and is greatest when the lesion occurs in early childhood; these findings suggest a role for adaptability of nervous function. A hypothetical pathway through the medial thalamus has been proposed (Landau et al., 1960). Whatever its mechanism, the amount of hearing is limited and is always very poorly connected to cognitive processes. The mechanisms underlying sound agnosia pose special difficulties. A cortical area specially related to processing speech has been discovered, but no similar localization of the processing of general sounds has been achieved. The disconnection theory of sound agnosia is therefore hard to test, but the finding that the lesion can be in efferent tracts from Heschl’s gyrus is consistent with a disconnection. Severe sound agnosia is rare, its pathology is variable, and its occurrence when pertinent pathology is present is unpredictable. There is evidence that in general for recognition of sounds discriminatory aspects are carried out more by the minor 238 JONATHAN LEICESTER hemisphere and language aspects more by the major hemisphere (Faglioni, Spinnler, & Vignolo, 1969). Perhaps sound agnosia is not a single condition, but can be produced by several different mechanisms. This suggestion would readily explain the variability of its pathology, but not its unpredictable occurrence or its rarity. The author prefers to suggest that in most subjects either hemisphere can recognize sounds, and that the occasional patients with sound agnosia from unilateral lesions are unusual in that they have learned to recognize sounds only in either their minor or their major hemisphere. Pure word deafness has a tendency to be associated with bilateral temporal lobe lesions. In terms of disconnection theory, it could be postulated that the right temporal lesion had acted by severing auditory input that had been reaching the left hemisphere language areas from the right auditory cortex. But in aphasia auditory comprehension frequently improves, suggesting that many brains probably have considerable plasticity of function with respect to comprehension of speech. The author favors the view that this adaptability is achieved at least in part by the minor hemisphere, and this is the reason that bilateral lesions are particularly likely to cause persistent word deafness. Subcortical Motor Aphasia Subcortical motor aphasia, pure motor aphasia, pure word mutism, cortical dysarthria, and anarthria of Marie are synonyms or nearly synonyms for motor aphasia with fluent writing. There has been disagreement about whether the condition is aphasia or dysarthria, or aphasia in some cases and dysarthria in others. An aphasia should have some disorder of language other than difficult articulation. In Broca’s aphasia the features that are usually accepted as evidence of aphasia are that writing is involved and that there is agrammatism (telegram style). In Otto S., who was completely mute, these matters were difficult to assess. A dysarthria should be due to some disorder of movement of the mouth and throat; a paralysis, dystonia, apraxia, or sensory ataxia-and each of these has been blamed for the speech difficulty of some types of motor aphasia. The mouth and throat of Otto S. may have had the disorder called limb-kinetic apraxia by Liepmann, where a partial lesion of motor cortex, insufficient to cause paralysis, causes some awkwardness of coarse movements and a loss of fine movements, in this case of speech. It has been suggested that there are two separate types of subcortical motor aphasia, aphasic cases with agrammatism and dysarthric cases without agrammatism (Brown, 1972). Mechanisms possibly underlying subcortical motor aphasia. Three old theories and one new one are considered here. The old theories are the classical subcortical theory, the Exner’s writing center theory, and the cortical dysarthria theory. DEAFNESS AND APHASIA 239 The classical subcortical theory is derived from the classical view of Broca’s aphasia, and can be stated thus: Broca’s area is an area for motor formulation of language. A lesion in Broca’s area causes Broca’s aphasia, a motor aphasia with partial or complete inability to speak and write. Efferent fibers from Broca’s area become separated as they pass through the subcortical white matter, speech fibers pass back to motor cortex for the mouth and throat, and writing fibers pass back and up to motor cortex for the hand. The theory predicts that a small white matter lesion beneath the back of Broca’s area will cause subcortical motor aphasia. The writing center theory proposes that speaking and writing are regulated by different centers-possibly by different parts of Broca’s area, possibly speaking by Broca’s area and writing by the posterior end of the second frontal gyms (Exner’s writing center). When both centers are destroyed the patient gets Broca’s motor aphasia; when the writing center is spared he gets subcortical motor aphasia. The theory predicts that a small lesion of Broca’s area will cause subcortical motor aphasia. Most advocates of the cortical dysarthria theory have predicted a lesion in the cortex or white matter of the Rolandic operculum, the mouth, and throat area. Marie predicted a lesion in the lateral putamen and external capsule, a lesion which he believed would interrupt efferent fibers concerned with articulation. Broca’s aphasia has recently been reviewed and restudied by Mohr and his colleagues (Mohr, 1976; Mohr et al., 1978). They concluded that a small infarct of Broca’s area causes no speech disorder in some cases, and in other cases causes a motor aphasia with some agrammatism from which the patient recovers, while Broca’s aphasia is the residual deficit after partial recovery from a large infarct of the operculum from anterior frontal through Broca’s area to anterior parietai regions, the insula, both banks of the Rolandic fissure, and usually deep into the hemisphere. If their view is correct, then the classical subcortical theory and the writing center theory of subcortical motor aphasia are non sequitur, and an alternative theory may be required. This is the fourth or new theory alluded to above. The theories are tested by case reports with clinical and pathological findings. Several of these cases are summarized below. Case Otto S. This patient had subcortical motor aphasia that persisted unchanged for 22 months despite speech therapy. There had been a temporary initial pseudobulbar palsy. He was mute. Writing was fluent; it was uncertain whether there was agrammatism. Earlier strokes had caused temporary left hemiplegia and permanent central deafness. Postmortem showed a small infarct limited to the motor cortex of the mouth and throat on the left side. Broca’s area and other structures were not involved. There was a large infarct of the right hemisphere that included the mouth and face area motor and premotor cortex. Case E. Fr. of Alajouanine, Pichot, and Durand (1949) and Lecours and 240 JONATHAN LEICESTER Lhermitte (1976). A right-handed man, aged 63, perfectly bilingual in English and French, had sudden right hemiplegia, hemianaesthesia, and subcortical motor aphasia. The hemiplegia rapidly improved. Writing with his right hand showed normal penmanship and no agrammatism. He was almost mute at first; after 4 weeks he was speaking rather efficiently in a slowed, syllabical, dysprosodic, and dysarthric way. There was then no obvious buccal apraxia. Despite speech therapy, further improvement was only modest. He was left with a moderate dysarthria and many phonetic substitutions and distortions. He lived for 10 years. There was an old infarct affecting the cortex and subcortex of the lower half of the left precentral gyrus (except for a narrow opercular fringe), and also involving the posterior few millimeters of the second frontal gyrus and the dorsal-most insular cortex. Case A. Del of Souques (1928). This right-handed man, aged 30, had convincing subcortical motor aphasia when seen 2 days after his stroke. He-remained virtually mute for 4 years. Then intensive speech therapy was begun and slow, laborious, agrammatic but reasonable speech returned gradually over some months. The brain was carefully studied by serial sections. There was an enormous lesion of the left hemisphere. The medial and lateral surfaces of the superior frontal gyrus (F I), the second frontal gyrus (F 2), and the precentral gyrus (F a) were destroyed beyond recognition. The third frontal gyrus (F 3), almost all the orbital frontal gyri, the anterior corpus callosum, the Rolandic operculum, putamen, head of caudate nucleus, insula, external capsule, arcuate fasciculus, occipitofrontal fasciculus, and anterior limb of the internal capsule were destroyed. The right hemisphere and Wernicke’s area were normal. Case Joel B. of Ogle (1867). This man had sudden right hemiplegia and loss of speech due to left middle cerebral artery embolism from rheumatic heart disease. Initially he could say only “yes” and “no,” later a few other short words also. Using his left hand, he could write words that he could not say. Comprehension seemed normal. He died after 2 months. There was a cortical infarct of the posterior part of the left third frontal gyrus, three-quarters of an inch (2 cm) across, that spared a narrow strip posteriorly by the precentral sulcus. There was a second small deep softening lateral to and above the corpus striatum and extending back toward the end of the Sylvian fissure. Case of Banti (Bastian 1897a). A right-handed patient was virtually mute and could write fluently without agrammatism soon after a stroke. There was a cortical infarct, extending only some millimeters into the white matter, of the posterior third of the left frontal gyms. The pathology of subcortical motor aphasia has been variable. Some cases have a lesion restricted to the Rolandic operculum (Otto S., E. Fr.), others have a lesion restricted to Broca’s area (Joel B., Banti’s case), and others have a very large lesion including all of the anterior speech area (A. Del). DEAFNESS AND APHASIA 241 The cases with pathology restricted to the Rolandic operculum confirm that there is a type of subcortical motor aphasia which is due to a cortical dysarthria. The usual result of unilateral surgical excision of the motor cortex for the mouth is a transient dysarthria that recovers in several weeks (Penfield 8z Jasper, 1954). This recovery is attributed to plasticity of nervous function; it is believed that the motor cortex of the other hemisphere can usually adapt. In some cases this adaptation partially fails, and a degree of dysarthria persists after a unilateral dominant hemisphere lesion (E. Fr.). When there is bilateral destruction of the Rolandic operculum severe mutism can be permanent (Otto S.). The cases with lesions restricted to the cortex of Broca’s area do not fit the predictions of the cortical dysarthria theory. They also do not fit the classical subcortical theory. They might be accounted for by the separate writing center theory, but there is no good direct evidence that Exner’s writing center exists (Bastian, 1897a), and the theory does not explain Case A. Del, who had a large lesion but wrote fluently. It is most interesting to look at the cases from the point of view of the alternative theory of Broca’s aphasia recently restated by Mohr. Broca’s aphasia and this subgroup of subcortical motor aphasia have the same pathology. Thus Joel B. and Banti’s case had subcortical motor aphasia when examined soon after a stroke with infarction limited to Broca’s area, and A. Del had an enduring subcortical motor aphasia with an extensive infarction of suprasylvian and deep structures. The clinical effects of this pathology are evidently variable, in some cases there is no aphasia, in others there is subcortical motor aphasia, and in others there is Broca’s aphasia. These different effects are possibly due to differences of organization of the brain, in particular differences in the extent to which the minor hemisphere has also contained the functions since childhood or can acquire the functions after the stroke. REFERENCES Alajouanine, T., Pichot, P., & Durand, M. 1949. Dissociation des alterations phonitiques avec conservation relative de la langue la plus ancienne dans un cas d’anarthrie pure chez un sujet francais bilingue. En&@/e, 28, 245-265. Albert, M. L., Sparks, R., von Stockert, T., & Sax, D. 1972. A case study of auditory agnosia: Linguistic and non-linguistic processing. Cortex, 8, 427-433. Bastian, H. C. 1897. Some problems in connexion with aphasia and other speech defects. Lancer, 1, 1005-1017. (a) Bastian, H. C. 1897. Some problems in connexion with aphasia and other speech defects. Lancer, 1, 1131-1137. (b) Brown, J. W. 1972. Aphasia, upruxia and ugnosiu. Springfield, IL: Thomas. P. 117. Celesia, G. G. 1976. Organization of auditory cortical areas in man. Bruin, 99, 403-414. Faglioni, P., Spindler, H., & Vignolo, L. A. 1969. Contrasting behaviour of right and left hemisphere-damaged patients on a discriminative and a semantic task of auditory recognition. Corfex, 5, 366-389. Jerger, J., Weikers, N., Sharbrough, F., & Jerger, S. 1969. Bilateral lesions of the temporal lobe. Actu Oto-Lutyngologicu, Suppl. 258. JONATHAN 242 LEICESTER Kanshepolsky, J., Kelley, J., & Waggener, J. 1973.A cortical auditory disorder. Neurology, 23, 699-705. Landau, W. M., Goldstein, R., & Kleffner, F. R. 1960. Congenital aphasia, a clinicopathologic study. Neurology, 10, 915-921. Lecours, A. R., & Lhermitte, F. 1976. The “pure form” of the Phonetic Disintegration Syndrome (Pure Anarthria); Anatomo-clinical report of a historical case. Brain and Language, 3,88-113. Lemoyne, J., & Mahoudeau, D. 1959. A propos d’un cas d’agnosie auditive pure avec surdite corticale associee a une dysphonie fonctionelle. Anna/es d’Oto-Laryngologie, 76, 293-310. Lhermitte, F., Chain, F., Escourolle, R., Ducame, B., Pillon, B., & Chedru, F. 1971. Etude des troubles perceptifs auditifs darts les lesions temporales bilaterales. Revue Neurologique, 124, 329-351. Mackenzie, R. A., & Klamus, J. 1979. Pure word deafness, cortical deafness and sound agnosia. In G. V. Stanley & K. W. Walsh (Eds.), Brain impairment. Proceedings ofthe 1978 Brain Impairment Workshop, Melbourne, Australia. Mohr, J. P. 1976. Broca’s area and Broca’s aphasia. In H. Whitaker & H. A. Whitaker New York: Academic Press. Vol. 1, pp. 201-235. (Eds.), Studies in neurolinguistics. Mohr, J. P., Pessin, M. S., Finkelstein, S., Funkenstein, H. H., Duncan, G. W., & Davis, K. R. 1978. Broca aphasia: Pathologic and clinical aspects. Neurology, 28, 31l-324. Mott, F. W. 1907. Bilateral lesions of the auditory cortical area: Complete deafness and aphasia. Archives of Neurology (London), 3, 401-423. (a) Mott, F. W. 1907. Bilateral lesions of the auditory cortical area: Complete deafness and aphasia. British Medical Journal, 2, 310-315. (b) Ogle, W. 1867. Aphasia and agraphia. St. George Hospital Reports, 2, 83-122. Penheld, W., & Jasper, H. 1954. Epilepsy and the functional anatomy of the human brain. Boston: Little, Brown. P. 109. Schuster, P., & Taterka, H. 1926. Beitrag zur Anatomie und Klinik der reiner Worttaubheit. Zeitschrifi fir Neurologie und Psychiatric, 105, 494-538. Souques, A. 1928. Quelques cas d’anarthrie de Pierre Marie. Revue Neurologique, 2, 319-368. Spreen, O., Benton, A. L., & Fincham, R. W. 1965. Auditory agnosia without aphasia. Archives of Neurology, 13, 84-92. Wortis, S. B., & Pfeffer, A. 2. 1948. Unilateral auditory-spatial agnosia. Journal Nervous and Mental Disease, 108, 181-186.