Drug therapy of trigeminal neuralgia

Nerve coblation for treatment of trigeminal neuralgia: A case report

BACKGROUND

Trigeminal neuralgia (TN) is a severe type of neuropathic pain which is often inadequately managed using conventional therapies. In this report, we present the first case of TN treated with gasserian ganglion nerve coblation (NC).

CASE SUMMARY

A 58-year-old man presented with right facial pain, mostly localized in the right zygomatic zone, alveolar region, and jaws. Similar to acupuncture and shock pain, the pain lasted about five seconds after each attack before resolving unaided. A diagnosis of TN was made, after which treatment with acupuncture therapy and oral carbamazepine was given. However, the pain was not satisfactorily controlled. Subsequently, gasserian ganglion NC of the right trigeminal nerve guided by computed tomography (CT) was performed on the patient. Following this procedure, the right zygomatic, alveolar, submandibular, and cheek pain disappeared completely. The right zygomatic and alveolar areas experienced mild numbness (level II). At 1-, 2-, 3-, and 6-mo follow-ups after surgery, the patient was painless and the numbness score was level I.

CONCLUSION

CT-guided gasserian ganglion (NC) is an effective treatment for TN and is associated with less or no postoperative numbness or hypoesthesia in comparison with current standard-of-care approaches.

[Effect of intraoperative intravenous lidocaine on pain and plasma interleukin-6 in patients undergoing hysterectomy]

BACKGROUND AND OBJECTIVES

Interleukin-6 (IL-6) is a predictor of trauma severity. The purpose of this study was to evaluate the effect of intravenous lidocaine on pain severity and plasma IL-6 after hysterectomy.

METHOD

A prospective, randomized, comparative, double-blind study with 40 patients, aged 18-60 years. G1 received lidocaine (2mg.kg(-1).h(-1)) or G2 received 0.9% saline solution during the operation. Anesthesia was induced with O2/isoflurane. Pain severity (T0: awake and 6, 12, 18 and 24hours), first analgesic request, and dose of morphine in 24hours were evaluated. IL-6 was measured before starting surgery (T0), five hours after the start (T5), and 24hours after the end of surgery (T24).

RESULTS

There was no difference in pain severity between groups. There was a decrease in pain severity between T0 and other measurement times in G1. Time to first supplementation was greater in G2 (76.0±104.4min) than in G1 (26.7±23.3min). There was no difference in supplemental dose of morphine between G1 (23.5±12.6mg) and G2 (18.7±11.3mg). There were increased concentrations of IL-6 in both groups from T0 to T5 and T24. There was no difference in IL-6 dosage between groups. Lidocaine concentration was 856.5±364.1 ng.mL(-1) in T5 and 30.1±14.2 ng.mL(-1) in T24.

CONCLUSION

Intravenous lidocaine (2mg.kg(-1).h(-1)) did not reduce pain severity and plasma levels of IL-6 in patients undergoing abdominal hysterectomy.

Therapeutic efficacy and safety of botulinum toxin type A in trigeminal neuralgia: a systematic review

Trigeminal neuralgia is a common disorder caused mainly by compression of the trigeminal nerve root by an overlying blood vessel. Pharmacotherapy and surgery are ineffective or unsuitable in many patients. Therefore, other therapeutic modalities have been tried, including injection of botulinum toxin type A (BTX-A). This study aims to systematically review the therapeutic efficacy and safety of BTX-A in trigeminal neuralgia. PubMed, EMBASE, Cochrane Library Clinical Trials and Web of Science from January 1966 to March 2013 were searched with the terms of “botulinum toxin” AND “trigeminal neuralgia”, and references of related articles were traced. Data on the efficacy and safety of BTX-A in this disorder were extracted and analyzed by at least 2 reviewers. Data for individual studies were reported, and pooled data were analyzed if appropriate. Five prospective studies and one double-blind, randomized, placebo-controlled study were identified. Response was achieved in approximately 70-100% of patients, and the mean pain intensity and frequency were reduced by approximately 60-100% at 4 weeks after treatment in most studies. Major adverse events were not reported. Available studies show BTX-A may be effective in treatment of trigeminal neuralgia. However, well-designed randomized, controlled, double-blinded trial is still lacking. Future BTX-A treatment studies on optimal dose, duration of the therapeutic efficacy, common AEs, and the time and indications for repeat injection would be promising.

Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study

BACKGROUND AND OBJECTIVES

Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment.

METHODS

Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group.

RESULT

In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time.

CONCLUSION

Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen.

Motor cortex stimulation for facial chronic neuropathic pain: A review of the literature

Background:

Facial chronic neuropathic pain (FCNP) is a disabling clinical entity, its incidence is increasing within the chronic pain population. There is indication for neuromodulation when conservative treatment fails. Motor cortex stimulation (MCS) has emerged as an alternative in the advanced management of these patients. The aim of this work is to review the worldwide literature on MCS for FCNP.

Methods:

A PubMed search from 1990 to 2012 was conducted using established MeSH words. A total of 126 relevant articles on MCS focused on chronic pain were selected and analysed. Series of cases were divided in (1) series focused on MCS for FCNP, and (2) MCS series of FCNP mixed with other chronic pain entities.

Results:

A total of 118 patients have been trialed for MCS for FCNP, 100 (84.7%) pursued permanent implantation of the system, and 84% of them had good pain control at the end of the study. Male: female ratio was about 1:2 in the whole group of studies; mean age was 58 years (range, 28–83), and mean pain duration was 7 years (range, 0.6–25). Four randomized controlled studies have been reported, all of them not focused on MCS for FCNP. The most common complication was seizure followed by wound infection. Preoperative evaluation, surgical techniques, and final settings varied among the series.

Conclusion:

MCS for FNCP is a safe and efficacious treatment option when previous managements have failed; however, there is still lack of strong evidence (larger randomized controlled multicentre studies) that MCS can be offered in a regular basis to FNCP patients.

Pharmacological versus microvascular decompression approaches for the treatment of trigeminal neuralgia: clinical outcomes and direct costs

In idiopathic trigeminal neuralgia (TN) the neuroimaging evaluation is usually normal, but in some cases a vascular compression of trigeminal nerve root is present. Although the latter condition may be referred to surgery, drug therapy is usually the first approach to control pain. This study compared the clinical outcome and direct costs of (1) a traditional treatment (carbamazepine [CBZ] in monotherapy [CBZ protocol]), (2) the association of gabapentin (GBP) and analgesic block of trigger-points with ropivacaine (ROP) (GBP+ROP protocol), and (3) a common TN surgery, microvascular decompression of the trigeminal nerve (MVD protocol). Sixty-two TN patients were randomly treated during 4 weeks (CBZ [n = 23] and GBP+ROP [n = 17] protocols) from cases of idiopathic TN, or selected for MVD surgery (n = 22) due to intractable pain. Direct medical cost estimates were determined by the price of drugs in 2008 and the hospital costs. Pain was evaluated using the Numerical Rating Scale (NRS) and number of pain crises; the Hospital Anxiety and Depression Scale, Sickness Impact Profile, and satisfaction with treatment and hospital team were evaluated. Assessments were performed at day 0 and 6 months after the beginning of treatment. All protocols showed a clinical improvement of pain control at month 6. The GBP+ROP protocol was the least expensive treatment, whereas surgery was the most expensive. With time, however, GBP+ROP tended to be the most and MVD the least expensive. No sequelae resulted in any patient after drug therapies, while after MDV surgery several patients showed important side effects. Data reinforce that, (1) TN patients should be carefully evaluated before choosing therapy for pain control, (2) different pharmacological approaches are available to initiate pain control at low costs, and (3) criteria for surgical interventions should be clearly defined due to important side effects, with the initial higher costs being strongly reduced with time.

Oral baclofen reduces visceral pain-related pseudo-affective responses to colorectal distension in rats: relation between plasma exposure and efficacy

OBJECTIVE

We previously showed that activation of GABA(B) receptors by intravenous baclofen reduces pseudo-affective responses to colorectal distension in rats. Here we evaluate the potential clinical significance of these observations.

MATERIAL AND METHODS

Clinically relevant colorectal distension protocols were used to assess the effects of oral baclofen on visceromotor and autonomic cardiovascular responses in conscious rats. Plasma levels of baclofen were monitored to provide clinical relevance to the doses used. Conscious female Sprague-Dawley rats were subjected to repeated noxious colorectal distension (12 × 80 mmHg), ascending-phasic colorectal distension (10-80 mmHg, 10 mmHg increments) or ramp colorectal distension (10 min ramp at 8 mmHg/min). Visceromotor and cardiovascular responses (mean arterial blood pressure and heart rate) were monitored. Pain-related response thresholds were assessed using ascending-phasic and ramp colorectal distension.

RESULTS

Baclofen (1-10 μmol/kg, p.o.) reduced the visceromotor response to colorectal distension, reaching a 40% maximal inhibition (p < 0.05). The highest dose (10 μmol/kg, p.o.) also inhibited pain-related cardiovascular responses in telemetrized rats (50-55% reduction in colorectal distension-evoked hypertensive and tachycardic responses; p < 0.05). Similar thresholds for pain-related visceromotor responses were determined during ramp or ascending-phasic colorectal distension (34.1 ± 1.9 and 31.7 ± 3.2 mmHg, respectively). Baclofen (10 μmol/kg, p.o.) increased thresholds to 71.1 ± 3.7 and 77.5 ± 1.8 mmHg during ramp and ascending-phasic colorectal distension, respectively (p < 0.001). Plasma levels of baclofen were 3.3 ± 0.2 μmol/l at 90 min post-dosing, corresponding to the end of the colorectal distension procedure.

CONCLUSIONS

Oral baclofen, at plasma levels similar to those reported safe and within a therapeutic range in humans, produced significant visceral anti-nociceptive effects in rats.

Effectiveness of the association between carbamazepine and peripheral analgesic block with ropivacaine for the treatment of trigeminal neuralgia

Treatment of trigeminal neuralgia (TN) is achieved by using adjuvant analgesics like antiepileptics, with carbamazepine (CBZ) being the first-line approach for TN patients, although side effects may be present. Other approaches using gabapentin, namely when associated with peripheral analgesic block of TN trigger points with the local anesthetic ropivacaine (ROP), resulted in decreased pain and daily drug intake (reduced side effects). This study evaluates if the association between CBZ and the peripheral block with ROP reinforces the clinical value of CBZ. In this parallel, double-blinded study, idiopathic TN patients were randomized to receive during 4 weeks either CBZ (CBZ; n = 21) or CBZ associated with the peripheral analgesic block using ROP (CBZ + ROP; n = 24). The primary outcome measures were the following: i) pain intensity, evaluated by the numerical rating scale; ii) number of pain crises; and iii) number needed to treat. Evaluation points were at the beginning (day 1) and end (day 29) of treatment and after a follow-up of 5 months (month 6). Both protocols resulted in a decrease of pain intensity and number of pain crises, but only the association CBZ + ROP showed i) a significant stronger reduction in pain intensity at month 6 and ii) a significant decrease in the daily dose of CBZ given to patients (both at day 29 and month 6). In contrast, the daily dose in CBZ-only patients remained constant or even increased. The number needed to treat for the association CBZ + ROP over the CBZ protocol reduced from 5 at the end of the 4-week treatment to 3 after the 5-month follow-up. Data reinforce the use of CBZ as a primary tool to control pain in TN patients, as the association CBZ + ROP i) improves the clinical qualities of CBZ, ii) strongly reduces the daily dose of CBZ, and iii) reduces the potential side effects attributed to high doses of CBZ.

[Bilateral trigeminal neuralgia: case report]

BACKGROUND AND OBJECTIVES

Trigeminal neuralgia is an extremely painful condition characterized by recurrent episodes of sudden, lancinating, shock-like pain lasting from a few seconds to two minutes usually unilateral. It has an annual incidence of approximately 4.3 in 100,000 in the general population and only 3% of those cases present bilateral manifestation. The objective of this report was to describe a rare case of bilateral trigeminal neuralgia.

CASE REPORT

A 61 years old housewife from Maranhão, Brazil, married, with a history of hypertension, presented with a six-year history of severe pain in the left V2-V3 regions, lasting 5 to 10 seconds, in the lateral aspect of the nose and mandible, worsening by talking, chewing, and with a decrease in temperature. She had been treated with chlorpromazine (3 mg every eight hours) and carbamazepine (200 mg every eight hours) during six months without improvement. On physical exam, the patient presented thermal and mechanical allodynia in the V2-V3 regions. She was using gabapentin (1,200 mg/day) with partial relief of the pain. The dose of gabapentin was increased to 1,500 mg/day and amitriptyline 12.5 mg at night was added to the therapeutic regimen. The patient evolved with mild and sporadical pain and a reduction in pain severity during 10 months; the dose of gabapentin was progressively reduced to 600 mg/day, and amitriptyline was maintained at 12.5 mg/day. After one year, the patient developed similar pain in the region of the right mandible, which improved with an increase in the dose of gabapentin to 900 mg/day. Head CT and MRI did not show any abnormalities.

CONCLUSIONS

Carbamazepine is the first choice for the treatment of trigeminal neuralgia; however, the use of gabapentin as the first pharmacological choice or in cases refractory to conventional therapy has been increasing.

Neurectomy of the trigeminal nerve branches: clinical evaluation of an "obsolete" treatment

INTRODUCTION

After all options of conservative treatment of trigeminal neuralgia have been exhausted, surgical methods are used. Peripheral neurectomy is one of the simplest among them. It is a relatively obsolete method, but can still be useful and effective.

AIMS

To analyse the remission period after repetitive neuroexeresis of the same neural branch, to calculate "predicted" remission, and to evaluate the benefits of repetitive neuroexeresis.

PATIENTS AND METHODS

Total of 85 neurectomies were performed in 36 patients in 5 years by intraoral access. The recurrence time was analysed by simple regression analysis, using the method of the least-squares. Thus, the average pain free time after repetitive neurectomy can be predicted.

RESULTS

After the first operation on the infraorbital nerve, recurrence mainly appeared in the period between 12 and 15 months, after the second between 9 and 12 months. After the first operation on the mandibular nerve, recurrence took place mainly after 15-18 months, after the second 12.3 months on the average. No interventions were performed on the first branch. Calculated prediction of the average time of remission was in agreement with the actual duration of painlessness.

CONCLUSION

Remission time after repetitive neurectomy decreases. There is no point in repeating the surgery on the same neural branch more than three times.

Treatment of trigeminal neuralgia with low doses of topiramate

Topiramate was administered to eight patients with classical trigeminal neuralgia with or without previous symptomatic therapy with other antiepileptic drugs. The topiramate doses ranged from 50 to 100 mg a day, according to the clinical response and the reported side effects. Three patients had complete symptoms remission, three reported moderate improvement, and the treatment was not effective in two. The most frequently registered side effects were dizziness, somnolence and weight loss. Topiramate can be considered an alternative treatment for patients with trigeminal neuralgia.

A Novel Enantioselective Microassay for the High-Performance Liquid Chromatography Determination of Oxcarbazepine and Its Active Metabolite Monohydroxycarbazepine in Human Plasma

A simple and innovative assay is described that allows the determination of the antiepileptic drug oxcarbazepine and the chiral separation of the two enantiomers of its active metabolite monohydroxycarbazepine (licarbazepine). The assay requires liquid-liquid extraction of the sample (200 microL) into tert-butyl methyl ether and dichloromethane, drying of the organic phase under a nitrogen stream, reconstitution with the mobile phase, and injection in the high-performance liquid chromatography system after filtering. Separation of oxcarbazepine, R-(-)-monohydroxycarbazepine, S-(+)-monohydroxycarbazepine, and the second-step metabolite 10,11-trans-dihydroxycarbamazepine (racemate) is achieved with a Chiralcel ODR column and potassium hexafluorophosphate/acetonitrile as mobile phase. Detection is by ultraviolet absorbance at 210 nm. Standard curves are linear (r2 > or = 0.999) over the range of 0.1 to 25 microg/mL for each analyte with a limit of quantification of 0.1 microg/mL (1 ng injected) for all compounds. Within-day and between-day precision is better than 12% and within-day and between-day accuracy is between 99% and 116% for each compound. These performance characteristics are adequate for pharmacokinetic studies and for therapeutic drug monitoring. However, because the two enantiomers of monohydroxycarbazepine exhibit similar pharmacologic activity, nonenantioselective assays are likely to be more cost-effective for therapeutic drug monitoring purposes.

Trigeminal neuralgia

The paroxysmal facial pain of trigeminal neuralgia is notoriously severe. Recent advances in medical science are achieving significant strides toward alleviating this incapacitating condition. High-resolution neuroimaging techniques are rendering detailed views of underlying neurovascular relationships. Newer antiepileptic medications and novel therapies are proving helpful in treating pain resistant to carbamazepine. Further developments also in targeted neurosurgical and radiosurgical techniques are providing pain relief within increasingly wider margins of safety. Much has been accomplished, yet much remains to be done.