Table 5 Causes of weakness on the intensive care unit
Disorders of the cortex and brainstem

  • Epilepsy—status epilepticus

  • Vascular—brainstem infarction or haemorrhage, subarachnoid haemorrhage, intracerebral haemorrhage

  • Infection—brainstem encephalitis, herpes simplex encephalitis, poliomyelitis

  • Inflammatory—acute disseminated encephalomyelitis, multiple sclerosis

  • Metabolic—central pontine myelinolysis

  • Hypoxic-ischaemic encephalopathy

  • White matter disease—posterior reversible leukoencephalopathy, toxic leukoencephalopathy

  • Autoimmune encephalitis—paraneoplastic, Morvan, Hashimoto

Disorders of the spinal cord

  • Trauma including surgery

  • Acute epidural compression due to neoplasm, infection, haematoma

  • Acute transverse myelitis (demyelination, infective)

  • Cord infarction

  • Arnold-Chiari malformation, cerebellar ectopia

Anterior horn cell

  • Motor neuron disease

  • Poliomyelitis and post polio syndrome

  • Spinal muscular atrophy

  • Paraneoplastic syndrome

Multiple radiculopathies

  • Carcinomatous meningitis

  • AIDS polyradiculitis

Acute polyneuropathy

  • Acute inflammatory demyelinating polyneuropathy (AIDP)

  • Acute motor and sensory axonal neuropathy (AMSAN)

  • Acute motor axonal neuropathy (AMAN)

  • Phrenic neuropathies

  • Critical illness polyneuropathy

  • Others—toxic neuropathies, vasculitis, diphtheria, porphyria, HIV, etc

Chronic polyneuropathies

  • Chronic inflammatory demyelinating polyneuropathy (CIDP)

  • Diabetic polyneuropathy

Neuromuscular transmission disorders

  • Myasthenia gravis

  • Lambert-Eaton myasthenic syndrome

  • Congenital myasthenic syndromes

  • Neuromuscular blocking agents

  • Others: botulism, snake bites, fish toxins, organophosphates, hypermagnesaemia, poisoning

Myopathy

  • Congenital:

    • Myotonic dystrophy

    • Acid maltase deficiency

    • Duchenne muscular dystrophy

    • Mitochondrial

    • Periodic paralysis

  • Acquired:

    • Inflammatory myopathies—polymyositis, dermatomyositis

    • Critical illness myopathy

    • Diffuse non-necrotising cachectic myopathy

    • Acute necrotising myopathy of intensive care

    • Others: HIV-related, sarcoid, hypokalaemia, hypophosphataemia, corticosteroids, rhabdomyolysis