Sensory nerve action potential in traumatic brachial plexus injuries

Abstract

To show the contribution of the sensory nerve action potential in the topographic diagnosis of traumatic brachial plexus injuries through an illustration of 7 clinical cases. We report 7 clinical cases of patients with unilateral traumatic brachial plexus injuries, following public highway accident. We realized an electroneuromyographic test (ENMG) for each patient in our service. A radiculopathy C5C6C7 were found in 3 subjects. Other patients had a radiculopathy C5 T1, a radiculopathy C7C8 T1, a lesion of the upper trunk or a lesion of the posterior cord. In all patients, pre- and post-ganglionic lesion was defined by the sensory potential: a sensory potential is unaffected in pre-ganglionic lesions, however, in a post-ganglionic lesion it is attenuated or absent. This electromyographic topographical definition was confirmed by myelography in two cases, by surgery for a patient and by clinical recovery for other patients. With the sensory nerve action potential, we could define the topography of the lesion in traumatic brachial plexus injury (pre or post-ganglionic lesion). This conclusion is concordant with the study of Ferrante. The myelography was the gold standard for radiological confirmation of a root avulsion. Currently, only the physical examination and the EMG exploration allows to have topographic definition of lesion in order to define surgical indication. A well-performed electrodiagnostic assessement and a correctly done sensory nerve action potential are helpful for the planning of a therapeutic strategy of traumatic brachial plexus injuries.