Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study

Abstract

OBJectiVe Gamma Knife surgery (GKS) is one of the surgical alternatives for the treatment of drug-resistant trigeminal neuralgia (TN). This study aims to evaluate the safety and efficacy of GKS in a large population of patients with TN with very long-term clinical follow-up. methOdS Between July 1992 and November 2010, 737 patients presenting with TN were treated using GKS. Data were collected prospectively and were further retrospectively evaluated at Timone University Hospital. The frequency and severity of pain, as well as trigeminal nerve function, were evaluated before GKS and regularly thereafter. Radiosurgery using the Gamma Knife (model B, C, 4C, or Perfexion) was performed with the help of both MR and CT targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range 4-14 mm) anterior to the emergence of the nerve (retrogasserian target). A median maximum dose of 85 Gy (range 70-90 Gy) was prescribed. reSultS The safety and efficacy are reported for 497 patients with medically refractory classical TN who were never previously treated by GKS and had a follow-up of at least 1 year. The median age in this series was 68.3 years (range 28.1-93.2 years). The median follow-up period was 43.8 months (range 12-174.4 months). Overall, 456 patients (91.75%) were initially pain free in a median time of 10 days (range 1-180 days). Their actuarial probabilities of remaining pain free without medication at 3, 5, 7, and 10 years were 71.8%, 64.9%, 59.7%, and 45.3%, respectively. One hundred fifty-seven patients (34.4%) who were initially pain free experienced at least 1 recurrence, with a median delay of onset of 24 months (range 0.6-150.1 months). However, the actuarial rate of maintaining pain relief without further surgery was 67.8% at 10 years. The hypesthesia actuarial rate at 5 years was 20.4% and at 7 years reached 21.1%, but remained stable until 14 years with a median delay of onset of 12 months (range 1-65 months). Very bothersome facial hypesthesia was reported in only 3 patients (0.6%). cONcluSiONS Retrogasserian GKS proved to be safe and effective in the long term and in a very large number of patients. Even if the probability of long-lasting effects may be modest compared with microvascular decompression, the rarity of complications prompts discussion of using GKS as the pragmatic surgical first- or second-intention alternative for classical TN. However, a randomized trial, or at least a case-matched control study, would be required to compare with microvascular decompression.http://thejns.org/doi/abs/10.3171/2015.2.JNS142144

The Very Long-Term Outcome of Radiosurgery for Classical Trigeminal Neuralgia

“…In 2010, Kondziolka et al [6] published a series from Pittsburgh, with a rather low rate of hypesthesia (10.5%) and a 10-year rate of 29% of patients who were pain free without medication. We recently reported our results [11] in a series of 497 patients with more than one-year follow-up (median = 43.8 months, range = 28.1-93.2). After a very good initial response (91.75%), 45.3% of patients were still pain free without medication at 10 years.…”

“…The current literature includes few studies with long-term follow-up [6,7,10,11]. In chronological order, in 2009, Dhople et al [10] reported a series of 102 patients with a median follow-up period of 5.6 years.…”

“…The present study gives an overview of radiosurgical results on the basis of the very long-term follow-up. With an importantly large cohort of patients and an extended follow-up period, it provides a worthy comparison to our global series [11], providing evidence of high safety and efficacy of radiosurgery in idiopathic TN.…”

“…Due to the former, it is becoming increasingly used for medically refractory TN. Its safety and efficacy have been commonly demonstrated in short- and intermediate-term follow-up studies [7], but only we and three other groups have reported long-term evidence of safety and efficacy [6,10,11,12]. …”

Overview and History of Trigeminal Neuralgia

“…However, with the advent of stereotaxis and better targeting over time at the dorsal root entry zone, 19,20 retrogasserian gamma knife surgery (GKS) has become a safe and efficacious modality for the treatment of TN for both first-and second-line treatment given its low side-effect profile, avoidance of open surgery, and patient satisfaction. 21,22 This involves using photon energy to create a destructive lesion using focused radiation to injure the sensory root. Although initial pain relief can be achieved in up to 90% of cases, patients typically do not experience immediate posttreatment pain relief because of a lag time ranging from 1 to 3 months.…”