Tracking patients with chronic occipital headache after occipital nerve decompression surgery: A case series

Increasing Collaboration between Headache Medicine and Plastic Surgery in the Surgical Management of Chronic Headache

INTRODUCTION

Chronic headache is one of the most disabling conditions afflicting humankind. The management of chronic headaches has, to date, been only partially successful. The goal of this paper is to highlight the importance of collaboration between surgeons and headache physicians in treating this condition.

METHODS

We present a narrative review of migraine pathophysiology, its medical and surgical treatment options, and the important role of collaboration between headache physicians and surgeons.

RESULTS

Migraine headaches can be treated with both medication-based regimens and surgery. Novel medications such monoclonal antibodies directed at the CGRP molecule or its receptor have recently been FDA approved as an effective treatment modality in chronic migraines. However, these medications are associated with a high cost, and there is a paucity in data regarding effectiveness compared to other treatment modalities. The pathophysiology of headache likely exists along a spectrum with peripheral - extracranial and meningeal - factors at one end and central - brain - factors at the other, with anatomic and physiologic connections between both ends. Recent evidence has clearly shown that surgical decompression of extracranial nerves improves headache outcomes. However, appropriate patient selection and preoperative diagnosis are of paramount importance to achieve excellent outcomes.

CONCLUSIONS

Surgeons and headache physicians who are interested in providing treatment for patients with chronic headache should strive to form a close collaboration with each other in order to provide the optimal plan for migraine/headache patients.

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.

OnabotulinumtoxinA alters inflammatory gene expression and immune cells in chronic headache patients

Occipital headache, the perception of pain in the back of the head, is commonly described by patients diagnosed with migraine, tension-type headache, and occipital neuralgia. The greater and lesser occipital nerves play central role in the pathophysiology of occipital headache. In the clinical setup, such headaches are often treated with onabotulinumtoxinA, a neurotoxin capable of disrupting ability of nociceptors to get activated and/or release proinflammatory neuropeptides. Attempting to understand better onabotulinumtoxinA mechanism of action in reducing headache frequency, we sought to determine its effects on expression of inflammatory genes in injected occipital tissues.

To achieve this goal, we injected 40 units of onabotulinumtoxinA into four muscle groups (occipitalis, splenius capitis, semispinalis capitis, and trapezius muscles—all located on one side of the occiput) of patients with chronic bilateral occipital headache scheduled for occipital nerve decompression surgery 1 month later. At the time of surgery, we collected discarded muscle, fascia and periosteum tissues from respective locations on both sides of the neck and occiput and performed targeted transcriptome analyses to determine expression level of inflammatory genes in onabotulinumtoxinA-injected and onabotulinumA-uninjected tissues.

We found that (i) onabotulinumtoxinA alters expression of inflammatory genes largely in periosteum, minimally in muscle and not at all in fascia; (ii) expression of inflammatory genes in uninjected periosteum and muscle is significantly higher in historical onabotulinumA responders than historical non-responders; (iii) in historical responders’ periosteum, onabotulinumA decreases expression of nearly all significantly altered genes, gene sets that define well recognized inflammatory pathways (e.g. pathways involved in adaptive/innate immune response, lymphocyte activation, and cytokine, chemokine, NF-kB, TNF and interferon signalling), and abundance of 12 different immune cell classes (e.g. neutrophils, macrophages, cytotoxic T-, NK-, Th1-, B- and dendritic-cells), whereas in historical non-responders it increases gene expression but to a level that is nearly identical to the level observed in the uninjected periosteum and muscle of historical responders; and surprisingly (iv) that the anti-inflammatory effects of onabotulinumA are far less apparent in muscles and absent in fascia.

These findings suggest that in historical responders’ periosteum—but not muscle or fascia—inflammation contributes to the pathophysiology of occipital headache, and that further consideration should be given to the possibility that onabotulinumA mechanism of action in migraine prevention could also be achieved through its ability to reduce pre-existing inflammation, likely through localized interaction that lead to reduction in abundance of immune cells in the calvarial periosteum.

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.

Surgical Management of Occipital Neuralgia: A Systematic Review of the Literature

BACKGROUND

Occipital neuralgia (ON) is a primary headache disorder characterized by severe, paroxysmal, shooting or stabbing pain in the distribution of the greater occipital, lesser occipital, and/or third occipital nerves. Both medical and surgical options exist for treating headaches related to ON. The purposes of this study are to summarize the current state of surgical ON management through a systematic review of the literature and, in doing so, objectively identify future directions of investigation.

METHODS

We performed a systematic review of primary literature on surgical management for ON of at least level IV evidence. Included studies were analyzed for level of evidence, therapeutic intervention, study design, sample size, follow-up duration, outcomes measured, results, and risk of bias.

RESULTS

Twenty-two studies met the inclusion criteria. All 22 studies used patient-reported pain scores as an outcome metric. Other outcome metrics included complication rates (7 studies; 32%), patient satisfaction (7 studies; 32%), quality of life (7 studies; 18%), and analgesic usage (3 studies; 14%). Using the ROBINS-I tool for risk of bias in nonrandomized studies, 7 studies (32%) were found to be at critical risk of bias, whereas the remaining 15 studies (68%) were found to be at serious risk of bias.

CONCLUSIONS

Greater occipital nerve decompression seems to be a useful treatment modality for medically refractory ON, but further prospective, randomized data are required.

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.

Mechanism of Action of OnabotulinumtoxinA in Chronic Migraine: A Narrative Review

Objective

To review the literature on the mechanism of action of onabotulinumtoxinA in chronic migraine.

Background

OnabotulinumtoxinA is a chronic migraine preventive treatment that significantly reduces headache frequency. The traditional mechanism described for onabotulinumtoxinA – reducing muscle contractions – is insufficient to explain its efficacy in migraine, which is primarily a sensory neurological disease.

Methods

A narrative literature review on the mechanism of action of onabotulinumtoxinA in chronic migraine.

Results

Following injection into tissues, onabotulinumtoxinA inhibits soluble N‐ethylmaleimide‐sensitive fusion attachment protein receptor (SNARE)‐mediated vesicle trafficking by cleaving one of its essential proteins, soluble N‐ethylmaleimide‐sensitive fusion attachment protein (SNAP‐25), which occurs in both motor and sensory nerves. OnabotulinumtoxinA inhibits regulated exocytosis of motor and sensory neurochemicals and proteins, as well as membrane insertion of peripheral receptors that convey pain from the periphery to the brain, because both processes are SNARE dependent. OnabotulinumtoxinA can decrease exocytosis of pro‐inflammatory and excitatory neurotransmitters and neuropeptides such as substance P, calcitonin gene‐related peptide, and glutamate from primary afferent fibers that transmit nociceptive pain and participate in the development of peripheral and central sensitization. OnabotulinumtoxinA also decreases the insertion of pain‐sensitive ion channels such as transient receptor potential cation channel subfamily V member 1 (TRPV1) into the membranes of nociceptive neurons; this is likely enhanced in the sensitized neuron. For chronic migraine prevention, onabotulinumtoxinA is injected into 31‐39 sites in 7 muscles of the head and neck. Sensory nerve endings of neurons whose cell bodies are located in trigeminal and cervical ganglia are distributed throughout the injected muscles, and are overactive in people with migraine. Through inhibition of these sensory nerve endings, onabotulinumtoxinA reduces the number of pain signals that reach the brain and consequently prevents activation and sensitization of central neurons postulated to be involved in migraine chronification.

Conclusion

OnabotulinumtoxinA likely acts via sensory mechanisms to treat chronic migraine.

Emerging evidence of occipital nerve compression in unremitting head and neck pain

Unremitting head and neck pain (UHNP) is a commonly encountered phenomenon in Headache Medicine and may be seen in the setting of many well-defined headache types. The prevalence of UHNP is not clear, and establishing the presence of UHNP may require careful questioning at repeated patient visits. The cause of UHNP in some patients may be compression of the lesser and greater occipital nerves by the posterior cervical muscles and their fascial attachments at the occipital ridge with subsequent local perineural inflammation. The resulting pain is typically in the sub-occipital and occipital location, and, via anatomic connections between extracranial and intracranial nerves, may radiate frontally to trigeminal-innervated areas of the head. Migraine-like features of photophobia and nausea may occur with frontal radiation. Occipital allodynia is common, as is spasm of the cervical muscles. Patients with UHNP may comprise a subgroup of Chronic Migraine, as well as of Chronic Tension-Type Headache, New Daily Persistent Headache and Cervicogenic Headache. Centrally acting membrane-stabilizing agents, which are often ineffective for CM, are similarly generally ineffective for UHNP. Extracranially-directed treatments such as occipital nerve blocks, cervical trigger point injections, botulinum toxin and monoclonal antibodies directed at calcitonin gene related peptide, which act primarily in the periphery, may provide more substantial relief for UHNP; additionally, decompression of the occipital nerves from muscular and fascial compression is effective for some patients, and may result in enduring pain relief. Further study is needed to determine the prevalence of UHNP, and to understand the role of occipital nerve compression in UHNP and of occipital nerve decompression surgery in chronic head and neck pain.

Non-Trigeminal Nociceptive Innervation of the Posterior Dura: Implications to Occipital Headache

Current understanding of the origin of occipital headache falls short of distinguishing between cause and effect. Most preclinical studies involving trigeminovascular neurons sample neurons that are responsive to stimulation of dural areas in the anterior 2/3 of the cranium and the periorbital skin. Hypothesizing that occipital headache may involve activation of meningeal nociceptors that innervate the posterior ⅓ of the dura, we sought to map the origin and course of meningeal nociceptors that innervate the posterior dura overlying the cerebellum. Using AAV-GFP tracing and single-unit recording techniques in male rats, we found that neurons in C2-C3 DRGs innervate the dura of the posterior fossa; that nearly half originate in DRG neurons containing CGRP and TRPV1; that nerve bundles traverse suboccipital muscles before entering the cranium through bony canals and large foramens; that central neurons receiving nociceptive information from the posterior dura are located in C2-C4 spinal cord and that their cutaneous and muscle receptive fields are found around the ears, occipital skin and neck muscles; and that administration of inflammatory mediators to their dural receptive field, sensitize their responses to stimulation of the posterior dura, peri-occipital skin and neck muscles. These findings lend rationale for the common practice of attempting to alleviate migraine headaches by targeting the greater and lesser occipital nerves with anesthetics. The findings also raise the possibility that such procedures may be more beneficial for alleviating occipital than non-occipital headaches and that occipital migraines may be associated more closely with cerebellar abnormalities than in non-occipital migraines.SIGNIFICANCE STATEMENT Occipital headaches are common in both migraine and non-migraine headaches. Historically, two distinct scenarios have been proposed for such headaches; the first suggests that the headaches are caused by spasm or tension of scalp, shoulders, and neck muscles inserted in the occipital region, whereas the second suggests that these headaches are initiated by activation of meningeal nociceptors. The current study shows that the posterior dura overlying the cerebellum is innervated by cervicovascular neurons in C2 DRG whose axons reach the posterior dura through multiple intracranial and extracranial pathways, and sensitization of central cervicovascular neurons from the posterior dura can result in hyper-responsiveness to stimulation of neck muscles. The findings suggest that the origin of occipital and frontal migraine may differ.