As outlined in the terrific accompanying review article, weakness acquired in the ICU can comprise the following:
[az_tab_section] [tab title=”Critical Illness Polyneuropathy” id=”tab-1″]• Symmetrical pattern of weakness affecting the limbs, particularly the legs, more obvious proximally. Can affect respiratory muscles. Sensory function preserved.
• Characterised by primary axonal degeneration with subsequent loss of anterior horn cells at the spinal cord
• EPS show: preserved nerve conduction velocity but reduction in the amplitudes of compound muscle action potentials and sensory nerve action potential
• CK levels normal [/tab]
[tab title=”Critical Illness Myopathy” id=”tab-2″]• More frequent than polyneuropathy
• Clinically difficult to distinguish from neuropathy
• Characterised histologically by selective loss of thick filaments in muscle reflecting myosin loss and muscle necrosis
• EPS also show preserved velocity and reduced amplitude of CMAPs but with increased duration
• CK levels may mildly to markedly elevated [/tab]
[tab title=”Critical Illness Neuromyopathy” id=”tab-3″]• Combination of the two based on histology or EPS[/tab]
[tab title=”Something else…” id=”tab-4″]• Cervical myelopathy
• Guillian-Barre Syndrome
• Myasthenia gravis
• Others including Porphyria, Eaton–Lambert syndrome and amyotrophic lateral sclerosis [/tab] [/az_tab_section]
The review article provides a diagnostic algorithm to differentiate between these.
Importantly the review also notes that “the greatest burdens that survivors of critical illness face are related to neuromuscular dysfunction and neuropsychological maladjustment”. As such, acute care should be focussed on “optimising early physical activity” through minimising sedation and early mobilisation.
Coming soon – Case 10: Traumatic Intracranial Hypertension!