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.
Participants aged 18 to 75 years old
Participants diagnosed with primary trigeminal neuralgia
Participants with definite facial trigger points located in the orbicularis oris muscle of upper lip
Participants whose pain meets the diagnostic criteria of classic or idiopathic primary trigeminal neuralgia
Secondary trigeminal neuralgia caused by tumor vascular compression inflammation or other organic lesions
History of facial surgery radiofrequency ablation or nerve block treatment within three months
Receiving acupuncture bloodletting or similar physical therapy on facial region within one month
Severe uncontrolled systemic diseases including heart liver kidney and hematological disorders
Parallel
Trigger Point Bloodletting Therapy
Procedure/SurgerySterile disposable bloodletting needles are used for pricking at confirmed facial trigger points of patients with primary trigeminal neuralgia. Cupping-assisted bleeding is conducted at anatomically appropriate regions. The treatment is delivered twice weekly for 8 consecutive weeks, with an interval of no less than two days between two adjacent treatment sessions.
Carbamazepine
DrugParticipants receive oral carbamazepine tablets. The dosage is adjusted individually according to clinical guidelines to control pain symptoms, and the maximum daily dose does not exceed 1.2 g. The treatment lasts continuously for 8 weeks.
Change in Brief Pain Inventory-Facial total score
Full unabbreviated scale title: Brief Pain Inventory-Facial. Total score minimum value = 0, maximum value = 100. This item measures the change in total score from baseline to the 8-week endpoint. Higher scores indicate more severe facial pain (worse outcome), lower scores indicate milder facial pain.
Change in Visual Analogue Scale pain score
Full unabbreviated scale title: Visual Analogue Scale. Score minimum value = 0, maximum value = 10. This outcome assesses the change in pain score from baseline to the 8-week endpoint. Higher scores indicate stronger pain sensation (worse outcome), lower scores indicate slighter pain.
Change in orbicularis oris muscle soft tissue thickness
This outcome evaluates the change in soft tissue thickness of orbicularis oris muscle measured via grayscale ultrasound from baseline to the 8-week endpoint, measured in millimeters (mm). Lower or higher thickness values reflect altered local soft tissue structure at trigger points.
Change in orbicularis oris muscle shear wave elasticity
This outcome evaluates the change in shear wave elasticity of orbicularis oris muscle measured via shear wave elastography ultrasound from baseline to the 8-week endpoint, measured in kilopascals (kPa). Higher elasticity values indicate stiffer soft tissue at trigger points.
Change in orbicularis oris muscle microvascular blood flow signal
This outcome evaluates the change in microvascular blood flow signal of orbicularis oris muscle measured via superb microvascular imaging from baseline to the 8-week endpoint, quantified by semi-quantitative blood flow grading. Higher grading scores represent richer local microvascular perfusion.
Incidence of adverse events
The number and incidence of adverse events occurring throughout the 8-week treatment period.
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