Pneumothorax: a complication of nerve conduction studies using needle stimulation.

Two patients developed left pneumothorax after nerve conduction studies were done as part of their evaluation for left thoracic outlet syndrome (TOS). Chest x-rays indicated a 20% and 10% left pneumothorax, respectively. Stimulation was accomplished at Erb point with a 1 1/2-inch needle electrode after unsuccessful attempts at percutaneous stimulation. Because of this complication, this procedure has been discontinued and only percutaneous stimulation at Erb's point is being used. The diagnosis of TOS is determined by other criteria.