Abstract
BackgroundCluster headache is an excruciating disorder with no cure. Greater occipital nerve blockades can transiently suppress attacks in approximately 50% of patients, however, its mechanism of action remains uncertain, and there are no reliable predictors of treatment response. To address this, we investigated the effect of occipital nerve blockade on regional cerebral blood flow (rCBF), an index of brain activity, and differences between treatment responders and non-responders. Finally, we compared baseline perfusion maps from patients to a matched group of healthy controls.Methods21 male, treatment-naive patients were recruited while in a cluster headache bout. During a pain-free phase between headaches, patients underwent pseudo-continuous arterial spin labelled MRI assessments to provide quantitative indices of rCBF. MRIs were performed prior to and 7-to-21 days following treatment. Patients also recorded the frequency of their headache attacks in a daily paper diary. Neuropsychological assessment including anxiety, depression and quality of life measures was performed in a first, scanning free session for each patient.ResultsFollowing treatment, patients demonstrated relative rCBF reductions in posterior temporal gyrus, cerebellum and caudate, and rCBF increases in occipital cortex. Responders demonstrated relative rCBF increases, compared to non-responders, in medial prefrontal cortex and lateral occipital cortex at baseline, but relative reductions in cingulate and middle temporal cortices. rCBF was increased in patients compared to healthy controls in cerebellum and hippocampus, but reduced in orbitofrontal cortex, insula and middle temporal gyrus.ConclusionsWe provide new mechanistic insights regarding the aetiology of cluster headache, the mechanisms of action of occipital nerve blockades and potential predictors of treatment response. Future investigation should determine whether observed effects are reproducible and extend to other headache disorders.
Highlights
Cluster headache (CH), a member of the group of trigeminal autonomic cephalgias, is an excruciating condition
Eight patients were designated as non-responders; within this group, two patients reported a reduction in weekly attacks lower than 50%, no changes were reported by two patients and remaining subjects reported an increased number of attacks after treatment
We examined regional cerebral blood flow (rCBF) changes following Greater occipital nerve blockade (GONB) in CH patients, using Pseudo Continuous Arterial Spin Labelling (pCASL) Functional magnetic resonance imaging (fMRI) imaging
Summary
Cluster headache (CH), a member of the group of trigeminal autonomic cephalgias, is an excruciating condition. While there are a number of treatments available to alleviate CH symptoms, at least partially [1], further development is still needed to achieve complete suppression of headache attacks and effective management of commonly associated psychological symptoms (e.g. anxiety, depression). It is still unclear how some of these therapies work in CH treatment responders, which suggests the involvement of several interrelated neural processes which require better characterisation. We compared baseline perfusion maps from patients to a matched group of healthy controls
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