Patient selection: critically ill patient in the ICU
Differential diagnosis of muscle weakness of new onset:
(1) hypokalemia
(2) hypophosphatemia
(3) hypocalcemia
(4) hypermagnesemia
(5) acute intermittent porphyria
(6) acute necrotizing myopathy
(7) critical illness myopathy
(8) myasthenia gravis
(9) organophosphate poisoning
(10) muscle relaxant-related neuromuscular blockade
(11) critical illness polyneuropathy
(12) acute inflammatory demyelinating polyradiculoneuropathy
(13) acute motor axonal neuropathy
where:
• Acute inflammatory demyelinating polyradiculoneuropathy and acute motor axonal neuropathy are listed as variants of the Guillain0Barre syndrome.
Recommended workup includes:
(1) serum chemistries (potassium, phosphorus, magnesium, calcium, urea)
(2) creatinine kinase (CK)
(3) protein electrophoresis and immunoelectrophoresis
(4) urine porphyrins
(5) CSF protein and cell count
(6) nerve conduction studies
(7) repetitive nerve stimulation
(8) electromyography
(9) muscle biopsy
