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

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.

Inclusion Criteria: * 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 * Participants with visual analogue scale pain score no less than 4 at screening * Participants who can understand scale evaluation and complete follow-up visits on schedule * Participants sign written informed consent voluntarily Exclusion Criteria: * 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 * Coexisting mental disorders that affect pain assessment and follow up Pregnant or lactating women * Known allergy to carbamazepine or bloodletting operation contraindications such as coagulation dysfunction * Participants who are unable to cooperate with ultrasound examination