What are the roles of EMG and NCS in the workup of limb-girdle muscular dystrophy (LGMD)?

Updated: Aug 15, 2019
  • Author: Monica Saini, MD, MBBS, MRCP(UK); Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Order EMG and NCSs in all patients with suspected LGMD to confirm the myopathic nature of the disease.

NCS results are normal in LGMD.

EMG shows early recruitment and the typical small-amplitude, narrow-duration, polyphasic motor-unit potentials that are seen in muscular diseases.

Abnormal spontaneous activity in the form of fibrillations and positive sharp waves is not prominent but has been described in a few cases of LGMD. When present, it should raise the clinician's suspicion for an inflammatory myopathy, such as polymyositis.

Myotonic or pseudomyotonic discharges may occasionally be noted in LGMD1A, LGMD1D, and LGMD1E.


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