Fundamental to the concept of idiopathic or primary headache, including
migraine, tension-type headache and cluster headache, is the currently accepted
view that these conditions are due to abnormal brain function with completely
normal brain structure1. Cluster headache is one such idiopathic
headache with many similarities to migraine, including normal brain structure
on magnetic resonance imaging and abnormal function in the hypothalamic grey
matter by positron emission tomography2. Given the consistency
of the positron emission tomography findings with the clinical presentation, we sought to assess whether the brains of such patients were structurally
normal. We used voxel-based morphometry, an objective and automated method
of analyzing changes in brain structure, to study the structure of the brains
of patients with cluster headache. We found a co-localization of structural
changes and changes in local brain activity with positron emission tomography
in the same area of the brain in the same patients. The results indicate that
the current view of the neurobiology of cluster headache requires complete
revision and that this periodic headache is associated with a hitherto unrecognized
brain abnormality in the hypothalamic region. We believe that voxel-based
morphometry has the potential to change in the most fundamental way our concept
of primary headache disorders, requiring a radical reappraisal of the tenet
of structural normality.
