Reduced Frontal P3a Amplitude in Migraine Patients during the Pain-Free Period

BACKGROUND AND PURPOSE

Neuropsychological and neuroimaging studies both suggest that frontal lobe dysfunction is present in migraineurs. Since P3a abnormalities manifest in other diseases associated with attention problems, such as attention deficit hyperactivity disorder, we hypothesized that migraine patients have P3a abnormalities, particularly in the frontal region.

METHODS

Event-related potentials were measured using a passive auditory oddball paradigm in 16 female migraineurs (aged 22.9±2.0 years, mean±SD) during the interictal period and in 16 age-matched healthy females (22.6±2.0 years). The amplitudes and latencies were analyzed independently using repeated-measures analysis of variance. Nonparametric statistical testing using a cluster-level randomization method was performed to localize the abnormalities.

RESULTS

The mean P3a amplitude at frontal areas during the third trials was significantly lower in migraineurs (1.06 µV) than in controls (1.69 µV, p=0.026). P3a amplitudes were negatively correlated with the duration of the migraine history (r=-0.618, p=0.014). Cluster-based nonparametric statistical analysis showed that the amplitudes over left frontal areas were significantly lower in migraine patients than in controls.

CONCLUSIONS

A reduced P3a amplitude of migraineurs reflects attentional deficits and frontal dysfunction. The negative correlation between P3a amplitude and the duration of the migraine history suggests that attentional deficits and frontal dysfunction are either the cause or the result of headache.

Migraine: an endemic disease inside the blood–brain barrier

Migraine is a complex neurological disorder that in recent years has received more and more attention. Knowledge regarding this primary headache has increased substantially, both with respect to its pathogenesis and how to effectively treat its symptoms. Over the years, the proposed location of the onset of migraine has moved from the periphery of the nervous system toward deeper parts of the brain. Migraine can be viewed as an inherited failure of trigeminal sensory processing with abnormal neuronal excitability in the trigeminal nucleus caudalis, which, in turn, causes central sensitization and amplification of the pain. Increased activation of the trigeminal nerve during a migraine attack causes release of the calcitonin gene-related peptide (CGRP) inside and outside the BBB. Within the CNS, CGRP promotes trigeminal sensory input and facilitates central sensitization. The future introduction of CGRP antagonists in clinical practice could represent significant progress for acute migraine therapy.

Brain lesions and cerebral functional impairment in migraine patients

Migraine is an independent risk factor for ischemic stroke, mainly in the subpopulation of women with migraine with aura who are younger than 45 years, particularly those that use estrogen containing oral contraceptives. Migraine however should be considered a benign condition as the absolute increase of stroke risk is small. Migraine is also associated with a high prevalence of cerebral white matter hyperintensities, occurring in the deep and periventricular white matter as well as infratentorial, mainly pontine. The pathogenesis and clinical significance of these hyperintensities is unclear. We do not know whether migraine may be considered a progressive disorder in a subset of patients because of accumulation of these hyperintensities over time. Studies on the relationship between migraine and cognitive functioning yielded conflicting results. Two recent studies have provided reassuring news for the migraine patient. A population-based twin study showed that a lifetime migraine diagnosis was not associated with cognitive deficits in middle-aged subjects. A long-term prospective study, assessing cognitive and memory changes in ageing individuals with and without a history of migraine, showed that migraineurs do not exhibit more decline on cognitive tests over time versus controls. Migraine is certainly not a recognized risk factor for (vascular) dementia.

Voxel-based morphometry reveals gray matter abnormalities in migraine

BACKGROUND

Migraine is generally considered a functional brain disorder lacking structural abnormalities. Recent magnetic resonance imaging (MRI) studies, however, suggested that migraine may be associated with subtle brain lesions.

OBJECTIVE

We evaluated the presence of global or focal gray or white matter alterations in migraine patients using voxel-based morphometry (VBM), a fully automated method of analyzing changes in brain structure. VBM data also were used to evaluate possible differences between episodic and chronic migraine.

METHODS

Twenty-seven migraine right-handed patients and 27 healthy controls were selected for the study. Sixteen patients fulfilled the International Headache Society criteria for episodic migraine and 11 for chronic migraine. MRI scans were analyzed with MATLAB 6.5 and SPM2 software, using VBM method.

RESULTS

In comparison with controls, migraineurs presented a significant focal gray matter reduction in the Right Superior Temporal Gyrus, Right Inferior Frontal Gyrus, and Left Precentral Gyrus. Chronic migraine patients, compared to episodic, showed a focal gray matter decrease in the bilateral Anterior Cingulate Cortex, Left Amygdala, Left Parietal Operculum, Left Middle and Inferior Frontal Gyrus, Right Inferior Frontal Gyrus, and bilateral Insula. Considering all the migraine patients, a significant correlation between gray matter reduction in anterior cingulate cortex and frequency of migraine attacks was found.

CONCLUSIONS

Our study shows that migraine is associated with a significant gray matter reduction in several of the cortical areas involved in pain circuitry. In addition, we found a significant correlation between frequency of migraine attacks and signal alteration in the Anterior Cingulate Cortex. Our data provide new insight into migraine pathophysiology and support the concept that migraine may be a progressive disorder.

Practical considerations for the treatment of elderly patients with migraine

Treatment of migraine presents special problems in the elderly. Co-morbid diseases may prohibit the use of some medications. Moreover, even when these contraindications do not exist, older patients are more likely than younger ones to develop adverse events. Managing older migraine patients, therefore, necessitates particular caution, including taking into account possible pharmacological interactions associated with the greater use of drugs for concomitant diseases in the elderly. Paracetamol (acetaminophen) is the safest drug for symptomatic treatment of migraine in the elderly. Use of selective serotonin 5-HT(1B/1D) receptor agonists ('triptans') is not recommended, even in the absence of cardiovascular or cerebrovascular risk, and NSAID use should be limited because of potential gastrointestinal adverse effects. Prophylactic treatments include antidepressants, beta-adrenoceptor antagonists, calcium channel antagonists and antiepileptics. Selection of a drug from one of these classes should be dictated by the patient's co-morbidities. Beta-adrenoceptor antagonists are appropriate in patients with hypertension but are contraindicated in those with chronic obstructive pulmonary disease, diabetes mellitus, heart failure and peripheral vascular disease. Use of antidepressants in low doses is, in general, well tolerated by elderly people and as effective, overall, as in young adults. This approach is preferred in patients with concomitant mood disorders. However, prostatism, glaucoma and heart disease make the use of tricyclic antidepressants more difficult. Fewer efficacy data in the elderly are available for selective serotonin reuptake inhibitors, which can be tried in particular cases because of their good tolerability profile. Calcium channel antagonists are contraindicated in patients with hypotension, heart failure, atrioventricular block, Parkinson's disease or depression (flunarizine), and in those taking beta-adrenoceptor antagonists and monoamine oxidase inhibitors (verapamil). Antiepileptic drug use should be limited to migraine with high frequency of attacks and refractoriness to other treatments. Promising additional strategies include ACE inhibitors and angiotensin II type 1 receptor antagonists because of their effectiveness and good tolerability in patients with migraine, particularly in those with hypertension. Because of its favourable compliance and safety profile, botulinum toxin type A can be considered an alternative treatment in elderly migraine patients who have not responded to other currently available migraine prophylactic agents. Pharmacological treatment of migraine poses special problems in regard to both symptomatic and prophylactic treatment. Contraindications to triptan use, adverse effects of NSAIDs, and unwanted reactions to some antiemetics reduce the list of drugs available for the treatment of migraine attacks in elderly patients. The choice of prophylactic treatment (beta-adrenoceptor antagonists, calcium channel antagonists, antiepileptics, and more recently, some antihypertensive drugs) is influenced by co-morbidities and should be directed at those drugs that are believed to have fewer adverse effects and a better safety profile. Unfortunately, for most of these drugs, efficacy studies are lacking in the elderly.

Chronic daily headaches in children

Chronic daily headache (CDH) is increasingly recognized as a problem in pediatrics and tertiary pediatric headache care. It is estimated that up to 4% of the adult population has CDH. Many of these are chronic migraine (CM). The fraction of the pediatric population with CDH appears to be lower, although the prevalence has not been adequately determined. The simplest definition of CDH is more than 15 headache days per month. In the International Classification of Headache Disorders, Second Edition (ICHD-II), several types of CDH have been identified. These criteria have been contrasted with the Silberstein-Lipton criteria, with revisions suggested. The diagnosis of CDH is further complicated and may be initiated by the overuse of analgesic medications (medication overuse headache) and requires the resolution of this issue before a final diagnosis can be established. In children, most CDH appears to have migraine features, although it may not completely meet the ICHD-II criteria for migraine or CM. Evaluation of CDH needs to include a complete history and physical examination to identify any possibility of the secondary headaches or headaches directly attributed to a secondary cause. Treatment and management involve a multidisciplinary approach, including acute therapy for when the headache severity increases (while avoiding medication overuse), preventative therapy to reduce the frequency and impact of the CDH, and biobehavioral therapy to assist with long-term outcome.