Quadrantanopia

Abstract: Fourteen (74%) of 19 patients obtained a significant reduction in seizures after posterior corticectomy; 6 (32%) were seizure-free over a median follow-up of 3.7 years (range, 1 to 14 years). Surgery included limited resections of the occipital lobe in 16 patients, posterior temporal region in 11, and posterior portion of parietal lobe in 7. Surgical failure related to probable multiple areas of epileptogenesis (4 patients), or limited resections (2 patients) to preserve visual fields (2 patients) and to avoid dyslexia (1 patient). Of 14 patients without a complete hemianopia preoperatively, 6 (43%) developed a new or increased visual field deficit, 2 (14%) of which were hemianopia. Four (36%) of 11 occipital lobe resections resulted in a new or increased visual field deficit: quadrantanopia in 3 and hemianopia in 1. Visual phenomena were the most common initial ictal symptoms, occurring in 13 (68%) of the 19 patients. Twelve patients had complex partial seizures: in 2, always without warning; in 7, always following an aura, usually visual; and in 3 patients, with or without warning. Scalp electroencephalography identified the origin of most recorded seizures in 12 (63%) of the 19 patients. A principal interictal spike focus appeared in 15 patients (79%), and always correlated with the epileptogenic lobe as defined by scalp and/or subdural-recorded seizures (14 patients) or by clinical analysis and computed tomography (1 patient).

Abstract: PURPOSE: This study was designed to examine the on-road driving performance of drivers with hemianopia and quadrantanopia compared with age-matched controls. METHODS. Participants included persons with hemianopia or quadrantanopia and those with normal visual fields. Visual and cognitive function tests were administered, including confirmation of hemianopia and quadrantanopia through visual field testing. Driving performance was assessed using a dual-brake vehicle and monitored by a certified driving rehabilitation specialist. The route was 14.1 miles of city and interstate driving. Two “back-seat” evaluators masked to drivers’ clinical characteristics independently assessed driving performance using a standard scoring system.--- RESULTS: Participants were 22 persons with hemianopia and 8 with quadrantanopia (mean age, 53 20 years) and 30 participants with normal fields (mean age, 52 19 years). Inter-rater agreement for back-seat evaluators was 96%. All drivers with normal fields were rated as safe to drive, while 73% (16/22) of hemianopic and 88% (7/8) of quadrantanopic drivers received safe ratings. Drivers with hemianopia or quadrantanopia who displayed on-road performance problems tended to have difficulty with lane position, steering steadiness, and gap judgment compared to controls. Clinical characteristics associated with unsafe driving were slowed visual processing speed, reduced contrast sensitivity and visual field sensitivity.--- CONCLUSIONS: Some drivers with hemianopia or quadrantanopia are fit to drive compared with age-matched control drivers. Results call into question the fairness of governmental policies that categorically deny licensure to persons with hemianopia or quadrantanopia without the opportunity for on-road evaluation.

Abstract: PURPOSE: The purpose of this study was to investigate the relationship between visual field loss and driving performance as determined by on-road driving assessments. METHODS: We reviewed the files of 1350 patients enrolled in a rehabilitation program at the Bloorview MacMillan Rehabilitation Centre, Toronto, Canada. We identified 131 patients with visual field loss who had undergone an on-road driving assessment. These patients had a primary diagnosis of visual impairment or a primary diagnosis of cerebral vascular accident (CVA) with a secondary diagnosis of visual impairment. None of these patients had documentation of neglect, substantial motor or cognitive deficits. We report the data obtained from 13 hemianopics, 7 quadrantanopics, 25 patients with monocular vision, 10 patients with moderate peripheral losses (<135 degrees of horizontal visual field measured at the midline), and 76 patients with mild peripheral losses (between 135 degrees and 186 degrees of horizontal visual field). The on-road assessment consisted of driving in the area surrounding the rehabilitation center, and the outcome was based on performance on a number of tasks commonly encountered in daily driving. For the purposes of this study, the assessment outcomes were classified as safe, unknown, or unsafe. RESULTS: Overall, the extent of visual field loss did not have a significant impact on driving performance (chi2 = 4.37, p = 0.358). However, hemianopia tended to have a worse impact on driving performance than quadrantanopia with a marginally significant result (chi2 = 3.33, p = 0.068). Overall, the location of the visual loss was not significantly related to driving fitness (chi2 = 1.05, p = 0.30). However, localized defects in the left hemifield (chi2 = 9.561, p = 0.002) and diffuse visual loss in the right hemifield (chi2 = 10.395, p = 0.001) seemed to be associated with driving impairments. A large proportion of monocular drivers were safe drivers and the location of their deficit had no significant impact. CONCLUSIONS: Although the extent of visual field defects appears to be related to driving performance as determined by an on-road driving assessment, large individual differences were observed. This highlights the need for individualized on-road assessments for patients with visual field defects.