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Show Journal of Ncuro- Ophthalmology 15( 2): 102- 104, 1995. © 1995 Raven Press, Ltd., New York Alexia Without Either Agraphia or Hemianopia in Temporal Lobe Lesion Due to Herpes Simplex Encephalitis Sevim Erdem, M. D. and Tiilay Kansu, M. D. We report a case of alexia without either agraphia or hemianopia following herpes simplex encephalitis. The patient had a temporal lobe lesion with involvement of the occipitotemporal gyrus. This is an unusual cause of alexia without agraphia. The location of the lesion supports the view that transcallosal fibers from the right hemisphere to the left angular gyrus course inferior to the posterior horn of the left lateral ventricle and pass close to the left occipitotemporal gyrus. Key Words: Alexia without agraphia- Herpes simplex encephalitis- Occipito- temporal gyrus. Alexia without agraphia was first described by Dejerine in 1892 ( 1), and since then many cases with left occipital lobe and splenium lesion associated with contralateral hemianopia have been reported ( 2- 4). Later, patients without hemianopia were reported, and the different localizations of lesions suggested that any lesion preventing bilateral visual stimuli from reaching the left angular gyrus might produce alexia without agraphia ( 5- 16). In this paper, we report a case of alexia without either agraphia or hemianopia in a patient with a lesion predominantly in the temporal lobe involving the occipitotemporal gyrus due to herpes simplex encephalitis. Manuscript received March 16, 1994; revised September 16, 1994. From the Department of Neurology, Hacettepe University Hospitals, Ankara, Turkey. Address correspondence and reprint requests to Dr. Tiilay Kansu, Department of Neurology, Neuro- Ophthalmology Unit, Hacettepe University Hospitals, Ankara, Turkey 06100. CASE REPORTS A 47- year- old right- handed man was admitted with a history of headache for 20 days, fever and confusion for a week. On admission he was stuporous, unable to understand questions, and speech was limited to a few words. Visual field defect was not detected by confrontation, and there was no motor or sensory deficit. Two lumbar punctures performed in another hospital prior to admission revealed lymphocytic pleocytosis ( 77 per mm3). Protein was 0.79 g/ L ( 79 mg/ dl), glucose 3.9 mmol/ L ( 70 mg/ dl) and simultaneous blood glucose 6.5 mmol/ L ( 117 mg/ dl). Electroencephalogram ( EEG) showed diffuse delta- wave background activity and periodic lateralized epileptiform discharges in the left temporal area. Magnetic resonance imaging showed a diffuse left fronto-temporal hypointense lesion on Tl- weighted and hyperintense lesion on T2- weighted images involving the occipitotemporal gyrus ( Fig. 1). The presence of confusion, fever, pleocytosis, and elevation of cerebrospinal fluid protein, EEG, and 102 ALEXIA WITHOUT AGRAPHIA IN HERPES 103 FIG. 1. ( a) coronal T1- weighted postcontrast and ( b) axi the temporal lobe lesion involving the occipitotemporal magnetic resonance imaging findings were thought to be compatible with herpes simplex encephalitis. Intravenous acyclovir 750 mg t. i. d. was started and continued for 20 days. The diagnosis was not confirmed by biopsy because consciousness and speech began to improve after the third day of therapy. The patient had difficulty in remembering recent events. Spontaneous speech was fluent and well articulated but not meaningful. He had difficulty in finding words but not in repetition. Reading ability was severely disturbed, he was only able to identify a few letters and unable to read words or sentences. He could not name the colors, was able to write spontaneously or by dictation, but had some errors in copying sentences. He could read numbers and make simple mental calculations. Repeat visual fields by confrontation and Goldmann perimetry failed to show a visual field defect. Three months later, he could read much better, reading whole words or syllables instead of single letters. Word finding difficulty still persisted but improved. Color naming difficulty was still present. A repeat magnetic resonance imaging 1 month later showed the persisting hyperintense lesion in the left temporal lobe, including the occipitotemporal gyrus ( Fig. 2). DISCUSSION Alexia without visual field defects is caused by disconnection of the pathways from the bilateral al T2- weighted magnetic resonance images demonstrate gyrus. visual cortex to the dominant angular gyrus. Visual information from the right calcarine cortex first reaches the ipsilateral lingual and occipitotemporal gyri, then the contralateral lingual and occipitotemporal gyri through the splenium ( 17). Although the shortest course for fibers passing through the splenium would be to go superior to the left lateral ventricle, pathology of cases with pure alexia have lesions in the pathway through FIG. 2. Repeat magnetic resonance imaging 1 month later showed persistence of the occipitotemporal gyrus lesion. / Neuro- Ophthalmol, Vol. 15, No. 2, 1995 104 S. ERDEM AND T. KANSU the inferior wall of the posterior horn of the left lateral ventricle ( 17). Visual information from the left visual cortex arrives at the association areas, and from there bilateral visual information is transmitted to the dominant angular gyrus through a pathway that Greenblatt ( 18) called the " vertical occipital fasciculus." This pathway runs close to the occipitotemporal and temporal gyri ( 13). Alexia without hemianopia occurs due to lesions in the left inferior occipitotemporal region or more superiorly and rostrally, undercutting the angular gyrus ( 17). We were able to document 12 cases of alexia without agraphia with preserved visual fields and anatomic localization ( Table 1). Four patients ( 7,8,10,16) had lesions subjacent to the left angular gyrus and others ( 5,6,9,11- 15) had lesions involving the occipitotemporal gyrus. In our case there was no visual field defect. The occipital cortex and splenium were intact but the TABLE 1. Cases of pure alexia without hemianopia Author ( Ref.) Lesion location and etiology Ajax, 1967 ( 5) Greenblatt, 1973 ( 6) Greenblatt, 1976 ( 7) Assal and Hadj- Djilani, 1976 ( 8) Vincent et al., 1977 ( 9) Pizorollo et al., 1981 ( 10) Castro- Caldas, 1984 ( 11) Uitti et al., 1984 ( 12) Henderson et al., 1985 ( 13) Weisberg et al., 1987 ( 14) Caffarra, 1987 ( 15) Iragui, 1991 ( 16) Excision of vascular malformation on undersurface of left occipital lobe impinging upon the lingual and probably the fusiform gyrus Glioblastoma involving left occipitotemporal gyrus, subcortical white matter of inferior left occipital lobe and splenium Excision of vascular malformation inferior to the left angular gyrus Left parietal- occipital hemorrhage Occipitotemporal compression by tentorial meningioma embedded in left inferior temporal lobe Left parietal hemorrhage underlying the angular gyrus Hypodensity in the mesial and inferior occipital lobe extending deeply into the white matter Left occipitotemporal and right frontal lobe metastasis of colon cancer Left occipitotemporal and inferior temporal gyri hemorrhage Left posteroinferior temporal hematoma Lateral temporo- occipital hematoma Parieto- occipital ischemic infarction temporal lobe and occipitotemporal gyrus were affected. Therefore we think that alexia without agraphia was caused by the temporooccipital gyrus lesion and interruption of information on the way to the angular gyrus from the visual association cortex. This finding supports the view that visual pathways needed for reading arise from or pass close to the visual association cortex of the left occipitotemporal gyrus or the inferior temporal gyrus ( 13). Although not confirmed by biopsy the clinical and radiological impression was herpes simplex encephalitis in our patient, and to our knowledge this is the first reported case of alexia without either agraphia or hemianopia caused by herpes simplex encephalitis. REFERENCES 1. Dejerine J. Sur un cas de cecite verbale avec agraphie, suivi d'autopsie. Mem Soc Biol 1891; 3: 197- 201. 2. Damasio AR, Damasio H. The anatomic basis of pure alexia. Neurology 1983; 33: 1573- 83. 3. Stommel EW, Friedman RJ, Reewes AG. Alexia without agraphia associated with spleniogeniculate infarction. Neurology 1991; 41: 587- 8. 4. Quint DJ, Gilmore JL, Alexia without agraphia. Neuroradiology 1992; 34: 210- 14. 5. Ajax ET. Dyslexia without agraphia. Arch Neurol 1967; 17: 645- 52. 6. Greenblatt SH. Alexia without agraphia or hemianopsia: anatomical analysis of an autopsied case. Brain 1973; 96: 307- 16. 7. Greenblatt SH, Subangular alexia without agraphia of hemianopsia. Brain Lang 1976; 3: 229^ 5. 8. Assal G, Hadj- Djilani. Une nouvelle observation d'alexie pure sans hemianopsie. Cortex 1976; 12: 169- 174. 9. Vincent FM, Sadowsky CH, Saunders RL, Reeves AG. Alexia without agraphia, hemianopia or color- naming defect: a disconnection syndrome. Neurology ( Minneap) 1977; 27: 689- 91. 10. Pirazzolo FJ, Kerr KL, Obrzut JE, et al. Neurolinguistic analysis of the language abilities of a patient with a " double disconnection syndrome": a case of subangular alexia in the presence of mixed transcortical aphasia. / Neurol Neu-rosurg Psychiatry 1981; 44: 152- 5. 11. Castro- Caldas A, Salgado V. Right hemifield alexia without hemianopia. Arch Neurol 1984; 41: 84- 7. 12. Uitti R], Donat JR, Romanchuk K. Pure alexia without hemianopia [ letter]. Arch Neurol 1984; 41: 1130. 13. Henderson VW, Friedman RB, Teng EL, Weiner JM. Left hemisphere pathways in reading: inferences from pure aleksia without hemianopia. Neurology 1985; 35: 962- 8. 14. Weisberg LA, Wall M: Alexia without agraphia: clinical computed tomographic correlation. Neuroradiology 1987; 283- 6. 15. Caffara P. Alexia without agraphia or hemianopia. Eur Neurol 1987; 27: 65- 71. 16. Iragui VJ, Kritchevsky M. Alexia without agraphia and hemianopia in parietal infarction. / Neurol Neurosurg Psychiatry 1991; 54: 841- 6. 17. Henderson VW. Anatomy of posterior pathways in reading: a reassessment. Brain Lang 1986; 29: 119- 33. 18. Greenblatt SH. Left occipital lobectomy and preangular anatomy of reading. Brain Lang 1990; 38: 576- 95. / Neuro- Ophthalmol, Vol. 15, No. 2, 1995 |
