Publication details
The value of EMG in the evaluation of critical illness polyneuromyopathy:prospective case series
| Authors | |
|---|---|
| Year of publication | 1999 |
| Type | Article in Periodical |
| Magazine / Source | Electroencephalography and Clinical Neurophysiology |
| MU Faculty or unit | |
| Citation | |
| Field | Neurology, neurosurgery, neurosciences |
| Keywords | critical illness polyneuromyopathy;electromyography;direct muscle stimulation |
| Description | OBJECTIVE: To study the relative incidence of critical illness polyneuropathy (CIP) and acute quadruplegic myopathy (AQM), and to verify the possibility to differentiate these entities using standard electrophysiological testing and sc. direct muscle stimulation (DMS). BACKGROUND: Several unique intensive care unit syndromes have been reported that can cause an acquired neuromuscular weakness. The most common of these is the CIP and the AQM. It is uncertain whether these conditions represent distinct disorders or a continuum of changes in a neuromuscular system. The electrophysiologic features of the AQM are similar to those of the CIP. Recently, Rich et al (Muscle & Nerve 1997;20:665-73) described the possibility to differentiate the AQM from the CIP using DMS. DESIGN/METHODS: Study design: Case series study. Group: Nine consecutive critically ill patients (age 30 - 81 years) admitted to a neurological intensive care unit followed the inclusion criteria: At least two abnormal organ Sepsis-Related Organ Failure Assessment (SOFA) scores, and/or the Glasgow Coma Scale < 8 points. The neuromuscular disorder as a cause of the admission to the intensive care unit (ICU) or a pre-existing neuromuscular disorder were excluded. Patients with conditions frequently associated with neuromuscular involvement (predominantly diabetes mellitus and alcohol abuse) were excluded. Methods: Clinical examination, SOFA score grading, routine EMG examination (including motor and sensory nerve conduction studies, needle EMG and repetitive motor nerve stimulation) and sc. direct muscle stimulation technique according to Rich were prospectively evaluated within 10 days from the onset of the acute illness (day 0) and 28 days after the initial examination (day 28). Muscle and nerve biopsy from quadriceps femoris muscle and sural nerve were performed in one patient. RESULTS: In 5 out of 9 so far completed cases we registered clinical and EMG signs of a new neuromuscular involvement: spontaneous abnormal activity of the fibrillation potentials type and significant drop in the compound muscle action potential amplitudes on the second examination were present in all cases. Routine EMG could be interpreted as new axonal sensorimotor polyneuropathy in one case while in the other 4 cases the finding were unequivocal with respect to differentiation between neuropathy and myopathy. DMS technique revealed nerve/muscle ratios close to 1 that were consistent with myopathy in three out of five cases with new neuromuscular abnormality. Muscle and nerve biopsy in a patient with equivocal EMG findings and DMS findings of neuropathic type corresponded with axonal neuropathy. CONCLUSIONS: Standard EMG techniques are not able to reliably distinguish between critical illness neuropathy and myopathy. Direct muscle stimulation is able to assess independently neuropathic and myopathic components of critical illness weakness even in the intensive care unit setting and is complementary to standard electrophysiological examination. Myopathy of critically ill patients is probably more frequent than previously supposed. Further studies using DMS may define the distinct epidemiology of the CIP and AQM or to support the concept of critical illness polyneuromyopathy with common etiology, probably systemic inflammatory response syndrome. |
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