Hopkins researchers think they've found the source of pain in migraines.
The research shifts explanations away from traditional ones involving dilating or constricting blood vessels to the back of the head and focuses instead on changes within the meninges, the protective tissue layers covering the brain.
The research, which involved SPECT scans of patients in the midst of a headache, points to a surer way to diagnose debatable migraines. It also offers scientists a straightforward method to judge therapy for the common headaches that plague millions nationwide. The study was presented at this week's American Academy of Neurology meetings in Toronto by Hopkins neurologist Marco Pappagallo, M.D., who headed a research team.
Patients in the study came to Hopkins in the midst of a well-documented migraine attack and pinpointed the site of their headache on a diagram. They then received IV injection of the common blood plasma protein, albumen, tagged with a radioactive isotope.
Radiologists took SPECT (single photon emission computerized tomography) scans of the head at 10 minutes and 3 hours, and then several days later, after headaches subsided, as a baseline. During inflammation that occurs during a migraine, Pappagallo says, blood vessels in the meninges become unusually permeable to molecules such as albumen. The SPECT scans then pick up the albumen leakage into surrounding tissues.
The images showed bright, diffuse patches -- a sign of inflammation -- at areas in the meninges that precisely matched places where patients said they felt their headaches, thus linking abnormalities in the meninges with the pain.
But the inflammation itself isn't the immediate cause of migraine pain,
Pappagallo adds. That, the researchers believe, comes from abnormal nerve
activity. Animal studies elsewhere show that electrically stimulating the
trigeminal nerve, the major nerve leading from the brain to head a
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Contact: Marjorie Centofanti
mcentofanti@jhmi.edu
410-955-8725
Johns Hopkins Medical Institutions
21-Apr-1999