Posterior tibial and sural nerve somatosensory evoked potentials: a study in spastic paraparesis and spinal cord lesions

Abstract In two groups of patients posterior tibial nerve (PTN) and sural nerve (SN) somatosensory evoked potentials (SEPs) were compared to each other and related to classified neurological signs. Group patients with hereditary spastic paraparesis (HSP) and 8 with primary lateral sclerosis (PLS), with solely or primarily motor deficits. Group B consisted of 12 patients with different spinal cord diseases causing varible mixed and motor impairments. Normal values were from 39 control. A clear trend towards more frequently prolonged PTN SEP latencies was found in both groups and appears to make PTN SEPs more useful for clinical application than SN SEPs. No significant differences were found in SEP abnormalities when the two patient groups were compared to each other. No relationships were found between SEP abnormalities and spasticity, weakness or any single sensory modality, making the two SEPs questionable as a quantitative test for neurological deficits in our patients.