Somatosensory evoked potentials in X-linked recessive bulbospinal neuronopathy: a case demonstration

Clinicopathological findings in X-linked recessive bulbospinal neuronopathy were characterized by loss of myelinated fibers in the fasciculus gracilis and depletion of neurons in the ventral horn throughout the same segments. Clinical profile of this rare motor neuron disease include sign and symptom of lower motor neuron involving bulbar and spinal level with minimal or no sensory deficit. Previous electrodiagnostic findings consist of electrophysiological evidence of anterior horn cell disease and decreased or absent sensory action potentials in the peripheral nerve. The role of somatosensory evoked potential which can uncover the involvement of posterior column has never been probed. We report a 22-year-old man who had a clinical syndrome of X-linked bulbospinal neuronopathy. The peripheral electrodiagnostic studies supported the evidence of prolonged anterior horn cell disease and decreased sensory response. The median SEPs revealed delayed N11-N13 and N13-N20 interpeak latencies representing demyelination in fasciculus gracilis of upper cervical cord. Therefore, the median SEPs, an uninvasive procedure, can be used as a supportive method to identify sensory neuronopathy with posterior column lesion in this syndrome, especially when the patient has no obvious sensory and endocrine symptom.