Critical Care Myopathy


a.k.a. acute quadriplegic myopathy


This is a clinical diagnosis supported by exclusion of other causes. Usually it does not require biopsy but often it is used in cases of uncertainty

Clinical features:

All limbs, diaphragmatic and intercostal weakness,
Occurs in severe illness +/-sepsis, +/-steroids, +/-neuromuscular blocking agents

Findings on investigations:

+CK normal or moderately raised
+EMG myopathic pattern +reduced excitability to direct muscle stimulation
+NCS normal, or slightly reduced CMAP, to exclude Critical care neuropathy
+RNST to exclude Myasthenia Gravis

+Muscle Biopsy:

HE: Nonspecific changes, fibre atrophy especially type 2, necrosis may occur
+EM loss of myosin (absent A bands= thick bands), preserved Z-bands and thin filaments
Immunohistochemistry: myosin heavy chain: reduced

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