Somatosensory evoked potentials (SSEPs) in rheumatoid cervical subluxation.

Somatosensory evoked potentials (SSEPs) were recorded in 34 patients with severe rheumatoid arthritis. Eighteen had atlanto-axial subluxation and 16 had no roentgenological evidence of cervical subluxation. Four patients in the group with cervical subluxation showed pathological SSEP values from both median and tibial nerves indicating conduction block in the upper cervical medulla. In the group with no cervical subluxation, 6 patients had prolonged SSEP latency, 5 of these on recordings from the tibial nerves with normal median nerve latencies and one with only bilaterally prolonged median nerve latencies. The pathological SSEP findings in the former group of patients we attribute to the cervical subluxation, while the findings in the latter group might be related to spinal cord vasculitis or extradural granulation tissue. The SSEP method can be useful in providing objective evidence for spinal cord lesions in patients with rheumatoid cervical subluxation.