Peroneal motor amplitude

Q: What is the best test to predict Critical Illness Myopathy (CIM) or Critical Illness Polyneuropathy (CIP) in ICU patients? 


Answer:  Peroneal motor amplitude

The CRIMYNE study was published in 2007 with a sample size of 92 patients. It has shown that a reduction of >25 percent in the peroneal motor amplitude (compound muscle action potential) on two consecutive days can predict CIM and/or CIP with 100 percent sensitivity and 67 percent specificity. Followup validity studies including CRIMYNE-2 study confirmed 94-100 sensitivity and 85-91 percent specificity. In these studies, all of the patients had normal nerve conduction 24 hours after ICU admission. Serial electrodiagnostic studies were performed. CRIMYNE study also showed that the timing of development to CIM and/or CIP cannot be predicted. It may occur abruptly within a day or over many days. Interestingly, though an association was found with multiorgan failure, there was no association found with SIRS, sepsis, drugs, or nutrition which have been conventionally believed to be factors.

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References:

Latronico N, Bertolini G, Guarneri B, et al. Simplified electrophysiological evaluation of peripheral nerves in critically ill patients: the Italian multi-centre CRIMYNE study. Crit Care 2007; 11:R11.

Latronico N, Nattino G, Guarneri B, et al. Validation of the peroneal nerve test to diagnose critical illness polyneuropathy and myopathy in the intensive care unit: the multicentre Italian CRIMYNE-2 diagnostic accuracy study. F1000Res 2014; 3:127.

Kelmenson DA, Quan D, Moss M. What is the diagnostic accuracy of single nerve conduction studies and muscle ultrasound to identify critical illness polyneuromyopathy: a prospective cohort study. Crit Care 2018; 22:342.