Cluster headache

Cluster headache is a relatively uncommon primary head pain syndrome. In this thesis a total of 230 individuals with cluster headache were interviewed, of whom 19 underwent functional imaging with positron emission tomography (PET) to address pathophysiological mechanisms of the syndrome, and to better understand the clinical problem. Seventy-six percent were recruited through national support groups. The male to female ratio was 2.5:1. Although there were some shared clinical features with migraine the syndrome of cluster headache was clinically distinct: a strictly unilateral first division trigeminal head pain, with ipsilateral autonomic features and a characteristic circadian periodicity to short-lived attacks and bouts of attacks. With presumed better access to neurologists the time to diagnosis has improved over the decades, however despite this, the management of such patients remains suboptimal. Nine patients with chronic cluster headache were imaged with PET during a nitroglycerine induced cluster headache. First, activation was seen during pain in structures associated with the processing of pain, e.g the cingulate cortex, the thalamus and insula. Secondly there was activation of the posterior hypothalamus, a region not reported in previous PET studies of pain, and consistent with clinical and experimental studies, supporting dysfunction of the hypothalamus in cluster headache. Thirdly, there was activation of structures corresponding to the cranial vessels. The activations observed were not seen in patients imaged out of the active bout after attempted triggering of an attack was unsuccessful (n=8). In a single patient with cluster headache and migraine, triggering with nitroglycerine induced a typical migraine attack. Activation was observed in structures associated with pain processing, the dorsorostral brainstem and in the region of the cranial vessels. There was no activation in the hypothalamus. This suggests that primary head pain syndromes may be pathophysiologically differentiated on the basis of distinct patterns of brain activation. Moreover, the term neurovascular headache more appropriately describes the syndromes of migraine and cluster headache