Scanning shows structural abnormality in headacheBMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7201.9a (Published 03 July 1999) Cite this as: BMJ 1999;319:9
Sophisticated imaging techniques have for the first time shown that people experiencing cluster headaches have systematic structural differences in their brains compared with matched controls, rather than simply having functional differences as had previously been thought.
A team from the Institute of Neurology, London, has found that the density of grey matter in the brains of patients experiencing cluster headaches (one sided, severe headache occurring seasonally and with clock-like regularity) was significantly increased compared with normal, matched volunteers.
These differences were seen both when patients had headaches and when they did not, showing that the changes seen were permanent (Nature Medicine 1999;5:836-8).
Peter Goadsby, professor of clinical neurology at the Institute of Neurology and member of the research team, said: “Fundamental to the concept of primary headache, like cluster headaches and migraine, is the currently accepted view that these conditions are due to abnormal brain function with completely normal brain structure. Our study shows that this is simply not the case.”
The researchers used voxel-based morphometry—an objective and automated method of analysing subtle changes in brain structure—to study the structure of the brains of 27 patients with cluster headache, compared with 25 matched controls. They found an increase in grey matter in the hypothalamus on the side of the brain where headache occurred. It was almost identical to the area of activation seen with positron emission tomography during an acute attack of cluster headache. The hypothalamus is the part of the brain associated with circadian rhythms.
Professor Goadsby commented: “Our results demonstrate for the first time the precise location in the brain involved in cluster headaches and help to explain why this condition shows such striking seasonality and regularity.”
It is too early to propose what the underlying nature of the structural abnormality might be, although abnormalities in membrane calcium channels have previously been implicated in headache.
He was quick to point out, however, that patients should be reassured that the finding does not suggest anything sinister is going on in their brains. “But the findings have profound implications for understanding how the brain is affected in primary headaches,” he concluded.