During nerve conduction studies, what does a distal motor latency of 5ms indicate?

A distal motor latency of 5ms indicates that the nerve is transmitting impulses effectively. In nerve conduction studies, distal motor latency refers to the time taken for an electrical impulse to travel from the stimulation point to the muscle, following the nerve pathway. Normal values for distal motor latency vary by nerve and can be influenced by factors such as the length of the nerve being tested, but generally, a latency of 5ms is considered to be within the normal range for many nerves, particularly in the upper extremities.

This suggests that the conduction velocity of the nerve is adequate and the nerve's ability to relay signals from the site of stimulation to the muscle is functioning properly. When conduction is effective, this means that there are no significant pathology or demyelination issues that would slow down or impede the signal. Understanding this helps clinicians assess the integrity of the motor fibers and can provide critical insights when evaluating neuromuscular conditions.