OnabotulinumtoxinA in chronic migraine: long-term efficacy in a prophylactic medication free cohort

Excerpt

Chronic migraine (CM) is a debilitating neurologic disorder defined as headaches occurring on ≥ 15 days per month for more than 3 months, with headaches having migraine features on ≥ 8 days per month. Patients with chronic migraine typically have a history of episodic migraine headaches that increase in frequency over a period of months to years until patients experience daily or near-daily, low-grade migraineous and nonmigraineous headaches with intermittent attacks of severe migraine. CM affects approximately 1.4 to 2.2% of adults worldwide with an important economic burden and impact in quality of life. Both frequency of attacks, severity of pain, and associated symptoms have a major role on migraine-related disability. The current understanding of headache pathophysiology is evolving. For patients affected by CM, a prophylactic headache treatment regimen is highly recommended to reduce the frequency, severity, and disability. OnabotulinumtoxinA is a focally acting protein that inhibits the release of the neurotransmitter acetylcholine from the presynaptic nerve endings and blocks the neuronal release of nociceptive mediators such as substance P, glutamate, and calcitonin gene-related peptide (CGRP) in the periphery, which suggests it may possess peripheral antinociceptive activity. The inhibition of nociceptive mediators in the periphery may reduce central sensitization, perhaps by inhibiting afferent inputs to the central nervous system, thereby reducing inflammatory signals to sensitized regions in the brain. Its biological effects are transient, and within approximately 3 months, normal neuronal signaling is restored. The recently published PREEMPT [1] and COMPEL [2] studies established the safety and efficacy of OnabotulinumtoxinA for treatment of chronic migraine. …