The migraine postdrome

: A clinical and neuroimaging study

Abstract

Migraine is a common and disabling neurological disorder. The postdrome phase of migraine, is poorly defined and studied, in comparison to the preceding phases. It has also not been defined in the International Classification of Headache disorders. Hence there exists a vital need to understand the pathophysiology involved in this phase. No imaging study has evaluated the postdrome phase. Preceding phases of migraine have been studied, but with PET imaging as the functional imaging modality. However, there are various limitations of PET which pose several logistical challenges in studying the postdrome phase. Arterial Spin Labelling (ASL) MRI is a novel MRI technique that measures tissue perfusion without ionizing radiation. Previous diary studies have shown the extent of postdrome amongst migraineurs to vary from 61-80%. A clinical audit carried out within our clinical cohort of patients showed that 86% of subjects reported postdrome symptoms. The primary hypothesis behind the ASL MRI study is that, brain areas with increased neuronal activations in the premonitory phase, remain persistently activated in the postdrome phase. The reasoning behind this is, the broadly similar nature of symptoms that patients complain of, in both these phases. A nitroglycerin induced migraine model was applied to study the activations. In this prospective imaging study involving 16 subjects, voxel based analysis showed a near global reduction in rCBF in the postdrome phase compared to the premonitory phase with a peak reduction over the left superior temporal gyrus (P<0.001). This study has shown that the biology of neural activations in the premonitory and postdrome phase are different and not due to persistent activation of similar neural networks. The symptoms experienced by subjects in the postdrome are associated with a significant, near global reduction in cerebral blood flow. In chapter 7, a subgroup analysis was carried out to see if there was any seasonal variation to nitroglycerin induced migraine. The analysis showed that the triggering rates were lowest during winter, which may have a profound impact on experimental migraine research.

Date of Award	2018
Original language	English
Awarding Institution	King's College London
Supervisor	Peter Goadsby (Supervisor) & Fernando Zelaya (Supervisor)