In-Depth Look at the Anatomical Relationship of the Lesser Occipital Nerve, Great Auricular Nerve, and Spinal Accessory Nerve and Their Implication in Safety of Operations in the Posterior Triangle of the Neck

An anatomical analysis of the occipital nerve complex: an essential tool for the application of occipital nerve blocks

BACKGROUND

Occipital nerve blocks are essential in diagnosing and treating headache disorders such as migraine, cervicogenic headache, occipital neuralgia, and cluster headache. In this study, we aimed to investigate the potential compression points of the greater occipital nerve (GON), third occipital nerve (TON), and lesser occipital nerve (LON) which are targeted to block in occipital nerve blocks and to develop a method to detect these points easily.

METHODS

To identify potential compression points of the GON, TON, and LON, we dissected 43, 41, and 26 cadavers, respectively. A rigid, transparent tool divided into 1 × 1 cm sections was placed on the external occipital protuberance to measure the determined points. The cadaveric head was viewed from above, vertically, and the coordinates corresponding to each point were noted separately.

RESULTS

Six, four, and one potential entrapment points were detected for the GON, TON, and LON, respectively. The distances of the point where the GON arose from the lower border of the obliquus capitis inferior muscle and the emerging point of the TON from the C2-C3 vertebrae to the posterior midline were statistically significant in terms of the sides (p = 0.040). Similarly, there was a statistical significance between genders for the distance of the point where the LON arose from the posterior edge of the sternocleidomastoid muscle to the posterior midline (p = 0.002).

CONCLUSIONS

We believe that with the method developed, the GON, TON, and LON compression points can be easily localized and blocked in diagnosing and treating patients experiencing headaches such as migraines, cervicogenic headaches, occipital neuralgia, and cluster headache.

Ultrasound-guided lesser occipital nerve combined with great auricular nerve block for vestibular schwannoma craniotomy via a suboccipital retrosigmoid approach: a prospective, double-blind randomized controlled trial

PURPOSE

This aim of this study was to investigate the analgesic efficacy and safety of lesser occipital nerve combined with great auricular nerve block (LOGAB) for craniotomy via a suboccipital retrosigmoid approach.

METHODS

Patients underwent vestibular schwannoma resection via a suboccipital retrosigmoid approach were randomly assigned to receive ultrasound-guided unilateral LOGAB with 5 ml of 0.5% ropivacaine (LOGAB group) or normal saline (NSB group). Numeric rating scale (NRS) scores at rest and motion were recorded within 48 h after surgery. Mean arterial pressure (MAP), heart rate (HR), opioid consumption and other variables were measured secondly.

RESULTS

Among 59 patients who were randomized, 30 patients received ropivacaine, and 29 patients received saline. NRS scores at rest (1.8 ± 0.5 vs. 3.2 ± 0.8, P = 0.002) and at motion (2.2 ± 0.7 vs. 3.2 ± 0.6, P = 0.013) of LOGAB group were lower than those of NSB group within 48 h after surgery. NRS scores of motion were comparable except for 6th and 12th hour (P < 0.05) in the LOGAB group. In LOGAB group, MAP decreased significantly during incision of skin and dura (P < 0.05) and intraoperative opoid consumption was remarkably reduced (P < 0.01). Postoperative remedial analgesia was earlier in the NSB group (P < 0.001). No patients reported any adverse events.

CONCLUSION

Among patients undergoing craniotomy for vestibular schwannoma via a suboccipital retrosigmoid approach, LOGAB may be a promising treatment for perioperative analgesia and has the potential to maintain intraoperative hemodynamic stability.

CLINICAL TRIAL REGISTRATION NUMBER

Chictr.org.cn ChiCTR2000038798.

Surgical Management of Headache Disorders - A Systematic Review of the Literature

PURPOSE OF REVIEW

This review article critically evaluates the latest advances in the surgical treatment of headache disorders.

RECENT FINDINGS

Studies have demonstrated the effectiveness of innovative screening tools, such as doppler ultrasound, pain drawings, magnetic resonance neurography, and nerve blocks to help identify candidates for surgery. Machine learning has emerged as a powerful tool to predict surgical outcomes. In addition, advances in surgical techniques, including minimally invasive incisions, fat injections, and novel strategies to treat injured nerves (neuromas) have demonstrated promising results. Lastly, improved patient-reported outcome measures are evolving to provide a framework for comparison of conservative and invasive treatment outcomes. Despite these developments, challenges persist, particularly related to appropriate patient selection, insurance coverage, delays in diagnosis and surgical treatment, and the absence of standardized measures to assess and compare treatment impact. Collaboration between medical/procedural and surgical specialties is required to overcome these obstacles.

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

The lesser occipital nerve (LON) has one of the most variations among occipital nerves. We aimed to investigate morphological and morphometric features of LON. A total of 24 cadavers, 14 males (58%) and 10 females (42%), were dissected bilaterally. LON was classified into 3 types. The number of branches and the perpendicular distances of the point where LON emerged from the posterior border of sternocleidomastoid muscle to vertical and transverse lines passing through external occipital protuberance were determined. The shortest distance between LON and great auricular nerve (GAN), and linear distance of LON to its branching point were measured. The most common variant was Type 1 (30 sides, 62.5%), followed by Type 2 (12 sides, 25%) and Type 3 (6 sides, 12.5%), respectively. In males, Type 1 (22 sides, 78.6%) was the most common, while Type 1 (8 sides, 40%) and Type 2 (8 sides, 40%) were equally common and the most common in females. On 48 sides, 2-9 branches of LON were observed. The perpendicular distance of said point to vertical and transverse lines was meanly 63.69 ± 11.28 mm and 78.83 ± 17.21 mm, respectively. The shortest distance between LON and GAN was meanly 16.62 ± 10.59 mm. The linear distance of LON to its branching point was meanly 31.24 ± 15.95 mm. The findings reported in this paper may help clinicians in estimating the location of the nerve and/or its branches for block or decompression surgery as well as preservation of LON during related procedures.

Spinal accessory nerve anatomy in the posterior cervical triangle: A systematic review with meta-analysis

This study aimed to investigate the anatomy of the spinal accessory nerve (SAN) in the posterior cervical triangle, especially in relation to adjacent anatomical landmarks, along with a systematic review of the current literature with a meta-analysis of the data. Overall, 22 cadaveric and three prospective intraoperative studies, with a total of 1346 heminecks, were included in the analysis. The major landmarks relevant to the entry of the SAN at the posterior border of the SCM muscle (PBSCM) were found to be the mastoid apex, the great auricular point (GAP), the nerve point (NP), and the point where the PBSCM meets the upper border of the clavicle. The SAN was reported to enter the posterior cervical triangle above GAP in 100% of cases and above NP in most cases (97.5%). The mean length of the SAN along its course from the entry point to its exit point from the posterior triangle of the neck was 4.07 ± 1.13 cm. The SAN mainly gave off 1 or 2 branches (32.5% and 31%, respectively) and received either no branches or one branch in most cases (58% and 23%, respectively) from the cervical plexus during its course in the posterior cervical triangle. The major landmarks relevant to the entry of the SAN at the anterior border of the TPZ muscle (ABTPZ) were found to be the point where the ABTPZ meets the upper border of the clavicle and the midpoint of the clavicle, along with the mastoid apex, the acromion, and the transverse distance of the SAN exit point to the PBSCM. The results of the present meta-analysis will be helpful to surgeons operating in the posterior cervical triangle, aiding the avoidance of the iatrogenic injury of the SAN.

Single midline incision approach for decompression of greater, lesser and third occipital nerves in migraine surgery

Background

The traditional approach for occipital migraine surgery encompasses three separate surgical incisions in the posterior neck to decompress the greater occipital nerves (GON), lesser occipital nerves (LON), and third occipital nerves (TON). Other incisions have been investigated, including singular transverse incisions. We sought to evaluate a single, vertical midline incision approach for decompression of all six occipital nerves.

Methods

Using 10 cadaveric hemi-sides (5 fresh cadaver head and necks). Anatomic landmarks and the location of the bilateral GON, LON, and TON were marked according to previous anatomic studies. A single, midline 9-cm incision was made, and lateral skin flaps were raised to decompress or avulse all six nerves.

Results

Through the midline incision, the GON and TON were identified at 3.5 and 6.2 cm, respectively, inferior to a line bisecting the external auditory canal (EAC) and 1.5 cm lateral to the midline. The LON was identified as 6-cm inferior and 6.5-cm medial to a line bisecting the EAC in the plane just above the investing layer of the deep cervical fascia until the posterior border of the sternocleidomastoid was encountered. The LON had the greatest amount of variation but was identified lateral to the posterior border of the SCM.

Conclusions

A single midline incision approach allows for successful identification and decompression of all six occipital nerves in migraine surgery.

Efficacy and Safety of Migraine Surgery: A Systematic Review and Meta-analysis of Outcomes and Complication Rates

OBJECTIVE

The objectives of this study are to assess the efficacy and safety of peripheral nerve surgery for migraine headaches and to bibliometrically analyze all anatomical studies relevant to migraine surgery.

SUMMARY BACKGROUND DATA

Migraines rank as the second leading cause of disability worldwide. Despite the availability of conservative management options, individuals suffer from refractive migraines which are associated with poor quality of life. Migraine surgery, defined as the peripheral nerve decompression/trigger site deactivation, is a relatively novel treatment strategy for refractory migraines.

METHODS

EMBASE and the National Library of Medicine (PubMed) were systematically searched for relevant articles according to the PRISMA guidelines. Data was extracted from studies which met the inclusion criteria. Pooled analyses were performed to assess complication rates. Meta-analyses were run using the random effects model for overall effects and within subgroup fixed-effect models were used.

RESULTS

A total of 68 studies (38 clinical, 30 anatomical) were included in this review. There was a significant overall reduction in migraine intensity (P < 0.001, SE = 0.22, I2 = 97.9), frequency (P < 0.001, SE = 0.17, I2 = 97.7), duration (P < 0.001, SE = 0.15, I2 = 97), and migraine headache index (MHI, P < 0.001, SE = 0.19, I2 = 97.2) at follow-up. A total of 35 studies reported on migraine improvement (range: 68.3%-100% of participants) and migraine elimination (range: 8.3%-86.5% of participants). 32.1% of participants in the clinical studies reported complications for which the most commonly reported complications being paresthesia and numbness, which was mostly transient, (12.11%) and itching (4.89%).

CONCLUSION

This study demonstrates improved migraine outcomes and an overall decrease in MHI as well as strong evidence for the safety profile and complication rate of migraine surgery.

The Potential Roles of Cervical Plexus Abnormalities in Occipital Neuralgia: An Anatomic Variant Explored

Occipital neuralgia (ON) is a condition defined as a headache characterized by paroxysmal burning and stabbing pain located in the distribution of the greater occipital nerve (GON), lesser occipital nerve (LON), or third occipital nerves (TON). This condition can be severely impairing in symptomatic patients and is known to have numerous etiologies deriving from various origins such as trauma, anatomical abnormalities, tumors, infections, and degenerative changes. This study reports four cases of a previously undescribed anatomical variant in which the (spinal) accessory nerve (SAN) fuses with the LON before piercing the sternocleidomastoid (SCM). The fusion of these two nerves and their route through the SCM points to a potential location for nerve compression within the SCM and, in turn, another potential source of ON. This anatomical presentation has clinical significance as it provides clinicians with another possible cause of ON to consider when diagnosing patients who present with complaints of a headache. Additionally, this study explores the prevalence of piercing anatomy of the LON and GAN and discusses their clinical implications.

Occipital Neuralgia: Advances in the Operative Management

Background

Occipital neuralgia (ON) is a primary headache disorder characterized by sharp, shooting, or electric shock-like pain in the distribution of the greater, lesser, or third occipital nerves.

Aim

To review the existing literature on the management of ON and to describe our technique of an endoscopic-assisted approach to decompress the GON proximally in areas of fibrous and muscular compression, as well as distally by thorough decompression of the occipital artery from the nerve.

Methods

Relevant literature on the medical and surgical management of ON was reviewed. Literature on the anatomical relationships of occipital nerves and their clinical relevance were also reviewed.

Results

While initial treatment of ON is conservative, peripheral nerve blocks and many surgical management approaches are available for patients with pain refractory to the medical treatment. These include greater occipital nerve blocks, occipital nerve stimulation, Botulinum toxin injections locally, pulsed radiofrequency ablation, cryoneuroablation, C-2 ganglionectomy, and endoscopic-assisted ON decompression.

Conclusion

Patients of ON refractory to medical management can be benefitted by surgical approaches and occipital nerve blocks. Endoscopic-assisted ON decompression provides one such approach for the patients with vascular, fibrous or muscular compressions of occipital nerves resulting in intractable ON.