Motor-evoked responses to transcranial brain stimulation persist during cataplexy: a case report.

Magnetic brain stimulation was performed in a patient with the narcolepsy-cataplexy syndrome during and after a cataplectic status. Amplitudes and thresholds of responses in six muscles (diaphragm, lumbar erector spinae, trapezius, biceps, tibialis anterior and abductor digiti V) remained unchanged during cataplexy as compared to the normal state. Our data suggest that, similar to rapid eye movement (REM) sleep, an enhanced cortical excitability to magnetic brain stimulation may compensate for the postsynaptic spinal inhibition of muscle tone during cataplexy, and that there is no difference in this respect between axial and distal muscles. Our data agree well with other evidence of increased cortex activity during cataplexy and REM sleep.