Clinical Validation of Sensory Conduction in the Ring Finger associated with Hand Numbness

Abstract

Median and ulnar sensory nerve conduction velocities and amplitudes were measured orthodromically on the ring finger in 10 normal hands and in 64 hands with numbness (31 hands with carpal tunnel syndrome (CTS), 16 hands with cubital tunnel syndrome (CubTS), 8 hands with paresthesia due to cervical spondylosis (CS) and 9 hands with diabetic neuropathy (DN)). Of 31 hands with CTS, 13 hands had slow conduction velocities (35.6±7.3m/s) and 18 hands had no sensory nerve action potential (SNAP) in the median nerve. Of 16 hands with CubTS, 12 hands had no SNAP and 4 had normal ulnar nerve conduction velocities. Nine hands with DN had low amplitudes and slow conduction velocities in both nerves. Eight hands with CS had normal SNAPs in both nerves. We concluded that measurement of SNAP of the ring finger is easy and useful for diagnosing numbness in hands.