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Insertional Activity

- Discussion:
    - when needle is inserted into muscle or moved w/in muscle, there is a single burst of activity that usually lasts 300 to 500 ms;
    - activity is related to movement of electrode and is thought to result from mechanical stimulation or injury of the muscle fibers;

- Increased Insertional Activity:
    - increased insertional activity is found in denervated mucle or in muscle that is being reinnervated;
    - insertional activity will be increased in nerve compression syndromes (axonotmesis, neurotmesis);
    - it is also increased in axonal neuropathies and anterior horn disease;
    - insertional activity that lasts longer than 300 to 500 ms may be an early sign of denervation and is also found in polymyositis, myotonic 
           disorders, and some of the other myopathies;

- Decreased:
    - reduction of insertion activity is found after prolonged denervation when muscle fibers have been replaced by connective tissue and with