Electro-physiological evaluation of nerves during reactions in leprosy.

Forty-two patients with leprosy (7 with tuberculoid type, 30 borderline, 5 lepromatous) were studied electrophysiologically during reactions. Thirty-three had type I reactions while 9 had type II reactions. Each patient received 60 mg/day prednisolone tapered over a 6-week period. Motor conduction studies were performed on one clinically affected and one unaffected nerve and were repeated 12 weeks after the beginning of steroid therapy. Significant motor conduction abnormalities were observed in 14 affected (33.3%) and 8 unaffected nerves (19.1%). The majority of these nerves were in patients with borderline leprosy having type I reactions. Following steroid therapy, nerve function improved in 14 affected (33.3%) and 20 unaffected nerves (47.66%). However, 5 affected (10.2%) and 12 unaffected nerves (28.5%) showed a worsening of nerve function following steroid therapy. The majority of the nerves that showed improvement with steroid therapy had type I reactions, while those that showed deterioration had type II reactions. Steroids improved nerve function mainly in patients with type I reactions. Their role in patients with type II reactions remains debatable.