Pitfalls in Superficial Radial Sensory Nerve Conduction Study

ABSTRACT

OBJECTIVE: To investigate the possibility of volume conduction in the superficial radial sensory nerve conduction study in patients with a complete radial nerve injury. METHOD: In patients with a complete radial neuropathy, a superficial radial sensory nerve conduction study was carried out by an antidromic and orthodromic methods. Antidromic technique was carried out by increasing stimulus intensity gradually. Median palmar cutaneous nerve conduction study was also carried out by an antidromic method. RESULTS: When the stimulus intensity was significantly higher than the optimal technique, a median palmar cutaneous nerve action potential was evoked instead of the superficial radial nerve action potential. This is a volume conducting potential which occurrs following a high intensity stimulus. CONCLUSION: Superficial radial sensory conduction study must be carried out by an optimal stimulus intensity and an orthodromic method to eliminate the effect of volume conduction.