Direct muscle stimulation in acute quadriplegic myopathy

• Published in: Muscle & nerve Vol. 20; no. 6; pp. 665 - 673
• Main Authors: Rich, Mark M., Bird, Shawn J., Raps, Eric C., McCluskey, Leo F., Teener, James W.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.06.1997; Wiley
• Subjects: Action Potentials - physiology; Adult; Aged; Aged, 80 and over; Biological and medical sciences; critical illness; Electric Stimulation; Electromyography; electrophysiology; Female; Humans; Male; Medical sciences; Middle Aged; myopathy; Nervous system (semeiology, syndromes); Nervous system as a whole; Neural Conduction - physiology; Neurology; Neuromuscular Junction - physiopathology; polyneuropathy; Quadriplegia - physiopathology; Human; Tetraplegia; Nervous system diseases; Motor system disorder; Electrical stimulus; Excitability; Action potential; Striated muscle; Polyneuropathy; Electrodiagnosis; Striated muscle disease; Neurological disorder; Myopathy
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/(SICI)1097-4598(199706)20:6<665::AID-MUS2>3.0.CO;2-6

We have previously found that muscle is electrically inexcitable in severe acute quadriplegic myopathy (AQM). In contrast, muscle retains normal electrical excitability in peripheral neuropathy. To study the relationship between muscle electrical excitability and all types of flaccid weakness occurring in the intensive care unit, we identified 14 critically ill, weak patients and measured the amplitude of compound muscle action potentials (CMAPs) obtained with direct muscle stimulation (dmCMAP) and with nerve stimulation (neCMAP). In 11 of 14 patients dmCMAP amplitudes were reduced and the ratio of the neCMAP amplitude to the dmCMAP amplitude (nerve/muscle ratio) was indicative of loss of muscle electrical excitability. In 2 other patients, the nerve/muscle ratio indicated neuropathy. Direct muscle stimulation may allow differentiation of AQM from neuropathy even in comatose or encephalopathic critically ill patients. AQM may be more common than has previously been appreciated. © 1997 John Wiley & Sons, Inc. Muscle Nerve, 20, 665–673, 1997.