Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study.
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.
Functional and Stereotactic Neurosurgery Service and Gamma Knife Unit, Centre Hospitalier Universitaire La Timone Assistance Publique-Hopitaux de Marseille, Université de la Méditerranée, Marseille, France;
Jean
J
Régis
Functional and Stereotactic Neurosurgery Service and Gamma Knife Unit, Centre Hospitalier Universitaire La Timone Assistance Publique-Hopitaux de Marseille, Université de la Méditerranée, Marseille, France;|Signal Processing Laboratory (LTS-5), Swiss Federal Institute of Technology, Lausanne, Switzerland;|Medical Image Analysis Laboratory, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland;|Department of Clinical Neurosciences, Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; and.|Faculty of Biology and Medicine, University of Lausanne, Switzerland.
Constantin
C
Tuleasca
Department of Public Health and Medical Information, Centre Hospitalier Universitaire La Timone, Assistance Publique-Hopitaux de Marseille, France;
Noémie
N
Resseguier
Functional and Stereotactic Neurosurgery Service and Gamma Knife Unit, Centre Hospitalier Universitaire La Timone Assistance Publique-Hopitaux de Marseille, Université de la Méditerranée, Marseille, France;
Romain
R
Carron
Department of Neurology, Clinical Neuroscience Federation, Centre Hospitalier Universitaire La Timone Assistance Publique-Hopitaux de Marseille, France;
Anne
A
Donnet
Department of Public Health and Medical Information, Centre Hospitalier Universitaire La Timone, Assistance Publique-Hopitaux de Marseille, France;
Jean
J
Gaudart
Department of Clinical Neurosciences, Neurosurgery Service and Gamma Knife Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; and.|Faculty of Biology and Medicine, University of Lausanne, Switzerland.
Marc
M
Levivier
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D061214:Patient Safety; D017060:Patient Satisfaction; D011183:Postoperative Complications / Q000209:etiology; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*; D012008:Recurrence; D012189:Retrospective Studies; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000175:diagnosis / Q000601:surgery*
BNI = Barrow Neurological Institute; CTN = classical trigeminal neuralgia; GKS = Gamma Knife surgery; Gamma Knife radiosurgery; MVD = microvascular decompression; TN = trigeminal neuralgia; efficacy; pain; safety; stereotactic radiosurgery; trigeminal neuralgia