Wahezi Sayed E, Silva Kyle, Shaparin Naum, Lederman Andrew, Emam Mohammed, Haramati Nogah, Downie Sherry A
Montefiore Medical Center Multidisciplinary Pain Program, Bronx, NY; Albert Einstein College of Medicine; Bronx, NY.
Albert Einstein College of Medicine, Bronx, NY.
Pain Physician. 2016 Sep-Oct;19(7):E1079-86.
Headache (HA) is a significant cause of morbidity globally. Despite many available treatment options, HAs that are refractory to conservative management can be challenging to treat. Third occipital nerve (TON) and greater occipital nerve (GON) irritation are potential etiologic agents of primary and cervicogenic HAs that can be targeted using minimally invasive treatment options such as nerve blocks or radiofrequency ablation. However, a substantial number of patients that undergo radiofrequency ablation do not experience pain relief despite a positive diagnostic medial branch block (MBB).
In this study, we investigate the underlying cause for the high rate of false positives associated with MBBs by evaluating injectate spread in cadaveric subjects.
Cadaveric study.
Academic medical center.
After obtaining exemption status from our Institutional Review Board, TON injections were performed on 5 preserved cadavers, a total of 10 TONs, using anatomic landmarks, partial dissection, and palpation to guide needle placement. Cadaveric dissections were performed to evaluate the location, vertical spread, and grossly observed injectate coating of the TON and GON for each quantity of methylene blue injectate, 0.3 mL and 0.5 mL, administered.
The average distance between the TON and GON at their respective foraminal exit points was 1.81 cm. The average vertical spread for 0.3 mL and 0.5 mL of methylene blue injectate was 2.02 + 0.35 cm and 3.26 + 0.48 cm when performing a TON block. When using 0.3 mL injectate, both the TON and GON were simultaneously coated 60% of the time. After increasing the injectate volume to 0.5 mL, both the TON and GON were simultaneously coated 100% of the time.
The cadaveric design of this study presents limitations when translating cadaveric findings to the clinical setting. Also, the small sample size limits its power and generalizability. Lastly, the potential for researcher bias exists as the investigators were not blinded.
This study demonstrates that currently recommended injectate volumes for TON blocks may result in concomitant coating of the GON. Conventional radiofrequency ablation (RFA) of these nerves may not lesion both the TON and GON given its restrictive circumferential lesioning diameter of 5 - 7 mm. As such, interventionalists should consider performing radiofrequency ablation to both the TON and GON after a positive TON block.
Chronic pain, cervicogenic headache, third occipital nerve, greater occipital nerve, injectate spread, radiofrequency ablation.
头痛（HA）是全球发病的一个重要原因。尽管有许多可用的治疗选择，但对保守治疗无效的头痛治疗起来可能具有挑战性。第三枕神经（TON）和枕大神经（GON）受刺激是原发性和颈源性头痛的潜在病因，可使用神经阻滞或射频消融等微创治疗方法进行针对性治疗。然而，相当一部分接受射频消融的患者尽管诊断性内侧支阻滞（MBB）呈阳性，但并未获得疼痛缓解。
在本研究中，我们通过评估尸体标本中的注射剂扩散情况，调查与MBB相关的高假阳性率的潜在原因。
尸体研究。
学术医疗中心。
在获得机构审查委员会的豁免地位后，对5具保存的尸体共10条TON进行注射，使用解剖标志、部分解剖和触诊来指导针头放置。进行尸体解剖以评估每次注射0.3 mL和0.5 mL亚甲蓝注射剂时TON和GON的位置、垂直扩散以及大体观察到的注射剂覆盖情况。
TON和GON在各自椎间孔出口点之间的平均距离为1.81 cm。进行TON阻滞时，0.3 mL和0.5 mL亚甲蓝注射剂的平均垂直扩散分别为2.02 + 0.35 cm和3.26 + 0.48 cm。使用0.3 mL注射剂时，TON和GON同时被覆盖的时间为60%。将注射剂体积增加到0.5 mL后，TON和GON同时被覆盖的时间为100%。
本研究的尸体设计在将尸体研究结果转化为临床情况时存在局限性。此外，样本量小限制了其效力和普遍性。最后，由于研究人员未设盲，存在研究人员偏倚的可能性。
本研究表明，目前推荐的TON阻滞注射剂体积可能会导致GON同时被覆盖。鉴于这些神经的传统射频消融（RFA）的限制性圆周损伤直径为5 - 7 mm，可能无法同时损伤TON和GON。因此，介入医生在TON阻滞阳性后应考虑对TON和GON都进行射频消融。
慢性疼痛；颈源性头痛；第三枕神经；枕大神经；注射剂扩散；射频消融
