Role of thenar electromyography in the evaluation of carpal tunnel syndrome.

In the evaluation of CTS, electromyography of various myotomes as well as proximal and distal muscles remains quite useful in helping to assess other clinically suspected differentials such as plexopathy, systemic neuropathies, radiculopathies, and proximal nerve entrapments. With regards to T-EMG specifically, it can provide information regarding axonal loss; however, it only crudely estimates relative severity and prognosis. These are better and less painfully determined by nerve conduction studies. The addition of nerve conduction studies to the clinical assessment gives one the ability to diagnose, determine severity and prognosis, and determine best management. The addition of T-EMG in typical cases of CTS causes excess pain and adds little to the information already gained. Therefore the author suggests that T-EMG be reserved for atypical or unusual presentations when additional information is needed such as when nerve conduction studies cannot be performed or when the pathology is potentially aggressive causing significant axonal injury over a short time.