Investigations
1st investigations to order
Electromyography
Test
Indicated when diagnosing extent and pattern of injury, when avulsion is suspected, and when planning reconstruction.
Specific findings generally should not be interpreted by non-specialists.
Patterns of involvement may be correlated with the clinical findings.
One important electrophysiological pattern that should be known is that of avulsion injury, which may present with findings similar to less severe injuries.
Paraspinals are innervated by nerve branches derived at the most proximal levels of the corresponding roots; involvement of these structures indicates high probability of avulsion injury.
One counterintuitive electrical finding is that the sensory conduction of the affected nerve root is generally intact, due to the anatomical position of the dorsal root ganglion, subserving sensory function.[17] The ganglion is located outside the spinal cord, preserving the sensory cell body. The ganglion is functionless since its connections to higher neural levels are severed.
Nerve conduction velocity testing can similarly detect nerve injury and, to some extent, severity of that injury.
Result
presence of fibrillation potentials indicating denervation; if avulsion injury is present, findings include fibrillation in distal affected muscle groups but also in the paraspinal muscles
Investigations to consider
MRI
Test
May be used when avulsion or spine involvements are suspected and nerve transfer is not available.
Due to lack of specificity, MRI is generally not useful in planning management of brachial plexus injuries.[25]
Direct visualisation of the brachial plexus is most useful in non-traumatic pathologies such as tumours or inflammation.[20][25]
Result
pseudomeningoceles presence indicates avulsion injury of the affected spinal roots
CT/myelography
Test
May be used when avulsion, brachial plexus compression, or spine involvement are suspected and nerve transfer is not available.
Due to lack of specificity, CT imaging is generally not useful in planning management of brachial plexus injuries.[25]
CT scans do not visualise soft tissue well, so the use of myelography is required to again attempt to visualise avulsions. Concerns with sensitivity and specificity remain.[20]
Result
pseudomeningoceles presence indicates avulsion injury of the affected spinal roots
Emerging tests
Ultrasound
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