Table 1 Diagnostic criteria for the severity of CTS
From: Ring finger sensory latency difference in the diagnosis and treatment of carpal tunnel syndrome
Severity | Criteria |
|---|---|
Mild | Prolonged sensory latencies ± SNAP amplitude below the lower limit of the normal value with normal motor studies |
Moderate | Prolonged median motor distal latency in addition to abnormal sensory latencies as noted for mild CTS |
Severe | Any of the aforementioned NCS abnormalities with evidence of axonal loss defined by either: (1) an absent or low amplitude SNAP; (2) a low amplitude or absent thenar CMAP; or (3) a needle electromyogram revealing fibrillation potentials or neurogenic motor unit changes |