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Show ORIGINAL CONTRIBUTION Homonymous Hemianopia in Stroke Xiaojun Zhang, MD, Sachin Kedar, MD, Michael J. Lynn, MS, Nancy J. Newman, MD, and Valerie Biousse, MD Background: Previous reports have suggested that most cases of homonymous hemianopia ( HH) are caused by occipital stroke. However, these reports have not always been supported by brain imaging. Methods: We reviewed the medical records of all patients seen in our unit between 1989 and 2004 who had HH documented by formal perimetry or confrontation visual fields and had undergone brain imaging. HHs were divided into those caused by stroke and by non- stroke conditions. The clinical and visual field characteristics were compared in the two groups. Results: Among 850 patients with 902 HHs, 629 ( 69.7%) resulted from stroke, of which 531 ( 84.4%) were from infarction and 98 ( 15.6%) from primary intraparenchymal hemorrhage. Non- stroke causes included head trauma ( 123), brain tumor ( 102), neurosurgical procedures ( 22), multiple sclerosis ( 13), and miscellaneous conditions ( 13). Occipital lesions most commonly resulted from stroke. The configuration of the HH did not predict where in the retrochiasmal visual pathway the responsible lesion lay. Conclusions: Ischemic stroke causes most HHs from lesions in the occipital lobe that generally do not produce other neurologic manifestations. The configuration of the HH does not predict the location of the lesion within the retrochiasmal visual pathway. (/ Neuro- Ophthalmol 2006; 26: 180- 183) Departments of Ophthalmology ( YZ, SK, NJN, VB), Neurology ( NJN, VB), and Neurological Surgery ( NJN), Emory University School of Medicine, Atlanta, Georgia; and the Department of Biostatistics ( MJL), Rollins School of Public Health of Emory University, Atlanta, Georgia. This study was supported in part by a departmental grant ( Department of Ophthalmology) from Research to Prevent Blindness, Inc., New York, NY, and by core grant P30- EY06360 ( Department of Ophthalmology) from the National Institutes of Health, Bethesda, Maryland. Dr. Newman is a recipient of a Research to Prevent Blindness Lew R. Wasserman Merit Award. Dr. Zhang was supported by unrestricted educational grants from NovaVision and TEVA Neuroscience. Address correspondence to Valerie Biousse, MD, Neuro- Ophthalmol-ogy Unit, Emory Eye Center, 1365- B Clifton Road, NE, Atlanta, GA 30322; E- mail: vbiouss@ emory. edu Homonymous visual field ( VF) defects impair visual function and frequently preclude driving ( 1- 4). Stroke is the most common cause of homonymous hemianopia ( HH) and approximately 10% of patients with stroke are found to have a HH, which may affect their functional neurologic outcome ( 1- 5). Interestingly, a large number of these patients are not aware of their VF defect and most are still driving ( 4). Most of our knowledge of HH in stroke is based on relatively few small series ( 1- 3,6- 14). However, these reports have not always been supported by brain imaging. This study describes the characteristics of HH caused by stroke in a large number of cases. METHODS We reviewed the medical records of all patients with HH seen in our unit between 1989 and 2004 as detailed in another report ( 15). All patients with a HH, detailed clinical information, and results of brain CT or MRI were included. Patients with a diagnosis of neglect were not included. Demographic characteristics, clinical features, characteristics of VF defects, causes of VF defects, neuroradiologic definition of lesion location, and associated neurologic deficits were recorded. Cases with bilateral HH were recorded twice so that each HH ( right and left) could be analyzed separately. All patients had a HH confirmed by Goldmann visual field testing ( GVF), Humphrey visual field testing ( HVF), or confrontation visual field examination. Humphrey visual fields were performed on the 24- 2 or 30- 2 full threshold program until the year 2000 and on the SITA- fast or SITA- standard programs after 2000. All GVF tests were performed in a standardized way by the same experienced technician. All confrontation visual field examinations were performed by an experienced neuro-ophthalmologist ( NJN and VB) using hand movement, finger counting, and color comparison ( red saturation across the vertical meridian). Reliability of HVFs was determined based on the number of fixation loss, false-positive and false- negative responses. Patients with unreliable HVF were tested with GVF. Reliability of GVF was determined by our technician and was based on accuracy of fixation and consistence of responses. HHs were classified into " complete" and " incomplete," the latter including homonymous quadrantanopia 180 J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 Homonymous Hemianopia in Stroke J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 ( superior and inferior homonymous visual field defects respecting both the vertical and horizontal meridians), partial HH ( incomplete HH not respecting the horizontal meridian), HH with macular sparing ( homonymous visual field defect sparing the central 5- 25° of visual field on the affected side), homonymous scotomatous defects, and homonymous sectoranopia as detailed in another report ( 15). Congruency was denned as visual field defects identical in size and shape in both eyes. The location of brain lesion was determined based on the head CT or brain MRI report ( 15). HHs were divided into two groups according to cause as stroke and non- stroke. The stroke group was further divided into infarction and primary intraparenchymal hemorrhage. The mean and the standard deviation or the median, 25th percentile, and 75th percentile were obtained for continuous variables; the percentages in the categories along with the standard errors were obtained for categorical variables. The demographic, clinical, and visual field characteristics were compared using a t test or Wilcoxon rank sum test ( for continuous variables) and a x2 test ( for categorical variables). RESULTS Among the 904 HHs included in our study, 629 ( 69.7%) resulted from stroke and 273 HHs ( 30.3%) from other conditions, including 123 from head trauma, 102 from brain tumor, 22 from neurosurgical procedures, 13 from multiple sclerosis, 13 from miscellaneous causes, and 2 from undetermined causes ( Table 1) ( 15). Formal visual field testing was obtained in 864 HHs, including 714 GVF, TABLE 1. Comparison of clinical features ofHH Total number of HHs Unilateral Bilateral Age ( Mean ± SD) Range Men Women Time from injury to initial VF test Median ( 25th, 75th percentile) Range Types of VF defects Complete HH Incomplete HH Partial HH HH with macular sparing Homonymous scotomatous defects Homonymous sectoranopia Congruity of VF defects Congruous Incongruous Not available* Associated neurologic deficits present Location of lesion Occipital Optic radiations Optic tract Multiple visual pathway segments Lateral geniculate body Not available * Congruity of visual field defects was not assessed in testing in one eye only. caused by stroke and HH 58 ± 296 293 2 ( 1 , in stroke 589 40 : 17 years 4- 92 ( 50.3%) ( 49.7%) 6) months 0.03- 330 242 387 247 57 81 2 279 97 312 331 ( 38%) ( 62%) ( 39%) ( 9%) ( 13%) ( 0.3%) ( 74%) ( 26%) 11 ( 51%) ( 54%) 200 ( 33%) 39 32 8 ( 6%) ( 5%) ( 1%) 19 non- stroke conditions HHin 36 ± 147 114 5 ( 2, 1 non- stroke 261 12 : 19 years 2- 80 ( 56.3%) ( 43.7%) 15) months 0.03- 420 98 175 131 9 34 1 93 77 156 64 84 51 68 3 ( 36%) ( 64%) ( 48%) ( 3%) ( 13%) ( 0.3%) ( 55%) ( 45%) 5 ( 60%) ( 24%) ( 31%) ( 19%) ( 25%) ( 1%) 3 HH confirmed by confrontation visual field testing only, or in patients P- value 0.03 < 0.0001 0.10 < 0.0001 0.014 < 0.0001 0.013 < 0.0001 who had visual field 181 J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 Zhang et al 115 HVF, and 35 with both GVF and HVF testing. Forty HHs were diagnosed by confrontation visual field testing only. Among these 40 HHs, 24 were complete and 16 were incomplete; all 16 were classified as partial HH. The 629 HHs caused by sfroke included 531 HHs ( 84.4%) caused by cerebral infarction and 98 HHs ( 15.6%) caused by primary infraparenchymal hemorrhage. As shown in Table 1, HH resulting from sfroke occurred in older patients, was more often bilateral and congruous and was more often unaccompanied by other neurologic manifestations (" isolated") than HH resulting from other causes. Occipital lesions were more common in sfroke than in non- stroke cases ( P < 0.0001). There were no significant differences in the frequencies of the different configurations of HH in patients with sfroke and non- stroke patients. The time from injury to initial visual field test tended to be shorter among sfroke cases. Compared with primary infraparenchymal hemorrhage, infarction occurred more often in older patients ( 60 ± 1 7 years vs 50 ± 18 years, P < 0.0001), was more often responsible for bilateral HH ( 40 vs 0, P = 0.001), and involved the occipital lobes more often relative to optic radiations ( 56% occipital vs 45% occipital and 30% optic radiations vs 47% optic radiations, respectively, P < 0.05). The configuration of the HH did not reliably predict the location of the responsible lesion within the refro-chiasmal visual pathway ( Fig. 1). DISCUSSION This report is the largest series of HHs secondary to sfroke. All patients were referred to our service for VF testing either because they had visual complaints or (/> CD </> CO O CD Multiple Segments Visual Cortex Optic Radiations Optic Tract HHMS HQU^ D HSCOT Configuration Of Visual Field Defect FIG. 1. Relationship between location of the lesion and configuration of the visual field defect. HH, homonymous hemianopia; HHMS, homonymous hemianopia with macular sparing; HQUAD, homonymous quadrantanopia; HSCOT, homonymous scotomatous defect; PHH, partial homonymous hemianopia. 182 © 2006 Lippincott Williams & Wilkins Homonymous Hemianopia in Stroke J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 because the treating physician thought the brain lesion could produce visual impairment. Although most patients were sent to us late, the median time was significantly lower for patients with stroke than for patients with other brain lesions ( Table 1). This may reflect better awareness of VF defects in the setting of stroke or possibly better outcome of patients with stroke ( whose HH was more often isolated) than of non- stroke patients. Previous studies have emphasized that most HH is caused by stroke and that most stroke HH is secondary to an occipital infarct ( 1- 3). In these studies, the diagnosis of stroke was based mostly on clinical evaluation and not all patients had undergone brain imaging. Our study, which included neuroimaging in all cases, confirms these results. Previous studies have emphasized that the nature of the lesion may be suggested by the presumed lesion location and the characteristics of the VF defect ( 1- 3). Indeed, macular sparing is considered to result from occipital lesions, specifically occipital infarctions in the distribution of the posterior cerebral artery ( 1- 3,6- 8,10,13,14). Our study showed that macular sparing was not only caused by lesions other than stroke, but also resulted from strokes involving the anterior portions of the visual pathways such as the optic tract. Similar findings were observed for homonymous scotomatous defects. Indeed, it has been previously suggested that one of the causes of macular sparing is incomplete damage to the anterior portions of the retrochiasmal visual pathways ( 3,16). Homonymous scotomatous VF defects have been reported in patients who with lesions of the optic tract after pallidotomy for Parkinson disease ( 17). These VF defects have been attributed to the particular anatomic fiber organization within the optic tract ( 17- 19). This study confirms that stroke is the commonest cause of HH. The long delay between stroke onset and the recognition of HH suggests that HH is often overlooked in patients with stroke. Because HH can interfere with rehabilitation and is associated with a worse functional outcome in patients with stroke, VF testing should be systematically performed in all patients after a stroke involving the cerebral hemispheres. Finally, HH often precludes driving and should be investigated before allowing patients with stroke to drive. REFERENCES 1. Smith JL. Homonymous hemianopia: a review of one hundred cases. Am J Ophthalmol 1962; 54: 616- 22. 2. Trobe JD, Lorber ML, Schlezinger NS. 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