RESTORATION OF CONDUCTION IN THE SPINAL ROOTS CORRELATES WITH CLINICAL RECOVERY FROM EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS

In the Lewis rat, acute experimental autoimmune encephalomyelitis (EAE ) induced by inoculation with myelin basic protein (MBP) and adjuvants is characterized by tail and hindlimb weakness that resolves spontane ously after several days. In rats with neurological signs of this form of EAE (MBP-EAE) we have previously demonstrated demyelination and ne rve conduction block in the proximal peripheral nervous system (PNS) a nd in the central nervous system (CNS). The present study was performe d to assess conduction in the PNS and CNS, after recovery from acute M BP-EAE, using direct recordings from surgically exposed spinal roots a nd spinal cord dorsal columns. The study revealed that 1-2 weeks after clinical recovery from tail paralysis there was almost complete resto ration of conduction in the sacral spinal roots but persistent severe conduction abnormalities in the dorsal columns. Significant restoratio n of conduction through the dorsal columns occurred over the following 2 weeks. These findings indicate that PNS conduction block due to a d emyelinating polyradiculitis is a major cause of the neurological sign s of acute MBP-EAE in the Lewis rat. (C) 1995 John Wiley & Sons, Inc.