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What is A pole vaulter had a fall during pole vaulting and had paralysis of the arm. Which of the following investigations gives the best recovery prognosis: and explain in detail?
Ans. is 'a' i.e. ElectromyographyRef: Adam's outline of Orthopedics 11th/e p 19; Schwartz Surgery 7th/e p 1885Electromyography-ProcedureIn this technique the electrical changes occurring in a muscle are picked up by a needle or surface electrodes.These electrical changes are then amplified and are studied in the form of sound through a loud speaker, or as a tracing on an oscillograph.First look at the patterns observed in various phase of muscle physiology (& pathology)(a) Normal muscle is electrically silent at rest.On voluntary contraction of a muscle, increasing electrical discharges are seen in the form of triphasic action potentialPartly denervated or totally denervated muscle shows only spontaneous contraction of individuals fibres (fibrillation potential)So repeated testing at intervals can be done to assess Reinnervation in a denervated muscle fibres.Reappearance of small polyphasic motor unit action potentials and disappearance of spontaneous fibrillation is evidence that reservation has begun.Remember that motor unit action potentials will gradually increase in duration and amplitude but do not return to normal pattern until remyelination of the nerve is complete.