Dichotic Listening in Crossed Aphasia 'Paradoxical' Ipsilateral Suppression Gianfranco Denes, MD, Franco Caviezel, MD \s=b\ In a 35-year-old right-handed man who had no personal or family history of left-handedness, left hemiparesis and aphasia suddenly predominantly developed following cerebrovascular accident. Clinical and laboratory data, including computerized tomographic scan, showed a clearly defined right hemisphere lesion. On dichotic listening test, motor a clear-cut right ear extinction was present. (Arch Neurol 1981;38:182-185) "P\ichotic listening (DL) tests have been, to our knowledge, rarely carried out in right-handed aphasie patients.1-3 Most of the patients dem¬ onstrated an impairment in reporting verbal material presented to the right ear, showing the so-called contralater¬ al ear effect or lesion effect.4 A consis¬ tent minority of patients showed, however, a left ear extinction or "par¬ adoxical ipsilateral ear effect"2 in DL tests. Whereas the contralateral ear effect has been proved to be a consequence of a lesion interrupting the left geniculocortical pathway, the paradoxical extinction was seen, as suggested by Sparks and Geschwind7 and by Milner et al,8 in the presence of a deep left-hemisphere lesion that extends to the point where the audi¬ tory pathway, after crossing the cor¬ pus callosum from the right temporal lobe, arrives in the dominant hemi¬ ''" sphere. Studies on DL in cases of crossed aphasia have not, to our knowledge, been reported. This term9 designates a pattern of aphasia of adult onset following a right-hemisphere lesion in a right-handed person. Some 90 cases are reported.10 " In the majority of the cases, however, a history of familial Accepted for publication May 24, 1980. From Clinica Neurologica dell'Universit\l=a`\di Padova, Italy. sinistrality, a lack of complete right- handedness, or the presence of bilater¬ al lesions have made acceptance of the syndrome open to question. From a careful analysis of the reported cases, Brown and Hécaen'2 found only nine valid cases in which "the following criteria were satisfied: thorough language testing, a patho¬ logical lesion limited to the right hemisphere, absence of childhood brain damage, strong right-handed¬ ness, and a negative family history of left-handedness." At least seven more cases13"1" (including unpublished re¬ port of G. Assai, MD) have since been described, to which the present case be added. These patients usually show disorders of spoken language, with little difficulty in comprehension of spoken or written language. As for etiology, Boiler11 points out that the great majority of the cases are of neoplastic or traumatic origin, whereas most of the reported cases of can aphasia following brain damage on the left side in right-handed people are of vascular origin. According to Boiler, the distance effects due to the tumor or the bilateral lesions caused by the trauma would produce disor¬ ders of language that could be mistak¬ enly attributed to the lesion on the right side. A last point of difference between normal and crossed aphasia is the age of incidence: the majority of the patients with crossed aphasia are under 40 years at the age of onset, whereas the mean age of those with normal aphasia is generally over 60 years. We report the result of DL studies in a right-handed patient in whom a typical pattern of crossed aphasia developed following right carotid ar¬ tery thrombosis. Also, we discuss some possible mechanisms of hemispheric specialization in such cases. Read in part before the Second International REPORT OF A CASE dell'Universit\l=a`\,Via Giustiniani, 5, 35100 Padova, Italy (Dr Denes). The patient was a 35-year-old man. He had been hypertensive (blood pressure, 180/100 mm Hg) for some years. He was ostensibly right-handed, and no instances Neuropsychological Society European Conference, June 28, 1979, Noordwijkerhout, Holland. Reprint requests to Clinica Neurologica Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/01/2015 of left-handedness were found in his fami- iy. In March 1978, he was admitted to anoth¬ hospital because of abrupt onset of left hemiparesis (more marked in the upper limb) and aphasia, which was described as predominantly expressive. The speech dis¬ turbance occurred first, immediately fol¬ lowed by the motor impairment, without loss of consciousness. A carotid angiography showed an occlusion of the right inter¬ nal carotid artery 4 mm above its origin. In the following days the patient showed a steady improvement in both motor and aphasie deficits. When first seen in our department in November 1978, the patient was oriented, alert, and cooperative. His mood was appropriate, and short- and long-term memory were within normal limits. There was a left hemiparesis, more marked in the upper limb, with hyperreflexia and left Babinski's sign. Results of sensory exami¬ er nation, including two-point discrimination, were normal. No cerebellar signs were noted. Visual fields were normal to con¬ frontation. Results of ophthalmoscopic examination were normal. Left central facial paresis was evident. In December 1978, a computerized tomographic (CT) (Fig 1) showed asymmetry of the lateral ventricles, the right being larger scan without shift. A large triangular area of hypodensity was evident in the right frontoparietal region that extended from the cortex downwards, with slight involvement of the basal ganglia, and close to the lateral wall of the body of lateral ventricle. On the basis of the scan, a mapping of the lesion was performed according to the criteria of Mazzocchi and Vignolo,11 showing the boundaries of the ischemie damage on both a superficial and a deep level (Fig 2). Handedness Study The patient reported that he had been right-handed since childhood. His handed¬ ness was tested by means of the Edinburgh Inventory,18 which yielded a laterality quo¬ tient of +9. Informal testing of the patient's relatives failed to show cases of left-handedness or ambidexterity. Neuropsychological Studies The patient's first language examina¬ tion took place 20 days after the ictus. Spontaneous speech was limited to a few words intermixed with pauses. Articulatory disturbances, associated with phonemic paraphasias and with a mild pattern of Fig 1—Computerized tomographic scan obtained in December 1978 showing area of triangular hypodensity in right frontoparietal region, which extends from cortex downwards, arriving close to lateral wall of body of lateral ventricle. agrammatism, were noted. Comprehension good for both words and sentences, but was he scored 12 of 36 in the shortened version of the Token test."' Repetition was good for letters, words, and short sentences, while he failed with sentences of more than five words. His ability to name was impaired (four items of 20). Reading aloud was fairly well preserved, with better per- formance with sentences than with words and better with words than with syllables and single letters. Some verbal paraphasias (tablecloth instead of table) were noted. A second examination was performed six months later using an Italian version of the Goodglass and Kaplan battery.-'0 Sponta¬ neous speech was of normal fluency and prosody, with correct use of grammatical Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/01/2015 parts and normal phrase length and with phonemic paraphasias. The informa¬ tional content was proportional to the length of the sentence, but frequent rare anomic disturbances were present. The patient showed good comprehension in a word-discrimination test (20 of 20) while he scored five of 11 in a test of execution of complex orders. He scored 26 of 36 in the Fig 2.—Mapping of lesion, showing bound¬ aries of ischemie damage at both superfi¬ cial (triangles) and deep (lines) levels. Token test, which is below the minimum in relation to his age and educational level. On an automated sequence test, he per¬ formed well in spite of a marked difficulty in starting the sequence. He obtained the maximum score in the repetition tests. His performance in the object-naming tests, in contrast with the word-searching difficul¬ ties noted in his spontaneous speech, was good: he scored 25 of 30 in the responsive naming test, 95 of 105 in the visual con¬ frontation naming test, and 26 of 30 in the body-parts naming test. Reading and understanding of written language were good. Writing was good, too, with normal fluency and without any paragraphia. Related Cortical Functions No signs of apraxia were noted apart from a mild pattern of oral apraxia during the first stages of his illness. His drawing abilities, both spontaneous and on copy, were good. No signs of oral or written dyscalculia were present. On Raven's pro¬ gressive matrices 1938, he scored 48 of 60 four months after the ictus. Two months later, a Wechsler Adult Intelligence Scale showed a verbal score of 67 and a perform¬ ance score of 45 with a total score of 112, corresponding to an IQ of 103. Finger gnosis was good. No signs of unilateral spatial agnosia were present. DL Tests Materials.—The tape used for these tests that adopted by Mazzucchi and Par¬ ma,21 prepared following the technique suggested by Rubino.22 Dichotic stimuli were recorded with a 5-s silence .between stimuli. Digits within a sequence were separated by half-second intervals. The tape was played on a stereo recorder through stereo headphones; the output of the two channels was calibrated to about 70 dB. Procedure.—Although an audiometrie test was not administered to our patient, we checked the subjective loudness at each ear carefully. He was told to inform the examiner if at any time during the test he felt a different volume in the two ears. Furthermore, before testing we deter¬ mined his digit span monoaurally; six digits were reported correctly in both was ears. Our test was formed of three sets of stimuli presented dichotically; each set con¬ sisted of 12 pairs of stimuli. The sequence of sets was as follows: two digits, three digits, two words. In set 3, the items used were common two-syllable words. Before the first two sets, the patient heard two pairs of stimuli as practice trials. He was instructed to report what he had heard after each pair without time limits. No instructions were given about the order of report. In the middle of each set, ie, after the sixth pair, the headphones were re¬ versed. As regards scoring procedures, 1 point was given for each item, digit, or word that he correctly reported; no guess¬ ing correction was adopted. The same test was repeated a few days later under the influence of selective atten¬ tion; the patient was instructed to recall the items presented in either his right or left ear, ignoring what he heard in the unattended ear. No instructions were giv¬ en about the order of report. Again, the performances of the two ears were com¬ pared using the same scoring procedures of the former test. The first set of stimuli (two digits) was used only as a practice trial. RESULTS The results of the series without focused attention were as follows: set 1,83% in the right ear (RE) and 75% in the left ear (LE); set 2, 33% (RE) and 97% (LE); and set 3, 50% (RE) and 79% (LE). Results of the test with focused attention were as follows: set 2, 97% (RE and LE); and set 3, 58% (RE) and 91% (LE). It can be seen that in the first trial his performance was good, without any notable difference- between the two ears. In the second and third trials, a marked decrease in reporting both digits and words was present. This fact was by far more evident for the items presented to the right ear, where the performance dropped to 33% for digits and to 50% for words. When, however, the dichotic listen¬ ing test was performed with precued unilateral recall, his performance im¬ proved, showing a nearly flawless report in set 2, independent of the attended ear. In set 3, however, though his performance was 91% cor¬ rect in recalling words presented to the left ear, he was able to report only 58% of the items presented to the right hemisphere, and definite lan¬ guage impairment tested with thor¬ ough language examination. His aphasia involved spoken speech pri¬ marily, although the poor Token-test performance suggested mild compre¬ hension deficits. When language disturbances follow right hemisphere damage in a righthanded patient, the question must naturally arise whether they are real¬ ly expressions of involvement of ner¬ vous structures could or if they subserving language be the result of an acute, confusional state following a right hemisphere lesion. This latter point is not academic, since quite recently Mesulam et al·'3 described some patients in whom an acute con¬ fusional state developed following an infarct in the distribution of the right middle cerebral artery. In a recent review of disorders of higher cortical functions in acute confusional states of various etiology, Chédru and Gesch¬ wind'-'1 found disturbances of language function in many cases that were often accompanied by disturbances in other cognitive functions. Our pa¬ tient's language disturbances were present in the absence of other neu¬ ropsychological deficits. His attention was good, as shown by his normal digit span. His ability in calculating and drawing was maintained, and his IQ was well within normal limits. In addition, it is important to point out the cerebrovascular etiology, which is not likely to produce long-distance effects, especially eight months after COMMENT its onset. The lack of right-hemi¬ sphere lesion signs as visuospatial neglect or constructional deficits is worth mentioning, since in our patient the right hemisphere seems to sub¬ serve only linguistic functions. At this point, it seems appropriate to remem¬ ber that Hécaen and Sauguet" found that a right-hemisphere lesion in lefthanded subjects is characterized by the comparatively high frequency of language disturbances, whereas dis¬ turbances of calculation, praxis, and visuognosis are similar to those found in right-handers with right-hemi¬ sphere lesions. On the contrary, a lefthemisphere syndrome in left-handers causes a language impairment similar to but of a less marked degree than that found in right-handers. Such lan¬ The present case seems to fit all of the criteria that are said to be neces¬ sary for a correct diagnosis of crossed aphasia: strict right-handedness with¬ out any history of familial sinistrality, absence of childhood brain damage, pathologic changes confined to the comitant with some other symptoms that are generally seen following right-sided lesions in right-handers. Another characteristic of these sub¬ jects appears to be a less marked intrahemispheric localization of the neurological loci subserving higher right ear. Downloaded From: http://archneur.jamanetwork.com/ by a New York University User on 06/01/2015 guage disturbances, however, are con¬ cortical functions. As far as DL performance is con¬ cerned, the following points are worth stressing: when the task was easy, he scored almost perfectly with both ears, showing neither dominance nor lesion effect; with increasing task dif¬ ficulty, however, he showed a dramat¬ ic loss in his ability to recall and report the items presented to the right ear, showing a clear-cut pattern of para¬ doxical extinction. In a very recent study, Damasio and Damasio2" found that an ipsilateral extinction on DL can be found with deep suprasylvian lesions in the parie¬ tal or parietooccipital regions, in the left or right hemisphere close to the lateral ventricles, blocking the interhemispheric auditory pathway travel¬ ing from the nondominant hemi¬ sphere to the posterior temporal region of the dominant one. In the present case, the findings of CT scan showing a deep lesion close to the wall of the lateral ventricle, although slightly more anterior than expected, seemed to indicate that the same pat¬ tern can be responsible for the ipsilat¬ eral extinction, which therefore is not at all paradoxical. A similar pattern was pointed out by Damasio et al,6 who found a right-ear extinction in a left-handed subject who was found to be right-hemisphere dominant by the Wada test,27 and by Rubens et al·' in right-handed aphasie patients follow¬ ing deep suprasylvian lesions. With regard to the effect of precued recall, it must be remembered'-'* that the degree of the dominant ear advan¬ tage usually is reduced by focused attention and increased by task diffi¬ culty. These considerations can ex¬ plain the lack of differences between the performances of the two ears when using digits and the noticeable bias when using words. Actually, set 3 (two words) proved to be more diffi¬ cult than did set 2 (three digits) not only in the present case but also when used by Mazzucchi and Parma21 both in control subjects and in temporallobe epileptic patients. A last point must be considered: our patient, like the majority of crossed aphasie patients, had a very good recovery. This fact has been judged by some authors12 as a sign of a minor degree of cerebral dominance for language, allowing a good recov¬ ery by the left hemisphere, which is endowed with linguistic functions. The DL studies in our patient, show¬ ing that the right hemisphere has maintained the dominance for lan¬ guage despite the lesion, cast some doubts on such a hypothesis. Anna Mazzucchi, MD, and Mario Parma, MD, provided the dichotic tape. Norman Geschwind, MD, revised an earlier version of this report. References 1. Schulhoff C, Goodglass H: Dichotic listening, side of brain injury, and cerebral dominance. Neuropsychologia 1969;8:149-160. 2. Sparks R, Goodglass H, Nickel B: Ipsilateral vs contralateral extinction in dichotic listening resulting from hemisphere lesions. Cortex 1970;6:249-260. 3. Rubens AB, Johnson MG, Speaks C: Loca- tion of lesions responsible for the 'paradoxical ipsilateral effect' with dichotic listening tests in patients with aphasia due to stroke, abstracted. Neurology 1978;28:396. 4. Kimura D: Some effects of temporal lobe damage on auditory perception. Can J Psychol 1961;15:156-165. 5. 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