Motor nerve conduction study of ulnar innervated hypothenar muscles with conduction block

This figure illustrates the typical findings for a motor nerve conduction study of the ulnar-innervated hypothenar muscles with conduction block and slowing across the elbow. The smaller response on the affected side is with stimulation above the elbow and reflects conduction block. In this case, the other two responses with stimulation at the wrist and below elbow are normal and the inset sensory response to the 5th digit is normal.