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Many patients with craniofacial pain syndromes such as trigeminal neuralgia, cluster headache, and migraine have an adequate response to pharmacologic therapies. For the subset of patients who are refractory to these treatment options, surgical interventions that include deep brain stimulation (DBS) and microvascular decompression (MVD) may be considered. In a review published in May 2019 in Neurological Sciences, researchers examined outcomes and safety profiles associated with these and other neurosurgical techniques used to treat craniofacial pain syndromes, as summarized here.1
Trigeminal neuralgia
MVD is a “non-ablative, open microsurgical procedure, which aims at relieving the trigeminal nerve from any compression along its intracisternal path,” noted the review authors. “Following the identification of neurovascular conflict, arachnoid bands that fix the conflicting artery are dissected to allow mobilization of the vessel.” Results of several studies indicate that 90% of patients who underwent MVD reported pain relief, which was sustained for 1, 3, and 5 years in 80%, 75%, and 73% of patients, respectively.2
This procedure is associated with an average mortality rate of 0.2%, and the most common complication is aseptic meningitis (11%). Cerebrospinal fluid (CSF) leaks, infarcts, or hematomas affect up to 4% of patients, and up to 10% may experience long-term ipsilateral hearing loss.2 MVD is “considered over other surgical techniques to provide the highest rates of pain relief and longest pain free duration,” noted the review authors.1
Patients with trigeminal neuralgia for whom MVD is contraindicated may be candidates for percutaneous procedures such as radiofrequency thermorhizotomy and balloon microcompression. These techniques have been found to lead to pain relief in 90% of patients, with 1-year pain relief rates of 68% to 85% and 3-year rates of 54% to 64%.1 Mortality rates are extremely low, and approximately 50% of patients develop sensory loss after undergoing these procedures. An estimated 4% of patients experience corneal numbness with a risk for keratitis, and <6% develop dysesthesias.1
An alternative to surgery for trigeminal neuralgia is stereotactic radiosurgery, conducted to irradiate the trigeminal ganglion. This surgery has been associated with pain control in 70% to 90% of patients, with recurrence rates of up to 50% from 3 to 5 years after surgery.1,3
Glossopharyngeal neuralgia
The majority of open and percutaneous surgical procedures are no longer used to treat this condition because of safety issues. At this time, the most commonly used technique for patients who do not tolerate drugs is MVD of the glossopharyngeal nerve and vagal nerve rootlets in the posterior cerebral artery. “Refinement of microsurgical and anesthetic techniques has allowed for the procedure to be performed with low complication rate, and several series have described the efficacy of this procedure in relieving pain,” noted the review authors.1
The use of stereotactic radiosurgery for the treatment of glossopharyngeal neuralgia has been associated with pain relief in 82% of patients after 45 months, although recurrence rates are high compared with MVD.
Occipital neuralgias
Occipital nerve stimulation (ONS) is an emerging technique with high efficacy (66%-100%) and safety for the treatment of patients with occipital neuralgia. Although the use of ONS for intractable occipital neuralgia is supported by the Congress of Neurological Surgeons with a level III recommendation, more research is needed to determine the long-term efficacy of the procedure.4
Cluster headache
Percutaneous and open surgical techniques for cluster headache have largely been abandoned because of high rates of recurrence and risk for complications, whereas the use of neuromodulation has increased. DBS of the posterior hypothalamus has been associated with pain relief in approximately 60% of patients with drug-resistant chronic cluster headache.1 Although the procedure is well-tolerated, there are a “number of potential surgery, hardware, and stimulation-related risks, with the latter being vegetative dysfunction during the procedure, transient diplopia, increase or decrease in appetite, and decrease in libido,” the authors wrote.
Several cases series also support the safety and efficacy of ONS for cluster headache, including a recent series of 30 patients in which 20 patients indicated sustained pain relief after a mean follow-up period of >6 years.5 Efficacy rates of up to 85% have been reported in other studies.When appropriate, ONS should be offered before considering DBS, and the “implant can be easily converted into a DBS system if ONS proves unsuccessful,” noted the review authors.1
Short-lasting unilateral neuralgiform headache attacks
Microvascular decompression of the trigeminal nerve has shown efficacy in short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) or with cranial autonomic symptoms (SUNA).1 In addition, results from small case series have shown promising results in patients undergoing ONS and DBS. MVD “should be offered as a first procedure to those patients with neurovascular conflict who remain symptomatic or suffer from significant side effects despite optimal medical management,” and ONS and DBS should be considered for patients who do not show a conflict on magnetic resonance imaging (MRI) and those who do not respond to MVD.1
Migraine
A growing body of research has examined the use of ONS for drug-refractory migraine. Although results have been mixed overall, several studies suggest moderate levels of efficacy. In one randomized controlled trial, success rates were 39% with ONS compared with 9% in individuals treated with a control procedure. In another study, response rates were 56% and long-term (4 years) efficacy was >40%.6 ONS combined with subcutaneous supraorbital nerve stimulation was found to reduce the frequency of severe headaches by 81% and to nearly eliminate headaches in some patients in another study.1
Further research is needed to clarify the role of neurosurgical techniques in the treatment of craniofacial pain syndromes. “In the future, a better understanding of their mechanisms of action and their validation in large randomized controlled studies could better define their actual therapeutic value and role in the management of facial pain,” concluded the review authors.1
Clinical Pain Advisor interviewed Nauman Tariq, MD, assistant professor of neurology and director of the Headache Center at Johns Hopkins School of Medicine, Baltimore, Maryland, for additional discussion regarding this topic.
Clinical Pain Advisor: What are some of the most promising neurosurgical techniques for craniofacial pain syndromes, and what is known thus far about their efficacy and safety?
Dr Tariq: The most promising surgical technique that has the most validation from multiple studies is MVD for trigeminal neuralgia. The long-term success rate is relatively high, and the surgical complications rate, such as for postoperative bleeding, infection, and CSF leak, is typically low. I agree with the authors’ reported outcomes of a >70% success even after 5 years. It is appropriate to refer these patients to neurosurgery after MRI reveals the finding of an artery or vein abutting the trigeminal nerve.
Except for MVD for trigeminal neuralgia, all the other conditions mentioned by the authors provide weak evidence for surgical procedures. These studies have typically included a small number of patients, and the complication rates are generally high; for example, lead migration in surgically implanted nerve stimulators and bleeding risk with DBS.
Clinical Pain Advisor: What would you recommend to clinicians in regard to referring patients to a surgeon to be considered for these techniques?
Dr Tariq: Referral to a surgeon is reasonable when the conventional drugs for trigeminal neuralgia such as carbamazepine, gabapentin, baclofen, and lamotrigine have failed to help relieve the pain. With regard to other conditions described in the review, such as SUNCT/SUNA, cluster headaches, occipital neuralgia, and migraine, there are so many nonsurgical options available currently. The medicines we commonly use in these conditions are triptans, antidepressants, antiepileptics, the new anti-calcitonin gene-related peptide antibodies, bedside superficial nerve blocks such as occipital nerve blocks, sphenopalatine ganglion blocks, and supraorbital nerve blocks, and onabotulinum toxin.
Neurologists, and headache specialists in particular, have more experience with the dose titration in these conditions. The decision is best left to headache and facial pain specialists as to whether a referral should be made for surgery, provided the patient has failed all conventional nonsurgical options.
Clinical Pain Advisor: What should be the focus of future research regarding neurosurgical procedures for these syndromes?
Dr Tariq: I would emphasize the need for larger prospective studies with long-term outcomes, preferably 3 to 5 years after these surgical procedures, to justify their widespread use. For chronic pain, the study outcomes should also be long-term; unfortunately, most available studies report less than 1-year outcomes.
There is also a significant placebo effect for interventions in pain trials, as high as 50%, especially in the first few weeks to months after the intervention. Therefore, large numbers of patients are needed to participate in the study so the statistical power can be increased. Understandably, however, it will be difficult for neurosurgeons to run a large trial with hundreds of patients, especially for some rare conditions such as SUNCT, glossopharyngeal neuralgia, cluster headaches, and isolated occipital neuralgia.
At this time, with the exception of MVD, the postprocedure risks and treatment failure potentially outweigh the short-term benefits.
References
1. Franzini A, Moosa S, D’Ammando A, et al. The neurosurgical treatment of craniofacial pain syndromes: current surgical indications and techniques. Neurol Sci. 2019;40(Suppl 1):159-168.
2. Cruccu G, Gronseth G, Alksne J, et al; European Federation of Neurological Society. AAN-EFNS guidelines on trigeminal neuralgia management. Eur J Neurol. 2008;15(10):1013-1028.
3. Berti A, Ibars G, Wu X, et al. Evaluation of CyberKnife radiosurgery for recurrent trigeminal neuralgia. Cureus. 2018;10(5):e2598.
4. Sweet JA, Mitchell LS, Narouze S, et al. Occipital nerve stimulation for the treatment of patients with medically refractory occipital neuralgia: Congress of Neurological Surgeons systematic review and evidence-based guideline. Neurosurgery. 2015;77(3):332-341.
5. Leone M, Proietti-Cecchini A, Messina G, Franzini A. Long-term occipital nerve stimulation for drug-resistant chronic cluster headache. Cephalalgia. 2017;37(8):756-763.
6. Saper JR, Dodick DW, Silberstein SD, et al. Occipital nerve stimulation for the treatment of intractable chronic migraine headache: ONSTIM feasibility study. Cephalalgia. 2011;31(3):271-285.
