Monocular pattern-shift visual evoked potentials in hemispheric strokes

Abstract

Monocular pattern-shift visual evoked potentials were obtained in (i) 33 patients with unilateral non-hemorrhagic hemispheric infarction (age 50–79 years; 23 males, 10 females), (ii) 21 age- and sex-matched patient controls (control group or CGI) with no remote or recent stroke, normal neurological examination and similar incidence of diabetes mellitus, hypertension and heart disease, and (iii) 21 age- and sex-matched healthy elderly community volunteers (CGII). Subjects with history of glaucoma, cataracts, other media opacities or symptomatic retinal lesions were not considered or included in any of the 3 study groups. In addition, all subjects in each of the 3 groups had a normal ocular and fundoscopic examination. The mean interocular P100 latency difference in the stroke group was significantly greater than that in CGI or II ( P < 0.01). The mean interocular P100 amplitude ratio (small P100/large P100) in the stroke subjects was significantly different from that of CGI or II ( P < 0.02). The mean P100 latency on ocular stimulation ipsilateral to the side of infarction was significantly longer than that of either left or right ocular stimulation in CGI or II ( P < 0.01). The mean P100 latency on ocular stimulation contralateral to the side of infarction was similarly but less significantly longer than that on left or right ocular stimulation in CGI or II ( P < 0.05). Evidence of anterior visual pathway dysfunction was thus elicited in the stroke population using the technique.