RESUMO
OBJECTIVE: The objective of this study is to investigate safety and effectiveness of a fluoroscopy-guided high-intensity focused ultrasound (HIFU) system for thermal ablation of the lumbar medial branch nerves. METHODS: This dual center prospective cohort study enrolled 30 participants with lumbar zygapophyseal joint syndrome. Each participant previously had a positive response to either a single diagnostic analgesic block or radiofrequency ablation (RFA). The primary effectiveness outcome was individual responder rate, defined as a reduction of two points or more on the pain intensity numerical rating scale without an increase in opioid intake, or a reduction in opioid intake without an increase in pain at 6 months after the intervention. The primary safety outcome was procedure-related or device-related adverse events (AEs). Secondary outcome variables included MRI evidence of tissue ablation, Oswestry Disability Index, 12-Item Short Form Health Survey, Brief Pain Inventory, and Patient Global Impression of Change. RESULTS: The individual responder rate was 89.7% at 2 days, 89.7% at 7 days, 72.4% at 14 days, 82.1% at 30 days, 59.3% at 90 days and 82.6% at 180 days. The average Numeric Rating Scale for pain severity decreased from 7.1 at baseline to 3.0 (N=29) after 2 days, 3.0 (N=29) after 7 days, 3.1 (N=29) after 14 days, 3.2 (N=28) after 30 days, 4.3 (N=27) after 90 days, and 3.3 (N=23) after 180 days. All participants tolerated the procedure well with no significant side effects or complications. CONCLUSIONS: Fluoroscopy-guided HIFU neurotomy achieved clinical responses comparable with RFA, and there were no significant device-related or procedure-related AEs. TRIAL REGISTRATION NUMBER: NCT04129034.
RESUMO
BACKGROUND: Radiofrequency ablation (RFA) is a common method for alleviating chronic back pain by targeting and ablating of facet joint sensory nerves. High-intensity focused ultrasound (HIFU) is an emerging, non-invasive, image-guided technology capable of providing thermal tissue ablation. While HIFU shows promise as a potentially superior option for ablating sensory nerves, its efficacy needs validation and comparison with existing methods. METHODS: Nine adult pigs underwent fluoroscopy-guided HIFU ablation of eight lumbar medial branch nerves, with varying acoustic energy levels: 1000 (N=3), 1500 (N=3), or 2000 (N=3) joules (J). An additional three animals underwent standard RFA (two 90 s long lesions at 80°C) of the same eight nerves. Following 2 days of neurobehavioral observation, all 12 animals were sacrificed. The targeted tissue was excised and subjected to macropathology and micropathology, with a primary focus on the medial branch nerves. RESULTS: The percentage of ablated nerves with HIFU was 71%, 86%, and 96% for 1000 J, 1500 J, and 2000 J, respectively. In contrast, RFA achieved a 50% ablation rate. No significant adverse events occurred during the procedure or follow-up period. CONCLUSIONS: These findings suggest that HIFU may be more effective than RFA in inducing thermal necrosis of the nerve.
