Posted on 04 September 2010. Tags: CLCN1 gene, congenital myotonia, diffuse insertional activity, EMG disease, myotonia congenita, positive sharp waves
By Chris Faubel, MD –
Photo from medicalacupuncture.org
EMG disease is a rare condition in which increased insertional activity (positive sharp waves and sometimes fibrillations) is seen in all muscles, in the absence of any known neuropathic, myopathic, or metabolic disorder.
- Normal nerve conduction study
- Short runs of positive sharp waves
- NO waxing and waning, early recruitment, sustained grip, or contractions with thenar muscle tapping (classic signs of myotonia)
Insertional activity is caused by local muscle damage from the passage of the needle.
Positive sharp waves (PSWs) and fibrillations are the result of single muscle fiber action potentials that have a destabilized membrane (such as after denervation of a muscle).
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Posted in Electrodiagnostics, EMG Disease, General
Posted on 17 July 2010. Tags: axonotmesis, electrodiagnostic, endoneurium, epineurium, injury, myelin, Nerve, neuropraxia, neurotmesis, perineurium, seddon, sunderland
By Chris Faubel, MD –
Understanding nerve injury classification is essential for prognostic value clinically.
Some basic anatomy, along with the two classification systems, and their corresponding EMG findings need to be learned and remembered.
Two classification systems exist (and are frequently tested in various exams):
- Seddon’s classification (neuropraxia, axonotmesis, neurotmesis)
- Sunderland’s classification (types 1-5)
To understand the systems, you must first review some basic nerve anatomy.
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Posted in Electrodiagnostics, General, Nerve Injury Classifications
