Temporary reversal of nerve and muscle dysfunction by serial electrical stimulation in critical illness neuromyopathy

Abstract

Objective: Critical Illness Neuromyopathy (CIPNM) is a complication in sepsis patients with still enigmatic disease mechanisms. We investigated a novel electrical stimulation method to better define neuromuscular dysfunction in patients with CIPNM.

Methods: We studied 18 sepsis CIPNM patients on intensive care units, 13 at an early and 5 at a later disease stage, 7 sepsis control, and 8 neuropathy control patients. We applied slow conditioning electrical pulses at motor nerves and directly at the muscle to investigate a facilitation phenomenon (FP) of small or absent compound motor action potentials (CMAPs).

Results: Serial pulses induced a 2 to 490-fold increase in CMAP amplitudes in 17/18 Intensive Care Unit (ICU)-CIPNM patients (p < 0.001). These effects were short lived and reproducible. Direct muscle stimulation in the tibialis anterior muscle resulted in up to 130-fold FP in 7/9 patients tested (p < 0.01). In 4/5 post-ICU CIPNM patients FP was up to 10-fold. None of the 7 ICU sepsis control patients without CIPNM with similar disease severity and none of 8 neuropathy patients showed FP (p < 0.001). On needle EMG only 5/16 ICU patients tested revealed spontaneous activity.

Conclusions: Conditioning electrical stimulation detected a functional component of the disease process showing temporary improvement in sepsis-associated CIPNM.

Significance: New test differentiates functional from degenerative pathology.

Keywords: Conditioning stimulation; Critical Illness neuromyopathy; Electrodiagnosis; Facilitation phenomenon; Sepsis; Voltage-gated sodium channels.