Condition | Sensory nerve action potential | Compound muscle action potential | Repetitive stimulation | Nerve stimulation/direct muscle stimulation ratio | Electromyography |
Critical illness polyneuropathy | Reduced | Reduced amplitude | Normal | <0.5 | Fibrillation and positive sharp waves. Recruitment—neurogenic motor units |
Critical illness myopathy | Normal | Reduced amplitude and prolonged duration | Normal | >0.5 | Fibrillation and positive sharp waves. Short duration small amplitude motor units with early full recruitment |
Prolonged neuromuscular blockade | Normal | Normal | Decremental response | Normal | No spontaneous activity |