PIN ENTRAPMENT US G RELEASE

38 years male physician ( scuba diver ) with chronic right lateral elbow pain over two years received three local steroid injections , two PRP injections as a case of Tennis elbow with partially and temporary relief
Returned from a scuba diving trip in Sharm El-Sheikh Egypt , complaining of sever shooting pain over the lateral aspect of elbow and forearm with sense of hand grip weakness but no tingling or numbness .Clinically negative Cozen test and tenderness is over proximal third of brachioradialis and mild weakness of finger and thumb extensors 4/5 compared to normal left side
MSK US shows swollen fascicles of PIN in the radial tunnel with positive sonopalpation
US guided hydrorelease of PIN at the tunnel and at the distal edge of supinator muscle using 3 cc 5 % dextrose and 30 mg triamcinolon resulted in complete resolution of his pain and recovery of his hand grip power within one weak

N. B. Tingling and numbness would occur if entrapment is more proximal involving the superficial branch of radial nerve
POSTERIOR INTEROSSEOUS NERVE SYNDROME,

Also known as supinator entrapment syndrome, is caused by compression of the deep branch of the radial nerve distal to the elbow.
The posterior interosseous nerve passes deep in relation to the arcade of Frohse (the proximal aspect of the supinator muscle, superficial head) and subsequently branches to supply the finger and
thumb extensors, extensor carpi ulnaris, and the abductor pollicis longus
Posterior interosseous nerve syndrome occurs when there is compression of the posterior interosseous nerve sufficient to cause paresis or, if more severe, paralysis
Compression of the posterior interosseous nerve by the arcade of Frohse, intermuscular septa, fibrous bands, muscle margins
(ECRB edge can compress both branches of radial nerve SR and PIN ),
vessels, rheumatoid arthritis, fractures, scar adhesions, ganglionic cysts,
and other soft-tissued masses are well-known causes MORE COMMON The posterior interosseous nerve can also be stressed during repetitive supination and pronation, as has been reported in swimmers, Frisbee players, tennis players, violinists, and orchestra conductors

Electromyographic studies show a nerve action potential with marked slowing of conduction
and low amplitude across the lesion, which affects the severity and location of the deficit. Initial nonoperative treatment includes rest, activity modification, and splinting. If no improvement is seen with conservative therapy, patients are usually offered surgery to relieve any extrinsic compression
Compression-induced neuronal swelling is well known

MSK US can offer accurate diagnosis , localisation of the lesion and guided release of entrapped nerve