New Trigeminal Stimulation Technique with Dorsal Root Ganglion Stimulation Electrode and Maxillary Fixation: Technique Description.

BACKGROUND: Trigeminal neuralgia is considered the worst pain a human being can experience. Initial treatment uses anticonvulsant sodium channel blockers, which relieve pain in approximately 70% of patients. In refractory cases, it is possible to perform ablative treatments, decompressive surgeries, and neuromodulatory techniques. METHODS: This report describes the treatment of a patient with refractory trigeminal neuralgia who continued to have a painful clinical presentation after four surgical procedures and three ablative procedures. The patient presented with severe pain (verbal numerical scale between 9 and 10), manifesting an evident suicidal ideation. A dorsal root ganglion (DRG) stimulation electrode was implanted in the trigeminal ganglion through intraoral puncture with maxillary fixation of the electrode, in order to minimize the chances of displacement. The test phase consisted of implanting a quadripolar electrode for DRG stimulation through puncture lateral to the buccal rim in a fluoroscopic coaxial view. The electrode was fixed to the skin and maintained for 5 days, during which the patient remained completely pain free. After the 5-day test period, the definitive stimulation electrode was implanted, this time with intraoral puncture and maxillary electrode fixation. RESULTS: The patient remains pain free in the 3-month follow-up, with no displacement of the electrode. CONCLUSIONS: The DRG electrode may be considered a therapeutic option in patients with severe trigeminal neuralgia. Controlled studies must be performed to determine the efficacy and safety of the method.

Chemical Ablation of Genicular Nerve with Phenol for Pain Relief in Patients with Knee Osteoarthritis: A Prospective Study.

BACKGROUND: Radiofrequency ablation of the genicular nerve is performed for knee osteoarthritis (KOA) when conservative treatment is not effective. Chemical ablation may be an alternative, but its effectiveness and safety have not been examined. The objective of this prospective open-label cohort study is to evaluate the effectiveness and safety of ultrasound-guided chemical neurolysis for genicular nerves with phenol to treat patients with chronic pain from KOA. METHODS: Forty-three patients with KOA with pain intensity score (Numeric Rating Scale, NRS) ≥ 4, and duration of pain of more than 6 months were considered for enrollment. Ultrasound-guided diagnostic blocks of genicular nerves (superomedial, inferomedial, and superolateral) with 1.5 mL of 0.25% bupivacaine at each site were performed. Those who reported more than 50% reduction in NRS went on to undergo chemical neurolysis, using 1.5 mL 7% glycerated phenol in each genicular nerve. NRS and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were assessed before intervention and at 2 weeks and 1, 2, 3, and 6 months following the intervention. RESULTS: NRS and WOMAC scores improved at all time points. Mean pain intensity improved from 7.2 (95% confidence interval [CI]: 6.8 to 7.7) at baseline to 4.2 (95%CI: 3.5 to 5.0) at 6-month follow-up (P < 0.001). Composite WOMAC score improved from 48.7 (95%CI: 43.3 to 54.2) at baseline to 20.7 (95%CI: 16.6 to 24.7) at 6-month follow-up (P < 0.001). Adverse events did not persist beyond 1 month and included local pain, hypoesthesia, swelling, and bruise. CONCLUSION: Chemical neurolysis of genicular nerves with phenol provided efficacious analgesia and functional improvement for at least 6 months in most patients with a low incidence of adverse effects.