Erenumab, a novel treatment for migraine prevention, has been approved by the European Medicines Agency (EMA) for the prophylaxis of migraine in adults who have at least 4 migraine days per month.
Erenumab is a first-in-class fully human monoclonal antibody that works by inhibiting the calcitonin gene‑related peptide (CGRP) receptors. The CGRP is believed to play a causal role in the pathophysiology of migraine. Erenumab is administered as a once-monthly subcutaneous injection. According to the EMA, the benefit of erenumab treatment is its ability to reduce the number of monthly migraine days. In two trials involving 667 patients with chronic migraine and 955 with episodic migraine, patients with chronic migraine showed a reduction of 2.5 monthly migraine days on average compared to placebo after 3 months of treatment. For patients with episodic migraine the reduction was either 1.3 or 1.8 days, depending on the dose taken. The most common side effects were injection site reactions, constipation, muscle spasms and pruritus.
The US Food and Drug Administration approved erenumab in May 2018 for the preventive treatment of migraine in adults.See Management: approach
In March 2018, the EMA announced stronger measures aimed at avoiding the exposure of babies to valproate medicines in the womb. Under the new restrictions, valproate medicines are contraindicated for migraine prophylaxis during pregnancy due to the high risk of congenital malformations and developmental problems in the child.
In addition, valproate medicines must not be used in female patients of childbearing potential unless there is a pregnancy prevention programme in place that includes the following:
An assessment of the patient’s potential for becoming pregnant
Pregnancy tests before starting (and during) treatment as needed
Counselling about the risks of valproate treatment and the need for effective contraception throughout treatment
A review of ongoing treatment by a specialist, at least annually
A risk acknowledgement form that patients and prescribers can go through at each such annual review to confirm that appropriate advice has been given and understood.
The EMA said the new measures were put in place because of evidence suggesting that information on the risks of valproate use in pregnancy was still not getting through to women, despite earlier steps aimed at ensuring this.See Management: approach
Migraine is a chronic, genetically determined, episodic, neurological disorder that usually presents in early-to-mid life.
Patients complain of intermittent headache and associated symptoms, such as visual disturbance, nausea, vomiting, and sensitivity to light or noise (photophobia and phonophobia).
The diagnosis is based on history and physical examination. No laboratory or imaging tests are essential for diagnosis.
Treatment approaches involve identification and avoidance of trigger factors, and the use of medication to treat the acute attack or prevent future attacks.
There are no clinical trials that identify one migraine therapy (acute therapy or prophylaxis therapy) as superior over others. Triptans in general are preferred over non-specific treatments. However, there are no trials directly comparing triptans.
Complications include status migrainosus, migrainous infarction, chronic migraine, persistent aura without infarction and seizures, analgesic gastropathy, transformation of episodic to chronic migraine, and medication-overuse headache.
Migraine is a chronic, genetically determined, episodic neurological disorder that usually presents in early-to-mid life. Key features in the history that support a diagnosis of migraine are nausea, photophobia, and disability, along with headache. Typical migraine aura (a complex of reversible visual, sensory, or speech symptoms), which occurs during or precedes headache, is pathognomonic of migraine but only occurs in 15% to 30% of patients.  
Associate Professor of Neurology
Department of Neurology
Duke University Medical Center
TAC was an unpaid site PI for the Alder study ALD403-CLIN-011 (monoclonal Ab against CGRP as treatment for chronic migraine), which ended in July 2017. TAC served as a paid consultant for Eli Lilly Co. in November 2016. In 2017 he served as a paid consultant for Alphasights, a global healthcare consulting organization, regarding migraine headache diagnosis and treatment. He has provided expert testimony regarding headache disorders for a legal case in 2015, and expects to be paid to provide expert testimony on headache disorders in 2018 for a legal case relating to the diagnosis, treatment, and standard of care for headache disorders.
Dr Timothy Collins would like to gratefully acknowledge Dr Ann Donnelly, the previous contributor to this monograph. AD declares that she has no competing interests.
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