A few drops of a lidocaine solution placed in the nose relieved migraines in 55% of patients in five to 15 minutes, Dr. Morris Maizels and his colleagues at the Southern California Permanente Medical Group report today in the Journal of the American Medical Assn.

But Dr. Neil Raskin of UC San Francisco found the results "not terribly impressive." Most important, he noted, the Permanente team did not attempt repeated use of the drug in the same patients. "We got even more impressive results when we first started using lidocaine to treat cluster headaches," he said, but the drug became steadily less effective with each use as "patients developed tolerance to it."

Although neither doctors nor patients were supposed to know which drug a patient received, patients actually did know because of the numbing effects of the lidocaine, Maizels acknowledges. Because patients often respond more positively when they know they are receiving the drug, that knowledge introduces the "possibility of bias" in the study, said Dr. Ninan T. Matthew, director of the Houston Headache Clinic. Some of the patients had also taken other drugs before coming to the emergency room, he said, which complicates the interpretation of the results.