Simplified electrophysiological evaluation of peripheral nerves in critically ill patients: the Italian multi-centre CRIMYNE study

Abstract

IntroductionCritical illness myopathy and/or neuropathy (CRIMYNE) is frequent in intensive care unit (ICU) patients. Although complete electrophysiological tests of peripheral nerves and muscles are essential to diagnose it, they are time-consuming, precluding extensive use in daily ICU practice. We evaluated whether a simplified electrophysiological investigation of only two nerves could be used as an alternative to complete electrophysiological tests.MethodsIn this prospective, multi-centre study, 92 ICU patients were subjected to unilateral daily measurements of the action potential amplitude of the sural and peroneal nerves (compound muscle action potential [CMAP]). After the first ten days, complete electrophysiological investigations were carried out weekly until ICU discharge or death. At hospital discharge, complete neurological and electrophysiological investigations were performed.ResultsElectrophysiological signs of CRIMYNE occurred in 28 patients (30.4%, 95% confidence interval [CI] 21.9% to 40.4%). A unilateral peroneal CMAP reduction of more than two standard deviations of normal value showed the best combination of sensitivity (100%) and specificity (67%) in diagnosing CRIMYNE. All patients developed the electrophysiological signs of CRIMYNE within 13 days of ICU admission. Median time from ICU admission to CRIMYNE was six days (95% CI five to nine days). In 10 patients, the amplitude of the nerve action potential dropped progressively over a median of 3.0 days, and in 18 patients it dropped abruptly within 24 hours. Multi-organ failure occurred in 21 patients (22.8%, 95% CI 15.4% to 32.4%) and was strongly associated with CRIMYNE (odds ratio 4.58, 95% CI 1.64 to 12.81). Six patients with CRIMYNE died: three in the ICU and three after ICU discharge. Hospital mortality was similar in patients with and without CRIMYNE (21.4% and 17.2%; p = 0.771). At ICU discharge, electrophysiological signs of CRIMYNE persisted in 18 (64.3%) of 28 patients. At hospital discharge, diagnoses in the 15 survivors were critical illness myopathy (CIM) in six cases, critical illness polyneuropathy (CIP) in four, combined CIP and CIM in three, and undetermined in two.ConclusionA peroneal CMAP reduction below two standard deviations of normal value accurately identifies patients with CRIMYNE. These should have full neurological and neurophysiological evaluations before discharge from the acute hospital.

Critical illness polyneuropathy (CIP) in neurological early rehabilitation: clinical and neurophysiological features

“…Mortality in our study (2.5%) was in line with previous results from a literature review suggesting no increase of unadjusted mortality in critical ill patients with neuromuscular abnormalities [9]. However, other studies revealed a higher mortality between 21 and 55% among CIP and CIM patients [10–12], in particular with coincident sepsis [16, 17]. …”

“…Most frequently, neurography of peroneal and sural nerves have been analyzed in CIP [10–12]. Our data confirmed the importance and sensitivity of peroneal nerve measurements [10].…”

“…We found a significant negative correlation between CRP and CMAP amplitudes of the peroneal nerve suggesting that nerve damage might be related to inflammatory mechanisms. One reason for this correlation could be the fact that the peroneal nerve shows most sensitivity for CIP diagnosis [10] and therefore most sensitivity for inflammatory processes. MOF ( n  = 21; 14%) was associated with decreased motor CV of the peroneal nerve.…”

“…Until now, there are no compulsory diagnostic criteria, but it has been suggested to perform neurophysiological measurements to confirm diagnosis of CIP, in particular of the peroneal and sural nerve [10–12]. An amplitude reduction of the compound muscle action potential (CMAP) of the peroneal nerve was found to be most sensitive and specific [10].…”

“…An amplitude reduction of the compound muscle action potential (CMAP) of the peroneal nerve was found to be most sensitive and specific [10]. …”