Intensive Care Unit Acquired Weakness: Under or Overdiagnosed?

Abstract

Intensive care unit-acquired weakness (ICU-AW) is recognized as an important and common clinical problem,associated with an increased morbidity in critical ill patients. This muscle weakness has been described in a widerange of clinical settings and therefore, has many different terminologies such as “critical illness myopathy – CIM”,“critical illness polyneuropathy - CIP”, “acute quadriplegic myopathy”, among others. Nowadays, thesedesignations are considered somewhat restrictive, therefore most authors adopt the more wide rangedesignation of “ICU-Acquired Weakness”. Generally, these patients have a flacid tetraparesis without cranial nerve palsy, normal or diminishedosteotendinous reflexes and no sensitive alterations unless on the cases traditionally classified as polyneuropathy.The diagnosis of ICU-AW is often difficult, and should be suspected whenever a critical ill patient has unexplainedweakness. Traditionally, the diagnosis of neuromuscular diseases is based in nerve conduction studies andelectromyography. Muscle biopsy can be used to confirm or exclude myopathy, but is not a routine exam.Since there is a significant percentage of critical patients that develop muscle weakness it is important to screenall patients in the ICU, avoid potential toxic re-exposures on the identified patients and begin early rehabilitation.However, two questions arise from this screening: if the screening is only clinical are we underestimating thesepatients? If electrophysiological are we overestimating ICU-AW?There are no specific therapies for ICU-AW. The criterious use of some drugs is one of the possible measures to betaken. On the other hand, the early inclusion of these patients in a rehabilitation program seems to be helpfulfor a speedy functional recovery.There are few studies regarding ICU-AW, and systematic studies with longer follow-ups and bigger samples arenecessary to determine the most effective rehabilitation approach for these patients.

Keywords: Muscle Weakness, Myopathy, Polyneuropathy, Critical illness, Intensive Care Unit.