The breathing hand: obstetric brachial plexopathy reinnervation from thoracic roots?

It has been found that in cases of obstetric brachial plexopathy, injured phrenic nerve or C3/4/5 roots may sprout into the adjacent injured upper and middle trunks of the brachial plexus. This aberrant regeneration produces co-contraction of the diaphragm and proximal upper limb muscles. This phenomenon, referred to as respiratory synkinesis or "the breathing arm", may not be limited to the upper cervical roots. We present two cases, identified through electromyographic investigations, of respiratory synkinesis selectively affecting intrinsic hand muscles, and propose that upper thoracic roots and their intercostal nerves may also produce respiratory synkinesis, resulting in a "breathing hand." This novel brand of synkinesis indicates that obstetric brachial plexus neuropathies can have quite proximal nerve injury in all trunks. The findings in our patients may not be entirely unique. The time required to develop distal muscle synkinesis and the subtle nature of our findings may suggest that with time and the assistance of EMG the breathing hand may be more common. When considering brachial plexus surgery, the significance of respiratory synkinesis should not be overlooked as its presence indicates injury at a root or proximal trunk level and may come from either nerves destined for the diaphragm or for the intercostal muscles.

Inflammation and neuropathic attacks in hereditary brachial plexus neuropathy

OBJECTIVE

To study the role of mechanical, infectious, and inflammatory factors inducing neuropathic attacks in hereditary brachial plexus neuropathy (HBPN), an autosomal dominant disorder characterised by attacks of pain and weakness, atrophy, and sensory alterations of the shoulder girdle and upper limb muscles.

METHODS

Four patients from separate kindreds with HBPN were evaluated. Upper extremity nerve biopsies were obtained during attacks from a person of each kindred. In situ hybridisation for common viruses in nerve tissue and genetic testing for a hereditary tendency to pressure palsies (HNPP; tomaculous neuropathy) were undertaken. Two patients treated with intravenous methyl prednisolone had serial clinical and electrophysiological examinations. One patient was followed prospectively through pregnancy and during the development of a stereotypic attack after elective caesarean delivery.

RESULTS

Upper extremity nerve biopsies in two patients showed prominent perivascular inflammatory infiltrates with vessel wall disruption. Nerve in situ hybridisation for viruses was negative. There were no tomaculous nerve changes. In two patients intravenous methyl prednisolone ameliorated symptoms (largely pain), but with tapering of steroid dose, signs and symptoms worsened. Elective caesarean delivery did not prevent a typical postpartum attack.

CONCLUSIONS

Inflammation, probably immune, appears pathogenic for some if not all attacks of HBPN. Immune modulation may be useful in preventing or reducing the neuropathic attacks, although controlled trials are needed to establish efficacy, as correction of the mutant gene is still not possible. The genes involved in immune regulation may be candidates for causing HBPN disorders.