Facial nerve neurographies in intensive care unit-acquired weakness

Area of Science:

• Neurology
• Critical Care Medicine
• Electrophysiology

Background:

• Intensive care unit-acquired weakness (ICU-AW) causes severe limb and trunk muscle paresis.
• Facial muscles often appear less affected in patients with ICU-AW.

Purpose of the Study:

• To investigate if facial nerves are partially spared in ICU-AW.
• To compare nerve conduction in limb and facial nerves of critically ill patients.

Main Methods:

• Performed peripheral and cranial nerve conduction studies in critically ill patients.
• Assessed motor and sensory nerve conduction velocities, muscle action potentials, and orbicularis oculi reflexes.
• Evaluated nerve function at admission, ICU day 7, and ICU day 14.

Main Results:

• Peroneal nerve compound muscle action potentials (CMAPs) reduced significantly by ICU days 7 and 14.
• No significant decrease in CMAP amplitudes for ulnar or facial nerves.
• Orbicularis oculi reflex reproducibility decreased, but latencies remained stable.

Conclusions:

• Facial and hand muscles show relative preservation of CMAPs compared to foot muscles.
• This supports clinical observations of less severe facial muscle involvement in ICU-AW.
• Nerve length and trophic factors may explain the relative sparing of shorter facial nerves.