Anatomical consideration of the occipital cutaneous nerves and artery for the safe treatment of occipital neuralgia

Abstract

There is no standardized approach to the greater occipital nerve (GON) block technique for treating occipital neuralgia. The aim of the present study was to validate the previously-suggested guidelines for conventional injection techniques and to provide navigational guidelines for safe GON block. The GON, lesser occipital nerve (LON) and occipital artery (OA) were carefully dissected in the occipital region of embalmed cadavers. Using a 3 D digitizer, the GON, LON, and OA were observed on the two reference lines. The distances between the landmarks were recorded and statistically analyzed. On the superior nuchal line, the mean distances between the external occipital protuberance (EOP) and the most medial branch of the GON was 33.5 mm. The mean distance between the EOP and the most medial branch of the OA was 37.4 mm. On the EOP-mastoid process (MP) line, the GON was on the medial third and the LON the lateral third of the EOP-MP line. The safe injection points on the EOP-MP line are about 3 cm from the EOP, 1 cm inferior parallel to the EOP-MP line, and about 3 cm away from the MP. Clin. Anat. 31:1058-1064, 2018. © 2018 Wiley Periodicals, Inc.

Anatomical analysis of the distribution patterns of occipital cutaneous nerves and the clinical implications for pain management

“…Despite the limited distributions of the LON and TON in the lower occipital region, our study using Sihler’s staining confirmed the presence of multiple interconnections or areas of overlap among the LON, TON, and GON that had been reported previously by several gross anatomical studies. 1 , 3 , 18 Importantly, the present study clearly shows that some branches of the TON traverse horizontally and cross the GONl, whereas previous descriptions only noted that the branches ascend vertically. 19 Collectively, our anatomical findings explain the complex pain patterns that are often experienced in the occipital regions.…”

“… 3 It serially passes or pierces the layered back muscles such as the obliquus capitis inferior (on 2.5–3 cm lateral to midline), the semispinalis capitis (on 1–1.5 cm inferior to the SNL and 3 cm lateral to midline), and the trapezius (on 1–1.5 cm inferior to the SNL and 2.5–3.5 cm lateral to midline). 1 , 16 , 17 In the past, previous studies have focused on the emergence of the nerves on the layered back muscles for guiding nerve blocks. However, the detailed distribution of the cutaneous nerve fibers should be examined for diagnosis and treatment of the nerve triggering the pain.…”

“…The greater occipital nerve (GON) arises from fibers of the dorsal primary ramus of the second cervical nerve and, to a lesser extent, from fibers of the third cervical nerve. 1 The GON provides cutaneous innervation to most of the posterior scalp. 1 A GON block is commonly performed to provide anesthesia and analgesia to the occipital area.…”

“… 1 The GON provides cutaneous innervation to most of the posterior scalp. 1 A GON block is commonly performed to provide anesthesia and analgesia to the occipital area. 2 , 3 Especially, a positive response to a GON block is necessary to establish a diagnosis of occipital neuralgia.…”

“… 6 There are variable landmark methods for GON block that have been proposed over the last few decades based on anatomical studies. 1 – 7 Making an injection just medial to the palpated occipital artery at the level of the superior nuchal line (SNL) or making an injection at one-quarter of the distance along a line connecting the external occipital protuberance to the mastoid (or 2 cm lateral and 2 cm inferior to the external occipital protuberance) are commonly used clinical practices. Some authors have described this point as being 1.5 cm lateral and 2–2.5 cm inferior to the external occipital protuberance.…”