Contraction response to muscle percussion is increased in peripheral nerve conduction block

Area of Science:

• Neurology
• Clinical Electrophysiology
• Peripheral Nerve Disorders

Background:

• Focal peripheral nerve disorders present with palsies, impacting skeletal muscle function.
• Distinguishing between conduction block (CB) and axonal degeneration is crucial for accurate diagnosis and treatment.
• Electrophysiological testing is the standard for assessing nerve lesions.

Purpose of the Study:

• To evaluate the utility of direct skeletal muscle percussion as a bedside diagnostic tool.
• To compare the muscle response to percussion in patients with peripheral nerve palsies versus healthy controls.
• To determine if percussion can differentiate between conduction block and axonal lesions.

Main Methods:

• 119 patients with peripheral nerve palsies underwent direct skeletal muscle percussion.
• Muscle response to percussion was compared between affected and contralateral normal limbs.
• Patients were subsequently assessed using electrophysiological testing to confirm lesion type (CB, axonal, or mixed).

Main Results:

• Increased muscle response to percussion was observed in 37 out of 47 patients with CB.
• Decreased muscle response was noted in 44 out of 53 patients with axonal lesions.
• Symmetric responses were found in 12 out of 19 patients with mixed lesions.

Conclusions:

• Direct skeletal muscle percussion can be a valuable bedside test for differentiating conduction block from denervation.
• This simple test may help guide further electrophysiological investigations.
• Percussion offers a rapid, non-invasive method to assess peripheral nerve integrity.