Recovery of visual-field defects after occipital lobe infarction: a perimetric study.

OBJECTIVE: To assess the temporal course of homonymous visual-field defects due to occipital lobe infarction, by using automated perimetry. METHODS: 32 patients with ischaemic infarction of the occipital lobe were studied prospectively, using a Humphrey Visual Field Analyser II. The visual field of each eye was divided into central, paracentral and peripheral zones. The mean visual sensitivity of each zone was calculated and used for the statistical analysis. The results of the initial examination, performed within 2 weeks of stroke, were compared with the results of the sixth-month control. The lesions were assigned to the localisations, optic radiation, striate cortex, occipital pole and occipital convexity, by MRI. RESULTS: A statistically significant improvement was noted, especially for the lower quadrants. Lesions of the occipital pole and convexity were not significantly associated with visual-field recovery. However, involvement of the striate cortex and extensive lesions involving all the areas studied was significantly associated with poor prognosis. CONCLUSIONS: Homonymous visual-field defects in our patients improved within 6 months. Restoration of the lower quadrants and especially the peripheral zones was noted. Incomplete damage to the striate cortex, which has a varying pattern of vascular supply, could explain this finding. Magnification factor theory, which is the increment of the receptive-field size of striate cortex cells with visual-field eccentricity, may explain the more significant improvement in the peripheral zones.

Balance in posterior and horizontal canal type benign paroxysmal positional vertigo before and after canalith repositioning maneuvers.

Benign paroxysmal positional vertigo (BPPV) is characterized by acute, brief and rotatory vertigo attacks provoked by changes in head position. Most patients complain of a loss of equilibrium and unstable gait during and between the vertigo attacks. Canalith repositioning maneuvers (CRM) relieve attacks and improve postural stability. In this study balance ability of 32 patients with PC BPPV and 12 patients with HC BPPV before and after treatment with CRM was investigated. 50 healthy volunteers served as the control group. Static balance was measured as mean center of gravity sway velocity recorded in four different conditions: on a static platform and on foam with eyes open and closed. Dynamic balance was measured in tandem walk test. PC BPPV patients demonstrated greater sway velocity in stance on foam with eyes closed. After CRM the velocity decreased significantly. The results of the HC BPPV patients were not different from the healthy volunteers all through the four test conditions. Walking speed of the patients both with PC BPPV and HC BPPV was significantly low. It increased after treatment in both groups. In conclusion, patients with PC BPPV had impaired static balance ability due to a clot in the affected canal. Dynamic balance ability measured by walking speed was impaired both in PC and HC BPPV patients. Static and dynamic deficits improved significantly after CRM.