Abstract
INTRODUCTION: The sphenopalatine ganglion (SPG) plays a role in orofacial pain and headaches and is a target for pain modulation. Onabotulinum toxin-A injections have been described as a treatment for several neuropathic pain conditions. However, there is limited evidence for using this medication at the sphenopalatine ganglion for orofacial pain. The goal of this study was to investigate the effectiveness, in terms of pain intensity and frequency of pain attacks, as well as the safety of fluoroscopy-guided Onabotulinum toxin-A injection administered directly to the sphenopalatine ganglion in patients with trigeminal neuralgia. METHOD: Fourteen patients diagnosed with trigeminal neuralgia who either could not tolerate the side effects of oral medication or did not respond to oral medication. Onabotulinum toxin-A 40 units was injected through the sphenopalatine ganglion under fluoroscopy guidance. The primary outcome was a reduction in pain intensity (using the Numerical Rating Scale). The secondary outcome was a reduction in the frequency of pain attack and safety profile of the procedure. RESULTS: The average pain scores and frequency of pain decreased significantly (p-value < 0.001). The mean baseline pain score before the injection was 8.15 ± 1.91. The mean pain score reduction 60 days after the procedure was 4.15 (95% CI: 2.72, 5.59; p < 0.001). The frequency of pain attacks also decreased significantly from 12.15 ± 8.61 times per day to 3.38 ± 2.53 times per day at 60 days after the procedure (p < 0.001). Complications directly associated with the procedure included hemifacial palsy (76.9%) and diplopia (7.7%). These symptoms resolved within three months after the procedure. CONCLUSION: Onabotulinum toxin-A injection at the SPG is effective in reducing pain symptoms in trigeminal neuralgia patients who cannot tolerate the side effects of medication or are refractory to oral medication. TRIAL REGISTRATION: This study was retrospectively registered in the Thai Clinical Trial Registry under registration number TCTR20240908004 on 3 September 2024.