Anatomic Anomalies of the Nerves Treated during Headache Surgery.

Background: Headache surgery is a well-established, viable option for patients with chronic head pain/migraines refractory to conventional treatment modalities. These operations involve any number of seven primary nerves. In the occipital region, the surgical targets are the greater, lesser, and third occipital nerves. In the temporal region, they are the auriculotemporal and zygomaticotemporal nerves. In the forehead, the supraorbital and supratrochlear are targeted. The typical anatomic courses of these nerves are well established and documented in clinical and cadaveric studies. However, variations of this "typical" anatomy are quite common and relatively poorly understood. Headache surgeons should be aware of these common anomalies, as they may alter treatment in several meaningful ways. Methods: In this article, we describe the experience of five established headache surgeons encompassing over 4000 cases with respect to the most common anomalies of the nerves typically addressed during headache surgery. Descriptions of anomalous nerve courses and suggestions for management are offered. Results: Anomalies of all seven nerves addressed during headache operations occur with a frequency ranging from 2% to 50%, depending on anomaly type and nerve location. Variations of the temporal and occipital nerves are most common, whereas anomalies of the frontal nerves are relatively less common. Management includes broader dissection and/or transection of accessory injured nerves combined with strategies to reduce neuroma formation such as targeted reinnervation or regenerative peripheral nerve interfaces. Conclusions: Understanding these myriad nerve anomalies is essential to any headache surgeon. Implications are relevant to preoperative planning, intraoperative dissection, and postoperative management.