An electronic device designed to "zap" migraine pain before it starts has been unveiled.
The hand-held device is placed at the back of the head and creates an electromagnetic field which interrupts the "aura phase" of the migraine - often described as electrical storms in the brain - before it causes headaches.
Dr Yousef Mohammad, a neurologist at Ohio State University Medical Centre, said patients in a study reported a significant reduction in nausea and noise and light sensitivity after the treatment.
Auras are neural disturbances that signal the onset of migraine headaches.
Sufferers often describe seeing showers of shooting stars, zig-zagging lines and flashing lights, and experiencing loss of vision, weak-ness, tingling or confusion.
After those initial symptoms comes intense throbbing h ead pain, nausea and vomiting.
The device, called Transcranial Magnetic Stimulation (TMS), sends a strong electric current through a metal coil, which creates an intense magnetic field for about a millisecond.
When the pulse is held against a person's head it creates an electric current in the neurons of the brain which interrupts the aura.
"The device's pulses are painless. The patients have felt a little pressure, but that's all," said Dr Mohammad, who presented the study at a meeting of the American Headache Society.
In a study of 43 patients, nearly 70 per cent of the half given TMS reported that they had a mild headache or none at all two hours later.
Among the other half of the group, who were given a placebo, the figure was only 48 per cent.
While 42 per cent of the TMS-treated patients graded their headache response as "very good" or "excellent", only 26 per cent of the placebo group did. "These are very encouraging results," Dr Mohammad said.
The device is made by a Californian company called Neuralieve.
Roughly one in eight Britons are afflicted by migraines, which are twice as common in women as they are in men.
Sufferers have an average of 13 attacks each year, each between four and 72 hours.