Radiosurgery in trigeminal neuralgia: Long-term results and influence of operative nuances.

Service de neurochirurgie fonctionnelle et stéréotaxique, hôpital de la Timone, boulevard Jean-Moulin, 13385 Marseille cedex 05, France; Unité Inserm 9926, 13385 Marseille, France.

Stereotactic radiosurgery is an alternative to conventional surgery for the treatment of trigeminal neuralgia. To better define the safety of radiosurgery and optimal technical choices, we reviewed our patient records and the literature. A total of 334 patients presenting with trigeminal neuralgia were treated between December 1992 and September 2005. A minimum of 1 year of follow-up was available for 262 patients. The mean age was 68 years (range: 30-90); 128 patients were male and 134 female. A neurovascular conflict was clearly visualized on MRI in 167 patients. Twenty-one had a past history of multiple sclerosis and 110 had already received conventional surgical treatment for trigeminal neuralgia. The intervention consisted of gamma knife radiosurgery (GKS) to the retrogasserian cisternal portion of the Vth cranial nerve. The median maximal dose used was 85Gy (range: 70-90). Actuarial curves show a plateau at 5 years for both the risk of hypoesthesia and recurrence. At 5 years, 58% of the patients remain pain-free and 83% have no trigeminal nerve disturbance. The median delay for pain cessation was 15 days. The initial pain-relief rate was 89%. None of the complications reported for the other techniques were observed. Patient selection (typical versus atypical, age, past surgery, multiple sclerosis) and details of operative technique (maximum dose, volume of nerve treated, target location, etc.) had a major influence on the probability of pain relief and toxicity risk. The details of operative technique are turning out to have a major influence on the clinical results. In our experience, high-dose (80-90Gy) retrogasserian (7-8mm from the brainstem) GKS provides the patient with a better chance of long-term pain relief and a lower risk of trigeminal nerve functional disturbance. GKS applied to the cisternal anterior trigeminal nerve using high doses provided safe and effective treatment for trigeminal neuralgia over the long term.

Gamma knife surgery for trigeminal neuralgia: outcomes and prognostic factors.

Lars Leksell Center for Gamma Surgery, Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia 22908, USA. jps2f@virginia.edu

OBJECT: Microvascular decompression (MVD) and percutaneous ablation surgery have historically been the treatments of choice for medically refractory trigeminal neuralgia (TN). Gamma knife surgery (GKS) has been used as an alternative, minimally invasive treatment in TN. In the present study, the authors evaluated the long-term results of GKS in the treatment of TN. METHODS: From 1996 to 2003, 151 cases of TN were treated with GKS. In this group, radiosurgery was performed once in 136 patients, twice in 14 patients, and three times in one patient. The types of TN were as follows: 122 patients with typical TN, three with atypical TN, four with multiple sclerosis-associated TN, and seven with TN and a history of a cavernous sinus tumor. In each case, the chosen radiosurgical target was located 2 to 4 mm anterior to the entry of the trigeminal nerve into the pons. The maximal radiation doses ranged from 50 to 90 Gy. The median age of the patients was 68 years (range 22-90 years), and the median time from diagnosis to GKS was 72 months (range 1-276 months). The median follow up was 19 months (range 2-96 months). Clinical outcomes and postradiosurgical magnetic resonance (MR) imaging studies were analyzed. Univariate and multivariate analyses were performed to evaluate factors that correlated with a favorable, pain-free outcome. The mean time to relief of pain was 24 days (range 1-180 days). Forty-seven, 45, and 34% of patients were pain free without medication at the 1-, 2-, and 3-year follow ups, respectively. Ninety, 77, and 70% of patients experienced some improvement in pain at the 1-, 2-, and 3-year follow ups, respectively. Thirty-three (27%) of 122 patients with initial improvement subsequently experienced pain recurrence a median of 12 months (range 2-34 months) post-GKS. Among those whose symptoms recurred, 14 patients underwent additional GKS, six MVD, four glycerol injection, and one patient a percutaneous radiofrequency rhizotomy. Twelve patients (9%) suffered the onset of new facial numbness post-GKS. Changes on MR images post-GKS were noted in nine patients (7%). On univariate analysis, right-sided neuralgia (p = 0.0002) and a previous neurectomy (p = 0.04) correlated with a pain-free outcome; on multivariate analysis, both rightsided neuralgia (p = 0.032) and patient age (p = 0.05) were statistically significant. New onset of facial numbness following GKS correlated with undergoing more than one GKS (p = 0.002).

CONCLUSIONS: At the last follow up, GKS effected pain relief in 44% of patients. Some degree of pain improvement at 3 years post-GKS was noted in 70% of patients with TN. Although less effective than MVD, GKS remains a reasonable treatment option for those unwilling or unable to undergo more invasive surgical approaches and offers a low risk of side effects.

Glycerol rhizotomy versus gamma knife radiosurgery for the treatment of trigeminal neuralgia: an analysis of patients treated at one institution.

Department of Radiation Oncology, Cooper University Medical Center, Camden, NJ, USA.

BACKGROUND: Medically refractory trigeminal neuralgia (TN) has been treated with a variety of minimally invasive techniques, all of which have been compared with microvascular decompression. For patients not considered good surgical candidates, percutaneous retrogasserian glycerol rhizotomy (GR) and gamma knife (GK) radiosurgery are two minimally invasive techniques in common practice worldwide and used routinely at Jefferson Hospital for Neuroscience. Using a common pain scale outcomes questionnaire, we sought to analyze efficacies and morbidities of both treatments. METHODS AND MATERIALS: Between June 1994 and December 2002, 79 patients were treated with GR and 109 patients underwent GK for the treatment of TN. GR was performed with fluoroscopic guidance as an overnight inpatient procedure. GK was performed using a single 4-mm shot positioned at the root exit zone of the trigeminal nerve. Radiation doses of 70-90 Gy prescribed to the 100% isodose line were used. Treatment outcomes including pain response, pain recurrence, treatment failure, treatment-related side effects, and overall patient satisfaction with GK and GR were compared using a common outcomes scale. Using the Barrow Neurologic Institute pain scale, patients were asked to define their level of pain both before and after treatment: I, no pain and no pain medication required; I, occasional pain not requiring medication; IIIa, no pain and pain medication used; IIIb, some pain adequately controlled with medication; IV, some pain not adequately controlled with medication; and V, severe pain with no relief with medication. We used posttreatment scores of I, II, IIIa, and IIIb to identify treatment success, whereas scores of IV and V were considered treatment failure. Results were compiled from respondents and analyzed using SAS software. Statistical comparisons used log-rank test, univariate and multivariate logistic regression, Fisher's exact test, and Wilcoxon test with significance established at p < 0.05.

RESULTS: There were 63 evaluable GK patients and 36 evaluable GR patients. The median follow-up time was 34 and 29 months for the GR and GK groups, respectively. The median age was 69 and 70 years and the median number of years with TN pain was 6 and 7 years in the GR and GK groups, respectively. Thirty-one GR (86%) and 58 GK (92%) patients achieved a successful treatment outcome (p = 0.49). The median time to pain relief was < or = 24 h in the GR group and 3 weeks in the GK group (p < 0.001, ordinal logistic regression). Nineteen GR and 26 GK patients experienced pain recurrence or pain never relieved (p = 0.30). The median time to pain recurrence was 5 and 8 months in the GR and GK groups, respectively (p = 0.22). At last follow-up, however, a statistically significant greater number of GR vs. GK patients had failed treatment. Twelve or 33% of GR patients, whereas 8 or 13% of GK patients, had BNI scores of 4 or 5 (p = 0.019, Fisher's exact test). When both initial and late treatment failures were combined, the overall rate of treatment failures was 39% in the GR group and 24% in the GK group (p = 0.023, log-rank). More GR patients developed facial numbness and facial numbness morbidity than GK patients: 19 GR (54%) and 17 GK patients (30%) developed new facial numbness and 12 GR and 7 GK patients reported either somewhat or very bothersome facial numbness (p = 0.018). On multivariate analysis, only treatment with GK and severity of pain before treatment significantly predicted treatment response. GK patients were more likely to have a lower pain score at last follow-up than were GR patients (p = 0.005, OR = 4.3), and patients with pretreatment pain scores of 5 were more likely to have lower posttreatment pain scores than patients with pretreatment pain scores of 4 and lower (p = 0.003, OR = 4.0).

CONCLUSION: Despite greater facial numbness morbidity and a higher failure rate, GR provided more immediate pain relief than GK. GR therefore should be considered in patients with disabling trigeminal pain requiring urgent pain relief. For all other patients, GK provides better long-term pain relief with less treatment-related morbidity, and should therefore be considered the preferred treatment for patients with medically refractory trigeminal neuralgia who are not suitable candidates for microvascular nerve decompression.