DIRECT MUSCLE STIMULATION IN ACUTE QUADRIPLEGIC MYOPATHY

We have previously found that muscle is electrically inexcitable in se vere acute quadriplegic myopathy (AQM). in contrast, muscle retains no rmal electrical excitability in peripheral neuropathy. To study the re lationship between muscle electrical excitability and all types of fla ccid weakness occurring in the intensive care unit, we identified 14 c ritically ill, weak patients and measured the amplitude of compound mu scle action potentials (CMAPs) obtained with direct muscle stimulation (dmCMAP) and with nerve stimulation (neCMAP). In II of 14 patients dm CMAP amplitudes were reduced and the ratio of the neCMAP amplitude to the dmCMAP amplitude (nerve/muscle ratio) was indicative of loss of mu scle electrical excitability. In 2 other patients, the nerve/muscle ra tio indicated neuropathy. Direct muscle stimulation may allow differen tiation of AQM from neuropathy even in comatose or encephalopathic cri tically ill patients. AQM may be more common than has previously been appreciated. (C) 1997 John Wiley & Sons, Inc.