Neurophysiologic Features of Carpal Tunnel Syndrome in Adults with an Isolated Elevated Plasma Level of Homocysteine

Carpal tunnel syndrome (CTS) is a mono- neuropathy of the median nerve at the wrist. CTS can be caused by a variety of pathophysiological conditions and can also be an early scenario of the underlying peripheral neuropathy. We recently reported that an elevated plasma level of homocysteine (eHcy) is an independent risk factor for development of peripheral neuropathy. However, the neurophysiologic features of CTS in subjects with an isolated eHcy have not been studied. We retrospectively reviewed clinical charts and neurophysiology databank to identify subjects with a clinical diagnosis of CTS with isolated elevated plasma levels of homocysteine, who had received electrodiagnostic evaluation. Subjects with a clinical diagnosis of neuropathy or with an identifiable etiology, other than isolated eHcy, for neuropathy were excluded. From 361 subjects with electrodiagnostically confirmed CTS, 7 subjects (age: 578 year-old, meanSD) were included. Nerve conduction study on median nerve showed a mildly increased distal latency (4.51.1 ms) but normal amplitude (8.42.4 mV) and conduction velocity (53.64.7 m/s) in motor median nerves; and mildly slowed velocity (41.48.2 m/s), but normal amplitude (19.416.9 µV) in sensory median nerves. Electromyography showed normal findings in all subjects. The electrodiagnostic studies suggested demyelination in nature. Our findings showed that the neurophysiologic features of CTS in adults with isolated eHcy were demyelinating in nature, which may suggest a favorable outcome with appropriate treatment.