Motor Unit Estimate Number in the Anterior Tibial Muscle: Normative Data versus Findings in Critically Ill Patients in Intensive Care Units.

Objectives: 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.