The basic science and clinical applications of neurophysiological investigations

Underpinning all neurophysiological investigations is the knowledge of the basic anatomy and physiology of the nervous system. We discuss the generation and propagation of action potentials, which can be generated by the electrical stimulation of a peripheral nerve and responses may be recorded along the course of the nerve or from the muscle (nerve conduction studies). Electrical activity from a muscle can also be recorded with a needle electrode (electromyography), whilst a stimulus in a peripheral sensory nerve can be recorded in the spinal cord or brain (somato-sensory evoked potentials). We discuss the aforementioned tests, looking at the indications for their use. Normal patterns of results as well as those that would be considered to be pathological will also be discussed.