All are true regarding brachial plexus injury, except
Preganglionic lesions have a better prognosis than postganglionic lesions* o Preanlionic Brachial Plexus Injury. o - preganglionic lesions represent root avulsions from the spinal cord o - preganglionic injuries have limited spontaneous recovery; o - surgical repair is impossible (bad pregnosis as compared to post-ganglionic lesion) o -- Exam. findings include: o - abnormal axonal reflex; o - Horner's syndrome: (pre-ganglionic injury) o - caused by avulsion of the T1 root resulting in interruption of the T1 sympathetic ganglion; o - results in interruption of sympathetic nerve supply to the eye; o - causes miosis (constriction of pupil), ptosis (dropping of upper eyelid), enophthalmos (sinking of the orbit), and anhydrosis (dry eyes); o - Diagnostic Studies: o -EMG: o - nerve conduction studies show absent motor conduction with intact sensory conduction; o - afferent sensory fibers will not undergo Wallerian degeneration following nerve root avulsion because cell bodies of afferent sensory fibers are located in dorsal root anlion which resides distally; o -if nerve conduction velocity demonstrates absence of both sensory and motor then lesion is pQj ganglionic; o - histamine test: o - differentiate preganglionic and postganglionic lesions; o - if the nerve is interrupted proximal to ganglion, there is anesthesia along its cutaneous course, but the normal axon response will be seen; o - normal axon response can be demonstrated by placing a drop of histamine on the skin o - the skin is scratched thru the histamine; o - triple response: o - vasodilatation, wheel formation, and flare; o - a sequential response consisting of cutaneous vasodilation and wheal formation are seen, the flare response is present; o - a normal response implies a preganlionic lesion and has a prognosis; o if the flare response is negative then the lesion may be at a site where recovery may be possible after repair
Preganglionic lesions have a better prognosis than postganglionic lesions
Erb's palsy causes paralysis of the abductors and external rotators of the shoulder
In Klumpke's palsy, Horner's syndrome may be present on the ipsilateral side
Histamine test is useful to differentiate between the preganglionic and postganglionic lesions