Morphological features of the greater occipital nerve and its possible importance for interventional procedures

Abstract

Being one of the most prevalent neurological symptoms, headaches are burdensome and costly. Blocks and decompression surgeries of the greater occipital nerve (GON) have been frequently used for migraine, cervicogenic headache, and occipital neuralgia which are classified under headache by International Headache Society. Knowledge of complex anatomy of GON is crucial for its decompression surgery and block. This study was performed to elucidate anatomical features of this nerve in detail. Forty‐one cadavers were dissected bilaterally. According to its morphological features, GON was classified into four main types that included 18 subtypes. Moreover, potential compression points of the nerve were defined. The number of branches of the GON up to semispinalis capitis muscle and the number of its branches that were sent to this muscle were recorded. The most common variant was that the GON pierced the aponeurosis of the trapezius muscle, curved around the lower edge of the obliquus capitis inferior muscle, and was loosely attached to the obliquus capitis inferior muscle (Type 2; 61 sides, 74.4%). In the subtypes, the most common form was Type 2‐A (44 sides, 53.6%), in which the GON pierced the aponeurosis of each of the trapezius muscle and fibers of semispinalis muscle at one point and there was a single crossing of the GON and occipital artery. Six potential compression points of the GON were detected. The first point was where the nerve crossed the lower border of the obliquus capitis inferior muscle. The second and third points were at its piercing of the semispinalis capitis muscle and the muscle fibers/aponeurosis of the trapezius, respectively. Fourth, fifth, and sixth compression points of GON were located where the GON and occipital artery crossed each other for the first, second, and third times, respectively. On 69 sides, 1–4 branches of the GON up to the semispinalis capitis muscle were observed (median = 1), while 1–4 branches of GON were sent to the semispinalis capitis muscle on 67 sides (median = 1). The novel anatomical findings described in this study may play a significant role in increasing the success rate of invasive interventions related with the GON.

Morphological and morphometric anatomy of the lesser occipital nerve and its possible clinical relevance

“…There was a statistical significance between genders for the perpendicular distance of the LON to the vertical line passing from the EOP ( p = 0.027). Saglam et al obtained a similar result for the GON and reported that this may be due to the differentiation of the nerve for the genders during embryologic development 20 . We think that the statistical difference we obtained may be due to similar reasons.…”

Morphological and morphometric anatomy of the lesser occipital nerve and its possible clinical relevance

“…There was a statistical signi cance between genders for the perpendicular distance of the LON to the vertical line passing from the EOP (p = 0.027). Saglam et al obtained a similar result for the GON and reported that this may be due to the differentiation of the nerve for the genders during embryologic development 20 . We think that the statistical difference we obtained may be due to similar reasons.…”

Preoperative visualization of the greater occipital nerve with magnetic resonance imaging in candidates for occipital nerve decompression for headaches

“…In cadaveric studies, the relationship between the GON and OA appears intricate, as they might run in a parallel fashion at certain junctures and intersect at others. In a study involving 73 cadavers, the GON and OA had crossed once in 78% of cases, twice in 7%, and three times in 4% 55 . Additional research is needed to investigate whether interactions between the OA and the GON are associated with symptomatic improvement following surgery.…”