Somatosensory evoked potential in neurosyphilis.

Since the development of effective antibiotic therapy, the occurrence of neurosyphilis has become less frequent. The number of syphilitic patients is gradually increasing as a complication in acquired immunodeficiency syndrome, but the diagnosis of neurosyphilis sometimes is difficult. We describe six patients with neurosyphilis and an analysis of their tibial nerve somatosensory evoked potentials. Four of them, including two with no tabes dorsalis symptoms, had delayed P15-N21 or the absence of N21. These abnormalities were ameliorated by treatment for syphilis. Analysis of tibial nerve SEPs provides a useful tool for the diagnosis of neurosyphilis and the evaluation of the extent to which neurosyphilis has progressed.