Correlation of Increase in Phosphene Threshold With Reduction of Migraine Frequency: Observation of Levetiracetam-Treated Subjects

EEG Changes in Migraine-Can EEG Help to Monitor Attack Susceptibility?

Migraine is a highly prevalent brain condition with paroxysmal changes in brain excitability believed to contribute to the initiation of an attack. The attacks and their unpredictability have a major impact on the lives of patients. Clinical management is hampered by a lack of reliable predictors for upcoming attacks, which may help in understanding pathophysiological mechanisms to identify new treatment targets that may be positioned between the acute and preventive possibilities that are currently available. So far, a large range of studies using conventional hospital-based EEG recordings have provided contradictory results, with indications of both cortical hyper- as well as hypo-excitability. These heterogeneous findings may largely be because most studies were cross-sectional in design, providing only a snapshot in time of a patient's brain state without capturing day-to-day fluctuations. The scope of this narrative review is to (i) reflect on current knowledge on EEG changes in the context of migraine, the attack cycle, and underlying pathophysiology; (ii) consider the effects of migraine treatment on EEG features; (iii) outline challenges and opportunities in using EEG for monitoring attack susceptibility; and (iv) discuss future applications of EEG in home-based settings.

Mitochondria in migraine pathophysiology - does epigenetics play a role?

The approximately three times higher rate of migraine prevalence in women than men may result from the mitochondrial transmission of this disease. Studies with imaging techniques suggest disturbances in mitochondrial metabolism in specific regions of the brain in migraine patients. Migraine shares some clinical features with several mitochondrial diseases and many other disorders include migraine headaches. Epigenetic regulation of mitochondrial DNA (mtDNA) is a matter of debate and there are some conflicting results, especially on mtDNA methylation. Micro RNAs (miRNAs) and long-noncoding RNA (lncRNAs) have been detected in mitochondria. The regulation of the miRNA-lncRNA axis can be important for mitochondrial physiology and its impairment can result in a disease phenotype. Further studies on the role of mitochondrial epigenetic modifications in migraine are needed, but they require new methods and approaches.

Refining the Benefit/Risk Profile of Anti-Epileptic Drugs in Headache Disorders

Anti-epileptic drugs are among the most effective drugs for migraine prophylaxis, and will likely continue to have a role even as new therapies emerge. Topiramate and valproate are effective for the preventive treatment of migraine, and other medications such as gabapentin or lamotrigine may have a role in the treatment of those with allodynia or frequent aura, respectively. Oxcarbazepine, carbamazepine, phenytoin, gabapentin, and others may alleviate pain in trigeminal neuralgia. While many anti-epileptic drugs can be effective in those with migraine or other headaches, most of these agents can potentially cause serious side effects. In particular, valproate, topiramate, carbamazepine, and phenytoin may lead to adverse outcomes for infants of exposed mothers. Valproate should not be given to women of childbearing potential for migraine prevention.

Beta-blocker migraine prophylaxis affects the excitability of the visual cortex as revealed by transcranial magnetic stimulation

The objective of this study is to assess effects of beta-blocker migraine prophylaxis on cortical excitability determined by transcranial magnetic stimulation (TMS). Phosphene and motor thresholds (PT, MT) were investigated in 29 patients with migraine, in 15 of them prior to and following preventive medication with metoprolol and in 14 patients without prophylaxis. Following prophylaxis headache frequency significantly decreased (p = 0.005) and mean PT were significantly increased (51.5 ± 7.5 vs. 63.6 ± 8.4%) compared to patients without preventive treatment (53.7 ± 5.3 vs. 52.3 ± 6.3%; p = 0.040). Mean MT did not significantly differ either between groups or due to treatment. In the group of all patients, a significant inverse correlation between headache frequency and the level of PT was found (R = -0.629; p < 0.01). There was, however, no significant correlation in the subgroups of patients. We conclude that (a) clinical efficacy of beta-blocker treatment in migraine could be (at least partly) linked to its ability to modulate the excitability of the visual cortex and (b) the PT determined by TMS appears suitable to assess the effects of prophylaxis on cortical excitability in the individual patient. This may be useful in clinical trials investigating migraine preventive drugs.

Levetiracetam in chronic daily headache: a double-blind, randomised placebo-controlled study. (The Australian KEPPRA Headache Trial [AUS-KHT])

INTRODUCTION

Chronic daily headache (CDH) represents a temporal profile of headache (15+ days/month; 4+ hours/day; >6 months). We report the first comprehensive and largest levetiracetam (LEV) trial in CDH.

METHODS

A 27-week, multi-centre, randomised, placebo-controlled, cross-over, phase III B study assessed efficacy of a target of 3 g/day LEV of 6 placebo tablets/day in CDH. Primary efficacy was headache-free rate (HFR) while secondary parameters were loss of diagnostic criteria; severity; duration; disability; associated features; pain; and quality of life.

RESULTS

Ninety-six patients were recruited (baseline HFR 10.4 ± 14.6%; median 0%). At onset of history 73 (74.1%) had migraine +/- aura and 35 (36.5%) had tension-type headache (TTH). Over the six months preceding recruitment 54 (56.3%) had migraine and 42 (43.8%) had TTH. Headache history was 22.6 ± 15.0 years (median 20.0). Eighty-eight received placebo and 89 received LEV with >80 receiving stable dose in either arm. LEV achieved 3.9% increased HFR over placebo, showing a trend but not significance. There was 9.9% increase in loss of CDH diagnostic criteria re: headache days/month for LEV over placebo (p = .0325), reduced disability (p = .0487) and reduced pain severity for LEV (p = .0162). The Short-Form Quality of Life assessment instrument (SF-36) showed impaired mental health on LEV (p = .001).

DISCUSSION

These findings conflict with reports of LEV efficacy, mandating placebo control in headache trials. Primary efficacy equated to one extra headache-free day/month with reduced disability and pain intensity. Mental health was reduced on LEV. The 10% loss of diagnostic criteria, decreased intensity and disability suggest a subpopulation with CDH where LEV remains a therapeutic option.

Local therapies in migraine

Fixed-site" approach and "follow-the-pain" approach briefly considered the techniques of local therapy that now generate more interest and discussion on headaches and, in particular, of migraine. Far from being a full discussion, the work aims only to stimulate further thought and interest in local therapies which often are not sufficiently considered and that conversely are a possibility in the treatment of migraine.