American Society for Peripheral Nerve

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Endoscopic-Assisted Decompression of the Greater Occipital Nerve in Migraine and Chronic Headache Patients: Identification of Dynamic Compression Points and Radical Excision of the Occipital Artery
Kyle Sanniec, MD; Michael Chung, BS; Karen Lu, BA; Bardia Amirlak, MD
University of Texas at Southwestern, Dallas, TX

Introduction: Site IV surgery involves the greater occipital nerve (GON) around the posterior neck. These surgeries are based on previous anatomical studies that revealed several points of muscular or fascial compression of the nerve, and variable relationships of the nerve with the occipital artery (OA). Despite detailed anatomical studies, 38% of patients who undergo GON decompression have incomplete response. In our experience conducting a modified endoscopic approach to occipital decompression that utilizes a counter-incision, we observed a clear and consistent pattern between the GON and OA, exhibiting a dynamic relationship with several areas of vascular compression.

Methods: Seventy-one patients underwent occipital nerve decompression, full length high-definition (HD) videos and photographs was recorded to correlate the dynamic relationship between the GON and OA. Retrospective review of these intraoperative imaging and patient charts was done to analyze branching patterns of the GON, including any deviations from the usual patterns and visualization of the vaso vasorum after radical lysis of the artery. The pre-operative topographic locations of maximal tenderness were also noted.

Results: A zone of dynamic compression was seen: 1) Hidden proximal dynamic compression of the bottom surface of the nerve as the OA approaches laterally under the GON, 2) more apparent dynamic compression on the upper surface of the nerve as the OA loops on top of the GON, 3) Intertwining compression point after GON bifurcation as the artery wraps around the GON, and 4) an intimate parallel travel of the terminal branch of the GON with the OA. This pattern existed in 92% of patients with slight variations including size, tortuosity, minor accessory nerves and branching, and minor lateral displacements. In all patients, the vaso vasorum was visualized intact on the GON after radical lysis. In addition to HD imaging, indocyanine angiography was performed and intact vascular supply to the nerve was confirmed. In all patients, the location of tenderness correlated with compression point 3, where the medial bifurcation of the GON intertwines with the occipital artery.

Conclusion: The incidence of residual symptoms suggests that current GON deactivation may be leaving areas of compression unaddressed, such as the four zones of GON dynamic compression reported in this study. The identification of these distal compression points provides an opportunity for plastic surgeons to decrease non-responder rate. Further prospective controlled studies are required to fully understand the effect of a modified endoscopic technique with counter incision in this area.

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