Critical illness myopathy and polyneuropathy
Critical illness myopathy and critical illness polyneuropathy are the muscle and axonal nerve forms of ICU-acquired weakness, a symmetric flaccid quadriparesis that spares the cranial nerves and most often declares itself as failure to wean from mechanical ventilation in patients with sepsis and multiorgan failure. Diagnosis is one of exclusion confirmed by electromyography, and there is no specific drug therapy: treat the critical illness, keep glucose 140-180 mg/dL, limit glucocorticoids and neuromuscular blockade, interrupt sedation daily, and mobilize early.
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What this article covers
- Overview
Definition: critical illness myopathy (CIM) and critical illness polyneuropathy (CIP) are acquired neuromuscular disorders that develop during critical illness, especially sepsis with multiorgan…
- Epidemiology
Very common in the ICU: between 25% and 100% of critically ill patients develop muscle weakness.
- Risk factors
Sepsis: the strongest association; sepsis drives both the myopathy and the axonal neuropathy.
- Pathophysiology
Myopathy from myosin loss: CIM is skeletal muscle degeneration with loss of myosin, of multifactorial and unclear cause, possibly a sepsis-triggered channelopathy; biopsy shows degenerative changes without inflammation.
- Clinical features
Defining picture (ICU-acquired weakness): new symmetric flaccid weakness of proximal and distal limb muscles in a critically ill patient, with no explanation other than the critical illness; this is…
- Differential diagnosis
Guillain-Barre syndrome: rapidly progressive ascending flaccid weakness from an acute autoimmune demyelinating polyradiculoneuropathy, with albuminocytologic dissociation in CSF and a demyelinating…
- Diagnosis
The diagnosis is established in two steps: first, ICU-acquired weakness is diagnosed clinically as symmetric flaccid weakness with no explanation other than the critical illness (a diagnosis of…
- Management
First, treat the driving critical illness: control the source of sepsis and support failing organs, because recovery is satisfactory if the patient survives sepsis and multiorgan failure; there is no specific drug therapy for CIM or CIP.
- Complications
Prolonged mechanical ventilation: diaphragmatic weakness causes repeated weaning failure, longer ICU stay, and reintubation.
- Prognosis
Recovery is expected if the critical illness resolves: ICU-acquired weakness generally improves over weeks to months, but it may persist for years.
- Prevention
Keep glucose at 140-180 mg/dL in every critically ill patient: start an IV insulin infusion when glucose exceeds 180 mg/dL, and avoid tight targets of 80-110 mg/dL, which cause severe hypoglycemia below 40 mg/dL.
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