|Year : 2019 | Volume
| Issue : 6 | Page : 239-242
Glossopharyngeal neuralgia treated using stereotactic Gamma Knife radiosurgery
Ping-Hsien Hsieh1, Chih-Chung Chen2, Ying-Chi Tseng3, David Hung-Chi Pan1
1 Department of Neurosurgery, Shuang Ho Hospital, Taipei Medical University, New Taipei City; Department of Neurosurgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei; Gamma Knife Center, Shuang Ho Hospital, Taipei Medical University, New Taipei City; Department of Neurosurgery, Taipei Neuroscience Institute, Taipei Medical University, Taipei, Taiwan
2 Department of Neurosurgery, Taipei Neuroscience Institute, Taipei Medical University, Taipei; Department of Neurology, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
3 Department of Neurosurgery, Taipei Neuroscience Institute, Taipei Medical University; Department of Radiology, School of Medicine, Taipei Medical University, Taipei, Taiwan
|Date of Submission||21-Jul-2019|
|Date of Decision||26-Aug-2019|
|Date of Acceptance||17-Oct-2019|
|Date of Web Publication||05-Dec-2019|
Prof. David Hung-Chi Pan
Department of Neurosurgery and Gamma Knife Center, Shuang Ho Hospital, Taipei Medical University, New Taipei City
Source of Support: None, Conflict of Interest: None
Glossopharyngeal neuralgia (GPN) is a rare disorder of the ninth cranial nerve. It affects patients' quality of life, with the characteristic symptoms of severe paroxysmal pain affecting the throat, tongue, and ear. Traditional treatment for GPN includes medical management with anticonvulsants and analgesics and surgery with microvascular decompression (MVD) for refractory cases. However, surgical complications such as neurovascular damage may occur. Gamma knife radiosurgery (GKRS) might be a viable surgical alternative for idiopathic GPN. Although GKRS is widely recognized as an effective and minimally invasive treatment for intractable trigeminal neuralgia, its role in GPN has not yet been clearly determined. Herein, we report a 45-year-old male patient who presented with the left throat intractable shooting pain for 6 months. The pain also radiated to his left ear and was triggered by swallowing. He was diagnosed as having GPN. The patient refused for MVD treatment. Thus, we instead performed GKRS. The target was placed over the cisternal segment of the glossopharyngeal nerve, close to the meatus of the jugular foramen, with a single 4-mm isocenter. The maximal dose to the target was 86 Gy. The patient's pain completely disappeared 2-week posttreatment. No major neurological complication was noted in series follow-up. The clinical response in this case report provides evidence of the efficacy of treating GPN with stereotactic radiosurgery. GKRS is a valuable surgical alternative for idiopathic GPN, with very high efficacy and without permanent complications. Additional studies with larger numbers of patients are needed to demonstrate the long-term safety and effectiveness for this treatment.
Keywords: Gamma knife dosimetry, glossopharyngeal neuralgia, stereotactic radiosurgery
|How to cite this article:|
Hsieh PH, Chen CC, Tseng YC, Pan DH. Glossopharyngeal neuralgia treated using stereotactic Gamma Knife radiosurgery. Formos J Surg 2019;52:239-42
|How to cite this URL:|
Hsieh PH, Chen CC, Tseng YC, Pan DH. Glossopharyngeal neuralgia treated using stereotactic Gamma Knife radiosurgery. Formos J Surg [serial online] 2019 [cited 2020 Jul 2];52:239-42. Available from: http://www.e-fjs.org/text.asp?2019/52/6/239/272320
| Introduction|| |
Glossopharyngeal neuralgia (GPN), also known as vago-GPN (VGPN), is a rare disorder resulting in pain over the sensory territory of the ninth cranial nerve. It can also be associated with health-threatening issues in severe cases, such as cardiac arrhythmias, syncope, hypotension, or malnutrition. According to the latest edition of the International Classification of Headache Disorders from the International Headache Society, a diagnosis of GPN should fulfill the following criteria: first, it is recurrent paroxysmal attacks of unilateral pain throughout the distribution of the glossopharyngeal nerve. Second, the severe pain, lasting from a few seconds to 2 min, is characterized by an electric shock like shooting, stabbing, or sharp quality. Third, the pain is precipitated by swallowing, coughing, talking, or yawning [Table 1]. GPN often remits and relapses, highly similar to the well-known trigeminal neuralgia (TN). However, the annual incidence of GPN is approximately 0.2–0.7/100,000 people with a relative frequency of 0.2%–16.9% compared to TN. GPN accounts for only 0.2%–1.3% of orofacial pain syndromes.
|Table 1: International Classification of Headache Disorders-3 diagnostic criteria for glossopharyngeal neuralgia|
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The first-line treatment for GPN is pharmacological therapy, and carbamazepine is frequently used. Other antiepileptic drugs, such as phenytoin, oxcarbazepine, gabapentin, and amitriptyline, are also effective. When medical treatment fails, surgical intervention is considered. Since the first favorable results of microvascular decompression (MVD) for GPN reported by Laha and Jannetta in 1977, many investigators have confirmed the efficacy of the nondestructive surgical procedure for the treatment of drug-resistant GPN.
However, severe morbidity or death can follow microsurgical procedures, even in the modern microsurgical era. Therefore, gamma knife radiosurgery (GKRS) was first proposed as a useful, efficient, and safe procedure for the treatment of GPN two decades ago. Some authors hypothesized that GKRS could also be used to treat GPN, particularly in cases in which the disease is medically refractory or the patient refuses MVD. The application of stereotactic radiosurgery (SRS) with GKRS for GPN was first reported by Stieber et al. in 2005. The outcome was then confirmed by other gamma knife radiosurgeons with similarly successful results and no major complications.,, In this report, we present a case of GPN successfully treated using GKRS.
| Case Report|| |
A 45-year-old male with no known major systemic disease complained of the left throat and posterior ear shooting pain for many years. The pain had worsened in the 6 months preceding his presentation to the neurology outpatient department of our hospital. The shooting pain lasted a few seconds and occurred daily, sometimes, every hour. His visual analog scale score was ≥7 points. The pain radiated to his left ear and was triggered by swallowing, which caused a pain intensity of 10/10, as well as gagging, nausea, and occasional vomiting. Magnetic resonance imaging (MRI) revealed neither tumor nor vascular compression. He was prescribed oxcarbazepine for 3 months, which slightly reduced but did not adequately relieve his pain. Because the pain was persistent and refractory to medical treatment, surgical intervention was advised. The patient refused the suggestion of MVD and elected for SRS.
GKRS was performed using a Leksell stereotactic frame under local anesthesia. GKRS was performed using a Leksell stereotactic frame under local anesthesia. The treatment was approved by the Bureau of National Health Institute (NHI), and the patient's consent was fully obtained before the treatment.
With high-resolution and thin slice MRI location, a three-dimensional stereotactic treatment dose plan was created. We chose the distal part of the glossopharyngeal nerve at the level of the glossopharyngeal meatus as the target. One single 4-mm collimator was used in the treatment. A prescription dose of 43 Gy to the 50% isodose level with a maximum dose of 86 Gy to the target was administered, while a particular attention was paid to avoid overdosage to the brainstem [Figure 1].
|Figure 1: Magnetic resonance imaging targeting images. (a) Thin cut (1 mm slice thickness) T2-weighted magnetic resonance image showed the left glossopharyngeal nerve and the site of the target (glossopharyngeal meatus) for gamma knife radiosurgery treatment. The green line indicates 95% isodose level, and the yellow line indicates 50% isodose level. The dose to the target center is 86 Gy delivered with a single 4-mm collimator. (b-d) Target location in coronal (b), sagittal (c), and T1 axial (d) views in magnetic resonance images|
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Follow-up and pain assessment
The patient was discharged the day after gamma knife surgery. He was then evaluated in the outpatient department for neurological examination. Pain was assessed with the widely used Barrow Neurological Institute (BNI) pain intensity scoring system adapted for GPN: BNI Grade I indicates no glossopharyngeal pain with no medication; BNI Grade II indicates occasional pain that does not require medication; BNI Grade IIIa indicates no pain with continued medication; BNI Grade IIIb indicates persistent pain controlled by medication; BNI Grade IV indicates some pain not adequately controlled by medication; and BNI Grade V indicates severe pain without any relief. BNI Grades I–IIIb indicate adequate pain relief, whereas BNI Grades IV–V indicate treatment failure [Table 2].
| Results|| |
The patient's shooting pain in the throat completely disappeared 2 weeks' post treatment. He noted slight discomfort in phonation initially after the treatment, but the condition improved to normal status several weeks later. His BNI Grade improved from V to I 1 month after GKRS. The improvement in pain was such that he no longer required medication in series follow-up (BNI Grade I at 3-, 6-, and 12-month follow-ups after GKRS).
| Discussion|| |
Compared to TN, at 28.9 cases/100,000 person/years, the incidence of GPN is approximately 0.4 cases/100,000 person/years., The characteristics of pain are similar for both TN and GPN, but the location is different. TN affects the face, mainly in the V1, V2, and/or V3 distributions of the fifth cranial nerve, whereas pain in GPN is typically localized to the posterior tongue, throat/pharynx, and ear on the affected side.
In 1927, Dandy first described the surgical treatment of VGPN by intracranial section of the glossopharyngeal nerve. At the end of the 1970s, Lazorthes and Verdie proposed percutaneous thermocoagulation as a therapeutic option in VGPN. In 1981, Rushton et al. reported 217 cases treated at the Mayo Clinic, including 129 that were treated surgically, with the large majority of procedures being rhizotomy. Because of their lesioning processes, the aforementioned procedures carry a risk of sensory deficits and complications such as dysphagia and hoarseness.
In 1977, Laha and Jannetta, based on the treatment of TN, proposed the use of MVD for the treatment of GPN. This approach has been supported by a few large North American cohort studies. However, with respect to MVD, a 5% mortality rate and up to 20% rate of temporal or permanent symptoms (mainly dysphagia and hoarseness) have been reported in the previous long-term follow-up studies. GKRS provides a valuable alternative treatment for GPN, especially patients who refused operation or very weak patients who were not able to tolerate any surgery.
The efficacy and safety of GKRS for TN have been well established since the 1990s. Thus far, over 60,000 patients with TN have been treated using GKRS worldwide. The success rate is high at up to 80% in long-term follow-up with minimal complications (hypoesthesia of the fifth cranial nerve). Because of the similarity in pathogenesis, some authors have started to recommend GKRS for patients with GPN. In 2005, Stieber et al. were the first to report GKRS for GPN. GKRS seems to be a valuable alternative treatment for GPN, particularly for patients who refuse an operation or those who are too weak to undergo surgery.
Gamma knife radiosurgery technical considerations
There are two challenging issues relating to GKRS for GPN: the anatomical target for placement of the treatment isocenter and the gamma knife dosimetry.
The most frequent targets are the cisternal part of the glossopharyngeal nerve and its distal end, at the level of the glossopharyngeal meatus. The Marseille team obtained optimal results using the meatus target with a dose of at least 75 G. Targeting the nerve root complex at its entry into the osseous canal of the jugular foramen has three advantages over the previous cisternal target. First, the opening of the jugular foramen is a useful landmark that is easily identifiable on computed tomography and MRI images. Second, the glossopharyngeal nerve is more difficult to visualize clearly than the trigeminal nerve, even with low-intensity lines on fast imaging employing steady-state acquisition images, and the glossopharyngeal nerve can be difficult to distinguish from the vagal nerve. Conversely, the nerve root complex enters into the jugular foramen, permitting greater distinction between the two nerves. Third, the relative distance from the brainstem permits a higher dose to be delivered, thereby achieving more effective treatment.
Therefore, we placed the target at the glossopharyngeal meatus on the cisternal portion of the nerve. This allowed us to more easily identify and separate the ninth nerve from the tenth to deliver a higher dose to the nerve, which has a clear bony landmark (represented by the jugular foramen opening), allowing accurate identification of the glossopharyngeal nerve. Our targeting method allows a sufficiently large distance from the brainstem, facilitating a higher prescription dose, and thereby ensuring higher rates of freedom from pain.
Gamma knife dosimetry
In 2005, Stieber et al. reported targeting the cisternal segment of the glossopharyngeal nerve, with a maximal dose of 80 Gy with a single 4-mm collimator. The patient had initial complete pain relief 3 months after SRS, but pain recurred 6 months after SRS.
Martínez-Álvarez et al. reported five patients who underwent SRS for intractable GPN. The maximum dose was 80–90 Gy at the level of the glossopharyngeal meatus of the jugular foramen. All five patients initially achieved BNI Grade I or II at a median of 6 months (range: 2–10 months) after SRS and maintained BNI Grade I or II at a mean follow-up of 43 months. No adverse effects of radiation were observed. This series of GKRS for GPN, along with that of Kano et al., is the largest study (21 cases with 25 procedures), with very long-term follow-up of up to 12 years. The authors suggested that the therapeutic dose must be a minimum of 80 Gy for greater efficacy. In our case, we prescribed doses as high as 86 Gy, similar to that used in the previous studies.
| Conclusion|| |
Thus far, GKRS is still not considered a primary treatment modality in the management of GPN. The number of treated patients and the proof level remain low. However, based on our case and previous studies, it appears to be a safe and effective therapeutic option for sustained relief of GPN. For patients with multiple surgical comorbidity, particularly elderly patients, and those who refuse an operation, GKRS might be considered a first-line treatment. It should be reserved for patients with typical primary GPN diagnosed after exhaustive exploration to rule out secondary GPN. The glossopharyngeal meatus of the jugular foramen should be targeted. In our opinion, a minimal dose of 80 Gy should be administered. Furthermore, patients should be strictly followed up for at least 3, 6, 9, and 12 months after treatment to monitor for complications.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]