Article Text

PDF
Origin of ICU acquired paresis determined by direct muscle stimulation
  1. J-P Lefaucheur1,
  2. T Nordine2,
  3. P Rodriguez2,
  4. L Brochard2
  1. 1Service de Physiologie – Explorations Fonctionnelles, CHU Henri Mondor, Assistance Publique-Hôpitaux de Paris, Créteil, France
  2. 2Service de Réanimation Médicale, CHU Henri Mondor
  1. Correspondence to:
 Dr Jean-Pascal Lefaucheur
 Service de Physiologie – Explorations Fonctionnelles, Centre Hospitalier Universitaire Henri Mondor, 51 avenue du Marechal de Lattre de Tassigny, 94010 Creteil, France; jean-pascal.lefaucheur{at}hmn.ap-hop-paris.fr

Abstract

Background: Acquired diffuse paresis in an intensive care unit (ICU) can result from critical illness myopathy or polyneuropathy. Clinical examination and conventional neurophysiological techniques may not distinguish between these entities.

Objective: To assess the value of direct muscle stimulation (DMS) to differentiate myopathic from neuropathic process in critically ill patients with diffuse severe muscle weakness.

Methods: 30 consecutive patients with ICU acquired diffuse motor weakness were studied. Responses of the right deltoid and tibialis anterior muscles to DMS and to motor nerve stimulation (MNS) were studied and compared with results of conventional nerve conduction studies and concentric needle electromyography (EMG). An original algorithm was used for differential diagnosis, taking into account first the amplitude of the responses to DMS, then the MNS to DMS amplitude ratio, and finally the amplitude of the sensory nerve action potentials recorded at the lower limbs.

Results: Evidence of neuropathy and myopathy was found in 57% and 83% of the patients, respectively. Pure or predominant myopathy was found in 19 patients. Other results were consistent with neuromyopathy (n = 5) and pure or predominant neuropathy (n = 2). Four patients had normal results with stimulation techniques, but spontaneous EMG activity and raised plasma creatine kinase suggesting necrotic myopathy.

Conclusions: A neurophysiological approach combining DMS and conventional techniques revealed myopathic processes in a majority of ICU patients. Reduced muscle fibre excitability may be a leading cause for this. The diagnosis of myopathy in ICU acquired paralysis can be established by a combination of DMS, needle EMG, and plasma creatine kinase.

  • CIM, critical illness myopathy
  • CIP, critical illness polyneuropathy
  • CK, creatine kinase
  • CMAP, compound muscle action potential
  • DMS, direct muscle stimulation
  • DMSamp, response amplitude to direct muscle stimulation
  • DMSlat, latency of direct muscle stimulation
  • ICU, intensive care unit
  • MNS, motor nerve stimulation
  • MNSamp/DMSamp ratio, ratio of response amplitude from motor nerve stimulation to direct muscle stimulation
  • MNSlat, latency of motor nerve stimulation
  • SNAP, sensory nerve action potential
  • SNAPamp, mean amplitude of the sensory nerve action potentials
  • critical care
  • electromyography
  • myopathy
  • nerve conduction
  • neuropathy

Statistics from Altmetric.com

Footnotes

  • Published Online First 25 November 2005

  • Competing interests: none declared

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.