Multi-channel visual evoked potential as an ancillary tool todiagnose intraorbital optic nerve lesions
Fonte: Xiaoliang Li, Yiliang Lu, Liming Li, Xinyu Chai and Qiushi Ren
Illustration of the visual evoked potential recording sites(top view) of a 4·4 electrode-array on the visual cortex area. Left,cortical area was for right eye multi-channel visual evoked potentialrecordings, and right cortical area for left eye. (‘‘fi’’ = dimensional,inter-distance of 3 mm; Digits stand for the number of each electrode.Electrodes No. 1, 5, 9 and 13 were assigned to the lateral side, and 4, 8,12 and 16, to the medial side).
Multi-channel visual evoked potential (MVEP) recording method was used to assist indiagnosing a 4-month-old Chinese Albino rabbit with an intraorbital mass.Subcutaneous MVEP of its both eyes were recorded simultaneously using 16electrodes (4·4) multi-channel array. Analysis of the cortical potential landscapes(CPL) showed that the conduction function of right eye was remarkably impaired interms of decreased amplitudes and prolonged latencies. Specific side-dominantdistribution asymmetry of the decreased MVEP amplitudes indicated that thetemporal side of the optic nerve (ON) was severely involved. Overall prolongedlatencies of the CPL without side differences suggested that the functionalimpairment could have been caused by the mechanical compression exerted by anintraorbital mass. Surgical removal procedures confirmed that the mass was locatedtemporally to the ON. Pathological examination provided a final diagnosis of a giantpolycystic mucocele. Beyond its significance as a standard tool to assess functionalchanges of the visual pathway, MVEP recordings might assist locating intraorbitallesions that involve the ON by careful analysis of abnormal CPLs.