Trigeminal neuralgia may be caused by abnormality of the trigger zone

The PATCH trial: 5% lidocaine-medicated plaster for trigeminal neuralgia-Results of a multicentric, enriched enrollment, randomized withdrawal, double-blind, vehicle-controlled, parallel-group study

OBJECTIVE

To explore the efficacy and safety of 5% lidocaine-medicated plaster (LMP) in patients with trigeminal neuralgia (TN).

BACKGROUND

TN is an excruciatingly painful type of neuropathic facial pain. Anti-epileptics are the first-line treatment for TN; however, these oral drugs alone sometimes fail to achieve satisfactory analgesic effects. Two retrospective studies have shown that LMP can be an effective and safe treatment option for some patients with TN. No other high-quality clinical studies have explored the effect and safety of LMP in patients with TN.

METHODS

The PATCH trial is an enriched enrollment with randomized withdrawal, double-blind, vehicle-controlled, parallel-group trial performed at five study centers. Eligible patients with TN received LMP during a 3-week initial open-label phase. Patients who met the response criteria entered the double-blind treatment phase and were randomly assigned for treatment with either LMP (LMP group) or vehicle patches (control group) at a 1:1 ratio. Patients who met the criteria for treatment failure were withdrawn from the double-blind treatment phase, and treatment was continued in the remaining patients for up to 28 days. The primary outcome was the number of treatment failures. The secondary endpoints were the time to loss of therapeutic response (LTR) in the double-blind phase and the weekly mean pain severity in both the open-label phase and the double-blind phase of the study.

RESULTS

The first patient was enrolled in this study on May 1, 2021, and the enrollment of the last patient was completed on August 26, 2022. A total of 307 patients were initially screened, 226 (74.0%) of whom entered the open-label phase. Of the 226 respondents, 124 (55.0%) were randomized to the double-blind phase. In the double-blind phase, 62 patients were assigned to the LMP group, and 62 were assigned to the control group. For the primary endpoint, 16 (26.0%) patients with LMP and 36 (58.0%) patients with vehicle patches met the treatment failure criteria during the double-blind phase (relative risk, 0.48; 95% confidence interval [CI], 0.31 to 0.75; p < 0.001). The survival curve of the LTR showed that the LTR of LMP was significantly longer than that of the vehicle patches (hazard ratio, 0.275; 95% CI, 0.15 to 0.50; log-rank p < 0.001). LMP also significantly reduced the weekly mean pain severity in the double-blind phase of the study (p = 0.007).

CONCLUSIONS

LMP produced partial relief of pain symptoms in some patients with TN. For responders, LMP may be used as an add-on therapy in a multidrug treatment protocol.

Atlas orthogonal chiropractic management of trigeminal neuralgia: A series of case reports

CONTEXT

Trigeminal neuralgia is a debilitating facial pain condition. Upper cervical chiropractic care has been mentioned as a possible solution OBJECTIVE: To determine the effects of Atlas Orthogonal upper cervical chiropractic technique adjustments on trigeminal neuralgia sufferers DESIGN: Case series SETTING: A private chiropractic practice PARTICIPANTS: Five persons with chronic, severe, daily trigeminal neuralgia pain, radiological findings of significant head tilt, pain upon upper cervical palpation, and supine leg length inequality INTERVENTIONS: Up to two consultations and/or Atlas Orthogonal adjustments a week for eight weeks OUTCOME MEASURES: Self-reported reduction in trigeminal neuralgia pain and changes in radiological findings, sensitivity to upper cervical palpation, and leg length inequality RESULTS: Four participants reported reduced trigeminal neuralgia pain, including two with complete cessation of pain. Three participants reduced medication dosages. One reported no change.

The PATCH trial: efficacy and safety of 5% lidocaine-medicated plaster for the treatment of patients with trigeminal neuralgia: a study protocol for a multicentric, double-blind, enriched enrolment randomised withdrawal, vehicle-controlled study

INTRODUCTION

Trigeminal neuralgia (TN) is characterised by a sudden, severe, electric shock like paroxysmal pain, which is almost always associated with triggers. Carbamazepine is the first-line medical management of TN. However, side effects are common. Currently, there is no ideal treatment for TN. Since there is a known abnormality of Na+ channels in the trigger zone, 5% lidocaine-medicated plaster (LMP), which can block the Na+ channels on Aδ and C fibres, is an effective treatment method in many chronic pain conditions. A case report has found the benefit of LMP for the treatment of TN without any side effects. Whether LMP is an option for the treatment of TN is worth exploring.

METHODS AND ANALYSIS

The PATCH trial is a double-blind, enriched enrolment with randomised withdrawal, vehicle-controlled trial, aiming to explore the effects and safety of LMP in patients with TN. There is a 3-week initial open-label phase, followed by a 4-week double-blind treatment phase for responders. In the double-blind phase, patients will have to withdraw from this PATCH study if they meet one of the following criteria for treatment failure such as: >50% increase in pain intensity or paroxysms, lack of efficacy or side effects. The primary outcome will be the number of treatment failures. Adverse events will also be monitored throughout the study.

ETHICS AND DISSEMINATION

This study protocol has been approved by the Institutional Review Board of Beijing Tiantan Hospital (approval number: KY 2020-102-02). The results will be disseminated in international academic meetings and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04570293.