Assessment of experimental autoimmune neuritis in the rat by electrophysiology of the tail nerve

The assessment of experimental autoimmune neuritis (EAN) by electrophysiological studies of the sciatic innervation of the plantar muscle may be complicated by local inflammation. We therefore utilized the tail nerve-muscle system to monitor disease progression in 20 rats with EAN and 10 control rats. Early changes were detected in motor nerve conduction velocity (32.06 ± 1.85 m/s versus 43.57 ± 3.98 m/s in controls, P < 0.001) at 15 days postimmunization (DPI), and conduction block (70.6 ± 9.4% compared to 12.4 ± 3.4%, P < 0.001) at 22 DPI. No consistent conduction block (22.4 ± 10.4%) was found in the plantar muscle measurements. The tail nerve response of EAN rats demonstrated severe temporal dispersion at 43 DPI, which returned to normal at 135 DPI, although motor nerve conduction velocity values were still lower than in controls (24.4 ± 0.9 m/s, P < 0.001). The tail nerve may be a useful addition to electrophysiological studies in this model of the Guillain-Barré syndrome.