Abnormalities of F response in cases with spastic spinal paralysis and effects of TRH-T on them.

F responses were recorded in 6 cases with SSP and in 22 normal controls. The present study confirmed that frequency, number of phases, F/M amplitude ratio and duration were significantly increased and CV of onset latencies was significantly reduced in cases with SSP. After intravenous injection of TRH (2 mg), all the parameters were altered toward normal sides. It was suggested that the hyperexcitability of motor neuron pool in SSP was stabilized by effects of TRH on injured pyramidal tracts and consequently abnormalities of F responses were improved. The Effect of TRH to correct the abnormal F responses in SSP might be consistent with effects of TRH to reduce spasticity in amyotrophic lateral sclerosis described previously.