Migraine surgery can be performed at four common trigger sites: trigger site I, frontal triggers, where glabellar muscles or vessels accompanying the nerves may irritate the supratrochlear and supraorbital nerves to cause frontal headaches; trigger site II, temporal triggers, where the temporalis muscle or the vessels adjacent to the nerve may cause inflammation of the zygomaticotemporal branch of the trigeminal nerve to induce temporal headaches; trigger site III, rhinogenic triggers, where intranasal abnormality (e.g., deviated septum, spurs, contact between the turbinates and the septum, concha bullosa, septa bullosa) may irritate the trigeminal end branches to cause paranasal and retrobulbar headaches; and trigger site IV, occipital triggers, where the semispinalis capitis muscle or the occipital artery can irritate the occipital nerve to cause occipital headaches.

Localized botulinum toxin type A injections have been used to detect and confirm suspected trigger sites I, II, and IV in migraine headache patients before surgery. The onset of action of botulinum toxin type A begins after 3 to 4 days, and the neuromuscular junction typically regains its full function 3 to 4 months after initial injection. Injections are targeted directly into muscle, where nerve terminals reside, to weaken the musculature. Aside from diagnostic purposes, botulinum toxin type A injections have also been approved by the U.S. Food and Drug Administration for temporary reduction of migraine headaches.

Surgery is performed on one or any combination of trigger sites in the same setting: trigger site I (frontal trigger site), removal of the glabellar muscle group (corrugator supercilii, depressor supercilii, and the lateral portion of procerus muscles) to decompress the supraorbital and supratrochlear nerves; trigger site II (temporal trigger site), avulsion of the zygomaticotemporal branch of the trigeminal nerve; trigger site III (rhinogenic trigger site), septoplasty and turbinectomy; and trigger site IV (occipital trigger site), removal of a small segment of the semispinalis capitis muscle to decompress the greater occipital nerve or remove the occipital artery. All of the above procedures are performed on an outpatient setting.