Ultra-early Gamma Knife stereotactic radiosurgery for trigeminal neuralgia (URGEnt-TN): study protocol for a single-center, two-arm, parallel group design, pragmatic, noninferiority, phase II, randomized controlled trial with intention-to-treat analysis for pre-refractory GK-SRS in classical or idiopathic TN.
Trigeminal neuralgia (TN) is a chronic, often debilitating neuropathic facial pain condition. First-line treatment is medical therapy, with carbamazepine (CBZ) being the gold standard. Surgery, including stereotactic radiosurgery in particular with Gamma Knife (GK-SRS), is usually considered when medical management fails, which occurs in >50% ofpatients. While surgery can provide long-term relief, prolonged disease duration before intervention is linked to a reduced response rate. A highly precise type of radiation therapy, GK-SRS is a non-invasive management option in TN, with a low risk of serious complications and fewer bothersome side effects compared to medical therapy. Evidence supports the safety and efficacy of GK-SRS in medically refractory TN, with published data suggesting that earlier intervention (within 3years of pain onset) leads to improved long-term outcomes. However, the safety and efficacy of ultra-early GK-SRS-administered soon after TN diagnosis and before medical refractoriness-have not been examined. We hypothesize that ultra-early GK-SRS will yield superior long-term pain relief compared to ongoing medical management while also having a lower incidence of treatment-related adverse events (AEs). We will perform a single-center, two-arm, randomized, controlled, parallel group design, pragmatic, noninferiority, phase II trial of ultra-early GK-SRS for TN in participants who will be treated before they have developed a medically refractory state and within 2years of diagnosed TN per study neurologist. Eighty participants will be randomized 1:1 to either GK-SRS (intervention arm) or ongoing medical management (non-intervention/control arm). Crossover from the non-intervention/control arm to the intervention arm will be permitted. An intention-to-treat analysis will be conducted. The primary outcome will be the proportion of participants with satisfactory pain control at 2years by the Barrow Neurological Institute Facial Pain Scale. This trial aims to test ultra-early GK-SRS as a first-line option in TN, based on a sound rationale for offering GK-SRS prior to failure of medical therapy. If validated, ultra-early GK-SRS will represent a paradigm shift in TN management leading to improved long-term pain control free from adverse medication-related side effects. ClinicalTrials.gov NCT06949436. Registered on April 28, 2025.
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