[Acute posterior interosseous nerve paralysis with constrictions possibly due to twists in the nerve trunk]

This report is concerning a case of acute spontaneous paralysis of the posterior interosseous nerve (P.I.O.N.), possibly caused by twists in the nerve trunk, in a 23-year-old woman. The subject felt a tingling pain over the lateral epicondyle of the right forearm when grasping and lifting a basin, and noticed that the fingers of the right hand could not be extended three days later. The fingers of the left hand also experienced paralysis 3 months after the first injury when she pronated and extended left forearm. Neurological examination revealed bilateral P.I.O.N. paralysis. When, after a period of time, the bilateral P.I.O.N. paralysis had not improved, surgical exploration of both P.I.O.N. was performed. It revealed that the right P.I.O.N. underwent a severe constriction at 2 cm proximal to the superficial portion of the supinator muscle, and that the proximal portion of the right nerve was swollen. The constricted portion of the right nerve was resected 5 mm in length, and nerve suturing was performed. The left P.I.O.N. was also constricted at the same location, and was found to be a sausage-like neurinoma with two constrictions. In the histological examination of the right resected P.I.O.N., edema of the interstitial tissue and a great number of regenerating cluster formations, including swollen axons, were observed proximal to the constriction. Distal to this, severe Wallerian degeneration was found. These histological findings were the same as those of chronic compression neuropathy. The authors reviewed and analysed reports on 20 other cases of P.I.O.N. paralysis that had compressions at 2 cm proximal to the superficial portion of the supinator muscle.(ABSTRACT TRUNCATED AT 250 WORDS)