Pain, referred sensations, and involuntary muscle movements in brachial plexus injury.

OBJECTIVES

Examination of the relationship between pain, sensory hypersensitivity, referred sensations and involuntary muscle jerks in patients with brachial plexus injury.

MATERIALS AND METHODS

Fourteen patients with brachial plexus lesions were included. Spontaneous background and paroxysmal pain and mechanically and thermally evoked pain were recorded. Areas with sensory hypersensitivity and referred pain were mapped on a body chart. This was supplemented by electrophysiological analysis in three patients.

RESULTS

Sensory hypersensitivity and areas with pinprick-induced referred phantom sensations were present in adjacent dermatomes. There was no clear relationship between chronic neuropathic pain and referred sensations, but there was a correlation between pain paroxysms and sensory hypersensitivity in dermatomes adjacent to deafferented areas. In three patients, simultaneous referred sensations and short latency motor action potentials ipsilateral to the denervated side suggested origin at subcortical sites.

CONCLUSION

The study suggests a possible role of a spinal generator for sensory hypersensitivity and referred sensations following denervation.