Author/Editor		Brecelj, J; Denišlič, M; Škrbec, M
Title		Visual evoked potential abnormalities in chiasmal lesions
Type		članek
Source		Doc Ophthalmol
Vol. and No.		Letnik 73, št. 2
Publication year		1989
Volume		str. 139-48
Language		eng
Abstract		Pattern reversal visual evoked potentials (VEPs) were recorded from 38 patients with lesions affecting the chiasmal area. Lesions were confirmed by computer tomography and all patients had ophthalmologic examination. VEPs to full-field stimulation (0-16 degrees r) were compared with those obtained with half-field stimulation. Changes in VEPs were seen as a nonrecordable or attenuated P 100 (abnormal amplitude ratio) or as a prolonged P 100. Analysis of the records showed that temporal half-field stimulation (crossed fibers) yielded a higher rate of abnormal responses (80 percent) than full-field stimulation (66 percent). The most frequent abnormality in the former stimulation was a nonrecordable P 100 (42 percent) and in the latter an abnormal amplitude ratio of P 100 (41 percent). When the uncrossed fibers were stimulated with the nasal half-field, abnormalities were detected in 32 percent of responses. Lesions in the region of the sella turcica were also associated with a high incidence of delayed responses (39 percent of patients when crossed fibers were stimulated). However, the magnitude of the delays was smaller (1-32 ms) compared with delays in patients with demyelinating disease. Findings of this study show that half-field stimulation assists in the interpretation of responses to full-field stimulation. In addition, half-field stimulation can reveal abnormalities that are not detected with full-field stimulation.
Descriptors		CRANIAL NERVE NEOPLASMS EVOKED POTENTIALS, VISUAL FORM PERCEPTION OPTIC CHIASM PATTERN RECOGNITION, VISUAL ADOLESCENCE ADULT CRANIAL NERVE NEOPLASMS CRANIOPHARYNGIOMA MENINGIOMA MIDDLE AGE OPTIC CHIASM PERIMETRY PITUITARY NEOPLASMS VISUAL FIELDS VISUAL PATHWAYS