James I. Ausman, MD, PhD
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University of California, Los Review Article
Microvascular decompression for glossopharyngeal neuralgia
through a microasterional approach: A case series
Rogelio Revuelta‑Gutiérrez, Andres Humberto Morales‑Martínez, Carolina Mejías‑Soto1,
Jaime Jesús Martínez‑Anda, Luis Alberto Ortega‑Porcayo
Departments of Neurosurgery and 1Neuroradiology, National Institute of Neurology and Neurosurgery "Manuel Velasco Suárez", Mexico City, Mexico E‑mail: Rogelio Revuelta‑Gutiérrez ‑ [email protected]; *Andres Humberto Morales‑Martínez ‑ [email protected]; Carolina Mejías‑Soto ‑ [email protected]; Jaime Jesús Martínez‑Anda ‑ [email protected]; Luis Alberto Ortega‑Porcayo ‑ [email protected] *Corresponding author Received: 17 January 16 Accepted: 07 March 16 Published: 05 May 16 Abstract
Glossopharyngeal neuralgia (GPN) is an uncommon craniofacial pain
syndrome. It is characterized by a sudden onset lancinating pain usually localized in the sensory distribution of the IX cranial nerve associated with excessive vagal outflow, which leads to bradycardia, hypotension, syncope, or cardiac arrest. This study aims to review our surgical experience performing microvascular decompression (MVD) in patients with GPN.
Methods: Over the last 20 years, 14 consecutive cases were diagnosed with GPN.
MVD using a microasterional approach was performed in all patients. Demographic data, clinical presentation, surgical findings, clinical outcome, complications, and long‑term follow‑up were reviewed.
Results: The median age of onset was 58.7 years. The mean time from onset
of symptoms to treatment was 8.8 years. Glossopharyngeal and vagus nerve compression was from the posterior inferior cerebellar artery in eleven cases (78.5%), vertebral artery in two cases (14.2%), and choroid plexus in one case Video Available on:
(7.1%). Postoperative mean follow‑up was 26 months (3–180 months). Pain analysis demonstrated long‑term pain improvement of 114 ± 27.1 months and pain Access this article online
remission in 13 patients (92.9%) (P = 0.0001) two complications were documented, one patient had a cerebrospinal fluid leak, and another had bacterial meningitis. There was no surgical mortality.
Conclusions: GPN is a rare entity, and secondary causes should be discarded.
Quick Response Code:
MVD through a retractorless microasterional approach is a safe and effective technique. Our series demonstrated an excellent clinical outcome with pain remission in 92.9%.
Key Words: Glossopharyngeal nerve, microvascular decompression, neuralgia,
neurovascular compression, vagus nerve This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
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How to cite this article: Revuelta-Gutiérrez R, Morales-Martínez AH, Mejías-Soto C, Martínez-Anda JJ, Ortega.Porcayo LA. Microvascular decompression for
glossopharyngeal neuralgia through a microasterional approach: A case series. Surg Neurol Int 2016;7:51. 2016 Surgical Neurology International Published by Wolters Kluwer - Medknow Surgical Neurology International 2016, 7:51 management; (3) pain not controlled with medication. All patients were previously managed with conservative Glossopharyngeal neuralgia (GPN) is an uncommon treatment including carbamazepine, gabapentin, and craniofacial pain syndrome, representing 0.2–1.3%[3,8] pregabalin. No pain improvement for at least 6 months of facial pain syndromes, with an annual incidence of before surgical procedure was documented. Diagnosis 0.7 cases per 100,000 habitants per year according to work‑up included a 3T magnetic resonance imaging a population‑based study.[14] It is characterized by a (MRI). T1, T2, gadolinium‑enhanced and FIESTA sudden onset of lancinating acute pain, lasting seconds sequences were assessed to discard a secondary cause of to minutes, usually in the sensory distribution of the the symptoms and identify vascular compression.
auricular and pharyngeal branches of the of the IX and X cranial nerve. The pain is felt in the pharynx, tongue, A statistical analysis was performed using SPSS Version tonsillar fossa, internal ear, and mandible angle. In some 20 (IBM SPSS Statistics, New York, USA). Categorical cases, it is associated with excessive vagal outflow; which variables were expressed as proportions and continuous leads to bradycardia, hypotension, syncope, variables were expressed using means and standard deviations. Clinical outcome was evaluated according to the surgical management, use of medications, pain The first GPN description is attributed to recurrence, and postoperative complications. Descriptive Theodore H. Weisenburg in 1910.[24] Dandy elucidated statistics was performed for the patient data and the the pathophysiology of trigeminal neuralgia and proposed grade of pain preoperatively and postoperatively was vascular compression as the main etiology, causing analyzed using Wilcoxon signed‑rank test. P < 0.05 was demyelization, and ephaptic transmission;[4,24] which is considered statistically significant.
the same pathophysiology of GPN. First line medical treatment, including carbamazepine and gabapentin, may sometimes improve pain paroxysms.[28] However, in cases Under general anesthesia patients were placed in park with refractory GPN various surgical approaches have been bench position with the head fixed in a Mayfield skull attempted. In 1920, Sicard and Robineau[31] proposed clamp. The upper shoulder was retracted, and the head sectioning the glossopharyngeal nerve through the neck was rotated 60° to the opposite side of the exposure as a definitive treatment; which evolved to intracranial with slight cervical lateral tilting (10°) toward the floor. rhizotomy of the glossopharyngeal nerve performed by A 5 cm retrosigmoid incision centered over the asterion Dandy.[8] Later on, Sweet,[35] introduced percutaneous was performed and a keyhole (2.5–3 cm) asterional compression at the middle fossa and finally Jannetta, craniectomy exposed the angle of the transverse and popularized microvascular decompression (MVD) as a sigmoid sinuses [Figures 1 and 2a]. Curvilinear durotomy definitive surgical treatment for this pathology.[12,17,32] was performed under microscope magnification and MVD series have reported good outcomes in 90–98%, intradural dissection started toward the dural angle long‑term pain improvement have been observed in 64% between the tentorium and petrous surface [Figure with a low mortality ranging from 0% to 5.8%.[13] 2b]. Cerebrospinal fluid (CSF) was released through arachnoid dissection without using cerebellar retractors. This study aims to review our surgical experience The dissection was directed caudally, and the lower performing MVD using a microasterional approach in vascular nervous complex involving the glossopharyngeal patients with GPN.
This study is a consecutive case series of 14 patients, who underwent MVD for the treatment of idiopathic GPN at the National Institute of Neurology and Neurosurgery "Manuel Velasco Suárez", in Mexico City, between 1994 and 2014. The senior author (Rogelio Revuelta‑Gutiérrez) performed all the surgeries. A retrospective analysis of the clinical charts was performed. Patient data including gender, the age of onset, symptoms, previous medical management, operative findings, complications, and clinical outcome were collected. Pain intensity was graded according a three‑grade scale: (1) No pain, no need for medication; (2) pain controlled with medical Figure 1: Craniotomy size and reference
Surgical Neurology International 2016, 7:51 nerve was exposed, identifying its exit through the jugular The pain was more common on the left side (78.6%) foramen. Once the identification of the vascular element compared to the right (21.4%). The primary location compressing the glossopharyngeal nerve was observed of the pain was pharyngeal in 13 cases (92.9%) and [Figure 2c], blunt dissection was done, and a small preauricular in one case (7.1%). Pain irradiation piece or multiple pieces of Teflon were placed between was referred in 6 cases (42.9%), 5 of them to the the glossopharyngeal nerve and the compressing vessels preauricular area and one to the pharynx. One patient (arterial or venous) [Figure 2d, Video 1].
(7.1%) presented with syncope and another one had an intraoperative vasovagal reflex during decompression.
Neuroradiological and operative findings
MRI showed vascular compression from the posterior inferior cerebellar artery (PICA) [Figure 3] in three A total of 14 patients were diagnosed with GPN and were patients (21.4%), vertebral‑basilar arteries in three surgically treated [Table 1]. The median age of onset was patients (21.4%), and an inflammatory process in one 58.7 ± 11 years, with a male to female ratio of (1:1.8). The mean time duration from symptom onset to surgery patient (7.1%). Seven patients were reported as normal was 8.8 years. Pain trigger was described when swallowing on MRI scan (49.7%). At the time of the surgery, all 14 in seven cases, talking in four cases and without previous patients were found to have compression of the vagal and stimuli in three cases. Carbamazepine was the most used glossopharyngeal nerve roots. Vascular compression was medication (78%), followed by gabapentin and pregabalin; from PICA in 11 cases (78.5%), vertebral artery in two 64.2% patients were on more than one drug. All patients cases (14.2%), and compression from the choroid plexus from this study had no clinical improvement with full in one case (7.1%).
dose carbamazepine, gabapentin, pregabalin, and daily Clinical outcome
analgesic medication. Three patients were misdiagnosed All 14 patients were contacted for long‑term follow‑up. before they were referred to our institution; stiloidectomy Postoperative mean follow‑up of was 26 months was performed in two patients (14.3%) and previous dental (3–180 months). All patients referred initial pain relief, surgery in one patient (7.1%). Mean time from diagnosis and 13 were pain‑free with no need of medication in to surgery was 106.3 ± 95.7 months (males 86.4 ± 78.4 the long‑term follow‑up. Only one patient referred pain months and females 117.3 ± 106.9 months; P = 0.58).
1 month after surgery and was treated with carbamazepine with complete relief of the pain and no further surgery Table 1: Clinical data and outcome of patients with
was required. Pain analysis demonstrated long‑term pain improvement of 114 ± 27.1 months and pain remission in 13 patients (92.9%) (P = 0.0001) [Table 1].
Pain localization Two patients presented complications related to surgical treatment. One patient presented with CSF leak, which resolved with lumbar drainage and acetazolamide 500 mg TID for 5 days without any complications. The second patient presented with meningitis and was treated with intravenous vancomycin 1 g. BID for 5 days recovering completely without clinical sequelae [Table 1]. There was no surgical mortality in this case series.
Wilfred Harris applied the term GPN when he described an entity similar to trigeminal neuralgia. At his initial Preoperative pain report in 1937, Harris described two types of pathologies: Primary or idiopathic and secondary to carcinoma. Long‑term follow‑up postoperative pain Idiopathic GPN is explained due to nerve compression by a vessel, as it exits the medulla oblongata.[24] This theory is supported by the success of MVD in the treatment of this pathology.[32] The main symptom of the GPN is a lancinating pain lasting seconds to minutes. However, Cerebrospinal fluid leak some cases have reported the presence of pain associated to syncope.[7] In this regard, Gardner associated the

Surgical Neurology International 2016, 7:51 Figure 2: Glossopharyngeal microvascular decompression through
Figure 3: Preoperative axial magnetic resonance FIESTA image
a minimal invasive asterional approach. (a) Right microasterional
demonstrates glossopharyngeal nerve compression from the left
approach (2.5–3 cm). (b) Durotomy exposing right cerebellar
hemisphere, the base of the dural opening is reflected at the
junction of the sigmoid and transverse sinus. (c) Cerebrospinal
can be performed. For lower cranial nerve exposure; fluid drainage after arachnoid dissection allows proper visualization
of the vertebral artery compressing the glossopharyngeal nerve.
McLaughlin et al.,[20] recommended a triangular (d) A piece of Teflon is interposed between the affected nerve and
craniectomy with the apex at the edge of the jugular the offending vessel
bulb. In our experience, our circular microasterional craniectomy [Figure 2a] at the edge of the transverse and proximity of the glossopharyngeal nucleus to the sigmoid sinuses gives enough bone exposure to access the vagal nucleus. The activation of the nucleus produces trigeminal, facial, and glossopharyngeal nerves.
activation of the vagal nerve, which results in bradycardia and hypotension secondary to a decrease of the peripheral In the MVD series, the overall surgical mortality is 1.1%. vascular resistance. Another theory explains the vascular The rate of long‑term pain remission is 84.7% with resistance impairment secondary to inhibition of recurrence in 7%. Transient X cranial nerve dysfunction vasomotor centers.[16] occurred in 13.2% and permanent deficits in 5.5%.[27] In our case series, we did not have any mortality, and no Traditionally, a lateral suboccipital approach provides permanent deficits occurred after the surgery. We did adequate exposure to the trigeminal, facial, and not have cerebellar lesions or hearing the loss in this case lower cranial nerves. Kawashima et al.[15] proposed series; it is explained because we do not use retractors a transcondylar fossa approach advocating the wide over the cerebellum, the surgical route place minimal operative view of the cerebellomedullary cistern, smaller traction on the VII–VIII nerve complex and we perform retraction of the cerebellum, less risk of cranial nerve a careful microsurgical vascular dissection with minimal injury, and enough space to perform the sling retraction bipolar coagulation. However, we had two complications; technique. However, we believed that a minimally a CSF leak and a case of meningitis that was successfully invasive technique as an asterional approach described previously by the senior author[25] is enough for adequate exposure of PICA, vertebral artery, and the relationship Rey‑Dios and Cohen‑Gadol demonstrated in his analyses with the glossopharyngeal nerve and the upper roots of that the most effective surgical procedure to treat GPN the vagus nerve. There is no need of retractors, and after is the MVD.[27] Several studies used rhizotomy[2,9,13,17,29,36] the CSF is released with adequate and careful arachnoid as the preferred procedure, but a 3‑fold increase in the dissection, the cerebellum is out of the way, and there risk of permanent postoperative vagus dysfunction[27] is enough space for working without the necessity of is objectionable in comparison to MVD. It is also well removing the jugular tubercle.
demonstrated that the rate of pain control is slightly better with rhizotomy (95%) than with MVD (86%).[27] Jannetta,[12] popularized the MVD using a suboccipital However, in our series we had 92.9% pain remission with craniotomy. After years of experience, the approach 3–180 months (mean 26 months) of follow‑up; only was modified according to the surgical goal. Initially, it one case had pain recurrence that was treated with is important to focus bone exposure to the junction of carbamazepine. GPN is a rare condition in which the the transverse and sigmoid sinuses. A smaller tailored clinical findings are not always typical. The mean duration craniectomy according to the cranial nerve approach from symptom onset to surgery is 5–8 years.[13,23,30] In our Surgical Neurology International 2016, 7:51 case series, we had a mean time for diagnosis of 8.8 years, Conflicts of interest
however, despite the time for diagnosing GPN the clinical There are no conflicts of interest.
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