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DOI: 10.1055/s-0034-1383802
Gamma Knife Surgery for Trigeminal Neuralgia: A Prospective Series of 30 Consecutive Cases
Aim: Trigeminal neuralgia (TN), also known as “tic douloureux” is a serious health problem. Surgical treatments include microvascular decompression, percutaneous procedures (thermocoagulation, balloon microcompression and glycerol injection), and radiosurgery. The current study aims to evaluate the safety-efficacy of Gamma Knife surgery (GKS) in TN in the context of this newly reimbursed procedure in Switzerland.
Methods: In July 2012, radiosurgery for functional disorders has been added to the list of treatments that are reimbursed by the basic medical insurance; since then, 30 consecutive patients (31 treatments) have been operated with GKS and prospectively evaluated in Lausanne University Hospital. Among them, 1 patient (3.3%) had multiple sclerosis and 3 (10%) atypical features (TN class 2, as defined by Eller et al). Pain attack frequency and severity, and trigeminal nerve function were evaluated before GKS and regularly after, at 3, 6 and 12 months. Radiosurgery using Gamma Knife Perfexion (Elekta Instruments, AB, Sweden) was performed based on both T1- & T2-weighted magnetic resonance imaging and computer tomography targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve, at a mean distance of 8.1 mm (range 6-10) from the entry zone of the trigeminal nerve into the brainstem (retrogasserian target). A mean maximum dose of 88 Gy (range 75-90) was delivered.
Results: The mean age was 66.9 year-old (range 39-94). The mean follow-up period was 9.4 months (range 1-16.2). Eighteen patients (60%) were females and 12 (40%) males. In half of the cases, a neurovascular conflict was present. Gamma Knife surgery was the first surgical procedure in 21 cases (70%); 5 patients (16.7%) had at least 3 previous surgical procedures. Twenty-six patients (83.3%) became initially pain free in a mean time of 18.5 days (range 1-90). Four patients (13.3%) developed a slight hypoesthesia, not bothersome (BNI hypoesthesia scale). One patient had a recurrence 15 months after a successful initial GKS procedure; a second GKS was performed, with a subsequently rapid pain freedom response.
Conclusions: Our recent experience confirms that GKS is an effective alternative as a first and/or second therapy for drug-resistant TN. Although MVD remains the reference technique, GKS is proposed as a first therapeutic option in many instances, due to its minimal invasiveness, with similar efficacy and less possible complications.
Note: References will be provided on request by authors.