Motor Unit Estimate Number in the Anterior Tibial Muscle: Normative Data versus Findings in Critically Ill Patients in Intensive Care Units.
OBJECTIVE
To determine the number of motor units (MUNEs) in the anterior tibial muscle of normal subjects for comparison with those of severely paretic or paralytic muscles of critically ill patients in intensive care units.


RESULTS
The mean MUNE for 24 normal subjects (194 +/- 5; mean +/- standard deviation) was similar to that of the 22 patients with critical illness (184 +/- 10). However, both the mean amplitude of the evoked compound muscle action potential (CMAP) and of the single motor unit action potential (S-MUAP) among patients were approximately one third of those in normal subjects.


CONCLUSIONS
Critically ill patients in this study demonstrated normal MUNEs with reduced CMAP and S-MUAP amplitudes in the setting of severe clinical weakness, suggestive of predominantly myopathic injury. MUNE may provide a valuable tool for distinguishing between neuropathy and myopathy in critically ill patients.
Trojaborg
Werner
W
From the *Department of Clinical Neurophysiology, National University Hospital, Copenhagen Denmark; and daggerColumbia University College of Physicians & Surgeons, New York, NY, U.S.A.
Kaufmann
Petra
P
Gooch
Cliff L
CL