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Comparison of Peripheral Neurectomy vs. Medical Treatment for Migraine: A Randomized Controlled Trial
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.315973
Keywords: Endoscopy, headache, medical treatment, migraine, peripheral neurectomy, surgical treatment
Migraine is a common form of primary neurologic headache.[1],[2] It is a chronic relapsing relenting disease resulting in many functional years lost in disability. This condition is generally treated with drugs. However, many patients are drug-refractory or chronic migraneurs and suffer from drug-related adverse effects.[3],[4] In these, surgery is indicated.[5],[6] Surgical intervention can lead to a cure for the migraine and can add many functional years to the patient's life. Also, it can be cost-effective compared to chronic medical treatment. There is insufficient literature comparing the peripheral neurectomy to the chronic medical treatment for migraine. Our study aimed to evaluate the surgical and functional outcomes of migraine surgery using peripheral neurectomies and compare them with chronic drug treatment.
It was a randomized controlled trial (RCT) done from April to November 2019 done at a tertiary center. The primary outcome assessed was to study the pain outcomes of migraine surgery using migraine headache index (MHI) and visual analogue scale (VAS). The secondary outcomes assessed were the functional outcomes of migraine surgery using the migraine disability assessment test (MIDAS) and the pain self-efficacy questionnaire (PSEQ) and complications of migraine surgery. Institutional ethics committee permission was taken (IEC no. 2019/3019 dated 16.4.19). The migraine was defined according to the International classification of headache 3rd edition criteria,[1] and the chronic migraine was defined as migraine lasting for more than three months. Inclusion criteria were patients with chronic or drug-refractory migraine and who had a positive response (temporarily pain freedom) to the bupivacaine block. All patients were on at least two prophylactic drugs (propanolol/flunarizine/divalproex sodium/sodium valproate). The exclusion criterion was the patient's refusal to take part in the study. Patient selection A detailed history was taken to make a diagnosis of migraine, and all patients were referred from the neurology department. Patients fitting into the chronic migraine definition were called for bupivacaine blocks. When they presented with a pain attack during the outdoor department visit, a local anesthetic block with bupivacaine 0.5% was given over the suspected trigger site. The efficacy of the blocks for the duration of action of the drugs, i.e., 3–8 h for bupivacaine, was noted. Pain relief with bupivacaine was defined as a positive response, and these patients were given the option for surgery. Patients consenting for surgery were put in the surgical arm and the other ones in the control arm. An independent person outside of the treatment team did the evaluations. Patient evaluation Patients were evaluated for their symptom duration and trigger sites. Baseline pain was calculated using MHI, VAS, and PSEQ scores. Disability was calculated using the MIDAS score. Percent benefit with bupivacaine block was calculated using the VAS score. At 1, 3, and 6 months follow-up, the same questionnaires were used again to determine the intergroup difference between the operative and conservative arms. The intragroup comparison of the operative arm between preoperative and postoperative status was also made. Anesthesia protocol All patients were operated under local anesthesia, i.e., 0.5% bupivacaine, in combination with 2% lignocaine. Surgical protocol The trigger site was explored, and neurectomies were done. Frontal site: The incision was given over medial 1/3rd of the eyebrow. The glabellar muscle group was incised to expose the supraorbital and supratrochlear nerves, and both the nerves were lysed. Temporal site: For the Zygomaticotemporal nerve (ZTN) triggers, the nerve was exposed and lysed in the temple area under endoscopic control by making an incision in the hair-bearing area. The landmark of the nerve was 16 mm lateral and 6 mm cranial to the lateral canthus. The nerve lies deep to the superficial temporal fascia. An essential point in this approach was to avoid injury to the branch of the facial nerve, which travels above the superficial temporal fascia.[7] The Auriculotemporal nerve (ATN) was explored and lysed in front of tragus in the hair-bearing area of the scalp. Occipital sites: The lesser occipital nerve was explored and lysed at a point of a 1/3rd distance between mastoid and external occipital protuberance. The greater occipital nerves were explored and lysed in the suboccipital area about 1.5 cm lateral to the midline and deep to the trapezius fascia. Statistical analysis The sample size was calculated using the expected efficacy of surgical treatment to be 88%[5],[8],[9] and medical treatment to be 27%.[10] The sample size came to be six in each arm. Data were recorded in a Microsoft excel sheet and was analyzed using SPSS 22.0 software (IBM Company, Chicago, IL, USA). The intergroup difference was calculated using one-way analysis of variance, and before-after comparison (for the surgical group) was made using the paired t-test.
The study included 26 patients (18 females) with chronic migraines who benefitted from a local bupivacaine block. The mean age was 28.15 ± 5.78 years. Symptom duration ranged from 12 to 60 months. A total of 13 of them underwent neurectomy of the affected area. The demographic profile with the preoperative and postoperative status of patients is given in [Table 1].
Both groups were of similar age and had a similar amount of benefit with the bupivacaine block (P = 0.89). There were 14 left, 11 right-sided, and one bilateral migraine patients. For the three frontal region migraines, both supraorbital and supratrochlear sites were the triggers, and they underwent supraorbital and supratrochlear neurectomies. One of the cases had a thickened supraorbital nerve, as shown in [Figure 1]. Four patients underwent ZTN neurectomy. The neurovascular conflict can be seen in [Figure 2], and the schema can be seen in [Figure 3]. The complete procedure can be seen in Video 1. Three patients underwent ATN neurectomy. [Figure 4] shows the neurovascular conflict between the branches of superficial temporal artery (STA) and ATN. Two patients underwent lesser occipital, and one bilateral greater occipital neurectomy.
Migraine pain indices: Comparison was made between baseline and 6 months follow-up. There was a significant improvement in pain scores judged with VAS, MHI, and PSEQ scores. At baseline, the VAS (P = 0.07), MHI (P = 0.66), MIDAS (P = 0.5), and PSEQ scores (P = 0.98) were similar in both the groups. At 6 months, these were significantly different between the groups (P = <0.001 for all). Details can be seen in [Table 1]. In the operative group, the VAS decreased from 8.3 ± 0.85 to 2.0 ± 0.81, MHI decreased from 335.3 ± 52.59 to 14.84 ± 7.85 (P = <0.001), and the PSEQ scores increased from 5.08 ± 0.99 to 56.30 ± 2.35 (P = <0.001). Migraine freedom: In the operative group, 11/13 (84.61%) patients reported a positive response (>50% improvement) and 4/13 (30.76%) reported complete freedom at 6 months. No patient of the conservative arm had migraine freedom. Migraine disability test: At baseline, the MIDAS score was also similar in both groups (P = 0.5) but was significantly different in the postoperative period (P = <0.001). In the operative group, the MIDAS score significantly decreased from 21.00 ± 6.05 to 3.61 ± 2.32 (P = <0.001). [Figure 5] shows a comparative analysis of preoperative and postoperative indices at baseline, 1, 3, and 6 months. It shows an improvement in all the indices in the operative group, immediately after the surgery that remains sustained until the last follow-up at six months.
Drug freedom: All patients of the surgery group got free from prophylactic migraine treatment; however, 11 out of 13 operated patients still need occasional use of analgesics (paracetamol/diclofenac). The medical group had no drug freedom. Complications: One patient in the surgery group complained of transient numbness in the temporal region. There was no other complication.
The study showed the effectiveness of peripheral neurectomies for chronic migraine cases that had an identified trigger site. There was a significant improvement in the pain scores and reduction in the migraine disability in the operative arm compared with the medical arm. We did all surgeries under local anesthesia as it helped the surgeon to confirm the trigger intraoperatively. The identification of the trigger factor was the most important step and was easy, as described in the methodology. Recently, many authors have suggested trigeminovascular theory regarding the peripheral triggers as a cause of migraine.[11],[12],[13] These have led to the surgical options, including peripheral neurolysis/neurectomy of migraine triggers,[14],[15],[16],[17] occipital nerve stimulation,[18],[19] trigeminal nerve stimulation,[20] sphenopalatine ganglion stimulation,[21] deep brain stimulation of posterior hypothalamus, and transcranial magnetic stimulation.[22] Surgery can lead to a cure for migraines, which is presently not possible with drugs. Chronic prophylactic migraine drugs are associated with adverse effects like weight gain, somnolence, depression, etc.[3],[4] These are bothersome for many patients and surgical treatment can prevent these. We chose peripheral neurectomy as it is a fast, safe, and effective method for migraine, which has been observed by other authors also.[5],[14],[23] [Table 2] shows the different studies for peripheral neurectomy for migraine. Guyuron et al. showed up to 88% positive responders and 29% complete elimination of migraine at a 5-year follow-up.[5] Because it is a one-time procedure, the long-term costs of peripheral neurectomies would be very less compared to the stimulation techniques, botulinum toxin, and drugs.[24] Peripheral neurectomy is a daycare procedure leading to early discharge from the hospital. The scars can be avoided by making incisions in the hairline. Complications are few and include numbness and hallowing of the areas, most of which were transient ones.[14],[25] The transient numbness after sensory neurectomies may be due to overlapping dermatomal supply of the nerves. On the contrary, the stimulation techniques have shown mixed results, are costly, and have mixed methodologies compared to other techniques.[26]
Most of the prior studies, as described in [Table 2], are either retrospective or case series and from a single group. Our series is an RCT and adds up to the literature. The strengths of the study included a randomized study design with the usage of objective assessment scales. The methodology and surgery were straightforward and can be replicated in any setup. The avoidance of scar by making incisions in the hairline was significant as most of the patients were young females and required the utmost cosmesis. In the past, two incisions have been made for the ZTN,[27] and we here described a single incision. The complication was only a case of transient temporal numbness. Limitations of the study include a small sample size and difficult to rule out the placebo effect of surgery. We took the follow-up to six months, considering the placebo effect should wean by that time. Guyuron et al. did a placebo-controlled surgical trial and found significant migraine freedom in the actual surgical arm compared to the sham surgical arm.[25] Although we did not come across the complication of a neuroma, a small percentage may develop it. It can be prevented if we cut the nerve sharply and bury the ends inside the muscle.[28] Even if it happens, redo surgery can be done. The small number of patients in our series was due to strict patient selection criteria and the reluctance of the patients to undergo surgery. Many patients are tolerant of pain and keep on taking drugs despite counseling. A lack of consensus among neurologists and neurosurgeons for its efficacy may also be a reason. The inclusion of only those patients into the surgical arm who were consenting for it and comparing them with those who did not give the consent may create selection bias. This was minimized by the evaluation performed by an independent person outside of the treatment team. There is a need to establish evidence-based migraine surgery protocols for drug-refractory and chronic migraineurs to reduce the migraine-related loss of working hours, drug side effects, cost of drugs, etc., Simple surgeries that may be curative should be given priority. Large-scale multicenter trials comparing the peripheral neurectomies with medical treatment can help in making the guidelines in this regard.
Migraine surgery seems to be a safe and effective option for appropriately selected chronic migraine cases. It was more effective than chronic drug treatment. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]
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