Motor and somatosensory evoked potentials in mice infected with Theiler's murine encephalomyelitis virus.

We used an in vivo technique to record spinal motor and somatosensory evoked potentials in SJL/J and B10 mice chronically (4-10 months) infected with Daniel's strain of Theiler's murine encephalomyelitis virus (TMEV). SJL/J mice demonstrated primary spinal cord demyelination with chronic TMEV infection, whereas B10 mice were resistant to TMEV induced demyelination. Analysis based on the velocity of the initial peak of evoked responses demonstrated significantly slower conduction velocities in infected SJL/J mice as compared to age-matched uninfected SJL/J controls (p < 0.01) and infected B10 mice (p < 0.01). We noted no significant differences in conduction velocities of spinal evoked potentials recorded between uninfected SJL/J mice, uninfected B10 mice and infected B10 mice. Chronic infection with TMEV in susceptible SJL/J mice is associated with slowed conduction of spinal motor and somatosensory evoked potentials. This sensitive electrophysiologic assay will provide an in vivo method to test therapeutic regimens to inhibit demyelination or promote remyelination.