Occipital Nerve Stimulation and Sphenopalatine Ganglion Stimulation for Treatment of Intractable Headache Syndromes
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.302477
Source of Support: None, Conflict of Interest: None
Keywords: Cluster headaches, field stimulation, intractable headache syndromes, occipital nerve stimulation, occipital neuralgia, percutaneous leads, sphenopalatine ganglion stimulation, trigeminal neuralgia
Intractable headache syndromes are a leading cause of disability in the world. Headache syndromes affect all age groups, men and women. Most chronic pain syndromes including headaches generally affect women more than men. Cluster headaches affect men more than women. Cluster headache consists of attacks of severe, strictly unilateral pain, which is orbital, supraorbital, temporal, or in any combination of these sites, lasting 15–180 min and occurring from once every other day to eight times a day. The attacks are associated with one or more of the following, all of which are ipsilateral: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, forehead and facial sweating, miosis, ptosis, and eyelid edema. Cluster headaches can be episodic or become chronic, associated with triggers such as smoking. Trigeminal neuralgia can coexist in patients with cluster headaches resulting in cluster-tic syndrome. Occipital neuralgia is another prevalent headache syndrome and usually coexists with migraine headaches. The vast majority of occipital neuralgia involves the greater occipital nerves. Other comorbidities such as cervical spinal osteoarthritis, fibromyalgia, autoimmune disorders can coexist with occipital neuralgia.
Occipital nerve stimulation using percutaneous leads
This is the preferred method of occipital nerve stimulation (ONS) by authors. The percutaneous leads are less invasive and provide ease of use even in elderly population. These leads to decrease the long-term incidence of patient discomfort due to being more pliable leads than the rigid surgical leads. Favourable response to diagnostic occipital nerve blocks is helpful in the workup. However, diagnostic occipital nerve blocks are unable to substitute for percutaneous trial leads due to coverage as well as programming advantages of the trial leads., If the diagnostic occipital nerve blocks do not provide adequate pain relief for extended period of time, neuromodulation could extend the time coverage. Hence short lived, diagnostic blocks are not a contraindication for trial leads but rather an indication to ascertain adequate pain relief. The techniques described below are similar for both trial and permanent leads. Trial leads can be placed with local and conscious sedation; permanent leads more likely with monitored anesthesia care or general anesthesia due to concurrent implantable generator (IPG) placement.
Fluoroscopy guidance is the more popular modality for both trial and permanent leads for occipital nerve stimulation. Patients are usually placed prone since most ONS involves both sides. However, in case of unilateral lead placement, lateral decubitus position is preferred for easier airway management. The original method involved placed the leads at C1 level, which has been supplanted by leads placed at the nuchal ridge [Figure 1]. The nuchal ridge is superior due to closer proximity of the leads to the greater occipital nerve. Another advantage is the probability of capturing less and lesser occipital nerve fields is higher with the nuchal ridge placement. The entry point for lead insertion can be lateral to medial in unilateral leads. Most operators prefer medial to lateral insertion with bilateral leads. Optimal depth placement of the leads is critical. Superficial leads can lead to dysesthesias of the scalp during stimulation in both trial and permanent leads. In case of permanent leads, superficial leads are more prone to skin erosion, ulceration, infection, etc. Conversely, deep leads can lead to flowover stimulation - muscle contraction and spasms that may lead to discomfort and worsening of headaches in the patient. In smaller patients, consideration should be given to programming appropriate contacts on the leads. The lateral most contacts can lead to noxious stimulation of the mastoid process and ears.
Usually the trial period can last from 3 to 5 days depending on operator preference. Usually trial leads are completely removed at the end of trial period. Permanent leads have additional considerations for IPG placement. IPG implantation can done over anterior or posterior chest wall; patient preference and cosmetic/aesthetic considerations should be made as shared decision-making with the patient. Furthermore, if patient has a preferred side of sleeping that must be considered as well. Since neck is a mobile location with constant flexion, extension, rotation and lateral flexion; adequate strain relieving loops must be provided. Anchors to tether IPG and leads also need to consider pivotal points in the neck and avoid those locations to prevent scarring, fibrosis and the consequent discomfort to patients. Lead migration and lead erosion are two long term complications of ONS.
Ultrasound guidance of percutaneous leads during occipital nerve stimulation.
Ultrasonography can provide valuable information with depth perspective as well as location of the greater occipital nerve. Furthermore, in patients with previous history of cranial surgeries, ultrasonography can demonstrate scar tissue, mesh implants as well as aberrant vasculature, which can be helpful. In revision surgeries of ONS and in the elderly population, ultrasonography can help ascertain optimal depth placement when anatomical considerations may have been altered. Optimal lead placement can reduce lead erosion, dysesthesias, noxious muscle stimulation as detailed above. In addition, optimal lead placement can not only prolong battery life of IPG but also improve efficacy of lead programming including subthreshold stimulation.
Occipital nerve stimulation with surgical leads
Surgical leads tend to be flat and consequently can capture a larger width of coverage. Also, they are more amenable to being anchored firmly and can be useful in revision surgeries especially in the presence of scar tissue. Some operators trial with percutaneous leads and implant surgical leads. Surgical leads being larger in surface area may lead to patient discomfort over longer periods of time. Lead migration is less likely with surgical leads. However, they are subject to increased wear and tear and metal fatigue lead to loss of efficacy. While both percutaneous as well as surgical leads have their unique advantages, patient selection and patient education is crucial for their long term retention and efficacy.
Sphenopalatine ganglion stimulation
Sphenopalatine ganglion (SPG) is an autonomic ganglion located in pterygopalatine fossa. Classically, it has been considered as a predominantly parasympathetic ganglion; however, recent advances in neuroimaging as well as neuro-immunochemistry demonstrate that it has sympathetic as well as sensory components. It has vast set of functions including sensory fibers to adjacent meninges, vascular control and autonomic control of secretory functions in the lacrimal and nasal glands. Patients with refractory cluster headaches as well as trigeminal autonomic cephalgias (TACs) can derive pain relief from Sphenopalatine ganglion stimulation. Some operators prefer fluoroscopy guided SPG block as a diagnostic test before trialing leads. Office-based transnasal as well as transoral SPG blocks are alternatives as well.
Percutaneous infrazygomatic approach
This is preferred method due to the location and access to pterygopalatine fossa. Fluoroscopy is the preferred imaging guidance modality followed by computed tomography (CT). The entry point is inferior to infrazygomatic process and usually anterior to the mandible. Some operators may prefer an entry point inferior to infrazygomatic process but through the coronoid notch. The needle is advanced on the pterygoid plate into the pterygopalatine fossa with imaging guidance. The percutaneous lead advanced through needle cannula and sensory stimulation performed. Paraesthesia over the base of the nose confirms ideal placement. During permanent placement of the percutaneous leads, the lead is tethered at the infrazygomatic location and the IPG is usually positioned in the infraclavicular region. Attention should be directed towards providing strain relief loops to prevent lead migration and patient discomfort due to strain during neck movements. An alternative technique is the transoral infrazygomatic approach where an incision is made over the gingival mucosa and the implant is placed over cheekbone with lead in the pterygopalatine fossa. The unit is driven by an external inductive current generator [Figure 2].
With the advent of newer technologies, neurostimulation of occipital nerves and sphenopalatine ganglion outlook is optimistic with possibility of improved pain control with lesser adverse effects. Burst stimulation which is proposed to modulate pain perception at cortical level in addition to traditional neurostimulation mechanisms may confer additional pain control and compliance in these intractable headache syndromes. Preliminary small studies appear promising. Furthermore, burst stimulation is usually sub perception and maybe more comfortable for patients in these relatively periosteal and subcutaneous locations. High-frequency stimulation provides paraesthesia free stimulation with improved patient comfort and is an option for these locations. Recently closed-loop spinal cord stimulation studies have been published and potentially show promise for uses for intractable headache syndromes in the future.
Invasive and minimally invasive procedures carry a risk potential. Minimizing risk and optimizing care starts with patient workup presurgically. This often is best accomplished with a multidisciplinary team spanning several specialities including Neurology, Neurosurgery, Radiology, Pain management, Pain Psychology and therapists. Medical workup to rule out secondary causes for intractable headache syndromes is vital. Imaging studies for presurgical planning, Pain Psychology evaluation for screening as well as diagnostic blocks by Pain management are essential for final patient selection as well as realistic expectations. Furthermore, long-term compliance is attained with continued medication optimization, treatment of comorbid psychiatric disorders such as depression and anxiety and reprogramming of neurostimulation which is best implemented as a multidisciplinary team.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2]