Reply: anatomy of the supratrochlear nerve: implications for the surgical treatment of migraine headaches.

BACKGROUND Migraine headaches have been linked to compression, irritation, or entrapment of peripheral nerves in the head and neck at muscular, fascial, and vascular sites. The frontal region is a trigger for many patients' symptoms, and the possibility for compression of the supratrochlear nerve by the corrugator muscle has been indirectly implied. To further delineate their relationship, a fresh tissue anatomical study was designed. METHODS Dissection of the brow region was undertaken in 25 fresh cadaveric heads. The corrugator muscle was identified on both sides, and its relationship with the supratrochlear nerve was investigated. RESULTS The supratrochlear nerve was found in all 50 hemifaces. Three potential points of compression were uncovered in this investigation: the nerve entrance into the brow through the frontal notch or foramen, the entrance of the nerve into the corrugator muscle, and the exit of the nerve from the corrugator muscle. The nerve generally bifurcates within the retro-orbicularis oculi fat pad, and these branches enter into one of four relationships with the corrugator muscle: both branches enter the muscle, one branch enters the muscle and one remains deep, both branches remain deep, and the branches further branch into ever smaller filaments that cannot be identified cranially. CONCLUSIONS Some patients are nonresponders to migraine decompression techniques that address the supraorbital nerve. The supratrochlear nerve may be compressed in these patients. A standard corrugator resection that comes more medially within 1.8 cm of the midline may be beneficial. The morphology of the frontal notch/foramen must be examined and addressed if necessary.