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Site V Surgery for Temporal Migraine Headaches

Background: Auriculotemporal nerve is demonstrated to contribute to migraine pain in temporal area. In particular, its relationship with the superficial temporal artery in the soft tissues superficial to the temporal parietal fascia has attracted researchers’ attention for many decades. The objective of this review was to explore whether site V nerve surgical decompression is effective for pain relief in temporal area. Methods: A literature search, according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, was conducted to evaluate the surgical treatment of auriculotemporal migraine. Inclusion was based on studies written in English, published between 2000 and February 2020, containing a diagnosis of migraine in compliance with the classification of the International Headache Society. The treatment must consist of surgical procedures involving the auriculotemporal nerve and/or arteries in site V, with outcome data available for at least 3 months. Results: Three hundred twenty-four records were identified after duplicates were removed, 31 full-text articles were assessed for eligibility, and 2 records were selected for inclusion. A total of 77 patients were included in the review. A direct approach at the anatomical site identified with careful physical examination and confirmed with a handheld Doppler probe is generally performed under local anesthesia. Blunt dissection to the superficial temporal fascia to expose the auriculotemporal nerve and the superficial temporal artery is followed by artery cauterization/ligament and eventual nerve transection/avulsion. Site V surgery results in a success rate from 79% to 97%. Conclusions: Despite the recent advances in extracranial trigger site surgery and a success rate (>50% improvement) from 79% to 97%, site V decompression is still poorly described. Elaborate randomized trials are needed with accurate reporting of patient selection, surgical procedure, adverse events, recurrencies or appearance of new trigger points, quality of life outcome, and longer follow-up times.


INTRODUCTION
Headache localized in the temporal region is characterized by dysfunction of both the zygomaticotemporal nerve (ZTN) and the auriculotemporal nerve (ATN). Although ZTN has been identified as the most important trigger site of this area, 1 several studies underline ATN's contribution to migraine pain in the temporal area 2 due to a mutually dependent relationship between the 2 nerves. [3][4][5][6] While ZTN is easily damageable during surgical procedure of the zygomatic area, 7-9 ATN dysfunction is generally linked to its complex anatomical connections in the infratemporal fossa 10 and to its relationship with the superficial temporal artery (STA) in the soft tissues superficial to the temporal parietal fascia. 11,12 Signs and symptoms of the dysfunction of these 2 nerves are easily distinguishable: ZTN injury causes diffused pain over the zygomatic arch and anterior temple near the lateral canthus, 13 and its irritation can be detected in the "hollow area" in the temple, about 2 cm lateral and 1 cm above the lateral canthus 5 ; ATN entrapment can cause pain in the high temple, ear, temporomandibular joint, preauricular, and parotid areas. 11 Ilaria Baldelli, MD, PhD* Maria Lucia Mangialardi, MD † Edoardo Raposio, MD, PhD, FICS* Background: Auriculotemporal nerve is demonstrated to contribute to migraine pain in temporal area. In particular, its relationship with the superficial temporal artery in the soft tissues superficial to the temporal parietal fascia has attracted researchers' attention for many decades. The objective of this review was to explore whether site V nerve surgical decompression is effective for pain relief in temporal area. Methods: A literature search, according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, was conducted to evaluate the surgical treatment of auriculotemporal migraine. Inclusion was based on studies written in English, published between 2000 and February 2020, containing a diagnosis of migraine in compliance with the classification of the International Headache Society. The treatment must consist of surgical procedures involving the auriculotemporal nerve and/or arteries in site V, with outcome data available for at least 3 months. Results: Three hundred twenty-four records were identified after duplicates were removed, 31 full-text articles were assessed for eligibility, and 2 records were selected for inclusion. A total of 77 patients were included in the review. A direct approach at the anatomical site identified with careful physical examination and confirmed with a handheld Doppler probe is generally performed under local anesthesia. Blunt dissection to the superficial temporal fascia to expose the auriculotemporal nerve and the superficial temporal artery is followed by artery cauterization/ligament and eventual nerve transection/avulsion. Site V surgery results in a success rate from 79% to 97%. Conclusions: Despite the recent advances in extracranial trigger site surgery and a success rate (>50% improvement) from 79% to 97%, site V decompression is still poorly described. Elaborate randomized trials are needed with accurate reporting of patient selection, surgical procedure, adverse events, recurrencies or appearance of new trigger points, quality of life outcome, and longer follow-up times.

Site V Surgery for Temporal Migraine Headaches
ORiginal aRticle

PRS Global Open • 2020
Endoscopic or open surgical approaches are described in literature to decompress the trapped nerves [14][15][16][17] ; however, site V has been often considered a minor site with respect to site II. 18 However, in the past, STA has been the focus of many authors in managing migraine headache through periarterial procaine infiltration, as well by cutting it as proximally as possible. 19 The objective of this review was to explore whether site V nerve surgical decompression is effective for pain relief in temporal area.

MATERIALS AND METHODS
A literature search using PubMed, Cochrane, and Google Scholar database according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines was conducted to evaluate the surgical treatment of auriculotemporal migraine. The following MeSH terms were used: "temporal migraine surgery," "temporal headache surgery," "temporal nerve decompression," "temporal headache surgical treatment," "temporal migraine surgical treatment," "temporal headache surgical therapy," "temporal migraine surgical therapy," "auriculotemporal migraine surgery," "auriculotemporal headache surgery," "auriculotemporal nerve decompression," "auriculotemporal headache surgical treatment," and "auriculotemporal migraine surgical treatment" (period: 2000-2020; last search on 17 March 2020). Two-stage screening and data extraction were performed by 2 independent reviewers. Abstracts were screened to identify eligible papers. Reference lists of relevant articles were searched for additional studies. The search strategy is shown in a flow chart (Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines) (Fig. 1). 20

Inclusion and Exclusion Criteria
Studies were selected based on the following inclusion criteria: (1) Studies selectively investigating surgical treatment of auriculotemporal headache (site V); (2) registration of outcomes after surgical treatment; (3) full text available in English; (4) studies published between 2000 and February 2020.
Studies were excluded due to any one of the following criteria: (1) review articles; (2) case report; (3) articles reporting only anatomic data and not surgical outcomes; (4) articles reporting only on surgical technique and not surgical outcomes; (5) articles describing studies that included fewer than 10 patients who underwent site V migraine headache surgery; (6) nonreferenced articles; (7) expert opinion (Level V).

Data Collection
Extracted data included authors' name, year of publication, number of patients included, sex, mean age, surgical

RESULTS
After the exclusion of repeated items, 315 articles were identified. All the records were analyzed by title and abstract by 2 different reviewers. Twenty-two full-text articles were examined for eligibility. Two studies published in 2018 were considered eligible based on inclusion/exclusion criteria and were included in this systematic review. 21,22 Both were retrospective studies. A total of 77 patients were included in the review (34 and 43, respectively). Only the second study reported patients' gender, showing a female prevalence (83.7%) and patients' age as median and as range (50 years; range 40-57 years) ( Table 1). Regarding the side of surgical treatment, in both studies, unilateral or bilateral decompression surgery was described (n = 9, 78%; n = 36, 84%, respectively).
All patients considered underwent decompression of the ATN through a direct approach (1.5 and 1 cm, respectively) under local anesthesia. Before surgery, a careful anamnestic and physical examination was done to identify patients' trigger points, which were confirmed with a handheld Doppler probe. Blunt dissection to the superficial temporal fascia was done in both studies to expose the ATN (and minor brunches) and the superficial temporal artery. Bertozzi et al 21  -Regarding outcome measures, a global migraine headache questionnaire to assess migraine frequency (number of migraine-free days per month), duration (hours per day), severity (scale 1-10), and anatomical location of pain (whether or not the specific surgical site continued to trigger migraines) was considered by Long et al, whereas only site-specific relief (complete relief, significant improvement, no improvement) was recorded by Bertozzi et al. More in detail, a positive surgical outcome (>50% improvement) was present in 97% of patients of the first study 21 and in 79% of those of the second one. 22 Moreover, Long et al described a significant improvement in migrainefree days per month (12.6 versus 25.1; P < 0.005), migraine intensity (8.3 versus 3.2; P < 0.005), and migraine duration (1.2 versus 0.5; P < 0.005) after surgery. Furthermore, migraine parameters before and after surgery were compared in patients with and without site V relief (migrainefree days per month, 11.6 versus 27. Unfortunately, in Bertozzi's study, more detailed results refer to a larger group, including patients who underwent simultaneous site II-site V decompression treatment, and it is not possible to extrapolate data referring to site V only. The onset of secondary trigger points is detected in only the 17% of patients by Bertozzi et al. Mean follow-ups for both these studies are 21 months (range 3-67 months) and 17.2 months, respectively. Neither study reported common postoperative complications of the case series described.

DISCUSSION
Migraines are believed to be a neurovascular disorder, with evidence supporting a mechanism starting within the brain and then spreading to the extracranial blood vessels. 23 For this reason, recently, prophylactic medical treatment with only drugs has evolved in the treatment of the affected tissues. 24 Botulinum toxin, nerve blocks, and neurostimulation have been tested to support these theories. 25 Surgery has been introduced as a complementary treatment option for patients in whom pharmacological control of the disease could not be achieved. Decompression/avulsion of specific extracranial trigeminal branches or of the occipital nerves and cauterization/ligation of extracranial arteries represent the mainly described treatments in the literature. [26][27][28] Surgical decompression seems to guarantee a success rate ranging from 79% to 90%, 29-31 with a not negligible percentage of patients who remain refractory to the treatments. Research on other surgical techniques is ongoing. Fat grafting, for example, could represent a new slightly invasive surgical option for patients who have failed decompression surgery 32 in relation to the regenerative effect that has been shown on peripheral nerve regeneration 33,34 and myelination. 35 Although some triggers like site I, site II, and site IV have been widely investigated, 36,37 our study underlines a lack of data for site V treatment. Both the chosen studies involve a retrospective analysis of case series, and the total number of patients did not reach 100. However, there is a consensus on the importance of an accurate preoperative evaluation to identify the precise trigger sites and on the surgical technique, which consider the direct approach to expose the nervous and vascular structures involved, under local anesthesia. Moreover, Doppler probe is considered an important means for the preoperative localization of STA by all the authors. More in detail regarding the surgical technique, a partial disagreement is present on the management of the main nerve and its minor branches: Bertozzi et al do not include any procedure for the nervous structures (merely STA cauterizing or binding), while Long et al perform the transection or avulsion of them (plus STA arteriectomy). Guyuron et al 15 in a prospective, blinded randomized cohort study compare these 2 different techniques at site II without finding a statistically significant difference in reduction of frequency, migraine days, severity, and duration at 1-year follow-up. No differences in terms of sensation and 2-point discrimination are observed. However, in our opinion, anatomical peculiarities of the site where ZTN lies differ from those of ATN ones, and specific research should be done.
Regardless of the surgical technique, site V surgery results in a success rate from 79% to 97%, even if, in Long's study, despite the presence of a more detailed preoperative and postoperative assessment, it is not clear whether patients have undergone a prior migraine surgery in another more common site. In Bertozzi's study, authors comment on the onset of secondary trigger points in nonrespondent patients; so we can assume site V as the first site for migraine surgery.
Both the studies deal with bilateral migraine headache, but only Long et al compared the results between patients who underwent unilateral and bilateral surgery, without finding a significant association among laterality and migraine duration, migraine-free days, and intensity.
Finally, adverse events after surgery and the evaluation of the impact of migraine on the quality of life preoperatively and postoperatively are completely absent or are not referred to in the results of the literature.

CONCLUSIONS
Our systematic review of the literature underlines the need of further research on auriculotemporal trigger site nerve decompression. Its relationship with the superficial temporal artery is, in fact, of particular interest in relation to the neurovascular disorder underlying migraine headache. Although there is a good degree of consensus on surgical technique, prospective studies on this specific trigger site would be useful in defining which patients can best benefit from this treatment.