Migraine is a common disabling condition likely to be associated with dysfunction of brain pathways involved in pain and other sensory modalities. A cardinal, indeed signature, feature of the disorder that led to its name is that the pain may be lateralized. H(2)15O-labelled PET was used to study 24 migraineurs and eight healthy controls. The migraineurs were divided into three groups according to the site of their headache: right, left or bilateral. In each group, a migraine was induced using a glyceryl trinitrate (GTN) infusion. The subjects were scanned at predefined points: pre-infusion, during GTN, during migraine and post-migraine. SPM99 software was used to analyse the data. Significant brainstem activation was seen in the dorsal lateral pons (P < 0.05 after small volume correction) during the migraine state versus the pain-free state when comparing migraineurs with controls. When each group was analysed separately, to investigate laterality, it was found that the dorsal pontine activation was ipsilateral in the right-sided and left-sided groups and bilateral in the bilateral headache group with a left-sided preponderance. Consistent with previous work, the activation persisted after pain was controlled by sumatriptan. These results suggest that lateralization of pain in migraine is due to lateralized brain dysfunction.

Most patients with primary headache syndromes who have frequent attacks of pain have tenderness in the sub-occipital region. Injection of the greater occipital nerve (GON) with local anesthetic and corticosteroids has been widely used in clinical practice for many years, yet there is no clear understanding of its mechanisms of action. Moreover, there is no current gold-standard of practice regarding GON injections in the management of headache. We audited of our practice to generate hypotheses about the range of primary headaches that might benefit, to determine response rates to power future studies, and to assess whether we should continue to do this procedure. Twenty-six of fifty-seven injections in 54 migraineurs yielded a complete or partial response that lasted for the partial response a median of 30 days. For cluster headache 13 of 22 injections yielded a complete or partial response lasting for a median of 21 days for the partial response. Tenderness over the GON was strongly predictive of outcome, although local anesthesia after the injection was not. The presence or absence of medication overuse did not predict outcome. Apart from two patients with a small patch of alopecia the injection was well tolerated. GON injection is a useful tool in some patients that provides interim relief while other approaches are explored. It is remarkable that in all conditions in which an effect is observed the response time so much exceeds the local anesthetic effect that the mechanism of action may well be through changes in brain nociceptive pathways.

Background: Functional brain imaging in acute migraine has proved challenging because of the logistic problems associated with an episodic condition. Since the seminal observation of brainstem activation in migraine, there has been only a single case substantiating this finding.Objective: To test the hypothesis that brainstem activation could be detected in migraine and to refine the anatomic localization with higher-resolution positron emission tomography than previously used.Design: Using positron emission tomography with radioactive water (H 2 15 O), we studied acute migraine attacks occurring spontaneously. Five patients underwent imaging in ictal and interictal states, and the differences were analyzed by means of statistical parametric mapping.Setting: Tertiary referral center.Patients: Six volunteers with episodic migraine were recruited from advertisements in migraine newsletters. One patient was excluded because of use of preventive medication.Main Outcome Measure: Brainstem activation during migraine state vs interictal state.Results: Two patients had a typical migrainous aura before the onset of the headache. All of the attacks studied fulfilled standard diagnostic criteria for migraine. Comparing the migraine scans with interictal scans, there was significant activation in the dorsal pons, lateralized to the left (small volume correction, P=.003). Activation was also seen in the right anterior cingulate, posterior cingulate, cerebellum, thalamus, insula, prefrontal cortex, and temporal lobes. There was an area of deactivation in the migraine phase also located in the pons, lateralized to the right. Conclusions:Our findings provide clear evidence of dorsal pontine activation in migraine and reinforce the view that migraine is a subcortical disorder modulating afferent neural traffic.

Studying attacks of migraine is considerably hampered by its fundamentally episodic nature. Developing approaches to triggering migraine reliably is important for advancing understanding of the disorder by facilitating its study. Based on the work of the Copenhagen Group we administered an intravenous infusion of 0.5 microg/kg/min glyceryl trinitrate (GTN) to 44 migraineurs, 23 migraine without aura, 21 migraine with aura, and to 12 healthy controls. We sought to characterise the GTN-induced migraine in terms of the clinical features of the attacks and reproducibility of triggering, and included a non-migraine control group for the purpose of comparing any effects to exclude an ordering effect. Of the 44 patients administered GTN, 33 had a migraine attack fulfilling International Headache Society criteria. Thirty-two attacks were of migraine without aura and one of migraine with aura. Twelve patients described typical premonitory symptoms, which have not been previously documented with GTN-induced migraine. A repeat attack was triggered in all subjects but one. In one case a visual aura was also triggered both times. Our study shows that GTN-induced triggering is common in our patients, and remarkably reproducible. The data will facilitate the use of the GTN model in studies requiring extensive planning, such as brain imaging, or where preventive questions are at issue. We also report the first patient with a reproducible GTN-triggered migraine with aura.