Cluster headache: imaging and other developments

Cluster headache, one of the most severe pain syndromes in humans, is usually described as a vascular headache. However, the striking circadian rhythmicity of this strictly unilateral pain syndrome cannot readily be explained by the vascular hypothesis. Recent studies using positron emission tomography suggest that a central nervous system dysfunction in the region of the hypothalamus is the primum movens in the pathophysiology of cluster headache. From a physiological viewpoint, therefore, cluster headache should be described as a neurovascular headache, thus placing equal emphasis on its fundamental pathophysiology and clinical expression.