Sporadic amyotrophic lateral sclerosis showing abnormal somatosensory evoked potentials: a report of three cases.

Although dysfunction of the sensory systems in sporadic amyotrophic lateral sclerosis (ALS) has been reported, the clinical characteristics of such cases still remain unknown. We therefore performed a clinico-electrophysiological analysis of sporadic ALS patients.Twelve ALS patients (aged 36-66 years), who had their somatosensory evoked potentials (SEPs) evaluated, were reviewed and their clinical characteristics were delineated. In addition, needle EMG, sensory nerve conduction velocities, motor evoked potentials (MEPs) and cervical MRI or plain X-ray of the neck were also recorded.Three cases were segregated from the other 9 patients because of predominant upper motor neuron signs with pseudobulbar palsy and abnormal posterior tibial nerve and/or median nerve SEPs. The MEPs were also abnormal in these 3 patients and the brainstem auditory evoked potentials were abnormal in one patient. EMG revealed less involvement in the lower motor neurons.Sporadic ALS with a predominant upper motor neuron sign and also demonstrating pseudobulbar palsy with abnormal SEPs, may therefore form a clinical subtype of ALS.