Sensory Nerve Conduction

To test a motor nerve, a surface electrode is placed on the skin over a muscle. The nerve is stimulated further up and a Compound Muscle Action Potential is recorded. The nerve is then stimulated at various sites to calculate its speed.

F waves an H reflexes are considered "long waves". When recorded, the conduction velocity and amplitudes of the responses are assessed over the entire nerve length. In the case of H-reflexes, there is an assessment of both a sensory and a motor nerve along its entire course. As a result, these are particularly helpful in assessing the presence of radiculopathy.

Repetitive nurse stimulation is the best method to assess the neuromuscular junction. A nerve and its response to stimulation is assessed with a train of five simulations. When there is a condition affecting the neuromuscular junction, the amplitude of the responses vary.

Needle electromyography consists in inserting a very small pin-like needle in muscles and recording potentials at rest and also when the patient contracts that muscle. It is a complement to nerve conduction as it assesses damage to the nerves going to specific muscles or damage in the muscle itself.

Neuromuscular ultrasound allows the clinician to visualize the nerve and pinpoint exactly where a lesion is. If nerve conduction and electromyography gives an idea of the physiology of the nerves and muscles, the ultrasound shows spacial relationships of the nerve with surrounding structures. It is a very useful tool to guide the surgeon.