Migraine is an episodic painful disorder occasionally developing into a chronic form. Such disorder represents one of the most common neurological diseases in clinical practice. Chronicization is often accompanied by the appearance of acute drugs overuse. Chronic
migraine (CM) constitutes
migraine's natural evolution in its chronic form and involves
headache frequency of 15 days/month, with features similar to those of
migraine attacks.
Medication Overuse Headache (MOH) has been defined as a
headache present on > or = 15 days/month, with regular overuse for > 3 months of one or more drugs used for acute and/or symptomatic
headache management. Subtypes of MOH attributed to different medications were delineated. Misuse of ergots,
triptans,
opioids or combination
analgesics on > or = 10 days/month was required to make the diagnosis of MOH, while > or = 15 days/month were needed for simple
analgesic-overuse headache. CM's low prevalence produces an extremely high disability grade. Therefore, special attention should be paid to both control and reduction of risk factors which might favour the
migraine chronicization process and/or the outbreak of MOH. In MOH sufferers, the only treatment of choice is represented by
drug withdrawal. Successful detoxification is necessary to ensure improvement in the
headache status when treating patients who overuse acute medications. Different procedures have been suggested for withdrawal namely at home, at the hospital, with or without the use of
steroids, with re-prophylaxis performed immediately or at the end of the washout period. At the moment we have not a total agreement whether prophylactic treatment should be started before, during, or after discontinuation of the overuse
drug. Both drugs have been approved for CM treatment in view of their well-defined resistance to previous prophylaxis drugs. Recently, the
PREEMPT clinical program has confirmed
onabotulinumtoxinA as an effective, safe, and well-tolerated prophylactic treatment for adults with CM.