Stereotactic topography of the greater and third occipital nerves and its clinical implication

Abstract

This study aimed to provide topographic information of the greater occipital (GON) and third occipital (3ON) nerves, with the three-dimensional locations of their emerging points on the back muscles (60 sides, 30 cadavers) and their spatial relationship with muscle layers, using a 3D digitizer (Microscribe G2X, Immersion Corp, San Jose CA, USA). With reference to the external occipital protuberance (EOP), GON pierced the trapezius at a point 22.6 ± 7.4 mm lateral and 16.3 ± 5.9 mm inferior and the semispinalis capitis (SSC) at a point 13.1 ± 6.0 mm lateral and 27.7 ± 9.9 mm inferior. With the same reference, 3ON pierced, the trapezius at a point 12.9 ± 9.3 mm lateral and 44.2 ± 21.4 mm inferior, the splenius capitis at a point 10.0 ± 5.3 mm lateral and 59.2 ± 19.8 mm inferior, and SSC at a point 11.5 ± 9.9 mm lateral and 61.4 ± 15.3 mm inferior. Additionally, GON arose, winding up the obliquus capitis inferior, with the winding point located 52.3 ± 11.7 mm inferior to EOP and 30.2 ± 8.9 mm lateral to the midsagittal line. Knowing the course of GON and 3ON, from their emergence between vertebrae to the subcutaneous layer, is necessary for reliable nerve detection and precise analgesic injections. Moreover, stereotactic measurement using the 3D digitizer seems useful and accurate for neurovascular structure study.

Comparing the injectate spread and nerve involvement between different injectate volumes for ultrasound-guided greater occipital nerve block at the C2 level: a cadaveric evaluation

“…In our previous cadaveric study, approximately 30.2 mm horizontal distance from the midline (C2 spinous process), the GON winds around the OCI muscle, then ascends vertically and turns medially at the upper border of this muscle. 14 This finding indicates that the distance between the GON and TON is closest at the superomedial area of the OCI muscle. 14 Therefore, the GON would be most suitable for target at the C2 level on the inferolateral area of the OCI muscle, where it is anatomically farthest away from the TON.…”

“…The blocks were performed by a single, experienced anesthesiologist specialized in regional anesthesia and pain medicine. A TE7 ultrasound unit (Mindray Bio-Medical Electronics, Shenzhen, People's Republic of China) with a high-frequency linear probe (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) and an 80-mm, 22-gage needle was used in every case. The ultrasound approach in this study follows the previously described method.…”

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

“… 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.…”

“…According to our previous study, where the reference point is external occipital protuberance, TON pierced the SSC at 1.2±1 cm lateral and 6.1±1.5 cm inferior, the splenius capitis at 1±0.5 cm lateral and 5.9±2 cm inferior, and the trapezius at 1.3±0.9 cm lateral and 4.4±2.1 cm inferior. 17 It is well known that this nerve is typically located medial to the GON at the cervico-occipital level. 16 , 17 However, we found that the TON did not appear to extend above the SNL.…”

“… 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. 3 – 5 In the modern ultrasound era, GON blocks performed under ultrasound guidance have gained popularity in clinical practice.…”