Which of the following diagnostic modalities can be used to distinguish between pre and postganglionic brachial plexus injuries.
|C||Intradermal histamine test|
Intradermal histamine test
a. A drop of histamine is placed on the skin along the distribution of the nerve being examined, after the skin is scratched through the drop a sequential response consisting of vasodilation, formation and flare response is normally seen.
b. If the nerve is interrupted proximal to the ganglion, there is anaesthesia along the course of the nerve but the normal axon response is .seen, If the injury is distal to the Ganglion there is also anaesthesia long the course of the nerve and vasodilation and wheal formation are seen but flare response is not seen.
c.Positive Intradermal histamine test Indicates poor prognoses.