Accessory Nerves of the Forehead: A Newly Discovered Frontotemporal Neurovascular Bundle and Its Implications in the Treatment of Frontal Headache, Migraine Surgery, and Cosmetic Temple Filler Injection

Background: Surgical decompression of peripheral cranial and spinal nerves at several anatomically studied trigger sites has demonstrated significant efficacy in bringing permanent relief to migraine sufferers. In their experience performing frontal nerve decompression on migraine patients, the authors noticed a previously undescribed accessory nerve and vessel in the frontotemporal area, and report its implication in migraine surgery and cosmetic filler injection. Methods: A retrospective review of 113 patients who underwent frontal migraine decompression surgery with the senior author at the University of Texas Southwestern Medical Center from July of 2012 to May of 2016 was performed. For the included 76 patients, measurements of this nerve had been taken intraoperatively using high-definition endoscopic assistance, and topographic measurements were correlated with endoscopic location of the nerve. Results: This frontotemporal nerve (FTN) was present in 55 percent, and the bilateral incidence was 57 percent of those. An accompanying vessel was also present in 81 percent of nerve complexes. Both nerve and vessel varied in size. A large vessel was present in 8 percent of all patients, and a medium vessel was present in 20 percent. Consistently, the nerve exited a foramen in the frontal bone on average 3.4 ± 0.47 cm superior to the lateral canthus. Conclusions: The identification and proper avulsion neurectomy of this newly described sensory FTN may lead to better surgical response rate during migraine surgery. In addition, this nerve should be considered during nerve block and botulinum toxin injections in migraine treatment. The existence of the accompanying vessel could have significant implications in the safety of filler and fat injections to this area.