Background
and Objective : Visual evoked potentials(VEPs) is considered to be a reliable diagnostic procedure for examining patients with anterior visual pathwyas. Some abnormalities in the recording on monocular stimulation have been said to indicate retrochiasmal lesion, but less consistent results have been reported. This study is to evaluate the positive predictability of VEP for the detection of retrochiasmal lesion. Methods : We reviewed VEPs that could be interpreted as indicative of a retrochiasmal lesions, based on amplitude or latency asymmetry recorded on the left(O1) and right(O2) occipital regions. Bilateral absent VEPs on both recording(O1 and O2) without evidence of prechiasmal lesions were included. During 5 years, we identified 31 patients who met the above criteria and who had undergone magnetic resonance imaging(MRI) of brain(one patient underwent computerized tomography). Twenty three patients underwent pattern reversal VEPs

Background
: The pathogenesis of acute inflammatory demyelinating polyradiculoneuropathy (AIDP), Guillain-Barr?syndrome (GBS) in not clear, but it has been known that the immune mechanisms play an important role. Authors performed this study to establish an animal model of experimental allergic neuritis(EAN) by immunizing the myelin components of peripheral nerves and to understand the electrophysiological and histopathological features as well as the CD5+ B-lymphocyte changes in peripheral bloods in the EAN models. Methods : Lewis rats weighing 150-200 gm were injected subcutaneously in soles two with total myelin, P0, P1, or P2 proteins purified from the bovine cauda eguina. The EAN induction was assessed by evaluating clinical manifestations. The electrophysiological and histopathological features were studied as routine methods. The CD5+ B-lymphocyte were double stained using monoclonal FITC conjugated anti-rat CD45RA and R-PE conjugated anti-rat CD5+antibodies and calculated using a fluorescence activated cell sorter (FACS). Results : The EAN animal models were established. In two out of five, in one out of two, in none out of three, and in none out of one Lewis rats injected with purified total myelin, P0, P1, P2 proteins respectively. They showed slow spontaneous motor activity and weak resistance against pulling back by tails. The typical electrophysiological and histologic findings in total protein and P0 induced EAN animal models were the decreased conduction velocity, the decreased compound muscle action potential (CMAP) amplitude and the dispersion phenomenon. The perivascular infiltrates of lymphocytes with focal demyelinating process were found in light microscopy. The CD5+ B-lymphocyte expression in three EANs were 2.38%, 3.50% 2.50%, which were not significantly increased, compared with those in normal controls. Conclusion : The EAN animal models were successfully established by injecting the total myelin and P0 myelin and they showed electrophysiological and histological features typical of demyelinating process. However they did not show an increased expression of CD5+ B-lymphocyte in peripheral bloods which could be indirect evidence of humoral autoimmunity.