Occipital neuralgia: anatomic considerations

Use of corticosteroids for adult chronic pain interventions: sympathetic and peripheral nerve blocks, trigger point injections - guidelines from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, the American Society of Interventional Pain Physicians, the International Pain and Spine Intervention Society, and the North American Spine Society

BACKGROUND

There is potential for adverse events from corticosteroid injections, including increase in blood glucose, decrease in bone mineral density and suppression of the hypothalamic-pituitary axis. Published studies note that doses lower than those commonly injected provide similar benefit.

METHODS

Development of the practice guideline was approved by the Board of Directors of American Society of Regional Anesthesia and Pain Medicine with several other societies agreeing to participate. The scope of guidelines was agreed on to include safety of the injection technique (landmark-guided, ultrasound or radiology-aided injections); effect of the addition of the corticosteroid on the efficacy of the injectate (local anesthetic or saline); and adverse events related to the injection. Based on preliminary discussions, it was decided to structure the topics into three separate guidelines as follows: (1) sympathetic, peripheral nerve blocks and trigger point injections; (2) joints; and (3) neuraxial, facet, sacroiliac joints and related topics (vaccine and anticoagulants). Experts were assigned topics to perform a comprehensive review of the literature and to draft statements and recommendations, which were refined and voted for consensus (≥75% agreement) using a modified Delphi process. The United States Preventive Services Task Force grading of evidence and strength of recommendation was followed.

RESULTS

This guideline deals with the use and safety of corticosteroid injections for sympathetic, peripheral nerve blocks and trigger point injections for adult chronic pain conditions. All the statements and recommendations were approved by all participants after four rounds of discussion. The Practice Guidelines Committees and Board of Directors of the participating societies also approved all the statements and recommendations. The safety of some procedures, including stellate blocks, lower extremity peripheral nerve blocks and some sites of trigger point injections, is improved by imaging guidance. The addition of non-particulate corticosteroid to the local anesthetic is beneficial in cluster headaches but not in other types of headaches. Corticosteroid may provide additional benefit in transverse abdominal plane blocks and ilioinguinal/iliohypogastric nerve blocks in postherniorrhaphy pain but there is no evidence for pudendal nerve blocks. There is minimal benefit for the use of corticosteroids in trigger point injections.

CONCLUSIONS

In this practice guideline, we provided recommendations on the use of corticosteroids in sympathetic blocks, peripheral nerve blocks, and trigger point injections to assist clinicians in making informed decisions.

Etiologies of iatrogenic occipital nerve injury: And outcomes following treatment with nerve decompression surgery

INTRODUCTION

This study analyzed the etiologies and treatment of iatrogenic occipital nerve injuries.

METHODS

Patients with occipital neuralgia (ON) who were screened for occipital nerve decompression surgery were prospectively enrolled. Patients with iatrogenic occipital nerve injuries who underwent nerve decompression surgery were identified. Data included surgical history, pain characteristics, and surgical technique. Outcomes included pain frequency (days/month), duration (h/day), intensity (0-10), migraine headache index (MHI), and patient-reported percent-resolution of pain.

RESULTS

Among the 416 patients with ON, who were screened for occipital nerve decompression surgery, 12 (2.9%) cases of iatrogenic occipital nerve injury were identified and underwent surgical treatment. Preoperative headache frequency was 30 (±0.0) days/month, duration was 19.4 (±6.9) h, and intensity was 9.2 (±0.9). Neuroma excision was performed in 5 cases followed by targeted muscle reinnervation in 3, nerve cap in 1, and muscle burial in 1. In patients without neuromas, greater occipital nerve decompression and/or lesser occipital nerve neurectomy were performed. At the median follow-up of 12 months (IQR 12-12 months), mean pain frequency was 4.0 (±6.6) pain days/month (p < 0.0001), duration was 6.3 (±8.9) h (p < 0.01), and intensity was 4.4 (±2.8) (p < 0.001). Median patient-reported resolution of pain was 85% (56.3%-97.5%) and success rate was (≥50% MHI improvement) 91.7%.

CONCLUSIONS

Iatrogenic occipital nerve injuries can be caused by various surgical interventions, including craniotomies, cervical spine interventions, and scalp tumor resections. The associated pain can be severe and chronic. Iatrogenic ON should be considered in the differential diagnosis of post-operative headaches and can be treated with nerve decompression surgery or neuroma excision with reconstruction of the free nerve end.

A novel 3D anatomical visualization system to avoid injuries of nerves in retrosigmoid approach

The retro-sigmoid approach (RA), widely used during different neurosurgical procedures, is burdened by the risk of injuries of the nerves that cross that region contributing to possible postoperative complications. By using, anatomage table (AT), a novel 3D anatomical visualization system, we described the nerves passing through the retromastoid area including the great occipital nerve (GON), the lesser occipital nerve (LON) and the great auricular nerve (GAN), and their courses from the origins, till terminal branches. Moreover, using dedicated software, we measured distances between the nerves and well-recognizable bony landmarks. After identifying the nerves and their distances from bony landmarks, we observed that the safest and risk-free skin incision should be made in an area delimited, superiorly from the superior nuchal line (or slightly higher), and inferiorly from a plane passing at 1-1.5 cm above the mastoid tip. The lateral aspect of such an area should not exceed 9.5-10 cm from the inion, while the medial one should be more than 7 cm far from the inion. This anatomical information has been useful in defining anatomical landmarks and reducing the risk of complications, mainly related to nerve injury, in RA. In-depth neuroanatomic knowledge of the cutaneous nerves of the retromastoid area is essential to minimize the complications related to their injury during different neurosurgical approaches. Our findings suggest that the AT is a reliable tool to enhance understanding of the anatomy, and thus contributing to the refinement of surgical techniques.

Evaluation of the Anatomical Reference Point in Posterior Minimally Invasive Atlantoaxial Spine Surgery: A Cadaveric Anatomical Study

OBJECTIVE

Minimally invasive atlantoaxial surgery offers the benefits of reduced trauma and quicker recovery. Previous studies have focused on feasibility and technical aspects, but the lack of comprehensive safety information has limited its availability and widespread use. This study proposes to define the feasibility and range of surgical safety using the intersection of the greater occipital nerve and the inferior border of the inferior cephalic oblique as a reference point.

METHODS

Dissection was performed on 10 fresh cadavers to define the anatomical reference point as the intersection of the greater occipital nerve and the inferior border of the inferior cephalic oblique muscle. The study aimed to analyze the safety range of minimally invasive atlantoaxial fusion surgery by measuring the distance between the anatomical reference point and the transverse foramen of the axis, the distance between the anatomical reference point and the superior border of the posterior arch of the atlas, and the distance between the anatomical reference point and the spinal canal. Measurements were compared using Student's t test.

RESULTS

The point where the occipital greater nerve intersects with the inferior border of the inferior cephalic oblique muscle was defined as the anatomical marker for minimally invasive posterior atlantoaxial surgery. The distance between this anatomical marker and the transverse foramen of the axis was measured to be 9.32 ± 2.04 mm. Additionally, the distance to the superior border of the posterior arch of the atlas was found to be 21.29 ± 1.93 mm, and the distance to the spinal canal was measured to be 11.53 ± 2.18 mm. These measurement results can aid surgeons in protecting the vertebral artery and dura mater during minimally invasive posterior atlantoaxial surgery.

CONCLUSIONS

The intersection of the greater occipital nerve with the inferior border of the inferior cephalic oblique muscle is a safe and reliable anatomical landmark in minimally invasive posterior atlantoaxial surgery.

The triangular area between the greater, lesser, and third occipital nerves and its possible clinical significance

PURPOSE

Occipital Neuralgia (ON) is defined as a unilateral or bilateral pain in the posterior area of the scalp occurring in the distribution area or areas of the greater occipital nerve (GON), lesser occipital nerve (LON), and/or third occipital nerve (TON). In the present study, the purpose was to show the possible importance of the triangular area (TA) in nerve block applied in ON by measuring the TA between GON, TON, and LON.

METHODS

A total of 24 cadavers (14 males, 10 females) were used in the present study. The suboccipital region was dissected, revealing the points where the GON and TON pierced the trapezius muscle and superficial area, and the point where the LON left the sternocleidomastoid muscle from its posterior edge and was photographed. The area of the triangle between the superficial points of these three nerves and the center of gravity of the triangle (CGT) were determined by using the Image J Software and the results were analyzed statistically.

RESULTS

The mean TA values were 952.82 ± 313.36 mm2 and 667.55 ± 273.82 mm2, respectively in male and female cadavers. Although no statistically significant differences were detected between the sides (p > 0.05), a statistically significant difference was detected between the genders (p < 0.05). The mean CGT value was located approximately 5 cm below and 3-3.5 cm laterally from the external occipital protuberance in both genders and sides.

CONCLUSION

In ON that has more than one occipital nerve involvement, all occipital nerves can be blocked by targeting TA with a single occipital nerve block, and thus, the side effects that may arise from additional blocks can be reduced. The fact that there was a statistically significant difference according to the genders in the TA suggests that different block amounts can be applied according to gender.

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

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.

H7N9 avian influenza with first manifestation of occipital neuralgia: A case report

BACKGROUND

Most of the first symptoms of avian influenza are respiratory symptoms, and cases with occipital neuralgia as the first manifestation are rarely reported.

CASE SUMMARY

A middle-aged patient complaining of paroxysmal pain behind the ear was admitted to our hospital. The patient’s condition changed rapidly, and high fever, unexpected respiratory failure, and multiple organ failure developed rapidly. The patient was diagnosed with H7N9 avian influenza based on etiology.

CONCLUSION

We believe that the etiology of occipital neuralgia is complex and could be the earliest manifestation of severe diseases. The possibility of an infectious disease should be considered when occipital neuralgia is accompanied by fever. Avian influenza is one of these causative agents.

Ipsilateral Limb Extension of Referred Trigeminal Facial Pain due to Greater Occipital Nerve Entrapment: A Case Report

We report a very rare case of referred pain associated with entrapment of the greater occipital nerve (GON) occurring not only in the ipsilateral hemiface but also in the ipsilateral limb. There is an extensive convergence of cutaneous, tooth pulp, visceral, neck, and muscle afferents onto nociceptive and nonnociceptive neurons in the trigeminal nucleus caudalis (medullary dorsal horn). In addition, nociceptive input from trigeminal, meningeal afferents projects into trigeminal nucleus caudalis and dorsal horn of C1 and C2. Together, they form a functional unit, the trigeminocervical complex (TCC). The nociceptive inflow from suboccipital and high cervical structures is mediated with small-diameter afferent fibers in the upper cervical roots terminating in the dorsal horn of the cervical cord extending from the C2 segment up to the medullary dorsal horn. The major afferent contribution is mediated by the spinal root C2 that is peripherally represented by the greater occipital nerve (GON). Convergence of afferent signals from the trigeminal nerve and the GON onto the TCC is regarded as an anatomical basis of pain referral in craniofacial pain and primary headache syndrome. Ipsilateral limb pain occurs long before the onset of the referred facial pain. The subsequent severe hemifacial pain suggested GON entrapment. The occipital nerve block provided temporary relief from facial and extremity pain. Imaging studies found a benign osteoma in the ipsilateral suboccipital bone, but no direct contact with GON was identified. During GON decompression, severe entrapment of the GON was observed by the tendinous aponeurotic edge of the trapezius muscle, but the osteoma had no contact with the nerve. Following GON decompression, the referred trigeminal and extremity pain completely disappeared. The pain referral from GON entrapment seems to be attributed to the sensitization and hypersensitivity of the trigeminocervical complex (TCC). The clinical manifestations of TCC hypersensitivity induced by chronic entrapment of GONs are diverse when considering the occurrence of extremity pain as well as facial pain.

Anatomy of the greater occipital nerve: implications in posterior fossa approaches

PURPOSE

Because of its superficial location in the dorsal regions of the scalp, the greater occipital nerve (GON) can be injured during neurosurgical procedures, resulting in post-operative pain and postural disturbances. The aim of this work is to specify the course of the GON and how its injuries can be avoided while performing posterior fossa approaches.

METHODS

This study was carried out at the department of anatomy at Bordeaux University. 4 specimens were dissected to study the GON course. Posterior fossa approaches (midline suboccipital, paramedian suboccipital, retrosigmoid and petrosal) were performed on 4 other specimens to assess potential risks of GON injuries.

RESULTS

The GON runs around the obliquus capitis inferior (100%), crosses the semispinalis capitis (100%) and the trapezius (75%) or its aponeurosis (25%). Direct GON injuries can be seen in paramedian suboccipital approaches. Stretching of the GON can occur in midline suboccipital and paramedian suboccipital approaches. We found no evidence of direct or indirect GON injury in retrosigmoid or petrosal approaches.

CONCLUSION

Our study provides interesting data regarding the risk GON injury in posterior fossa approaches. Direct GON injuries in paramedian suboccipital approaches can be avoided with careful dissection. Placing retractors in contact with the periosteum and performing a minimal retraction may help to avoid excessive GON stretching in midline suboccipital and paramedian suboccipital approaches. Furthermore, the incision for retrosigmoid approaches should be as lateral as possible and not too caudal. Finally, avoiding extreme patient positioning reduces the risk of GON stretching in all approaches.

Comparative Effectiveness of Landmark-guided Greater Occipital Nerve (GON) Block at the Superior Nuchal Line Versus Ultrasound-guided GON Block at the Level of C2: A Randomized Clinical Trial (RCT)

OBJECTIVES

The purpose of this single center, prospective randomized controlled trial was to compare clinical outcomes between an ultrasound-guided greater occipital nerve block (GONB) at the C2 vertebral level versus landmark-based GONB at the superior nuchal line.

METHODS

Patients with occipital neuralgia or cervicogenic headache were randomized to receive either a landmark-based GONB with sham ultrasound at the superior nuchal line or ultrasound-guided GONB at the C2 vertebral level with blinding of patients and data analysis investigators. Clinical outcomes were assessed at 30 minutes, 2 weeks, and 4 weeks postinjection.

RESULTS

Thirty-two patients were recruited with 16 participants in each group. Despite randomization, the ultrasound-guided GONB group reported higher numeric rating scale (NRS) scores at baseline. Those in the ultrasound-guided GONB group had a significant decrease in NRS from baseline compared with the landmark-based GONB group at 30 minutes (change of NRS of 4.0 vs. 2.0) and 4-week time points (change of NRS of 2.5 vs. -0.5). Both groups were found to have significant decreases in Headache Impact Test-6. The ultrasound-guided GONB had significant improvements in NRS, severe headache days, and analgesic use at 4 weeks when compared with baseline. No serious adverse events occurred in either group.

CONCLUSIONS

Ultrasound-guided GONBs may provide superior pain reduction at 4 weeks when compared with landmark-based GONBs for patients with occipital neuralgia or cervicogenic headache.

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.

Decompression of the Greater Occipital Nerve for Occipital Neuralgia and Chronic Occipital Headache Caused by Entrapment of the Greater Occipital Nerve

BACKGROUND

 Chronic entrapment of the greater occipital nerve (GON) can not only manifest in typical stabbing pain of occipital neuralgia (ON) but also lead to continuous ache and pressure-like pain in the occipital and temporal areas. However, the effect of GON decompression on these symptoms has yet to be established. We report the follow-up results of GON decompression in typical cases of ON and chronic occipital headache due to GON entrapment (COHGONE).

METHODS

 A 1-year follow-up study of GON decompression was conducted on 11 patients with typical ON and 39 COHGONE patients with GON entrapment. The degree of pain reduction was analyzed using the numerical rating scale-11 (NRS-11) score and percent pain relief before and 1 year after surgery. A success was defined by at least a 50% reduction in pain measured via NRS-11 during the 12-month follow-up. To assess the degree of subjective satisfaction, a 10-point Likert scale was used. Postoperative outcome was also evaluated using the Barrow Neurological Institute (BNI) pain intensity score. The difference in GON decompression between the patients with typical ON and those with COHGONE was studied.

RESULTS

 GON decompression was successful in 43 of 50 patients (86.0%) and percent pain relief was 72.99 ± 25.53. Subjective improvement based on a 10-point Likert scale was 7.9 ± 2.42 and the BNI grade was 2.06 ± 1.04. It was effective in both the ON and COHGONE groups, but the success rate was higher in the ON group (90.9%) than in the COHGONE group (84.6%), showing statistically significant differences in the results based on average NRS-11 score, percent pain relief, subjective improvement, and BNI grades (p < 0.05, independent t-test).

CONCLUSION

 GON decompression is effective in chronic occipital headache and in ON symptoms induced by GON entrapment.

Intrathecal Morphine Infusion for Trigeminal Deafferentation Pain Following Percutaneous Intervention for Unexplained Facial Pain: A Case Report

Chronic pain in painful post-traumatic trigeminal neuropathy, formerly called trigeminal deafferentation pain (TDP) or anesthesia dolorosa, is virtually incurable neuropathic pain. In severe cases, no effective method has yet been established. A 58-year-old woman presented with chronic dysesthetic pain in the right side of her face that had persisted for 8 years. It was caused by percutaneous balloon compression for an unexplained, persistent right gingival pain. The TDP did not respond to any medications or radiosurgery. Considering the typical occipital neuralgia that occurred later, the incomprehensible gum pain was interpreted as referred trigeminal pain from occipital neuralgia. Decompression of the greater occipital nerve improved occipital neuralgia; however, TDP did not respond to internal neurolysis or invasive brain stimulation. The last attempt was made to administer an intrathecal opioid because of pain sufficiently severe to cause suicidal ideation. Trial administration of intrathecal opioids had some effect on pain relief. Although incomplete, the effects of intrathecal morphine infusion were maintained up to 1 year later. Invasive neurosurgical interventions should be cautiously performed for continuous pain in persistent idiopathic facial pain and referred facial pain cases that do not show typical neuralgic pain in primary trigeminal neuralgia because of the risk of TDP.

Cranial Neuralgias in Children and Adolescents A review of the literature

Cranial neuralgias are a well-established cause of headache-related morbidity in the adult population. These disorders are poorly studied in general due to their relative rarity, particularly in children and adolescents, and they are likely underdiagnosed in these populations. Recognizing these disorders and differentiating them from more common headache disorders, such as migraine, is important, as secondary disease is common. This review will cover the basic epidemiology, diagnosis, and treatment of trigeminal, occipital, glossopharyngeal and other, less common, cranial neuralgias. We have reviewed pediatric case reports of these conditions. For trigeminal neuralgia, the most common of these disorders, we have compiled the clinical features and treatment response of previous reports.

An Update on the Diagnosis, Treatment, and Management of Occipital Neuralgia

ABSTRACT

This report intends to summarize the underlying pathophysiology, relevant symptoms, appropriate diagnostic workup, necessary imaging, and medical and surgical treatments of occipital neuralgia (ON). This was done through a comprehensive literature review of peer-reviewed literature throughout the most relevant databases. The current understanding of ON is that it causes neuropathic pain in the distribution of the greater occipital nerve, the lesser occipital nerve, the third occipital nerve or a combination of the 3. It is currently a subset of headaches although there is some debate if ON should be its own condition. Occipital neuralgia causes chronic, sharp, stabbing pain in the upper neck, back of the head, and behind the ears that can radiate to the front of the head. Diagnosis is typically clinical and patients present with intermittent, painful episodes associated with the occipital region and the nerves described above. Most cases are unilateral pain, however bilateral pain can be present and the pain can radiate to the frontal region and face. Physical examination is the first step in management of this disease and patients may demonstrate tenderness over the greater occipital and lesser occipital nerves. Anesthetics like 1% to 2% lidocaine or 0.25% to 0.5% bupivacaine can be used to block these nerves and anti-inflammatory drugs like corticosteroids can be used in combination to prevent compressive symptoms. Other treatments like botulinum toxin and radiofrequency ablation have shown promise and require more research. Surgical decompression through resection of the obliquus capitis inferior is the definitive treatment however there are significant risks associated with this procedure.

Decompression of the Greater Occipital Nerve for Persistent Headache Attributed to Whiplash Accompanying Referred Facial Trigeminal Pain

OBJECTIVE

Persistent headache attributed to whiplash (PHAW) is defined as a headache that occurs for the first time in close temporal relation to whiplash lasting more than 3 months. We investigated the results of decompression of the greater occipital nerve (GON) in patients with PHAW who presented with referred trigeminal facial pain caused by sensitization of the trigeminocervical complex) along with occipital headache.

METHODS

A 1-year follow-up study of GON decompression was conducted in 7 patients with PHAW manifesting referred facial trigeminal pain. The degree of pain reduction was analyzed using the numeric rating scale (NRS-11) and percent pain relief before and 1 year after surgery. Success was defined by at least 50% reduction in pain measured via NRS-11. To assess the degree of subjective satisfaction, a 10-point Likert scale was used. Clinical characteristics of headache and facial pain and surgical findings were studied.

RESULTS

GON decompression was effective in all 7 patients with PHAW manifesting referred trigeminal pain, with a percent pain relief of 83.06 ± 17.30. The pain had disappeared in 3 of 7 patients (42.9%) within 6 months and no further treatment was needed. Patients' assessment of subjective improvement based on a 10-point Likert scale was 7.23 ± 1.25. It was effective in both occipital and facial pain.

CONCLUSIONS

Although chronic GON entrapment itself is an individual constitutional issue, postwhiplash inflammatory changes seem to trigger chronic occipital headaches in GON distribution and unexplained referred trigeminal pain caused by sensitization of the trigeminocervical complex.

Occipital Neuralgia

PURPOSE OF REVIEW

Occipital neuralgia is a painful condition that affects the posterior aspect of the head and can be difficult to distinguish from other common forms of headaches. This article reviews the anatomy, pathophysiology, clinical presentation, differential diagnosis, diagnostic testing, and management approaches for occipital neuralgia.

RECENT FINDINGS

Non-pharmacological treatments aim to alleviate muscle tension and improve posture. Acupuncture shows some promise. The occipital nerve block is considered the first line in a minimally invasive intervention, but the duration of relief may be short term. An onabotulinum toxin A injection may improve the sharp but not the dull component of the pain of occipital neuralgia. Radiofrequency ablation and occipital nerve stimulation may provide effective long-term relief in refractory patients. Surgical decompression, neurotomies, and neurolysis are last-resort treatment options. Occipital neuralgia is a debilitating condition that can be difficult to treat. Studies with larger sample sizes and randomized control trials are needed to further determine the effectiveness and safety of different therapies.

Qualitative Analysis of Single-Site Headache Surgery: Is It Different From Multiple-Site Surgery?

BACKGROUND

Migraine surgery has been shown to be efficacious, but nuanced effects of surgery on pain and individuals' lives remain incompletely understood. Surgery may be performed at a single or multiple "primary" sites. The aims of this study were to investigate patient perceptions following single-site surgery and compare themes in patients undergoing single-site surgery with those from a previously published conceptual framework generated with patients undergoing multisite surgery.

METHODS

Patients who underwent single-site headache surgery participated in open-ended interviews at least 1 year after surgery. Participants (n = 14) had undergone either occipital, temporal, or nasoseptal site surgery. A multidisciplinary team analyzed transcripts. Recurring themes were identified and compared and contrasted to those observed in patients who underwent multiple-site surgery (n = 15) in a previous study (Plast Reconstr Surg 2019;144(4):956-964).

RESULTS

Similar recurring themes emerged from the single-site cohort, and the conceptual framework was applicable to all participants. Two new themes emerged from the single-site analysis. First, 5 of 14 participants described being "migraine-free" postoperatively, a finding not observed in the multisite group. Second, several individuals described financial benefits after surgery, via decreased prescription medication requirements, raises at work, and improved productivity.

CONCLUSIONS

Single-site headache surgery appears to positively impact patients' lives in ways that support and expand upon previously published outcomes. Patients undergoing surgery at a single site may be more likely to experience a "pain-free" state, which may relate to the underlying pathophysiology of chronic headache. The effect of surgery on finances appears to be an outcome of interest to patients, which should be explored further.

Occipital Neuralgia and Its Management: An Overview

Background

Greater and lesser occipital neuralgias are primary neuralgias that are relatively uncommon, where the pain is felt in the distribution of these nerves.

Objective

This review paper was intended to describe the features and management of occipital neuralgia in the context of a challenging case.

Material and Methods

We looked at succinct literature from the past 30 years. We compared the features of our challenging case given in the current literature. In addition, an overview of the current literature is provided.

Results

The case, although proved to be a diagnostic challenge, we were able to reach a conclusion and render the patient almost complete pain relief by conservative management modalities. It proved to be a rare presentation of occipital neuralgia with unusual pain distribution, and we are able to describe a literature-based explanation for this entity to be a diagnostic and management challenge.

Conclusion

Primary headaches, i'n general, are a group of headache disorders that require exquisite diagnostic skills. The clinical history is a key factor when making an accurate diagnosis, and to establish an appropriate management plan.

Entrapment of the Greater Occipital Nerve with Chronic Migraine and Severe Facial Pain: A Case Report

Migraine is thought to be a primary neurovascular headache due to brain dysfunction and is known to involve peripheral and central sensitization. A female patient with chronic migraine symptoms for 30 years reported severe pain in the deep ear and face. This headache always showed the same pattern and temporal progression. The sudden onset of ache and throbbing pain in the right temporo-occipital area extended to the left temporo-occipital areas. She felt sick as if the head would burst, and nausea and vomiting occurred. During the last 3 years, the patient endured sharp pain in bilateral deep ears and severe pain in the face as if all the facial bones were broken, and tears flowed. Chronic disabling headache and facial pain improved with the decompression of the greater occipital nerve. This case suggests that peripheral sensitization may be related to the pathophysiology of migraine, especially in the migraine without aura.

Craniofacial neuralgias

While non-headache, non-oral craniofacial neuralgia is relatively rare in incidence and prevalence, it can result in debilitating pain. Understanding the relevant anatomy of peripheral branches of nerves, natural history, clinical presentation, and management strategies will help the clinician better diagnose and treat craniofacial neuralgias. This article will review the nerves responsible for neuropathic pain in periorbital, periauricular, and occipital regions, distinct from idiopathic trigeminal neuralgia. The infratrochlear, supratrochlear, supraorbital, lacrimal, and infraorbital nerves mediate periorbital neuralgia. Periauricular neuralgia may involve the auriculotemporal nerve, the great auricular nerve, and the nervus intermedius. The greater occipital nerve, lesser occipital nerve, and third occipital nerve transmit occipital neuralgias. A wide range of treatment options exist, from modalities to surgery, and the evidence behind each is reviewed.

Referred Trigeminal Facial Pain from Occipital Neuralgia Occurring Much Earlier than Occipital Neuralgia

We report a very rare case in which a patient believed to have auriculotemporal neuralgia due to the repeated recurrence of paroxysmal stabbing pain in the preauricular temporal region for four years developed occipital neuralgia, which finally improved with decompression of the greater occipital nerve (GON). The pain of occipital neuralgia has been suggested to be referred to the frontoorbital (V1) region through trigeminocervical interneuronal connections in the trigeminal spinal nucleus. However, the reports of such cases are very rare. In occipital neuralgia, the pain referred to the ipsilateral facial trigeminal region reportedly also occurs in the V2 and V3 distributions in addition to that in the V1 region. In the existing cases of referred trigeminal pain from occipital neuralgia, continuous aching pain is usually induced, but in the present case, typical neuralgic pain was induced and diagnosed as idiopathic auriculotemporal neuralgia. In addition, recurrent trigeminal pain occurred for four years before the onset of occipital neuralgia. If the typical occipital neuralgia did not develop in four years, it would be impossible to infer an association with the GON. This case shows that the clinical manifestations of referred trigeminal pain caused by the sensitization of the trigeminocervical complex by chronic entrapment of the GON can be very diverse.

Immersive Surgical Anatomy of the Craniocervical Junction

With the advent and increased usage of posterior, lateral, and anterior surgical approaches to the craniocervical junction (CCJ), it is essential to have a sound understanding of the osseous, ligamentous, and neurovascular layers of this region as well as their three-dimensional (3D) orientations and functional kinematics. Advances in 3D technology can be leveraged to develop a more nuanced and comprehensive understanding of the CCJ, classically depicted via dissections and sketches. As such, this study aims to illustrate - with the use of 3D technologies - the major anatomical landmarks of the CCJ in an innovative and informative way. Photogrammetry, structured light scanning, and 3D reconstruction of medical images were used to generate these high-resolution volumetric models. A clear knowledge of the critical anatomical structures and morphometrics of the CCJ is crucial for the diagnosis, classification, and treatment of pathologies in this transitional region.

Diffusion tensor imaging of the C1-C3 dorsal root ganglia and greater occipital nerve for cervicogenic headache

Background

Previous studies showed neurography and tractography of the greater occipital nerve (GON). The purpose of this study was determining diffusion tensor imaging (DTI) parameters of bilateral GONs and dorsal root ganglia (DRG) in unilateral cervicogenic headache as well as the grading value of DTI for severe headache. The correlation between DTI parameters and clinical characteristics was evaluated.

Methods

The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in bilateral GONs and cervical DRG (C2 and C3) were measured. Grading values for headache severity was calculated using a receiver operating characteristics curve. The correlation was analyzed with Pearson’s coefficient.

Results

The FA values of the symptomatic side of GON and cervical DRG (C2 and C3) were significantly lower than that of the asymptomatic side (all the P < 0.001), while the ADC values were significantly higher (P = 0.003, P < 0.001, and P = 0.003, respectively). The FA value of 0.205 in C2 DRG was considered the grading parameter for headache severity with sensitivity of 0.743 and specificity of 0.999 (P < 0.001). A negative correlation and a positive correlation between the FA and ADC value of the GON and headache index (HI; r = –0.420, P = 0.037 and r = 0.531, P = 0.006, respectively) was found.

Conclusions

DTI parameters in the symptomatic side of the C2 and C3 DRG and GON were significantly changed. The FA value of the C2 DRG can grade headache severity. DTI parameters of the GON significantly correlated with HI.

Ventrolateral Tonsillar Position Defines Novel Chiari 0.5 Classification

BACKGROUND

Cervicomedullary compression in young children has been described in the context of Chiari type 1 malformation, with symptoms associated with the extent of tonsillar herniation below McRae line. Historically, Chiari type 1 malformation has been defined by tonsillar herniation of at least 5 mm. However, in certain populations, including very young children, Chiari symptoms may be present without this finding. A new Chiari classification is thus necessary.

METHODS

Cases involving patients up to 5 years of age evaluated for possible posterior fossa decompression were retrospectively reviewed. Preoperative symptoms, magnetic resonance imaging findings, surgical management, and short- and long-term outcome and follow-up were recorded. Tonsillar descent and presence of ventral herniation (VH) were recorded. We define VH as the tonsils crossing a line that bisects the caudal medulla at the level of the foramen magnum, thus creating a novel entity, Chiari type 0.5 malformation. Patients with ventrally herniated tonsils were compared with patients exhibiting more typical Chiari morphology.

RESULTS

Of 41 cases retrospectively reviewed, 20 met criteria for VH. These differed from cases without VH because of the predominance of medullary symptoms. In the VH cohort, 11 patients underwent surgical decompression with symptom resolution; 9 were initially managed conservatively, but 3 subsequently required surgery.

CONCLUSIONS

We define a novel Chiari entity, Chiari type 0.5 malformation, characterized by ventral tonsillar wrapping around the medulla in young children in the absence of classic Chiari type 1 malformation imaging findings. These patients are more likely to present with medullary symptoms than patients without VH. They are also more likely to require surgical decompression and respond favorably to intervention.

Targeting Occipital Headache Pain: Preliminary Data Supporting an Alternative Approach to Occipital Nerve Block

BACKGROUND AND OBJECTIVES

Occipital nerve block (ONB) is an effective procedure for treating occipital headache pain. However, traditional suboccipital approaches to ONB remain underutilized in acute and chronic settings. An alternative location for ONB is the superior nuchal line, where anatomic studies show a reliable relationship between the occipital artery (OA) and greater occipital nerve. This study evaluated the efficacy and validity of an alternative, single skin insertion, paresthesia-based approach to block both the greater and lesser occipital nerve.

MATERIALS AND METHODS

Patients with a clinical diagnosis of occipital headache were included in this study. External landmarks of the cervical spinous process and ipsilateral tragus were used to predict the location of the OA pulse at the superior nuchal line. Alternative ONB technique was used to block both the greater and lesser occipital nerves using single skin insertion and paresthesia confirmation. Demographic data, preprocedure, and postprocedure pain scores were collected, along with the incidence of procedural outcomes, including OA pulse palpation, paresthesia, and postprocedure numbness.

RESULTS

Data were obtained prospectively from 50 patients. Mean pain scores for the sample decreased by 54.64% postprocedure (P<0.001). Greater occipital nerve paresthesia was confirmed 90.0% on the left (95% confidence interval [CI]: 76.3-97.2) and 90.9% on the right side (95% CI: 78.3-97.5). Postprocedure numbness in greater occipital nerve distribution was reported 80.6% on left (95% CI: 64.0-91.8) and 90% on right (95% CI: 76.3-97.2).

DISCUSSION

The results suggest that this alternative approach to ONB effectively reduces occipital headache pain and reliably predicts OA pulse and related greater occipital nerve location as confirmed by paresthesia.

Pulsed Radiofrequency of C2 Dorsal Root Ganglion Under Ultrasound-Guidance and CT Confirmed for Chronic Headache: Follow-Up of 20 Cases and Literature Review

Background

Chronic headache is common but difficult to treat. Most patients respond poorly to drugs. Nerve block is an effective treatment but has no continuous effect. The pulsed radiofrequency (PRF) technique has been shown to be effective in relieving head pain and extending the effect of nerve block.

Objective

The purpose of this study is to evaluate the long-term efficacy of C2 dorsal root ganglion after pulsed radiofrequency (PRF) guided by ultrasound for chronic headache.

Setting

The Department of Pain Management, West China Hospital.

Methods

Twenty patients who did not respond to medications and peripheral nerve blocks underwent ultrasound-guided PRF of the C2 dorsal root ganglion. The patients were followed up for 6 months. Visual analog scale (VAS) score was evaluated at 1 week, 1 month, 3 months, and 6 months. The quality of life (QOL) was assessed by Brief Pain Inventory (BPI) scores which were rated at pre-procedure and 1 month, 3 months, and 6 months after the procedure. The occurrence of complications was evaluated and reported.

Results

Mean VAS scores were significantly decreased at 1 week, 1 month, 3 months and 6 months compared to the pre-procedure mean VAS score. Mean BPI scores decreased significantly at each postoperative time point compared to the preoperative baseline and low scores remained throughout the follow-up period: 45.05±3.44 at pre-procedure, 10.60 ± 2.37 at 1 weeks, 12.50 ± 2.46 at 1 month, 12.90 ± 2.62 at 3 months, and 11.63 ± 2.98 at 6 months. Mild complications occurred, including 1 case (4.7%) of transient cervicalgia (lasting for 24 hrs) and 3 cases (14.2%) of transient dizziness (lasting for 30 mins).

Limitations

Firstly, it included a small sample of patients. Another is the short duration of the follow-up.

Conclusion

C2 PRF may be considered as an alternative treatment for chronic headache.

Preservation of the Lesser Occipital Nerve Prevents Occipital Sensory Disturbance After Microvascular Decompression: Long-Term Results

BACKGROUND

In microvascular decompression (MVD) surgery for hemifacial spasm (HFS), preservation of the lesser occipital nerve (LON) will prevent occipital sensory disturbance, a frequent complication of MVD, but the long-term outcome is unknown. This study was designed to evaluate the long-term efficacy of LON preservation.

METHODS

This retrospective study included 257 patients with HFS who underwent suboccipital craniotomy with MVD. Among them, 175 were followed-up for more than 2 years. Occipital sensation was examined at 1, 12, and 24 months after MVD. The patients were classified into 3 groups based on their operative findings: LON preservation (group A; n = 112), LON not identified (group B; n = 117), and LON excision (group C; n = 28). The degree of sensory disturbance was evaluated using a visual analog scale (VAS) ranging from 1 (no sensation) to 10 (intact).

RESULTS

The VAS score at 1 month was significantly better in group B (7.9 ± 0.2) than in groups A and C (7.3 ± 0.2 and 6.8 ± 0.4, respectively). At 24 months, the VAS scores were significantly higher in groups A and B (9.7 ± 0.1 and 9.7 ± 0.1) than in group C (8.8 ± 0.4), and occipital scalp sensation remained intact (VAS scores 9 and 10) in 91.9%, 92.9%, and 62.5% of the patients in groups A, B and C, respectively.

CONCLUSIONS

Our long follow-up study has demonstrated that preservation of the LON during MVD prevents sensory disturbance of the occipital scalp. Efforts to preserve the LON appear to be worthwhile when the suboccipital approach is chosen.

DTI of great occipital nerve neuropathy: an initial study in patients with cervicogenic headache

AIM

To assess differences in bilateral great occipital nerves (GONs) in patients with unilateral cervicogenic headache (CEH) using diffusion tensor imaging (DTI).

MATERIALS AND METHODS

Twenty-three patients with unilateral CEH underwent GON magnetic resonance imaging (MRI). The clinical characteristics and fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) values in bilateral GONs were determined by two observers with 7 and 3 years of experience in MRI. Three segments of GON were defined based on anatomy. The correlation of DTI measurements to the clinical characteristics and inter-/intra-observer performance were also evaluated.

RESULTS

The mean GON FA for the symptomatic side was significantly lower (0.198±0.056) than that on the other side (0.311±0.04; p=0.000). The mean GON ADC for the symptomatic side was significantly higher (0.682±0.174) than that on the other side (0.465±0.138; p=0.000). Among the three defined segments of GON, statistically significant differences of ADC values were not found at segment S3 (0.692±0.257 versus 0.557±0.230; p=0.068). There were statistically significant differences of FA and ADC values in bilateral GON of segments S1 and S2. The intraclass correlation coefficient (ICC) of intra-/interobserver statistical analysis showed excellent inter/intra-observer agreement for FA and ADC. Significant correlation was only found between the duration and ADC.

CONCLUSION

In patients with unilateral CEH, quantitative evaluation of the GON using DTI demonstrated FA decreases and ADC increases of the symptomatic side. Larger population and other occipital nerve neuropathy can be included in future research.

The Greater Occipital Nerve and Obliquus Capitis Inferior Muscle: Anatomical Interactions and Implications for Occipital Pain Syndromes

BACKGROUND

The compression/injury of the greater occipital nerve has been identified as a trigger of occipital headaches. Several compression points have been described, but the morphology of the myofascial unit between the greater occipital nerve and the obliquus capitis inferior muscle has not been studied yet.

METHODS

Twenty fresh cadaveric heads were dissected, and the greater occipital nerve was tracked from its emergence to its passage around the obliquus capitis inferior. The intersection point between the greater occipital nerve and the obliquus capitis inferior, and the length and thickness of the obliquus capitis inferior, were measured. In addition, the nature of the interaction and whether the nerve passed through the muscle were also noted.

RESULTS

All nerves passed either around the muscle loosely (type I), incorporated in the dense superficial muscle fascia (type II), or directly through a myofascial sleeve within the muscle (type III). The obliquus capitis inferior length was 5.60 ± 0.46 cm. The intersection point between the obliquus capitis inferior and the greater occipital nerve was 6.80 ± 0.68 cm caudal to the occiput and 3.56 ± 0.36 cm lateral to the midline. The thickness of the muscle at its intersection with the greater occipital nerve was 1.20 ± 0.25 cm. Loose, tight, and intramuscular connections were found in seven, 31, and two specimens, respectively.

CONCLUSIONS

The obliquus capitis inferior remains relatively immobile during traumatic events, like whiplash injuries, placing strain as a tethering point on the greater occipital nerve. Better understanding of the anatomical relationship between the greater occipital nerve and the obliquus capitis inferior can be clinically useful in cases of posttraumatic occipital headaches for diagnostic and operative planning purposes.

Ultrasound-guided greater occipital nerve block with botulinum toxin for patients with chronic headache in the occipital area: a randomized controlled trial

Background

Ultrasound-guided greater occipital nerve (GON) block has been frequently used to treat various types of headaches, and botulinum toxin has recently begun to be used in patients with headache. Our study presents the long-term effect of botulinum toxin on GON block using ultrasound in patients with chronic headache in occipital area.

Methods

Patients with occipital headache were divided into two groups (bupivacaine: BUP group [n = 27], botulinum toxin: BTX group [n = 27]), and ultrasound-guided GON block was performed at the C2 level. GON was detected with ultrasound and distance from GON to midline, from the skin surface to GON, and size of GON were measured in both groups. Visual analogue scale (VAS) scores and Likert scale were assessed at pretreatment and at 1, 4, 8, and 24 weeks after treatment in both groups.

Results

The distance from GON to midline was 18.9 ± 4.4 mm (right) and 17.3 ± 3.8 mm (left). The depth from the skin was 12.9 ± 1.5 mm (right) and 13.4 ± 1.6 mm (left). GON size was 3.1 mm on both sides. The VAS score and patient satisfaction score (Likert scale) in 4, 8, and 24 weeks after injection were superior for the BTX than the BUP group.

Conclusions

Ultrasound-guided GON block using BTX is effective in reducing short-term and long-term pain in patients with chronic headache in the occipital area.

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

Purpose

Establishing the distribution patterns of occipital cutaneous nerves may help us understand their contribution to various occipital pain patterns and ensure that a proper local injection method for treatment is employed. The aim of this study was to demonstrate the detailed distribution patterns of the greater occipital nerve (GON), lesser occipital nerve (LON), and third occipital nerve (TON) using the modified Sihler's staining technique.

Methods

Ten human cadavers were manually dissected to determine the nerve distributions. Specimens from eight human cadavers were treated using the modified Sihler's staining.

Results

In all cases, distinct GON branches proceeded laterally and were intensively distributed in the superolateral area from their emerging point. Very thin twigs were observed at the middle-trisected area, which had a fan-like shape, in the middle-upper occipital region.

Conclusion

The LON and TON distribution areas were biased to the lateral side below the superior nuchal line, although these nerves exhibited multiple interconnections or overlapping areas with the GON. Furthermore, a nerve rarified zone in the shape of an inverted triangle was identified in the middle occipital area. Our findings improve our understanding of the occipital nerve anatomy and will aid in the management of occipital pain in clinical practice.

Pulsed radiofrequency of C2 dorsal root ganglion under ultrasound guidance for chronic migraine: a case report

Chronic migraine is common but difficult to treat. Most patients respond poorly to drugs. Occipital nerve block such as stellate ganglion block is an effective treatment without continuous effect for migraine. Pulsed radiofrequency (PRF) technique has been shown to be effective in relieving headache and prolonging the effect of nerve block. This case report is about a patient who suffered from chronic migraine with occipital pain and was successfully treated with PRF of C2 (axis) dorsal root ganglion (DRG) under ultrasound guidance confirmed by computed tomograpy scan. The patient did not feel headache after 1-year follow-up. This suggests that C2 DRG PRF might be considered as an alternative treatment for chronic migraine with occipital pain.

Lateral Atlantoaxial Osteoarthritis: A Narrative Literature Review

Lateral atlantoaxial osteoarthritis (AAOA), or C1-C2 lateral mass arthritis (LMA), is an unfamiliar degenerative cervical disease with a clinical presentation that markedly differs from subaxial spondylosis. The prevalence of LMA in the nonsurgical outpatient setting is 4%. Risk factors include age and occupation. The typical patient is between 50 and 90 years old, presents with upper cervical or occipital pain, has limited rotation, and has pain provocation during passive rotation to the affected side. Pain stems from degeneration of the lateral C1-C2 articulation and may be referred or radicular, through the greater occipital nerve. Although there is no consensus on diagnostic work-up, the disease is classically seen on the open-mouth odontoid radiograph. Computerized tomography, magnetic resonance imaging, bone scan, and diagnostic injections are also useful. Initial treatment is conservative, and upwards of two-thirds of LMA patients obtain lasting relief with noninvasive measures and injections. In patients with severe, recalcitrant pain, limited C1-C2 fusion offers satisfactory and reliable relief. The goals of this review article are to provide a synthesis of the literature on LMA, to offer a treatment approach to LMA, and to identify problems with the current state of knowledge on LMA.

Anatomical basis for simultaneous block of greater and third occipital nerves, with an ultrasound-guided technique

PURPOSE

In some headache disorders, for which the greater occipital nerve block is partly effective, the third occipital nerve is also suggested to be involved. We aimed to establish a simple technique for simultaneously blocking the greater and third occipital nerves.

METHODS

We performed a detailed examination of dorsal neck anatomy in 33 formalin-fixed cadavers, and deduced two candidate target points for blocking both the greater and third occipital nerves. These target points were tested on three Thiel-fixed cadavers. We performed ultrasound-guided dye injections into these points, examined the results by dissection, and selected the most suitable injection point. Finally, this target point was tested in three healthy volunteers. We injected 4 ml of local anesthetic and 1 ml of radiopaque material at the selected point, guided with a standard ultrasound system. Then, the pattern of local anesthetic distribution was imaged with computed tomography.

RESULTS

We deduced that the most suitable injection point was the medial head of the semispinalis capitis muscle at the C1 level of the cervical vertebra. Both nerves entered this muscle, in close proximity, with little individual variation. In healthy volunteers, an anesthetic injected was confined to the muscle and induced anesthesia in the skin areas innervated by both nerves.

CONCLUSIONS

The medial head of the semispinalis capitis muscle is a suitable landmark for blocking the greater and third occipital nerves simultaneously, by which occipital nerve involvement in various headache disorders may be rapidly examined and treated.

Cervical myelitis presenting as occipital neuralgia

AIM

Occipital neuralgia is a common form of headache that is characterized by paroxysmal severe lancinating pain in the occipital nerve distribution.

METHODS

The exact pathophysiology is still not fully understood and occipital neuralgia often develops spontaneously. There are no specific guidelines for evaluation of patients with occipital neuralgia.

RESULT

Cervical spine, spinal cord and posterior neck muscle lesions can induce occipital neuralgia. Brain and spine imaging may be necessary in some cases, according to the nature of the headache or response to treatment.

DISCUSSION

We report a case of cervical myelitis presenting as occipital neuralgia.

Postoperative occipital neuralgia in posterior upper cervical spine surgery: a systematic review

Postoperative occipital neuralgia (PON) after upper cervical spine surgery can cause significant morbidity and may be overlooked. The causes, presentation, diagnosis, management, prognosis, and prevention of PON were reviewed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. English-language studies and case reports published from inception to 2017 were retrieved. Data on surgical procedures, incidence, cause of PON, management, outcomes, and preventive technique were extracted. Sixteen articles, including 591 patients, were selected; 93% of the patients with PON underwent C1 lateral mass screw (C1LMS) fixation, with additional 7% who underwent occipitocervical fusion without C1 fixation. PON had an incidence that ranged from 1 to 35% and was transient in 34%, but persistent in 66%. Five articles explained the possible causes. The primary presentation was constant or paroxysmal burning pain located mainly in the occipital and upper neck area and partially extending to the vertical, retroauricular, retromandibular, and forehead zone. Treatment included medications, nerve block, revision surgery, and nerve stimulation. Two prospective studies compared the effect of C2 nerve root transection on PON. PON in upper cervical spine surgery is a debilitating complication and was most commonly encountered by patients undergoing C1LMS fixation. The etiology of PON is partially clear, and the pain could be persistent and hard to cure. Reducing the incidence of PON can be realized by improving technique. More high-quality prospective studies are needed to define the effect of C2 nerve root transection on PON.

Practical considerations of linear accelerator-based frameless extracranial radiosurgery for treatment of occipital neuralgia for nonsurgical candidates

Occipital neuralgia generally responds to medical or invasive procedures. Repeated invasive procedures generate increasing complications and are often contraindicated. Stereotactic radiosurgery (SRS) has not been reported as a treatment option largely due to the extracranial nature of the target as opposed to the similar, more established trigeminal neuralgia. A dedicated phantom study was conducted to determine the optimum imaging studies, fusion matrices, and treatment planning parameters to target the C2 dorsal root ganglion which forms the occipital nerve. The conditions created from the phantom were applied to a patient with medically and surgically refractory occipital neuralgia. A dose of 80 Gy in one fraction was prescribed to the C2 occipital dorsal root ganglion. The phantom study resulted in a treatment achieved with an average translational magnitude of correction of 1.35 mm with an acceptable tolerance of 0.5 mm and an average rotational magnitude of correction of 0.4° with an acceptable tolerance of 1.0°. For the patient, the spinal cord was 12.0 mm at its closest distance to the isocenter and received a maximum dose of 3.36 Gy, a dose to 0.35 cc of 1.84 Gy, and a dose to 1.2 cc of 0.79 Gy. The brain maximum dose was 2.20 Gy. Treatment time was 59 min for 18, 323 MUs. Imaging was performed prior to each arc delivery resulting in 21 imaging sessions. The average deviation magnitude requiring a positional or rotational correction was 0.96 ± 0.25 mm, 0.8 ± 0.41°, whereas the average deviation magnitude deemed within tolerance was 0.41 ± 0.12 mm, 0.57 ± 0.28°. Dedicated quality assurance of the treatment planning and delivery is necessary for safe and accurate SRS to the cervical spine dorsal root ganglion. With additional prospective study, linear accelerator-based frameless radiosurgery can provide an accurate, noninvasive alternative for treating occipital neuralgia where an invasive procedure is contraindicated.

Occipital Nerve Stimulation for the Treatment of Refractory Occipital Neuralgia: A Case Series

BACKGROUND

Occipital neuralgia is a chronic pain syndrome characterized by sharp, shooting pains in the distribution of the occipital nerves. Although relatively rare, it associated with extremely debilitating symptoms that drastically affect a patient's quality of life. Furthermore, it is extremely difficult to treat as the symptoms are refractory to traditional treatments, including pharmacologic and procedural interventions. A few previous case studies have established the use of a neurostimulation of the occipital nerves to treat occipital neuralgia.

OBJECTIVE

The following expands on that literature by retrospectively reviewing the results of occipital nerve stimulation in a relatively large patient cohort (29 patients).

METHODS

A retrospective review of 29 patients undergoing occipital nerve stimulation for occipital neuralgia from 2012 to 2017 at a single institution with a single neurosurgeon.

RESULTS

Of those 29 patients, 5 were repair or replacement of previous systems, 4 did not have benefit from trial stimulation, and 20 saw benefit to their trial stage of stimulation and went on to full implantation. Of those 20 patients, even with a history of failed procedures and pharmacological therapies, there was an overall success rate of 85%. The average preoperative 10-point pain score dropped from 7.4 ± 1.7 to a postoperative score of 2.9 ± 1.7. However, as with any peripheral nerve stimulation procedure, there were complications (4 patients), including infection, hardware erosion, loss of effect, and lead migration, which required revision or system removal.

CONCLUSION

Despite complications, the results suggest, overall, that occipital nerve stimulation is a safe and effective procedure for refractory occipital neuralgia and should be in the neurosurgical repertoire for occipital neuralgia treatment.