Place Of Stereotactic Radiosurgery In The Managment Of Drug-Resistant Trigeminal Neuralgia

Context: essential trigeminal neuralgia is a neuropathic pain, describe as a severe and sudden pain in the face. In about 20% of the cases, the pain attacks are resistants to the specific pharmacological treatement. At this stage, differents surgical alternatives can be proposed : percutaneous techniques (thermocoagulation, microcompression and glycerol injection) realized on the gasserian ganglion; direct open surgery on the cerebollo-pontine angle and microvascular decompression.Method: the indication of RDS was based on the following criteria : certitude of the diagnosis; conformed failure of the pharmacological treatment; surgical alternative choosen after informed consent; accurate MRI identification of the trigeminal roots. The radiosurgical procedure was realised with a dedicated LINAC (Novalis (R), BrainLab). The first step is the image planning anatomical definition of the target, based on the image fusion of a pre-operative MRI (sequences T13D and T2-CISS) with a stereotactic CT-Scan. The (plexus triangularis) target point in localised at the level of crossing of the trigeminal roots with the petrous bone. After image and dose planning, a single dose is delivered on a single isocenter. The maximum dose is between 85 an 90 Gy, in function of the cisterna dimensions, i.e the distance from the brain stem. The clinical follow-up is organized 3 months, 6 months and 12 months later, and after yearly. A MRI control is done at + 6 months.Results: after RDS : 39 patients were followed for minimun of 6 months. The mean age is 70 years (43-109); 12 patients were male and 27 were female. The analgesic effect was progressive and the delay is variable (mean : 1 month). It could be early and even immediate. At the last visit : 87% of patients were totaly pain free with complete drug interruption or reduction. A partial relief or failure or recurrence was observed in 13% of the cases. The indesirable side effects were moderate : (paresthesia and hypoesthesia)Conclusion: our experience is in accordance with the literature. Radiosurgery is a safe and effective alternative surgical treatment for drug-resistant idiopathic trigeminal neuralgia. It could be proposed in first intention, if there is no indication of microvascular decompression.