Clinical and Electrophysiological Mapping of Nerve Root Injury Following Trauma of Brachial Plexus: A Retrospective Study in 23 Dogs and 42 Cats

Objective of this study is to report mapping of nerve root injury with clinical and electrophysiological examination in cats and dogs following trauma of brachial plexus (TBP). Medical record of 65 patients (23 dogs and 42 cats) with brachial plexus injury without any fracture between July 2009 and January 2014 were reviewed. Needle electromyography, motor nerve conduction and/or sensory nerve conduction and somatosensory evoked potentials (SEP) of the forelimb were studied. Injured area was examined at necropsy in 3 cases (1 dog, 2 cats), and in 11 cases (4 dogs, 7 cats) during surgery. Assessment of cutaneous zone innervation revealed caudal brachial plexus lesion in 40 cases (29 cat and 11 dogs) and complete brachial plexus lesions in 25 cases (13 cats, 12 dogs). Nociception was also absent at the denervated cutaneous zone in all cases. Complete avulsion of isolated radial nerve roots was diagnosed in 11 cats and 5 dogs, and injury of isolated radial nerve roots was diagnosed in 4 dogs and 11 cats. Rest of the cases had complete avulsion (17 cats, 14 dogs) or injury (3 cats) of radial nerve roots in addition to other nerves' of the brachial plexus. In conclusion, Radial nerve roots prone to TBP, but other nerve roots of brachial plexus can also be affected. Electrophysiological assessment of TBP should be carried out as an ancillary diagnostic tool for determining affected nerves and type of lesion for radial nerve.