Avi Ashkenazi

Expert consensus recommendations for the performance of peripheral nerve blocks for headaches - A narrative review

To describe a standardized methodology for the performance of peripheral nerve blocks (PNBs) in the treatment of headache disorders.

Peripheral Nerve Blocks and Trigger Point Injections in Headache Management – A Systematic Review and Suggestions for Future Research

(Headache 2010;50:943‐952)

Cluster Headache—Acute and Prophylactic Therapy

(Headache 2011;51:272‐286)

Hormone-related headache: pathophysiology and treatment.

Epidemiological data suggest a link between migraine and the female sex hormones. Indeed, it is known that estrogen affects various brain functions, including pain perception. The prevalence of migraine is similar in boys and girls before puberty, but is 3-fold higher in postpubertal females compared with males. Migraine attacks in women are more likely to occur in the perimenstrual period and occur exclusively so in some women. The acute treatment of menstrual migraine is similar to that of non-menstrually related attacks, but the response to treatment may be less favourable. Perimenstrual prophylaxis, with NSAIDs, triptans or estradiol, is effective in decreasing attack frequency and severity.The use of oral contraceptives (OCs) may change migraine frequency and severity. Since both migraine and hormonal contraceptive use are risk factors for ischaemic stroke, the use of OCs in women who experience migraine should be made only after consideration of the benefit-risk ratio.Migraine typically, but not invariably, improves during the last two trimesters of pregnancy, and may worsen in the postpartum period. When using drugs to treat migraine during pregnancy, potential risks to the mother and fetus should be considered.The prevalence of migraine decreases with advancing age and it improves in many, but not all, women after the menopause. However, in the perimenopausal period, migraine may worsen as a result of fluctuations in estrogen levels. Reducing the estrogen dose and changing the estrogen type or the route of administration of hormone replacement therapy (HRT) from oral to transdermal may reduce headache. Migraine is not a risk factor for stroke in postmenopausal women. When considering symptomatic HRT for postmenopausal migraneurs, the usual indications and contraindications should be applied. HRT may also exacerbate migraine.

Dynamic mechanical (brush) allodynia in cluster headache.

Objective.—To examine the occurrence of dynamic mechanical (brush) allodynia (BA) in patients with cluster headache (CH).

Zonisamide for Migraine Prophylaxis in Refractory Patients

Zonisamide is a new antiepileptic drug with multiple mechanisms of action and a favourable pharmacokinetic profile. Preliminary data suggest that zonisamide may be effective in migraine prophylaxis. We evaluated the efficacy and tolerability of zonisamide for migraine prophylaxis in refractory patients. We reviewed the charts of adult patients with International Headache Society-defined episodic migraine (EM) or with transformed migraine (TM) according to the Silberstein- Lipton criteria, who had been treated with zonisamide at our out-patient clinic for at least 60 days. Demographic data, zonisamide dosage and duration of treatment were collected and analysed. Headache frequency, attack duration, headache severity and headache-related disability before and after treatment initiation with zonisamide were compared. Thirty-three patients were included in the study (average age 43.9 ± 8.4 years; 23 (70%) with TM and 10 (30%) with EM). The patients had failed an average of 6.2 migraine prophylactic drugs prior to zonisamide. The average zonisamide daily dose was 337.9 ± 146.3 mg and the average duration of treatment was 186.4 ± 174.0 days. The average number of days with headache per month was reduced in the entire study population from 20.7 ± 9.5 before zonisamide treatment to 18.0 ± 11.3 after its initiation (P = 0.06) [in TM from 24.7 ± 7.3 to 21.0 ± 10.7 (P = 0.06); in EM from 11.6 ± 7.6 to 11.0 ± 9.7 (P = NS)]. No significant changes in other headache parameters were found. Fourteen patients (42.4%) reported adverse events (AEs), the most common of which was fatigue. Most patients (12/14, 85.7%) rated AEs as mild or moderate. In this group of refractory migraine patients, zonisamide therapy did not result in a statistically significant beneficial effect on headache or on associated symptoms.

Patterns of Use of Peripheral Nerve Blocks and Trigger Point Injections Among Headache Practitioners in the USA: Results of the American Headache Society Interventional Procedure Survey (AHS‐IPS)

(Headache 2010;50:937‐942)

Three common neuralgias. How to manage trigeminal, occipital, and postherpetic pain.

PREVIEW The pain experienced by patients with trigeminal, occipital, or postherpetic neuralgia is often severe, chronic, and difficult to treat. In this article, Drs Ashkenazi and Levin outline the pathologic mechanisms of pain in these common neuralgias and discuss individually tailored pharmacologic and surgical approaches to their treatment.

Trigger point injections for headache disorders: expert consensus methodology and narrative review.

To review the existing literature and describe a standardized methodology by expert consensus for the performance of trigger point injections (TPIs) in the treatment of headache disorders. Despite their widespread use, the efficacy, safety, and methodology of TPIs have not been reviewed specifically for headache disorders by expert consensus.

OnabotulinumtoxinA for the Treatment of Headache

Botulinum toxin, a potent muscle relaxant, has been found to have analgesic effects in patients with various pain syndromes. Both in vitro and in vivo studies showed the ability of the toxin to block the release of pain neurotransmitters, such as substance P, glutamate, and calcitonin gene‐related peptide. The effect of the toxin, and specifically of one of its serotypes, botulinum neurotoxin type A, on headaches, has been extensively studied. This serotype is available in the United States in 3 forms, including as onabotulinumtoxinA. Data from clinical trials confirmed the efficacy, safety, and tolerability of onabotulinumtoxinA in the prophylactic treatment of chronic migraine, the most severe and debilitating type of migraine, in adults. The drug was approved by the Food and Drug Administration for this indication in 2010. The drug was not found to be effective for episodic migraine or tension‐type headache. Noncontrolled studies suggest the efficacy of the toxin for headache associated with craniocervical dystonia. Proper injection technique and appropriate patient selection are essential for achieving positive results after treatment with onabotulinumtoxinA. The recommended injection paradigm combines a fixed site/fixed dose and follow the pain approaches, with the toxin injected to multiple sites of the head and neck, at a total dose of 155U‐195U. The treatment is given at intervals of 12 weeks on average. The efficacy of onabotulinumtoxinA for some headaches, its long duration of action, and its favorable adverse effect profile make it a viable treatment option for the appropriate headache patients. The drug may be particularly suitable for patients who cannot tolerate, or are not compliant with, the daily intake of oral headache preventive drugs.