Effects of immunotherapy on motor cortex excitability in Stiff Person Syndrome

A number of cortical and spinal excitability variables have been tested in a patient with Stiff Person Syndrome (SPS), before and after immunotherapy with mycophenolate mofetil, intravenous immunoglobulin and corticosteroids, which normalized plasma levels of anti-GAD antibodies and dramatically improved the clinical picture. The overlapping time-course of neurophysiological, clinical and bio-umoral findings suggests that immunotherapy might have changed GABA/Glutamate balance at cortical level, favoring the former, as reflected by normalization of the startle reflex, lengthening of the cortical silent period and clear-cut reduction of intracortical facilitation to paired-pulse transcranial magnetic stimulation. This represents the first report investigating effects of immunotherapy on cortical excitability in SPS.