Reducing noise and artifacts in sensory NCS

Sensory nerve conduction studies (SNCS) are useful to detect nerve pathology. They are perhaps the most sensitive method in diagnosis of mono-neuropathy (e.g. carpal tunnel syndrome). They are also useful to study polyneuropathies, e.g. from diabetes. The SNCS also helps localize the site of lesion: preganglionic (radiculopathy) or post-ganglionic (brachial plexus injury). However, the SNCS are technically demanding. The voltage (also called amplitude) of the sensory nerve action potential (SNAP) is low (< 50 microvolts) even in healthy subjects. Furthermore, it is easily contaminated by noise and artifacts. In this communication we will look at the source of this interference, and suggest many strategies to reduce them. This will allow one to record good quality SNAP without spending excessive time, or causing significant discomfort from repeated stimulations to the patient.