Clinical Pharmacology of Drugs Used to Treat Head and Face Pain

Trigeminal and Glossopharyngeal Neuralgia

Trigeminal neuralgia and glossopharyngeal neuralgia are craniofacial pain syndromes characterized by recurrent brief shock-like pains in the distributions of their respective cranial nerves. In this article, the authors aim to summarize each condition's characteristics, pathophysiology, and current pharmacotherapeutic and surgical interventions available for managing and treating these conditions.

Glossopharyngeal Neuralgia

Glossopharyngeal neuralgia (GPN) is a rare disease that must be differentiated from trigeminal neuralgia. The purpose of this article is to provide a comprehensive review of anatomy, pathophysiology, diagnostic criteria, and several options of treatment for GPN. Lessons learned through our experience of treating GPN are presented in detail, as well as cases of misdiagnosis and diagnostic pitfalls. Microvascular decompression (MVD) should be primarily considered for medically intractable GPN. Techniques employed in MVD for GPN are categorized and described. Especially, we underscore the advantages of the 'transposition' technique where insulating material is positioned 'off' the root entry zone (REZ), instead of 'on' it. We believe this 'off-the-REZ' technique can fundamentally prevent recurrence, if applicable. In addition, Gamma Knife radiosurgery can be an alternative option when a patient is ineligible for MVD, though it is categorized as a destructive procedure.

Intravenous Fosphenytoin Therapy as an Acute Rescue Treatment for Glossopharyngeal Neuralgia Crisis in Patients Awaiting Neurosurgical Procedures: A Case Series

INTRODUCTION

Few treatments exist for acute attacks of glossopharyngeal neuralgia (GPN). We investigated the efficacy of intravenous fosphenytoin therapy (IFT) during GPN crisis.

CASE PRESENTATION

We evaluated records of 4 consecutive patients with GPN awaiting microvascular decompression (MVD) who received IFT (total, 750 mg). Pain severity was evaluated using a Numerical Rating Scale (NRS). The score was 10 (maximum pain) before treatment. Case 1 (a 52-year-old woman, left GPN): for 12 hours after IFT, pain was eliminated (NRS 0/10); however, severe pain recurred 2 days later. She received MVD 9 days after IFT. Case 2 (a 72-year-old woman, right GPN): pain score reduced to 0/10 immediately after IFT and remained so for 2 days. Severe pain recurred, and she underwent MVD 4 days after IFT. Case 3 (a 69-year-old woman, right GPN): pain was reduced (NRS, 5/10) immediately after IFT and nearly eliminated (1/10) 1 hour later. After 6 hours, severe pain recurred; she received a second IFT 3 days later, and pain score dropped to 1/10. She was pain-free for 24 hours but intermediate pain recurred in 2 days. Microvascular decompression was performed 9 days after the second IFT. Case 4 (a 32-year-old woman, right GPN): Pain score reduced to 0/10 immediately after IFT and remained so for 4 days. She underwent MVD 4 days after IFT. No evidence of recurrence was found throughout the 24-, 22-, 20-, and 5-month follow-ups.

CONCLUSIONS

These results provide new insights into the innovative therapeutic option of intravenous fosphenytoin and contribute to advancements in treating acute GPN crisis.

Glossopharyngeal Neuralgia Treatment Outcomes After Nerve Section, Microvascular Decompression, or Stereotactic Radiosurgery: A Systematic Review and Meta-Analysis

BACKGROUND

Glossopharyngeal neuralgia (GPN) is a rare neuralgic pain syndrome amenable to neurosurgical treatments, including nerve section (NS), microvascular decompression (MVD), and stereotactic radiosurgery (SRS). However, thorough comparisons of the modalities have not been performed to date. The objective of the present study was to compare the pain and complication outcomes after these approaches to GPN.

METHODS

Searches of 7 electronic databases from inception to June 2018 were conducted following the appropriate guidelines. The incidence rates (IRs) of short-term (≤3 months) and long-term (≥12 months) pain relief and complications were extracted and analyzed using a meta-analysis. Meta-regression was used to assess for heterogeneity.

RESULTS

A total of 792 GPN cases managed by NS, MVD, or SRS were described by 6, 11, and 6 studies, reporting outcomes for 282 (36%), 446 (56%), and 67 (8%) cases. The short-term pain relief rate was highest after NS postoperatively (IR, 94%; 95% confidence interval [CI], 88%-98%) and lowest after SRS at 3 months postoperatively (IR, 80%; 95% CI, 68%-96%). The postoperative complication rate was greatest after MVD (IR, 26%; 95% CI, 16%-38%) and lowest after SRS (IR, 0%; 95% CI, 0%-4%). The long-term pain relief rate was greatest after NS (IR, 96%; 95% CI, 91%-99%) and lowest after SRS (IR, 82%; 95% CI, 67%-94%). Statistically significant differences between the approaches were found for each outcome.

CONCLUSION

Neurosurgical treatment of GPN is frequently performed by 1 of 3 modalities with unique outcomes profiles. NS might provide the most favorable treatment response, with respect to short- and long-term pain relief and postoperative outcomes.

MRI Findings and Outcomes in Patients Undergoing Microvascular Decompression for Glossopharyngeal Neuralgia

BACKGROUND AND PURPOSE

Glossopharyngeal neuralgia causes extreme paroxysmal pain in the posterior pharynx, tonsillar region, base of tongue, or deep ear, that is, the distribution of the glossopharyngeal nerve. Some cases of glossopharyngeal neuralgia are associated with neurovascular conflict, usually by the posterior inferior cerebellar artery. Such symptomatic compression occurs only in proximal, centrally myelinated portions of the glossopharyngeal nerve near the brainstem. Microvascular decompression provides effective and durable pain relief for properly selected patients with medically refractory glossopharyngeal neuralgia. The purpose of this study is to describe a tailored MRI evaluation of neurovascular conflict in glossopharyngeal neuralgia to improve candidate selection for microvascular decompression.

METHODS

Our team developed a glossopharyngeal neuralgia imaging and evaluation protocol including a grading system for neurovascular conflict of the glossopharyngeal nerve and applied it to evaluate candidates for microvascular decompression.

RESULTS

Our team grades neurovascular conflict as "contact" (vessel touching nerve without intervening cerebrospinal fluid) versus "deformation" (deviation or distortion of nerve from its normal course by the offending vessel). MRIs of patients with glossopharyngeal neuralgia demonstrate proximal neurovascular conflict. Postoperative MRI demonstrates separation of the glossopharyngeal nerve from the offending vessel.

CONCLUSION

A tailored glossopharyngeal neuralgia imaging evaluation protocol is presented. We believe this approach has helped improve microvascular decompression outcomes and reduce unnecessary procedures at our institution. Further research may elucidate whether clinical and imaging features, including neurovascular conflict severity, predict surgical outcome for glossopharyngeal neuralgia.

Gamma Knife radiosurgery for glossopharyngeal neuralgia: A study of 21 patients with long-term follow-up

Objective

Glossopharyngeal neuralgia (GPN) is a very rare condition, affecting the patient’s quality of life. We report our experience in drug-resistant, idiopathic GPN, treated with Gamma Knife radiosurgery (GKRS), in terms of safety and efficiency, on a very long-term basis.

Methods

The study was opened, self-controlled, non-comparative and bicentric (Marseille and Lausanne University Hospitals). Patients treated with GKRS between 2003 and 2015 (models C, 4C and Perfexion) were included. A single 4-mm isocentre was positioned in the cisternal portion of the glossopharyngeal nerve, with a targeting based both on magnetic resonance imaging (MRI) and computed tomography (CT). The mean maximal dose delivered was 81.4 ± 6.7 Gy (median = 85 Gy, range = 60–90 Gy at the 100% isodose line).

Results

Twenty-one patients (11 women, 10 men) benefited from 25 procedures. The mean follow-up period was 5.2 ± 3 years (range = 0.9–12.1 years). Seventeen (81%) were initially pain-free after GKRS. At three months, six months and one year after radiosurgery, the percentage of patients with good outcome (BNI classes I to IIIA) was 87.6%, 100% and 81.8%, respectively. Ten cases (58.8%) from the initial pain-free ones had a recurrence, after a mean period of 13.6 ± 10.4 months (range = 3.1–36.6 months). Only three patients (14.2%) had recurrences (two for each one of them) requiring further surgeries. Three patients underwent a second GKRS procedure; one case needed a third GKRS. The former procedures were performed at 7, 17, 19 and 30 months after the first one, respectively. Furthermore, two patients needed additional interventions. At last follow-up, 17 cases (80.9%) were still pain-free without medication. The actuarial pain relief without new surgery was 83%. A transient complication (paraesthesia of the edge of the tongue) was seen in one case (4.8%).

Conclusion

GKRS is a valuable, minimally invasive, surgical alternative for idiopathic GPN, with a very high short- and long-term efficacy and without permanent complications. A quality imaging, including T2 CISS/Fiesta MRI and bone CT acquisitions for good visualisation of the nerve and the other bony anatomic landmarks, is essential for targeting accuracy and successful therapy.

Long-term outcomes of percutaneous radiofrequency thermocoagulation for glossopharyngeal neuralgia: A retrospective observational study

The aim of this study was to investigate the long-term results of computed tomography (CT)-guided percutaneous radiofrequency thermocoagulation (PRT) for glossopharyngeal neuralgia (GPN).A retrospective review of medical records for patients with GPN who were treated with CT-guided PRT between 2003 and 2014 was performed to investigate baseline characteristics and immediate outcomes during the hospitalization. Long-term pain relief outcomes and complications were obtained via telephone survey. Duration of pain-free was assessed by Kaplan-Meier analysis.Eighty patients with GPN were treated with CT-guided PRT, and 71 patients could be contacted for the follow-up. The mean length of follow-up after PRT was 56.2 ± 43.3 months. Pain relief occurred in 63 patients (78.8%) immediate after the PRT procedure. The percentage of patients who remained in an "excellent" or "good" pain relief condition was 73.2%, 63.0%, 53.2%, and 43.0% at 1, 3, 5, and 10 years. Postprocedure complication included dysesthesias, dysphagia, and diminished gag reflex. No mortality was observed during or after PRT procedures.This study indicates that CT-guided PRT is a safe and effective method for patients with GPN and should be considered as an alternative treatment for these patients.

Neurosurgical treatment of glossopharyngeal neuralgia: analysis of 103 cases

OBJECT

The object of this study was to investigate the immediate and long-term follow-up results of glossopharyngeal nerve rhizotomy (GPNR) with or without partial vagus nerve rhizotomy (VNR) for treating glossopharyngeal neuralgia (GPN).

METHODS

A retrospective review of the case notes of patients who had undergone surgery for GPN in the authors’ department between 2008 and 2013 was performed to investigate baseline characteristics and immediate outcomes during the hospitalization. For the long-term results, a telephone survey was performed, and information on pain recurrence and permanent complications was collected. Pain relief meant no pain or medication, any pain persisting after surgery was considered to be treatment failure, and any pain returning during the follow-up period was considered to be pain recurrence. For comparative study, the patients were divided into 2 cohorts, that is, patients treated with GPNR alone and those treated with GPNR+VNR.

RESULTS

One hundred three procedures, consisting of GPNR alone in 38 cases and GPNR+VNR in 65 cases, were performed in 103 consecutive patients with GPN. Seventy-nine of the 103 patients could be contacted for the follow-up study, with a mean follow-up duration of 2.73 years (range 1 month–5.75 years). While there were similar results (GPNR vs GPNR+VNR) in immediate pain relief rates (94.7% vs 93.8%), immediate complication rates (7.9% vs 4.6%), and long-term pain relief rates (92.3% vs 94.3%) between the 2 cohorts, a great difference was seen in long-term complications (3.8% vs 35.8%). The long-term complication rate for the combined GPNR+VNR cohort was 9.4 times higher than that in the GPNR cohort.

There was no operative or perioperative mortality. Immediate complications occurred in 6 cases, consisting of poor wound healing in 3 cases, and CSF leakage, hoarseness, and dystaxia in 1 case each. Permanent complications occurred in 20 patients (25.3%) and included cough while drinking in 10 patients, pharyngeal discomfort in 8 patients, and hoarseness and dysphagia in 1 case each.

CONCLUSIONS

In general, this study indicates that GPNR alone or in combination with VNR is a safe, simple, and effective treatment option for GPN. It may be especially valuable for patients who are not suitable for the microvascular decompression (MVD) procedure and for surgeons who have little experience with MVD. Of note, this study renews the significance of GPNR alone, which, the authors believe, is at least valuable for a subgroup of GPN patients, with significantly fewer long-term complications than those for rhizotomy for both glossopharyngeal nerve and rootlets of the vagus nerve.

Trigeminal and glossopharyngeal neuralgia

Trigeminal neuralgia and glossopharyngeal neuralgia are two causes of paroxysmal craniofacial pain. Either can be debilitating in affected individuals. This article reviews the epidemiology, pathogenesis, diagnosis, and treatment options for these disorders.

Glossopharyngeal neuralgia

In this review, the clinical characteristics, differentiating features from other forms of neuralgia, etiology and treatment options of glossopharyngeal neuralgia will be discussed.

Effectiveness and safety of Gamma Knife radiosurgery for glossopharyngeal neuralgia

Glossopharyngeal neuralgia (GPN) is a rare disorder of the ninth cranial nerve characterized by severe paroxysmal pain affecting the ear, tongue, and throat. GPN can be associated with life-threatening issues such as cardiac arrhythmias, syncope, or malnutrition and weight loss from odynophagia. Though traditional treatment for GPN involves medical management at first and surgery for refractory cases, these therapies are often poorly tolerated in the elderly population. We describe the case of a 99-year-old woman, the oldest reported patient with GPN treated successfully with Gamma Knife radiosurgery. We conclude that Gamma Knife radiosurgery for GPN can be both effective and very well tolerated in the elderly and deserves further study and careful consideration as a treatment option in this population.

Glossopharyngeal neuralgia treated with gamma knife radiosurgery

BACKGROUND

Although gamma knife radiosurgery is an established treatment option for trigeminal neuralgia, its role in the management of glossopharyngeal neuralgia is unclear. We report a case of glosspharyngeal neuralgia treated effectively with gamma knife radiosurgery, review the literature, and discuss the rationale supporting dose and target selection.

CASE DESCRIPTION

A 47-year-old woman presented with persistent lancinating pain to the left throat, which was refractory to medical therapy. She declined a microvascular decompression and instead chose stereotactic radiosurgery. Gamma knife radiosurgery to the glossopharyngeal nerve at the glossopharyngeal meatus was used, and a maximum dose 80 Gy was delivered. She was pain-free off medications 1 month after the procedure and remains pain-free 11 months. There were no adverse neurologic effects attributable to the procedure.

CONCLUSIONS

This clinical response provides encouraging evidence for the treatment of glossopharyngeal neuralgia with stereotactic radiosurgery and is consistent with previous reports. Further investigation is needed to define the role of stereotactic radiosurgery in the management of glossopharyngeal neuralgia.

Gamma Knife surgery for glossopharyngeal neuralgia

Gamma Knife surgery (GKS) is widely recognized as an effective, minimally invasive treatment for intractable trigeminal neuralgia, but the role of GKS in glossopharyngeal neuralgia (GPN) remains unclear. This study involved 2 patients with medically intractable GPN who were treated using GKS. One patient required 2 treatments because of a recurrence of symptoms (at maximum doses of 60 and 70 Gy), and the other patient had a single intervention (at a maximum dose of 75 Gy). The GKS target was the distal part of the glossopharyngeal nerve. Patients were investigated prospectively, treated, and then assessed periodically with respect to pain relief and neurological function. Complete pain relief was achieved initially after all 3 interventions. The first patient was pain free without medication for 2 months after the first treatment (60 Gy) and for 4 months after the second treatment (70 Gy). The second patient (treated with 75 Gy) was still pain free without medication at the last follow-up (12 months). Neither patient had any neurological complications. The initial response of GPN to low-dose GKS was favorable, but symptoms may recur. No adverse neurological effects were observed in any of the lower cranial nerves. It will be necessary to investigate the optimal radiation dose and target of GKS for achieving long-term pain relief in GPN.

Trigeminal Neuralgia with Intraoral Trigger Points: Report of Two Cases

A variety of pathologic conditions can cause orofacial pain. Establishing the etiology of the pain is key to providing appropriate treatment. Trigeminal neuralgia (TN) is a relatively uncommon condition and can present a diagnostic challenge to even the experienced dental practitioner. The authors discuss two cases of TN that exhibited intraoral trigger points, which initially resulted in confusion regarding the establishment of a correct diagnosis and treatment.

Acute phenytoin intoxication: causes, symptoms, misdiagnoses, and outcomes

Phenytoin is a commonly prescribed antiepileptic drug. Due to its saturation (zero-order) pharmacokinetics, phenytoin carries a special risk of dose-related toxicity that is an important issue in emergency medicine. The purpose of this cross-sectional case-series study was to investigate the causes, symptoms, misdiagnoses, and outcomes of acute phenytoin intoxication. It was based on a retrospective chart review of 30 inpatients (mean age, 41.6 +/- 22.8 years) with 36 episodes of acute phenytoin intoxication at our university hospital in the past 13 years. The average initial serum phenytoin level was 47.3 +/- 9.7 microg/mL (range, 27.9-70.4 microg/mL). Excessive self-medication, misunderstanding of the prescription order, and probable drug interaction were the three leading causes of acute phenytoin intoxication. Unsteady gait, dizziness/vertigo, nausea/vomiting, general weakness, and drowsiness were the most common presenting symptoms. The tentative diagnostic accuracy was 67%. The most common initial misdiagnosis was brainstem or cerebellum stroke (14%). The clinical course in all patients was uneventful under temporary withdrawal of phenytoin and supportive care. We concluded that acute phenytoin intoxication was relatively under-diagnosed in the emergency service. Although acute phenytoin intoxication causes no mortality and has a good outcome, the unsteady gait increases the risk of injuries caused by falls. The management of acute phenytoin intoxication includes temporary withdrawal of phenytoin and supportive care.

A review of pharmacotherapeutics for prosthetic dentistry: Part II

STATEMENT OF PROBLEM

Successful preoperative and postoperative care often depends on systemically administered drugs. The competent and successful practitioner must therefore have a strong background in basic pharmacology, be knowledgeable of pharmacotherapeutics, and keep abreast of the latest advances in medicinal agents.

PURPOSE

The purpose of this article is to review pharmacologic properties of prototype and new drugs that are primarily used to allay anxiety and pain or reduce inflammation and infection. This information should enable clinicians to improve clinical outcomes and make a more knowledgeable assessment and comparison of standard drugs with recently released drugs.

Trigeminal neuralgia mimicking odontogenic pain. A report of two cases

Trigeminal neuralgia or tic douloureux is characterized by paroxysmal episodes of facial pain in the distribution of the trigeminal nerve, although patients may have a variety of symptoms that mimic odontogenic pain. This article presents two cases of trigeminal neuralgia that were misdiagnosed and initially treated endodontically as pain of odontogenic origin. A therapeutic regimen of carbamazepine alleviated the pain in both patients. These two cases demonstrate the importance of having a thorough knowledge of both odontogenic and nonodontogenic causes of orofacial pain, as well as the need for careful diagnosis before undertaking any treatment.

Anticonvulsants suppress c-Fos protein expression in spinal cord neurons following noxious thermal stimulation

The expression of the nuclear immediate-early gene-encoded protein c-Fos in spinal cord dorsal horn neurons of the rat following noxious thermal stimulation was compared in carbamazepine-, valproate- and phenytoine-treated animals. Single intraperitoneal injection of carbamazepine (50 mg/kg), valproate (300 mg/kg) or intravenous injection of phenytoine (20 mg/kg) before noxious stimulation reduced the number of c-Fos immunoreactive neurons to 65-80% of control levels in superficial laminae and to 30-60% in deep laminae of the dorsal horn. Pretreatment with carbamazepine or valproate for 4 or 8 days combined with an injection immediately before noxious stimulation further significantly decreased the number of c-Fos neurons in the deep dorsal horn only in animals treated with valproate. The observation that activity-dependent gene expression in the spinal cord is effectively modulated by anticonvulsants discloses a novel therapeutic potential of these compounds. Presumably via an acute suppression of high-frequency repetitive firing and/or altered synaptic transmission of intraspinal or descending neurotransmitter systems these drugs gain access to neuroplastic mechanisms which might be relevant for the restoration of physiological levels of neuronal excitability in the central nervous system.