Comparison of posterior fossa exploration and stereotactic radiosurgery in patients with previously nonsurgically treated idiopathic trigeminal neuralgia

Trigeminal and Glossopharyngeal Neuralgia

Trigeminal neuralgia and glossopharyngeal neuralgia are craniofacial pain syndromes characterized by recurrent brief shock-like pains in the distributions of their respective cranial nerves. In this article, the authors aim to summarize each condition's characteristics, pathophysiology, and current pharmacotherapeutic and surgical interventions available for managing and treating these conditions.

Microvascular Decompression Versus Gamma Knife Surgery in Patients with Drug-Resistant Trigeminal Neuralgia: A Systematic Review and Meta-Analysis

OBJECTIVE

There are 2 cardinal approaches for drug-resistant trigeminal neuralgia (TN), including microvascular decompression (MVD) and gamma knife surgery (GKS). This study aimed to compare the results of MVD versus GKS in the treatment of drug-resistant TN.

METHODS

The search strategy was formulated in accordance with PRISMA recommendations for publications retrieved from electronic databases, such as PubMed, Scopus, and web of science. Inclusion and exclusion criteria were examined for relevant research. The meta-analysis was conducted by combining data using odds ratios.

RESULTS

Four papers were included in our study. 582 patients were treated with MVD, and 607 patients were treated with GKS for drug-resistant TN. Findings revealed that MVD related to higher rates of pain relief and lower rates of pain recurrence compared to GKS. It seems that GKS had lower post-procedural complications in our review.

CONCLUSIONS

MVD and GKS both reduce pain in patients with drug-resistant TN, but MVD was superior to GKS in pain relief. Furthermore, recurrence rate was lower. Post-operative complications except facial numbness were higher in MVD.

Trigeminal neuralgia and other cranial pain syndromes

Spontaneous Trigeminal Neuralgia is a painful condition of the face which may require interventional treatment if medicines fail to control the pain. These include microvascular decompression (MVD) and GKNS. The former is moderately more effective but GKNS has become accepted both as an alternative to MVD or as an adjunct. Like all treatments of the condition, it is successful in a majority of patients but by no means all. Repeat treatments are possible. When Trigeminal Neuralgia is secondary to other conditions the response to GKNS is different. With AVMs, Dural Arteriovenous Fistulae and Epidermoids, the dose to treat the visible lesion usually cures the neuralgia. With meningiomas it is necessary to treat the neuralgia as a separate entity with a neuralgia dose focused on the nerve. GKNS does not improve the rare neuralgia associated with Vestibular Schwannomas. It works with Multiple Sclerosis but not as well as with the spontaneous illness. There is some evidence that GKNS can be useful with the rare Glossopharyngeal and Sphenopalatine Neuralgias.

The changing face of trigeminal neuralgia-A narrative review

OBJECTIVE

This narrative review aims to update the reader on the new classification of trigeminal neuralgia (TN), clinical signs, pathophysiologic evidence, and their implications on management. This review is based on the authors' collective experience and knowledge of the literature in addition to a literature search.

BACKGROUND

In recent years, the phenotype of TN has been intensively studied leading to discrete groups of patients. These include patients with TN with additional continuous pain, and patients with and without neurovascular compression of the trigeminal dorsal root entry zone. A number of associated clinical signs such as tearing and sensory changes need further research.

METHODS

The literature on TN was searched in PubMed with the aims of providing evidence for the recently published third edition of the International Classification of Headache Disorders (ICHD) and update the clinical phenotype and management of the TN subcategories.

RESULTS

The ICHD's new classification for TN is based on reliable clinical data, imaging, and neurophysiologic studies. The TN classification reflects current knowledge and has improved the possibility for clinicians to choose adequate management options. However, there is a lack of effective, safe drugs for the management of TN and sparse, robust data on neurosurgical options.

CONCLUSION

Research into all aspects of TN-diagnosis, pharmacotherapy, surgery, long-term management prognosis, and natural history-is needed. Research should adhere to the ICHD's schema for TN. Improved drugs are needed along with rigorous research into surgical options and their efficacy for different subtypes of TN.

Comparison of first-time microvascular decompression with percutaneous surgery for trigeminal neuralgia: long-term outcomes and prognostic factors

Objective

Common surgical treatments for trigeminal neuralgia (TN) include microvascular decompression (MVD) and percutaneous procedures (glycerol rhizolysis; thermocoagulation; and balloon compression). Although the efficacy of each procedure has been documented, direct comparisons of their relative efficacies for TN are lacking. We aimed to directly compare long-term outcomes after first-time MVD with percutaneous surgery in primary (idiopathic and classical) TN and identify predictors of outcome.

Methods

We conducted a retrospective analysis of prospectively collected data on 185 patients undergoing MVD and 129 undergoing percutaneous surgery. Procedures were performed by one of two neurosurgeons in a single centre; an independent observer collected long-term follow-up data by interviews, using the same outcome measures for all procedures.

Results

MVD patients were younger than those undergoing percutaneous surgery (P <.001). MVD provided superior initial pain relief (P <.001): 87.0% had Barrow Neurological Institute class I or II pain scores after MVD compared with 67.2% after percutaneous surgery. The complication rate for percutaneous procedures was 35.7% and for MVDs was 24.9% (P =.04), including minor and transient complications. Kaplan-Meier analysis demonstrated that MVD provided longer pain relief than percutaneous procedures (P <.001); 25% of patients had recurrence at 96 months following MVD compared with 12 months after percutaneous surgery. Subgroup analysis showed that balloon compression provided more durable relief amongst percutaneous procedures. Multivariate analysis revealed that post-operative numbness and age were prognostic factors for percutaneous procedures (P =.03 and .01, respectively).

Conclusions

MVD provides better initial pain relief and longer durability of relief than percutaneous surgery, although carrying a small risk of major complications. Amongst percutaneous procedures, balloon compression gave the most durable relief from pain. Older age and post-operative numbness were predictors of good outcome from percutaneous surgery. These results can help clinicians to counsel patients with primary TN on neurosurgical treatment selection for pain relief.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-04793-4.

Long-term pain outcomes for recurrent idiopathic trigeminal neuralgia after stereotactic radiosurgery: a prospective comparison of first-time microvascular decompression and repeat stereotactic radiosurgery

OBJECTIVE

Microvascular decompression (MVD) and stereotactic radiosurgery (SRS) are common surgical treatments for trigeminal neuralgia (TN). Many patients who receive SRS have pain recurrence; the ideal second intervention is unknown. The authors directly compared pain outcomes after MVD and repeat SRS in a population of patients in whom SRS failed as their first-line procedure for TN, and they identified predictors of pain control.

METHODS

The authors reviewed a prospectively collected database of patients undergoing surgery for TN between 1997 and 2014 at the University of California, San Francisco (UCSF). Standardized data collection focused on preoperative clinical characteristics, surgical characteristics, and postoperative outcomes. Patients with typical type 1, idiopathic TN with ≥ 1 year of follow-up were included.

RESULTS

In total, 168 patients underwent SRS as their first procedure. Of these patients, 90 had residual or recurrent pain. Thirty of these patients underwent a second procedure at UCSF and had ≥ 1 year of follow-up; 15 underwent first-time MVD and 15 underwent repeat SRS. Patients undergoing MVD were younger than those receiving repeat SRS and were more likely to receive ≥ 80 Gy during the initial SRS. The average follow-up was 44.9 ± 33.6 months for MVD and 48.3 ± 45.3 months for SRS. All patients achieved complete pain freedom without medication at some point during their follow-up. At last follow-up, 80% of MVD-treated patients and 33.3% of SRS-treated patients had a favorable outcome, defined as Barrow Neurological Institute Pain Intensity scores of I-IIIa (p < 0.05). Percentages of patients with favorable outcome at 1 and 5 years were 86% and 75% for the MVD cohort and 73% and 27% for the SRS cohort, respectively (p < 0.05). Multivariate Cox proportional hazards analysis demonstrated that performing MVD was statistically significantly associated with favorable outcome (HR 0.12, 95% CI 0.02-0.60, p < 0.01). There were no statistically significant predictors of favorable outcome in the MVD cohort; however, the presence of sensory changes after repeat SRS was associated with pain relief (p < 0.01).

CONCLUSIONS

Patients who received MVD after failed SRS had a longer duration of favorable outcome compared to those who received repeat SRS; however, both modalities are safe and effective. The presence of post-SRS sensory changes was predictive of a favorable pain outcome in the SRS cohort.

Stereotactic radiosurgery for trigeminal neuralgia: a systematic review

OBJECTIVES

The aims of this systematic review are to provide an objective summary of the published literature specific to the treatment of classical trigeminal neuralgia with stereotactic radiosurgery (RS) and to develop consensus guideline recommendations for the use of RS, as endorsed by the International Society of Stereotactic Radiosurgery (ISRS).

METHODS

The authors performed a systematic review of the English-language literature from 1951 up to December 2015 using the Embase, PubMed, and MEDLINE databases. The following MeSH terms were used in a title and abstract screening: "radiosurgery" AND "trigeminal." Of the 585 initial results obtained, the authors performed a full text screening of 185 studies and ultimately found 65 eligible studies. Guideline recommendations were based on level of evidence and level of consensus, the latter predefined as at least 85% agreement among the ISRS guideline committee members.

RESULTS

The results for 65 studies (6461 patients) are reported: 45 Gamma Knife RS (GKS) studies (5687 patients [88%]), 11 linear accelerator (LINAC) RS studies (511 patients [8%]), and 9 CyberKnife RS (CKR) studies (263 patients [4%]). With the exception of one prospective study, all studies were retrospective.The mean maximal doses were 71.1-90.1 Gy (prescribed at the 100% isodose line) for GKS, 83.3 Gy for LINAC, and 64.3-80.5 Gy for CKR (the latter two prescribed at the 80% or 90% isodose lines, respectively). The ranges of maximal doses were as follows: 60-97 Gy for GKS, 50-90 Gy for LINAC, and 66-90 Gy for CKR.Actuarial initial freedom from pain (FFP) without medication ranged from 28.6% to 100% (mean 53.1%, median 52.1%) for GKS, from 17.3% to 76% (mean 49.3%, median 43.2%) for LINAC, and from 40% to 72% (mean 56.3%, median 58%) for CKR. Specific to hypesthesia, the crude rates (all Barrow Neurological Institute Pain Intensity Scale scores included) ranged from 0% to 68.8% (mean 21.7%, median 19%) for GKS, from 11.4% to 49.7% (mean 27.6%, median 28.5%) for LINAC, and from 11.8% to 51.2% (mean 29.1%, median 18.7%) for CKR. Other complications included dysesthesias, paresthesias, dry eye, deafferentation pain, and keratitis. Hypesthesia and paresthesia occurred as complications only when the anterior retrogasserian portion of the trigeminal nerve was targeted, whereas the other listed complications occurred when the root entry zone was targeted. Recurrence rates ranged from 0% to 52.2% (mean 24.6%, median 23%) for GKS, from 19% to 63% (mean 32.2%, median 29%) for LINAC, and from 15.8% to 33% (mean 25.8%, median 27.2%) for CKR. Two GKS series reported 30% and 45.3% of patients who were pain free without medication at 10 years.

CONCLUSIONS

The literature is limited in its level of evidence, with only one comparative randomized trial (1 vs 2 isocenters) reported to date. At present, one can conclude that RS is a safe and effective therapy for drug-resistant trigeminal neuralgia. A number of consensus statements have been made and endorsed by the ISRS.

Prospective comparison of long-term pain relief rates after first-time microvascular decompression and stereotactic radiosurgery for trigeminal neuralgia

OBJECTIVE

Common surgical treatments for trigeminal neuralgia (TN) include microvascular decompression (MVD), stereotactic radiosurgery (SRS), and radiofrequency ablation (RFA). Although the efficacy of each procedure has been described, few studies have directly compared these treatment modalities on pain control for TN. Using a large prospective longitudinal database, the authors aimed to 1) directly compare long-term pain control rates for first-time surgical treatments for idiopathic TN, and 2) identify predictors of pain control.

METHODS

The authors reviewed a prospectively collected database for all patients who underwent treatment for TN between 1997 and 2014 at the University of California, San Francisco. Standardized collection of data on preoperative clinical characteristics, surgical procedure, and postoperative outcomes was performed. Data analyses were limited to those patients who received a first-time procedure for treatment of idiopathic TN with > 1 year of follow-up.

RESULTS

Of 764 surgical procedures performed at the University of California, San Francisco, for TN (364 SRS, 316 MVD, and 84 RFA), 340 patients underwent first-time treatment for idiopathic TN (164 MVD, 168 SRS, and 8 RFA) and had > 1 year of follow-up. The analysis was restricted to patients who underwent MVD or SRS. Patients who received MVD were younger than those who underwent SRS (median age 63 vs 72 years, respectively; p < 0.001). The mean follow-up was 59 ± 35 months for MVD and 59 ± 45 months for SRS. Approximately 38% of patients who underwent MVD or SRS had > 5 years of follow-up (60 of 164 and 64 of 168 patients, respectively). Immediate or short-term (< 3 months) postoperative pain-free rates (Barrow Neurological Institute Pain Intensity score of I) were 96% for MVD and 75% for SRS. Percentages of patients with Barrow Neurological Institute Pain Intensity score of I at 1, 5, and 10 years after MVD were 83%, 61%, and 44%, and the corresponding percentages after SRS were 71%, 47%, and 27%, respectively. The median time to pain recurrence was 94 months (25th–75th quartiles: 57–131 months) for MVD and 53 months (25th–75th quartiles: 37–69 months) for SRS (p = 0.006). A subset of patients who had MVD also underwent partial sensory rhizotomy, usually in the setting of insignificant vascular compression. Compared with MVD alone, those who underwent MVD plus partial sensory rhizotomy had shorter pain-free intervals (median 45 months vs no median reached; p = 0.022). Multivariable regression demonstrated that shorter preoperative symptom duration (HR 1.005, 95% CI 1.001–1.008; p = 0.006) was associated with favorable outcome for MVD and that post-SRS sensory changes (HR 0.392, 95% CI 0.213–0.723; p = 0.003) were associated with favorable outcome for SRS.

CONCLUSIONS

In this longitudinal study, patients who received MVD had longer pain-free intervals compared with those who underwent SRS. For patients who received SRS, postoperative sensory change was predictive of favorable outcome. However, surgical decision making depends upon many factors. This information can help physicians counsel patients with idiopathic TN on treatment selection.

Microvascular Decompression Versus Stereotactic Radiosurgery for Trigeminal Neuralgia: A Decision Analysis

INTRODUCTION

 Both microvascular decompression (MVD) and stereotactic radiosurgery (SRS) have been demonstrated to be effective in treating medically refractory trigeminal neuralgia. However, there is controversy over which one offers more durable pain relief and the patient selection for each treatment. We used a decision analysis model to calculate the health-related quality of life (QOL) for each treatment.

METHODS

 We searched PubMed and the Cochrane Database of Systematic Reviews for relevant articles on MVD or SRS for trigeminal neuralgia published between 2000 and 2015. Using data from these studies, we modeled pain relief and complication outcomes and assigned QOL values. A sensitivity analysis using a Monte Carlo simulation determined which procedure led to the greatest QOL.

RESULTS

MVD produced a significantly higher QOL than SRS at a seven-year follow-up. Additionally, MVD patients had a significantly higher rate of complete pain relief and a significantly lower rate of complications and recurrence.

CONCLUSIONS

With a decision-analytic model, we calculated that MVD provides more favorable outcomes than SRS for the treatment of trigeminal neuralgia.

Comparative evaluation of surgical procedures for trigeminal neuralgia

Trigeminal neuralgia (TN) is a debilitating ailment. Pharmacotherapy still remains the first line therapy for the management of TN. However, often the patients become refractory to the pharmacotherapy and need surgical interventions. There is a wide array of surgical treatment modalities available for TN and it is important to select the most appropriate surgery for a patient. This review evaluates the various surgical modalities by employing a comparative analysis with respect to patient selection, success rate, complications and cost effectiveness. For the evaluation, a critical review of literature was done with predefined search terms to obtain the details of individual procedures, which were then compared, under similar parameters. The results suggested that microvascular decompression seem to be the most effective treatment in terms of patient satisfaction and long term cost effectiveness. However, if patient factors do not permit, then the peripheral procedures may be employed as a substitute, though they have higher recurrence rate and complications and have relatively lower long term cost effectiveness. The newer modalities like stereotactic radiosurgery and botulinum injections have promising results and further refinement in these procedures will provide additional options for the patients suffering from TN.

Outcome predictors after gamma knife radiosurgery for recurrent trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia (TN) that recurs after surgery can be difficult to manage.

OBJECTIVE

To define management outcomes in patients who underwent gamma knife stereotactic radiosurgery (GKSR) after failing 1 or more previous surgical procedures.

METHODS

We retrospectively reviewed outcomes after GKSR in 193 patients with TN after failed surgery. The median patient age was 70 years (range, 26-93 years). Seventy-five patients had a single operation (microvascular decompression, n=40; glycerol rhizotomy, n=24; radiofrequency rhizotomy, n=11). One hundred eighteen patients underwent multiple operations before GKSR. Patients were evaluated up to 14 years after GKSR.

RESULTS

After GKSR, 85% of patients achieved pain relief or improvement (Barrow Neurological Institute grade I-IIIb). Pain recurrence was observed in 73 of 168 patients 6 to 144 months after GKSR (median, 6 years). Factors associated with better long-term pain relief included no relief from the surgical procedure preceding GKSR, pain in a single branch, typical TN, and a single previous failed surgical procedure. Eighteen patients (9.3%) developed new or increased trigeminal sensory dysfunction, and 1 developed deafferentation pain. Patients who developed sensory loss after GKSR had better long-term pain control (Barrow Neurological Institute grade I-IIIb: 86% at 5 years).

CONCLUSION

GKSR proved to be safe and moderately effective in the management of TN that recurs after surgery. Development of sensory loss may predict better long-term pain control. The best candidates for GKSR were patients with recurrence after a single failed previous operation and those with typical TN in a single trigeminal nerve distribution.

Prospective Comparison of Posterior Fossa Exploration and Stereotactic Radiosurgery Dorsal Root Entry Zone Target as Primary Surgery for Patients With Idiopathic Trigeminal Neuralgia

BACKGROUND

Trigeminal neuralgia (TN) is the most common facial pain syndrome, with an incidence of approximately 27 per 100 000 patient-years.

OBJECTIVE

To prospectively compare facial pain outcomes for patients having either a posterior fossa exploration (PFE) or stereotactic radiosurgery (SRS) as their first surgery for idiopathic TN.

METHODS

Prospective cohort study of 140 patients with idiopathic TN who had either PFE (n = 91) or SRS (n = 49) from June 2001 until September 2007. The groups were similar with regard to sex, pain location, and pain duration. Patients who had SRS were older (67.1 vs 58.2 years; P &lt; .001). The median follow-up after surgery was 38 months.

RESULTS

Patients who had PFE more commonly were pain free off medications (84% at 1 year, 77% at 4 years) compared with the SRS patients (66% at 1 year, 56% at 4 years; hazard ratio = 2.5; 95% confidence interval, 1.4–4.6; P = .003). Additional surgery for persistent or recurrent face pain was performed in 14 patients after PFE (15%) compared with 17 patients after SRS (35%; P = .009). Nonbothersome facial numbness occurred more frequently in the SRS group (33% vs 18%; P = .04). No difference was noted in other complications between patients who had PFE (12%) (dysesthetic facial pain, n = 3; cerebrospinal fluid leakage, n = 3; hearing loss, n = 2; wound infection, n = 1; pneumonia, n = 1; deep vein thrombosis, n = 1) and patients who had SRS (8%) (dysesthetic facial pain, n = 4; P = .47).

CONCLUSION

PFE is more effective than SRS as a primary surgical option for patients with idiopathic TN.

Gamma Knife stereotactic radiosurgery for idiopathic trigeminal neuralgia

OBJECT

Trigeminal neuralgia pain causes severe disability. Stereotactic radiosurgery is the least invasive surgical option for patients with trigeminal neuralgia. Since different medical and surgical options have different rates of pain relief and morbidity, it is important to evaluate longer-term outcomes.

METHODS

The authors retrospectively reviewed outcomes in 503 medically refractory patients with trigeminal neuralgia who underwent Gamma Knife surgery (GKS). The median patient age was 72 years (range 26-95 years). Prior surgery had failed in 205 patients (43%). The GKS typically was performed using MR imaging guidance, a single 4-mm isocenter, and a maximum dose of 80 Gy.

RESULTS

Patients were evaluated for up to 16 years after GKS; 107 patients had > 5 years of follow-up. Eighty-nine percent of patients achieved initial pain relief that was adequate or better, with or without medications (Barrow Neurological Institute [BNI] Scores I-IIIb). Significant pain relief (BNI Scores I-IIIa) was achieved in 73% at 1 year, 65% at 2 years, and 41% at 5 years. Including Score IIIb (pain adequately controlled with medication), a BNI score of I-IIIb was found in 80% at 1 year, 71% at 3 years, 46% at 5 years, and 30% at 10 years. A faster initial pain response including adequate and some pain relief was seen in patients with trigeminal neuralgia without additional symptoms, patients without prior surgery, and patients with a pain duration of < or = 3 years. One hundred ninety-three (43%) of 450 patients who achieved initial pain relief reported some recurrent pain 3-144 months after initial relief (median 50 months). Factors associated with earlier pain recurrence that failed to maintain adequate or some pain relief were trigeminal neuralgia with additional symptoms and > or = 3 prior failed surgical procedures. Fifty-three patients (10.5%) developed new or increased subjective facial paresthesias or numbness and 1 developed deafferentation pain; these symptoms resolved in 17 patients. Those who developed sensory loss had better long-term pain control (78% at 5 years).

CONCLUSIONS

Gamma Knife surgery proved to be safe and effective in the treatment of medically refractory trigeminal neuralgia and is of value for initial or recurrent pain management. Despite the goal of minimizing sensory loss with this procedure, some sensory loss may improve long-term outcomes. Pain relapse is amenable to additional GKS or another procedure.

Long-term pain response and quality of life in patients with typical trigeminal neuralgia treated with gamma knife stereotactic radiosurgery

OBJECTIVE

The long-term outcome of patients treated with gamma knife radiosurgery (GKRS) for typical trigeminal neuralgia has not been fully studied. We evaluated 185 patients who underwent their first GKRS treatment between 1997 and 2003 at the Barrow Neurological Institute.

METHODS

Follow-up was obtained by surveys and review of medical records. Outcomes were assessed by the Barrow Neurological Institute Pain Intensity Score and Brief Pain Inventory. The most common maximum dose was 80 Gy targeted at the root entry zone. Outcomes are presented for the 136 (74%) patients for whom more than 4 years of clinical follow-up data were obtained.

RESULTS

Treatment failed in 33% of the cohort within 2 years, but only an additional 1% relapsed after 4 years. Actuarial analysis demonstrated that 32% of patients were pain-free off medication and 63% had at least a good outcome at 7 years. When GKRS was used as the primary treatment, 45% of the patients were pain-free at 7 years. In contrast, 10% of patients in whom previous treatment had failed were pain-free. When needed, salvage therapy with repeat GKRS, microvascular decompression, or percutaneous lesioning was successful in 70%. Posttreatment facial numbness was reported as very bothersome in 5%, most commonly in patients who underwent another invasive treatment. After GKRS, 73% reported that trigeminal neuralgia had no impact on their quality of life.

CONCLUSION

GKRS is a reasonable long-term treatment option for patients with typical trigeminal neuralgia. It yields durable pain control in a majority of patients, as well as improved quality of life with limited complications and it does not significantly affect the efficacy of other surgical treatments, should they be needed.

Operative treatment of trigeminal neuralgia: review of current techniques

Surgical approaches to pain management are performed when medication cannot control pain or patients cannot tolerate the adverse effects of the medication. Microvascular decompression (MVD) is generally performed when the patient is healthy and relatively young. Partial sensory rhizotomy is performed in addition to, or instead of MVD, in patients in whom significant compression of the trigeminal sensory root does not exist or in whom MVD is technically not feasible. Three percutaneous ablative procedures and gamma knife radiosurgery (GKS) are also performed when MVD cannot be performed. The result of MVD is superior to that of the 3 ablative procedures. GKS is inferior to the 3 ablative procedures in terms of initial pain relief and recurrence, but superior in terms of complications. Peripheral procedures are usually performed in patients not suitable for or not wishing to have other procedures. However, no strict rules exist and each patient should be evaluated individually.

PROGNOSTIC FACTORS FOR RADIOSURGERY TREATMENT OF TRIGEMINAL NEURALGIA

OBJECTIVE

Trigeminal neuralgia treatment results are thought to be highly dependent upon selection criteria. We retrospectively analyzed a series of patients to determine the likelihood of treatment success for patients treated with radiosurgery.

METHODS

A retrospective analysis of 82 patients treated with linear accelerator radiosurgery was undertaken with a median follow-up period of 18 months. Patients were evaluated with a standard inventory using the Barrow Neurological Institute pain scale as the primary means of outcome measurement. Patients were treated with a linear accelerator using a single isocenter plan delivered via a 4-mm collimator, typically with seven noncoplanar arcs to a peak dose of 85 or 90 Gy in primary treatments and 60 Gy in retreatments. The primary target was the cisternal component of the trigeminal nerve. Posttreatment outcomes were analyzed in light of pretreatment patient characteristics, including age, sex, anticonvulsant responsiveness, quality and pattern of pain, length of disease, number of previous procedures, and radiation dose exposure to the root entry zone. Univariate analysis and multivariate logistic regression analysis were used to determine the prognostic significance of various pretreatment variables.

RESULTS

Good results as defined by a Barrow Neurological Institute outcome score of IIIb or better were seen in 85.3% of patients. Excellent results as defined by a Barrow Neurological Institute outcome score of I were seen in 49% of patients. The median time to satisfactory improvement of pain was 4 weeks. Only one variable, sensitivity to anticonvulsant medication, was found to be statistically significant in both univariate (P = 0.003) and multivariate analysis (P = 0.025). All other variables analyzed failed to reach statistical significance. Complications were not common, with seven patients (8.5%) developing new-onset hypoesthesia and two patients (2%) developing dry eye symptoms.

CONCLUSION

Anticonvulsant responsiveness is the single most important prognostic indicator of treatment success for patients presenting with facial pain. Other predictive factors generally failed to reach statistical significance. Linear accelerator radiosurgery for trigeminal neuralgia is a safe and effective treatment for well-selected patients, with results similar to those obtained with gamma unit radiosurgery.

INFLUENCE OF NERVE RADIATION DOSE IN THE INCIDENCE OF TRIGEMINAL DYSFUNCTION AFTER TRIGEMINAL NEURALGIA RADIOSURGERY

OBJECTIVE

The authors conducted a comparative study to analyze dosimetry and results to understand the significant difference in the rate of trigeminal dysfunction after gamma knife radiosurgery for trigeminal neuralgia between two centers using the same target.

METHODS

The data of 358 patients (109 patients from Brussels and 259 patients from Marseilles) were analyzed. Three different dosimetric strategies were found: treatment with less than 90 Gy and no selective beam channel blocking (Group 1; patients from Marseilles only), treatment with 90 Gy and no selective beam channel blocking (Group 2; patients from Brussels and Marseilles), or treatment with 90 Gy and use of selective beam channel blocking (Group 3; patients from Brussels only).

RESULTS

The prescription dose and the use of selective beam channel blocking have been significantly associated with a higher energy received by the retrogasserian trigeminal nerve root. The different radiation dose delivered to the nerve root in these three groups of patients was significantly associated with the incidence of mild (15, 21, and 49% for Groups 1, 2, and 3, respectively) and bothersome (1.4, 2.4, and 10% for Groups 1, 2, and 3, respectively) trigeminal dysfunction. The good and excellent rates of pain relief were 81 and 66%, respectively, for Group 1, 85 and 77%, respectively, for Group 2, and 90 and 84%, respectively, for Group 3, and were also related to the amount of energy received by nerve root volume.

CONCLUSION

Using a similar target, the incidence of trigeminal dysfunction and the pain relief rate can vary according to the radiation energy received by the retrogasserian part of the trigeminal nerve root. The prescription dose and the use of beam channel blocking modify the integrated dose delivered to the nerve and may contribute to the different rates of trigeminal numbness and pain outcome. The radiobiological effect of gamma knife radiosurgery may be related to the energy delivered to nerve root volume, rather than to the maximal dose delivered.

Microvascular Decompression vs. Gamma Knife Radiosurgery for Typical Trigeminal Neuralgia: Preliminary Findings

BACKGROUND

Patients with typical trigeminal neuralgia were treated by one neurosurgeon with either microvascular decompression (MVD) or Gamma Knife radiosurgery (GKRS) and were prospectively evaluated with a uniform protocol.

METHOD

GKRS was done with 75 Gy maximum to the cisternal trigeminal nerve near the pons. MVD was done without cauterizing or cutting the trigeminal nerve.

RESULTS

Twenty-four patients were treated with MVD and 61 with GKRS. Complete pain relief (no pain no medicines) occurred at 12 and 18 months in 68 and 68% of patients treated with MVD and 58 and 24% with GKRS (p = 0.089), and >or=90% pain relief (with or without medicine) at 12 and 18 months in 90 and 78% with MVD and 75 and 48% with GKRS (p = 0.171). There were no permanent complications.

CONCLUSION

Although many trigeminal neuralgia patients treated with either MVD or GKRS have pain relief, MVD is more likely than GKRS to result in complete pain relief.