Neurop~ycholoqto. Vol. 22, No. 5. pp. 621-626, PrInted ,n GreatBnta,n. 0028 -3932184 1984. 53.W+ 0.00 c 1984 Pcrgamon Press Ltd. NOTE UNILATERAL RIGHT CEREBRAL FAMILIAL REPRESENTATION LEFT-HANDER OF READING IN A MARC D. WINKELMAN Department of Neurology, Cleveland Metropolitan School of Medicine, General Hospital Cleveland, Ohio, and Case Western U.S.A. Reserve University Hospital, Cleveland. and CHLOE C. GLASSON Department of Physical Medicine and Rehabilitation, Ohio. Cleveland U.S.A. Metropolitan General (Acceppred 19 April 1984) recent hypotheses of cerebral functional organization in natural left-handers hold that language, including reading, is localized either unilaterally in the left hemisphere or bilaterally. but not unilaterally in the right hemisphere. A case of alexia without agraphia in a left-hander with an infarct in the right occipital lobe and splenium of the corpus callosum is reported. That a permanent and complete alexia resulted from a single. right hemisphere lesion indicated that reading was completely lateralized to that hemisphere. The case demonstrates that in some natural left-handers language functions can be unilaterally represented in the right hemisphere. Abstract-Several INTRODUCTION IN OVER907: of right-handers the left hemisphere is dominant for language; that is to say, language is represented unilaterally in the left hemisphere [29. 333. Among left-handers cerebral dominance is not so uniform. Most authorities have recognized three different patterns of language laterality among left-handers: unilateral left cerebral. unilateral right cerebral and bilateral ([16. 29. 311: for additional references, see [13]). However. recent clinical studies of natural left-handers with unilateral lesions [ZO] and dichotic listening. visual half-field and verbal task studies in normals [IX, IY] have delineated only two. not three types of cerebral organization of language. These studies conclude that in a portion of left-handers, said to be those without a family history of sinistraltty. the left hemisphere is dominant, as in right-handers. In the remainder. those with a family history of left-handedness. functional lateralization is said to be mcomplete. Neither hemisphere is dominant; rather, language. including reading. is bilaterally represented. No group of left-handers with right cerebral dominance for language is defined [1X-20]. In accord with these results. many current models of cerebral organization in natural left-handers do not allow for unilateral right cerebral representation of language [7-Y. 18, IY]. The present case is reported because it signifies that reading. at least. can be represented unilaterally in the right hemisphere. CASE REPORT A 6X-yr-old, hypertensive woman suffered the sudden onset of left homonymous hemianopia, dysnomia and alexia. She was a ‘mtxeJ left-bander‘ [5. 201; she wrote with her right hand but sewed. combed her hair and stirred a pot with her left hand. sighted with her left eye and kicked a ball with-her left foot. She was a college-educated. retired secretary: there was no history of epilepsy. Two of her three children were left-handed; their fdther and his family were right-handed. Four months after the ictus. examination disclosed a congruous left homonymous hemianopia. Visual acuity and the response to optokinetic stimulation were normal. She could visually fixate an object, hold tixatton and refixate a series of objects: she could scan a line of numbers and move to the next line. Spontaneous speech was Huent and well-articulated. but there was mild word-finding difficulty. There was also a mild defect in naming seen objects. A pen. for example. was “something to write with”. Palpating or listening to the 621 Nort 622 obtect. she did no better. She correctly pomted to objects named by the exammer Colors uere named correctly Comprehenston of speech. repetttion and wrtting spontaneously and to dtctatton [Fig. l(A)] were normal Word5 were copied poorly. slowly and slavishly [Fig. I(B)] She could neither read aloud nor comprehend printed maternal. Letters were read better than v.ords. Some errors consisted of mtstaking a letter for a morphologtcally stmilar one. e.g. G for C. 0 for Q. M for IV. K for X. but many errors were random. As the reading of letters Improved. she attempted to read words by nammg the letters and putting them together m syllables, which were pronounced audtbly. Eventually she attempted to read whole words Mtsreading of the first few letters of a word accounted for some errors (e.g. c~~~~/-+“srnog”. nrarcG.\ --“clothes”) However. other misreadings had novisual (or semantic) relationshtp to the test word (e.g. .vllr,ll,r,r-“happ!“). Some short words. such as cat. pen and the. were read correctly. but most were not and longer words could not be read. At times she complained that words “move around and keep popping up on the page” She recogntzed words spelled aloud and tactilely (graphesthesia). and she spelled correctly. Numbers were correctly read. Unless directed to the left margin. the patient often began to read in the mtddle of the page. Honever. she btsected aline.counted 15dotsscattered overapage,setaclockandplaced thenumbersofaclockmcorrect posttion. Tacttle extinction. dressing apraxia, topographic disorientation and loss of topographic memory were not present. She copied a house front. trtangle and square but could not reproduce the three-dtmenstonal aspect of a cube Simultanagnosia and visual agnosia for objects. faces and hngers. acalcuha and right-left dtsortentatton were absent. Computed tomographic (CT) scans (5 mm sections) at the ttme of the tctus and four months later showed a stngle infarct, m the terrttory of the right postertor cerebral artery (Fig. 2). DISCUSSION The central feature of thts case was loss of the ability to read with preservation of the abtltty to wrne Alexta without agraphia (pure alexia) from a single, right occipital lesion is rare: only four cases have been reported-- three in rtght-handers 115, ?I, 261 and one in a left-hander [12]. In the last patient [I??], an infarct resulted ma dense left homonymous hemianopia. color anomia and alexia. The alexia was incomplete: letters and SO”, of words were read FIG I. (A) Sample of patient’s writing to dictation. (B) Patient’s in script (above) and Gregg shorthand copy (below) of a phrase in block letters (above). (below). FIG. 2. CTscan. The infarct involves (a) the right inferomedial temporal lobe; (b) poslerior thalamus: (c) mrd~;~l nnd lareral occipital lobe: (tl) forceps mqor: (e) splenium ofthe corpus callosum and (f) the mos1 posterwr portion of the p;irielal lobe. NOTE 625 correctly. The reading of numbers was not reported. The case [12] cannot be considered an example of unilateral right cerebral representation of reading. because it is possible that the residual readmg ability inhered in the left. not the right, hemisphere; in other words. there may have been bilateral representation of reading. Interestingly. an intracarotid amobarbital test demonstrated left cerebral laterality of speech. In our patient. the presence of anemic aphasia indicated some degree of right hemtsphere representalion of speech but does not exclude bilateral representation. Spatial dysplexia, a variety of reading disability associated more often than alexia with a right cerebral lesion. 1s due to left visual neglect and takes the form of verbal paralexias. substitutions. omissions and errors restricted to the left homonymous visual field [22]. It is not. however. a true alexia. since patients correctly read what falls m thetr right visual fields, Prominent associated signs include a left cortical sensory defictt and tactile extinctton. constructional apraxia and topographic disorientation. reflecting the location of the lesion in the parietal lobe: smce the dominant hemisphere is not involved. individual letters are read correctly and there is no aphasta. Our patient. however. demonstrated true alexia without agraphia. not spatial dyslexia. Reading of letters as well as words was impaired. Although paralexic errors involving only the left side of a word were observed. they were not the only type oferror. are not specific for spatial dyslexia and have been described in alexia without agraphta [23]. Reading words letter by letter (spelling dyslexia) [2. 6. 321 and the illusion of movement of printed material [I!. 3) are typical of pure alexia in right-handers. The prominent associated sign was a mild anemic aphasia. probably the result of extension of the infarct into the inferomedial temporal lobe [I] or posterior thalamus [27. 281; vtsual neglect and constructional apraxia. though present. were mild. Finally. the infarct was located mainly in the occipital lobe. There was no evidence of a lesion in the left hemisphere. Mild degrees of constructional apraxia may be present with lesions in either hemisphere [25], and in left-banders, like right-handers. the sign is more common with right cerebral lesions [20]. In our patient both constructional apraxia and left visual neglect were probably due to the extension of the infarct into the right parietal lobe. Alexia without agraphia or right hemianopia has been reported in several right-handed patients with lesions in the left occipital lobe ventral to the calcarine cortex and optic radiation and in the splenium of the corpus callosum [4]. and in one right-hander with a lesion just deep to the left posterior insula [ 173. The presence of such lesions in our patient can be excluded on clinical and radiologic grounds. Most of those patients had abnormalities. such as visual extinction or hallucinations. in their right homonymous fields, and in all the patients the lesions were of a size large enough to be easily detected by CT scanning. No second lesion (in the left or right hemisphere) need be invoked to account for the dysnomia. Although not an essential feature of the syndrome. dysnomia often figures as part of the clinical picture of alexia without agraphia in righthanders and may represent an anemic aphasia as in the present patient and others [Z, 23.321. or an ‘optic‘ aphasia [24]. Also, in our patient the onset of dysnomia coincided temporally with that of alexia and hemianopia. Our patient. like 3&600, of right-handers with pure alexia [IO, 141. did not show color anomia. in the majority of righthanded patients with pure alexia. the site of the lesion is. as in our patient, the occipital lobe and the splenium of the corpus callosum, or its extension. the forceps major, but of the left hemisphere [IO]. In short, in the case of this lefthander the clinical and anatomic features conformed as a mirror image to those of alexia without agraphta as seen in right-handed patients. The conclusion of this analysis is that a single. right hemisphere infarct resulted in pure alexia. The alexia was permanent and as severe as in affected right-handers (with a left-sided lesion). in whom. presumably, language representation is unilateral. The reading of words was practically abolished; that of letters was less affected and that of numbers was spared. This pattern is also seen in the majority of right-handed patients and does not indicate an incomplete or mild form of the syndrome [6]. Had reading been represented in both the right and left hemtspheres of our patient. a unilateral lesion would not have resulted in a permanent. complete syndrome of pure alexia. It is reasonable. therefore, to infer complete right cerebral laterality of reading in this left-hander. Satz has shown that relationships between handedness and cerebral dominance inferred from the study of pathologtcal left-handers (mainly epileptics and the mentally retarded) may not hold for natural left-handers [30]. In our patient there was no clinical evidence of early brain damage. which might have led to a shift of cerebral dominance. Moreover. the patient’s family history of sinistrality suggests that her left-handedness was genetically determined. Thus she must be viewed as a natural left-hander. Recently a non-familial left-hander with a permanent. classic Wernicke aphasia from a right temporo-parietal infarct was reported as an example of unilateral right cerebra1 representation of language [I I]. Current models of language laterality in natural left-handers that posit either left or bilatertal localization [7-9. 18. I93 should be reevaluated in the light of that and the present cases, which demonstrate that language functions may also be unilaterally represented in the right hemisphere. REFERENCES 1. ADAMS. R. D. and VICTOR. M. Principles qf Neurolo.qy. p. 332. McGraw-Hill, New York. 1981. 2. AJAX. E. T. Dyslexia without agraphta: prognostic considerations. Archs Neural. 17, 645--652. 1967. 3. AJAX. E. T.. SCHENKENBERC;.T. and KASTELJANETZ, M. Alexia without agraphia and the inferior splenium. Neuroloq~ 27. 685-6X8, 1977. 626 NOTE 4. ALBERT, M. L. Alexia. In Clinical Neuropstrho/o,y~. K. M. HF~ILMANand E. VALENSTEIN(Editors). pp. 70 73. Oxford University Press, New York, 1979. 5. ANNETT, M. A classification of hand preference by association analysis. Br. J P.+Io/. 61, 303-321. 1970 6. BENSON. D. F. and GESCHWIND. N. The alexias. In Handbook of Clinical Neuroloy~~.P. J. VIUKEN and G. H’ BRUYN (Editors). Vol. 4. North-Holland, Amsterdam, 1969. 7. BROWN. J. W. and H~CAEN. H. Lateralizatlon and language representation: observations on aphasia in children, left-handers. and “anomalous” dextrals. Netrrolo,yj, 26, 183-189, 1976. 8. BROWN, J. W. and JAFFE. J. Hypothesis on cerebral dominance. Neurops.vcho/t)yia 13, 107-l 10. 1975. 9. CARTER, R. L., HOHENEGGER. M. and SATZ. P. Handedness and aphasia: an inferenttal method for determmmg the mode of cerebral speech specialization. Neuropswholoyia 18, 569-574. 19X0. 10. DAMASIO, A. R. and DAMASIO. H. The anatomic basis of pure alexia. Neurolo,yr 12, l573- 1583. 19X3. 1 I. DELIS, D. C.. KNIGHT, R. T. and SIMPSON. G. Reversed hemispheric orgamzatlon m a left-hander Neurops.vcho/o,yia 21, 13-24. 1983. 12. ERKULVRAWATR. S. Alexla and left homonymous hemianopia in a non-right-hander. Antr. ,Vt,urcd. 3,549-552. 1978. 13. GLONING. K. Handedness and aphasia. Neuropsvcho/o,yia 15, 355-35X. 1977 14. GLONING. I., GLONING. K. and How. H. Neurops)rholo,ylca/ Symproms and Swdromes rn Lesrons of rhe Occrpilal Lobe and Adjocenr Areas. Gauthier-Vtttars. Parls, 196X. 15. GLONING. 1.. GLONING, K.. SEITELBERGER.F. and TSCHABITSCHER.H. Em fall von remer wortblmdhelt mlt obduktionsbefund. Wein Z. Nerrenheifkd 12, 194215. 1955. 16. WDGLASS. H. and QUADFASEL, F. A. Language laterality in left-handed aphasics. Brur?~ 77, 521~ 54X. 1954. 17. GREENBLATT, S. H. Subangular alexia without agraphia or hemianopsia. Brain Lang. 3, 229 245, 1976. IX. HARDYCK. C. A model of individual differences in hemispheric functlonmg. In Sludres ,n Neurolingursrrcs. H. WHI~AKER and H. A. WHITAKER (Editors), Vol. 3. Academic Press. New York. 1977. 19. HARDYCK. C. and PETRINOVICH. L. F. Left-handedness. fswhol. Bull. 84, 385404. 1977. 20. H~~(.AEN.H.. AGOSTINI, M. DE and MONZON-MONTES, A. Cerebral organization m left-handers. Brain Latlg. 12, 261-284. 1981. 21. HIROSE, G., KIN, T. and MURAKAMI, E. Alexia without agraphlaassociated with right occlpltal lesion. J. Neural. Neurosury. Ps.vchiar. 40, 225-227. 1977. 22. K~NSBOURNE, M. and WARRINGTON. E. K. A variety of reading dlsdbilit) associated with right hemisphere lesions. J. Neural. Neurosucy. Psvchiar. 25, 339-344. 1962. 23. LEVINE, D. N. and CALVANIO. R. A study of the visual defect in verbal alexla-simultanagnosla. Brurn 101,65%X1. 1978. 24. LHERMITTE. F. and BEAUVOIS. M. F. A visual-speech disconnexion syndrome: report of a case with optic aphasia. agnosic alexia, and colour agnosia. Brain 96, 695 -714, 1973. 25. MCFIE. J.. RERCY, M. F. and ZANGWILL. 0. L. Visual-spatial agnosia associated with lesions of the right cerebral hemisphere. Brain 73, 167-190. 1950. 26. MOCHIZUKI. H.. SUGISHITA. M., TOHGI, H. and SATOH. Y. Alexis without agraphla wtth right occipital lobe lesion in a rrght-hander. C/in. Neural. 20, 75&756. 1980. 27. OJEMANN, G. A. Subcortical language mechanisms. In Sfudies m Nruro/rr~~~~r~.srrt~.s, H WHITAUX and H. A. WHITAKER (Editors). Vol. I. Academic Press. New York. 1976. 2X. OJEMANN. G. A.. FEDIO. P. and VAN BUREN. J. Anomla from pulvmar and subcortical parletal stimulatton Brain 91, 99-I 16. 197X 29. RASMUSSE&,T. and MILNER. B. The role of early left-brain injury In determining lateralkzation of cerebral speech functions. In Erolurio~r and Lareroli~arion of /he Bruin, S. J. DIMONII and D. A. BLIZARI) (Editors). pp. 355-369. New York Academy of Sciences. New York. 1977. 30. SATZ. P. Pathological left-handedness: an explanatory model. Car/c.\- 8. 171 1.15,1972. 3 I. SUBIRANA. A. Handedness and cerebral dominance. In Hum/book o/ C//t~rcu/ Ncurol~q~~.P. J. VIKEN and G. W BRUYN (Editors). Vol. 4. North-Holland, Amsterdam. 1969. 32. WARRINGTOPI;.E. K. and SHALLICE. T. Word-form dysplexla. Brairr 103, 99 I I?. 1980. 33. ZANCWILL. 0. Cerebral Domimmcv and its Re/u/imi IO P.~~,c,/io/o!/rc.cr/ Fwrc/iou. Oliver and Boyd. Edinburgh. 1960.