Clinical Efficacy and Peripheral Ultrasound Mechanism of Trigger Point Bloodletting Therapy for Primary Trigeminal Neuralgia

Overview

This randomized controlled trial integrates baseline observational ultrasound analysis to assess the clinical efficacy of trigger point bloodletting therapy for primary trigeminal neuralgia and explore peripheral ultrasound mechanisms of trigger point lesions and treatment response. Eligible subjects are adults aged 18-75 with unilateral classic primary trigeminal neuralgia and confirmed trigger points in the orbicularis oris muscle. The primary research question is whether 8-week trigger point bloodletting achieves a greater reduction in Brief Pain Inventory-Facial total score (primary endpoint) than oral carbamazepine. Secondary questions explore inter-side differences in orbicularis oris thickness, elasticity and microvascular perfusion, correlations between ultrasound biomarkers, pain severity and disease duration, as well as differential dynamic ultrasound changes under the two treatments and their links to pain relief. Participants complete baseline assessments: demographic data, medical history, pain, anxiety, depression and quality-of-life scales, trigger point mapping, and bilateral orbicularis oris ultrasound (grayscale imaging, shear wave elastography, superb microvascular imaging). Subjects are randomly assigned 1:1 to bloodletting intervention or carbamazepine control for 8 weeks. The bloodletting group receives twice-weekly sterile trigger point pricking with cupping bleeding at suitable sites. The control group takes guideline-based individualized carbamazepine, with all subjects maintaining daily pain and medication diaries. Follow-up evaluations occur at Weeks 2, 4, 6 and 8, covering pain scoring, trigger point re-evaluation and adverse event monitoring. Post-treatment bilateral orbicularis oris ultrasound is performed at Week 8 to quantify changes in soft tissue structure and microcirculation. All adverse reactions and concurrent medications are documented throughout the trial. Baseline observational analysis compares pretreatment bilateral facial muscle ultrasound features and correlates imaging indicators with clinical pain, to provide objective imaging evidence for peripheral sensitization pathology of trigger points in trigeminal neuralgia patients.

The goal of this randomized controlled clinical trial with embedded observational baseline analysis is to evaluate the clinical efficacy of trigger point bloodletting therapy for primary trigeminal neuralgia and explore peripheral musculoskeletal ultrasound mechanisms of trigger point lesions and treatment response. This study enrolls adult participants aged 18 to 75 years with unilateral classic or idiopathic primary trigeminal neuralgia and definite trigger points located in the upper lip orbicularis oris muscle. The main questions it aims to answer are: Does eight weeks of trigger point bloodletting therapy deliver a larger decline in Brief Pain Inventory Facial total score which serves as the primary efficacy endpoint compared with routine oral carbamazepine treatment among participants with primary trigeminal neuralgia? Do orbicularis oris muscle ultrasonographic indicators including soft tissue thickness elasticity and microvascular blood flow present discrepancies between affected sides and contralateral unaffected sides, and do these imaging indicators correlate with pain severity and disease course length? Do the two intervention regimens lead to distinct dynamic variations in orbicularis oris muscle ultrasound parameters, and do such structural and microcirculation variations correlate with clinical pain relief degrees? Researchers will compare participants receiving trigger point bloodletting intervention and participants receiving carbamazepine control treatment to identify whether trigger point bloodletting therapy yields better pain relief and more obvious recovery of soft tissue structure and microcirculation in trigger point regions. Participants will finish all scheduled study procedures within an eight week treatment cycle as follows Complete baseline screening and systematic assessments covering demographic information medical history collection clinical pain evaluation and quality of life scale measurement. Scales adopted include Brief Pain Inventory Facial visual analogue scale self rating depression scale self rating anxiety scale and the 36 Item Short Form Health Survey. Researchers conduct full range trigger point localization feature recording and bilateral orbicularis oris muscle ultrasound detection. Ultrasound detection includes grayscale imaging shear wave elastography and superb microvascular imaging modules. Receive random grouping allocation at a one to one ratio to either trigger point bloodletting group or carbamazepine control group. Accept corresponding standardized intervention for eight consecutive weeks. Participants in bloodletting group receive trigger point bloodletting therapy two times each week with no less than two days interval between adjacent treatment sessions. Operators implement sterile pricking on confirmed trigger points and conduct cupping auxiliary bleeding for anatomical positions suitable for cupping operation to reach standardized therapeutic blood volume. Participants in control group take oral carbamazepine tablets following official clinical guidelines with individualized dose adjustment range. All participants record daily medication dosage and real time pain conditions in designated pain diaries. Attend follow up assessment visits at week two week four week six and week eight. Each follow up includes pain scale scoring repeated trigger point feature evaluation and whole process adverse event surveillance. Undergo post treatment orbicularis oris muscle ultrasound re examination at week eight to quantify longitudinal changes of soft tissue thickness tissue elasticity and microvascular blood flow signals. Record all adverse reactions concomitant drugs and unexpected adverse events throughout the entire research period. The observational baseline analysis takes all pre treatment ultrasound data to compare imaging differences between bilateral facial muscles and analyze correlation relationships between ultrasonic indicators and clinical pain indexes. This part of analysis intends to provide imaging based objective evidence supporting peripheral sensitization pathological changes of trigger points in primary trigeminal neuralgia patients.