EVOKED-POTENTIAL (EP) ALTERATIONS IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS (EAE) - EARLY DELAYS AND LATENCY REDUCTIONS WITHOUT PLAQUES

Experimental allergic encephalomyelitis (EAE) in its chronic relapsing (CR-EAE), chronic progressive (CP-EAE) and acute (A-EAE) forms was ob tained in 24 juvenile strain 13 guinea pigs. Visual, brainstem acousti c and somatosensory evoked potentials (EPs) were recorded in these ani mals prior to the sensitizing injection and during the course of the d isease. Delays in the EPs appeared 15 days post-sensitization (dps), p receding or simultaneously with clinical alterations: electron microsc opy revealed myelin stripping and vacuolation in the animals sacrifice d 25 dps. Decreases in EP latency were recorded 32 dps; when electron microscopy revealed myelin layers indicating remyelination, whereas li ght microscopy showed only inflammatory changes. When confluent plaque s were revealed by light microscopy 120 dps, the EP wave shapes were d istorted or absent. The discussion reviews the literature on early mye lin and conduction changes during central demyelination.