Rate of recovery in motor and sensory fibres of the radial nerve: clinical and electrophysiological aspects.

Electromyography and conduction studies in motor and sensory fibres were performed in 58 patients with different types of radial nerve injury. The site of nerve injury was predicted by clinical and electromyographic findings and correlated with changes in conduction, thereby permitting a more exact classification of the type of nerve injury. In patients with Saturday-night palsy, there was considerable slowing of conduction in both motor and sensory fibres across the presumed site of the lesion with return to normality within six to eight weeks. These observations suggest that local demyelination is the cause of nerve palsy. There were changes in sensory conduction even when there was no sensory deficit clinically, with no difference in susceptibility of motor and sensory fibres to ischaemia. In patients with radial nerve palsy secondary to fracture of the humerus, out-growth in motor and sensory fibres was equal and estimated to be about 1 mm per day. When the radial nerve palsy was attributed to traction or mild blunt injury the site of lesion was based on clinical and electromyographic findings. The rate of conduction in motor and sensory fibres was normal, suggesting that axonal damage was the cause of paresis, with sparing of some of the fastest conducting fibres.