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Surgical Options for Migraine: An Overview
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.315999
Keywords: Headache, migraine, migraine surgery, occipital nerve, peripheral, preventive, trigeminal nerve, trigger points
Migraine is a complex neurological disorder known since ancient times based on available literature. It is the most prevalent neurological disorder worldwide. Despite advances in our understanding of the pathophysiology of the disease, there is an unmet need for better treatment of this condition. Migraine is still one of the leading causes of disability worldwide, particularly in younger ages where it has been reported to be the principal cause of disability.[1],[2] As a complex brain disorder, the central nervous system plays a critical role in the pathophysiology of migraine, and the “brainstem migraine generator” has been described years ago.[3],[4] Later advancements in understanding the pathophysiology of migraine revealed the role of different parts of the central nervous system in migraine, including the cerebral cortex and hypothalamus has been identified.[5],[6] Migraine has been classically described to have four phases: the premonitory, aura, headache, and postdrome phase although all need not be present during each and every attack.[7] For most patients, the headache phase is the most important and bothersome phase during a migraine attack. Activation of the “trigeminovascular” pain pathways that innervate the dural vasculature is thought to be responsible for the headache phase of the migraine.[8] The role of the “trigeminovascular” complex in the headache phase of migraine is well described. It is believed that peripheral and central sensitization of the “trigeminovascular” complex may contribute to migraine headaches.[9] Within the past decade, the important role of Calcitonin Gene-Related Peptide (CGRP) has been identified as being released in the trigeminovascular complex, leading to neurogenic inflammation and vasodilation. However, the activation site of CGRP remains open to discussion with a growing body of evidence supporting a peripheral site of action of CGRP as well.[10]
Surgical management for migraine was attempted by Dr. Harvey Cushing - the father of modern neurosurgery during the early 1900s, but many of his results were never published because many of his procedures proved to be unsuccessful.[11] The current trend in migraine surgery was started by the senior author (BG) in 1999 when two of his patients reported relief of their headache after forehead rejuvenation. In this surgery usually, glabellar muscles are removed around the supraorbital and supratrochlear nerves.[12] This incidental finding along with the discovery that Botulinum toxin A is beneficial for treating headaches in some individuals prompted the senior author to conduct a retrospective study. The common grounds between botulinum toxin A injection and forehead surgery were deactivation of the glabellar muscles. However, other attributes of botulinum toxin A may have a role in reducing or halting migraine headaches.[13] In the beginning, the hypothesis was that sensory nerves are being compressed or irritated by the muscles around them.[14] However anatomical studies suggested that nerves can be compressed or irritated by other structures like vessels, fascia, and bone.[15],[16],[17],[18] The idea of trigger site deactivation using an injection of local anesthetics in migraine patients has been recorded in neurology literature as well and it is routinely used in practice by headache medicine providers.[19] Since the initial observation, more than 60 scientific studies have been published by multiple centers to further validate the concept of migraine surgery, including a placebo-controlled (sham surgery) by the senior author of this review.[14],[20],[21],[22],[23],[24] Further anatomical studies delineated the course of the nerves in the head and neck area, and surgical techniques have been refined.[15],[16]
Overall, four major trigger sites and a few minor trigger sites have been described in the surgical treatment of migraine headache:
Initially, botulinum toxin A was used for patient selection but throughout the years we learned that constellations of symptoms and diagnostic nerve blocks for identification of trigger points could be as helpful.[25],[26] Therefore, with a careful history and detailed headache diary plus a thorough head, neck, and nose exam, we are usually able to identify the correct trigger point/s. A computerized tomography (CT scan) of the nose and paranasal sinuses is useful in nasal trigger sites and the use of Doppler ultrasound could be helpful in some peripheral and smaller trigger sites.[27]
Frontal trigger site: Involved nerves: supraorbital and supratrochlear nerves The constellation of symptoms: patients' headache starts from the frontal area, above the eyebrows which could be unilateral or bilateral. These patients usually have strong frowning muscles. Patients with the chronic frontal trigger might develop eyebrow or eyelid ptosis. Blocking of the affected nerve with a local anesthetic alleviates the patient for a short period and has diagnostic value. Pathophysiology: the nerves could be irritated by either glabellar muscles (including the corrugator supercilii, depressor supercilii, and procerus) or vessels accompanying them. In some patients, nerves are also under significant pressure in the supraorbital notch by a fibrous band or bony tunnel [Figure 1]. However, the vessels have a prodigious role in this site.
Surgical procedure: The focus is to relieve the Supraorbital and Supratrochlear nerves from any pressure, this is done by an incision on the eyelid or endoscopically and skeletonizing the nerves throughout their pass from orbital rim to subcutaneous tissue, this usually involves removal of Corrugator, part of procerus and depressor supercilii muscles, removal of the accompanying vessels and release of the nerve in the supraorbital rim from any pressure caused by a notch or bony tunnel.[12] In the end, nerves are wrapped with a fat graft, or the area is injected with fat to minimize the scarring and possible recurrence of the nerve irritation. The supraorbital and supratrochlear vessels are removed as thoroughly as possible. Temporal trigger site Involved nerves: Zygomaticotemporal and auriculotemporal nerves The constellation of symptoms: Headache starts on the temple, usually one side is more prominent, and headache often presents in the morning. Patients usually have a history of teeth clenching or grinding. Jaw pain is very common in this patient and often misdiagnosed as temporomandibular joint disorder (TMD). It is very important to differentiate the pain originating from the Zygomaticotemporal branch of the trigeminal (ZTBTN) nerve and Auriculotemporal nerve (ATN). Patients with ZTBTN trigger point usually point toward the hallowing in the temporal area which is located around 17 mm posterior to the lateral orbital commissure is 6 mm cephalic to it. On the other hand, patients with auriculotemporal trigger points have their pain more posterior, along the temporal hairline. Pathophysiology: ZTBTN can be compressed by temporalis muscle, deep temporal fascia, or vessels. ATN can be irritated by vessels traveling with it (superficial temporal artery) or fascia. Surgical procedure: ZTBTN is treated endoscopically by avulsion of the nerve [Figure 2] as it emerges from the deep temporal fascia. ATN is more superficial and treated with a small incision identification and transection of a small segment of the superficial temporal artery or removal of the nerve [Figure 3].
Intranasal Trigger site (Rhinogenic Migraine) Involved nerves: Rich nervous supply of nasal mucosa. These sensory nerves are branches of the maxillary nerve through sphenopalatine ganglion. The constellation of symptoms: Headache starts from behind the eye and usually is unilateral at the onset. Patients usually wake up in the morning with a headache. Whether or barometric changes can trigger the headache by affecting the size of the turbinate or lining of the concha bullosa. Since nasal mucosa size responds to hormonal fluctuation, these patients usually experience prominent menstrual migraines. Treatment with botulinum toxin A is usually not effective in this group. On the other hand, these patients often get relief using intranasal decongestants or oral antihistamine and therefore commonly mistaken for sinus disorder and label as “sinus headache.”[28] Also since they can have rhinorrhea, nasal congestion, and breathing difficulty and therefore can be mistaken for cluster headache or other trigeminal autonomic cephalalgias. Pathophysiology: Irritation of rich nervous supply of nasal mucosa due to the anatomical contact point (septum or turbinate) or pressure from entrapped air pocket (concha bullosa) [Figure 4].
Surgical procedure: Depends on the anatomic pathology, septoplasty, elimination of contact points between the turbinate and the septum, reduction of the enlarged turbinate, and decompression of concha bullosa. Occipital trigger site Involved nerves: Greater Occipital Nerve (GON), Lesser Occipital Nerve (LON), and rarely Third Occipital Nerve (TON) The constellation of symptoms: Pain starts from the occipital and neck area, throbbing and stabbing in nature. Stress has a high impact on this trigger point, also physical activity can make it worse. Patients usually complain of neck and shoulder muscle tightness particularly with sitting or sleeping in certain positions. They tend to change their pillow to help this tightness. In neck exams, there is significant tenderness on pressure or even tapping on the affected nerve. History of a neck injury, particularly whiplash-type injury may correlate with onset/worsening of headaches. This type of migraine is commonly mistaken as “occipital neuralgia,” despite neuralgia having an apparent clear definition as “sudden onset lancinating (electric shock-like) pain” with “abrupt onset and termination.” Also based on ICHD-3, the pain of occipital neuralgia is recurring in paroxysmal attacks lasting from a few seconds to minutes. Another differential diagnosis is a cervico-genic headache which sometimes is challenging to distinguish from migraine.[29] If the diagnosis is not clear, we need to proceed with a diagnostic blockade of a cervical structure or its nerve supply. Also, if the diagnosis of migraine is not clear, magnetic resonance imaging (MRI) of the neck and cervical spine is indicated for high-quality visualization of both the cervical spine as well as the surrounding occipital and cervical soft tissues. Pathophysiology: Greater occipital nerve can be compressed by semispinalis muscle [Figure 5], trapezius fascia, or laterally by the greater occipital artery. The third occipital nerve is more superficial to the greater occipital nerve and it is not consistently found during surgery and is less relevant to the pathophysiology of migraine headache. The Less occipital nerve is more lateral and is found medial to the mastoid tuberosity; this nerve is irritated by local thick fascia and occasionally blood vessels.
Surgical procedure: GON is managed with a midline vertical incision on the caudal occipital region, the trunk of the greater occipital nerve is located approximately 1.5 cm from the midline and 3 cm caudal to the occipital protuberance. At this point, the nerve passes through the semispinalis capitis muscle then travels laterally to pass through the trapezius fascia and then over the greater occipital artery. Deactivation of the trigger site is achieved by removing small pieces of muscle and fascia around the nerve as well as great occipital arteries. LON is addressed by removing the compression sites over the nerve if the nerve is large or transection of the nerve if the is a smaller nerve. Recovery and Complication Most of these procedures are performed at outpatient surgery centers. However, major complications are very rare minor issues like temporary paresthesia and itching in the area of surgery might happen. In rhinogenic trigger points, patients might observe transient nasal dryness.
Although migraine is a brain disorder, migraine pain can be caused by peripheral mechanisms also in addition to the mechanisms intrinsic to the central nervous system.[30] There is considerable evidence supporting the notion of peripheral etiology as an initiating step in the headache phase of migraine. These studies suggest that migraine is not just a brain disorder but it also involves functional and structural plasticity of both the central and peripheral nervous system.[31] Therefore, it is believed that the complex pathophysiology of migraine involves both the central and peripheral nervous systems.[32] Do et al. described the “bottom-up model” for headache by stating that increased peripheral nociceptive transmission sensitizes the central nervous system to lower the threshold for perceiving pain.[33] This can describe how a peripherally originated pain can affect a brain disorder like a migraine. Therefore, preventing the initiation of the migraine process by trigger point deactivation surgery, particularly in patients who do not respond or cannot tolerate traditional migraine treatments can be rewarding. Patients who present for surgical treatment should have a thorough headache evaluation by a neurologist or a headache specialist. This evaluation will not only help confirm the diagnosis of migraine but also rule out other potential causes or triggers for headache. Furthermore, the thorough evaluation will also assure that the patients have had the appropriate medical treatments before choosing the surgery option. Besides, since patients with chronic migraines have a higher possibility to overuse headache medications, this would need to be investigated and ruled out. Lastly, the trigger sites are identified by reviewing the headache logs, the thorough physical exam, and by the constellation of the symptoms, and in some cases by diagnostic nerve block or CT scan of sinuses. Close collaboration between the headache specialist and the migraine surgery specialist is the key to success in this surgery. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
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