Abstract
Objectives: Traumatic lesions of brachial plexus are serious periferal nerve injuries. Neurological examination and CT myelography or MRI are the basic examination methods that can confirm spinal root avulsion.
To specify severity of the injury electromyography and evoked potentials are used. The objective of this study was to determine whether implementation of cutaneous silent period that asseses function of small diameter A-delta fibers, is useful as a diagnostic tool in cervical root avulsion and brachial plexus injury.
Material and methods: Clinical examination, imaging studies (CT myelography or MRI) and neurophysiological examination were performed in 23 patients with traumatic brachial plexus injury (16 males, age 18-62 years). Needle EMG was obtained from muscles supplied by C5-T1 myotomes.
CSP was recorded after painful stimuli were delivered to the thumb (C6 dermatome), middle (C7) and little (C8) fingers while subjects maintained voluntary contraction of intrinsic hand muscles. Results: Electrodiagnostic and CT/MRI studies confirmed brachial plexopathy involving mainly the upper trunk or corresponding C5, C6 roots in all patients.
However, well defined CSP was still present in 16 subjects. CSP was absent in at least one of the dermatomes in the remaining seven patients.
All these patients had severe plurisegmental sensitive lesion. Conclusion: CSP was still present, although not absolutely normal, in the majority of patients with severe brachial plexus injury.
This suggests there are plurisegmental innervations with residual function of A-delta fibers and the presence of spinal inhibitory reflexes. Resistance of A-delta fibers seems to be higher compared to motor fibers despite of severe traumatic lesion.