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LETTERS: Peter J Mahaffey Nerve studies are not that useful in diagnosis BMJ 2007; 335: 414 [Full text]

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Nerve tests are only diagnostic of a complication of an entrapment neuropathy

Carlos A Selmonosky.MD   (31 August 2007)

Nerve Conduction Studies for Carpal Tunnel Syndrome

Timothy EJ Hems   (16 September 2007)

Nerve tests are only diagnostic of a complication of an entrapment neuropathy 31 August 2007
Carlos A Selmonosky.MD, Physician Inova Fairfax Hospital.Falls Church. VA .USA Send response to journal: Re: Nerve tests are only diagnostic of a complication of an entrapment neuropathy	The electrophysiological neurological tests are not diagnostic of an entrapment neuropathy,only of its complications .The compresion is severe or prolonged enough to produce neuropraxia or more severe nerve damage.The entrapment neuropathy can be present symptomatically or asymptomatically with normal neurological tests. They are not cost effective tests and have the same diagnostic accuracy that the pertinent history and physical examination. Competing interests: None declared
Nerve Conduction Studies for Carpal Tunnel Syndrome 16 September 2007
Timothy EJ Hems, Consultant Hand and Orthopaedic Surgeon The Victoria Infirmary, Glasgow, G42 9TY Send response to journal: Re: Nerve Conduction Studies for Carpal Tunnel Syndrome	The Editor, British Medical Journal. Dear Sir, I read the article by Bland1 and the letter Mahaffey2 with interest. I would agree with Mr Mahaffey that nerve conduction studies (NCS) are not necessary for all cases of suspected carpal tunnel syndrome (CTS). With a long waiting time for tests in some units it is important to use the resource selectively. However, I would disagree with Mr Mahaffey that NCS have a “high rate of false negatives”. Bland presents evidence that the false negative rate is about 5%, which can hardly regarded as high. My own experience is that, on review, most patients with normal NCS do not have symptoms typical of CTS or that their symptoms are not severe enough to warrant surgery. A factor which is often ignored is that the sensitivity of NCS may vary between Neurophysiology Departments depending on the criteria used for diagnosis. A recent audit of NCS reports in patients referred from our Hand Clinic with suspected CTS, looking at the actual measurements, suggested that there might have been a false negative rate of 10 – 15% had different criteria for diagnosis been used. It is therefore important to be familiar with the tests that are being performed. Tim Hems, Consultant Hand and Orthopaedic Surgeon, The Victoria Infirmary, Glasgow. 1. Bland JDP. Carpal tunnel syndrome. BMJ 2007;335:343-6. 2. Mahaffey PJ. Carpal tunnel syndrome. Nerve studies are not useful in diagnosis. BMJ 2007;335:414. Competing interests: None declared