Acute management of ruptured cavernous malformation of the optic nerve: illustrative case.

BACKGROUND: A cavernous malformation of the optic nerve (CMON) is a rare condition that often presents with an abrupt decline in vision. Acute management of ruptured optic nerve cavernous malformations is generally surgical, although the timing of surgery is controversial. OBSERVATIONS: A 47-year-old female experienced the sudden loss of vision in her left eye. Examination showed that this eye was nearly blind, and her right eye had a temporal field defect. Neuroimaging showed hemorrhage in her left optic nerve and optic chiasm. She was taken to the operating room on an emergent basis where the optic canal was decompressed, the hemorrhage was evacuated, and a vascular malformation with features of a cavernoma was removed from the optic nerve. Over the next 2 days, the vision in her right eye significantly recovered. LESSONS: CMONs remain rare, and it is unlikely that enough cases can be gathered to form a larger trial to compare the role and timing of surgery. On the basis of our experience with this case, the authors recommend that acute CMON-related hematomas should be treated as a surgical emergency and managed with acute optic nerve decompression, hematoma evacuation, and cavernoma resection to improve chances of vision recovery and prevent further vision loss.

Facial Nerve Schwannoma Treatment with Stereotactic Radiosurgery (SRS) versus Resection followed by SRS: Outcomes and a Management Protocol.

Background Stereotactic radiosurgery (SRS) and resection are treatment options for patients with facial nerve schwannomas without mass effect. Objective This article evaluates outcomes of patients treated with SRS versus resection + SRS. Method We retrospectively compared 43 patients treated with SRS to 12 patients treated with resection + SRS. The primary study outcome was unfavorable combined endpoint, defined as worsening or new clinical symptoms, and/or tumor radiological progression. SRS (38.81 ± 5.3) and resection + SRS (67.14 ± 11.8) groups had similar clinical follow-ups. Results At the time of SRS, the tumor volumes of SRS (mean ± standard error; 1.83 ± 0.35 mL) and resection + SRS (2.51 ± 0.75 mL) groups were similar. SRS (12.15 ± 0.08 Gy) and resection + SRS (12.16 ± 0.14 Gy) groups received similar radiation doses. SRS group (42/43, 98%) had better local tumor control than the resection + SRS group (10/12, 83%, p = 0.04). Most of SRS (32/43, 74%) and resection + SRS (10/12, 83%) group patients reached a favorable combined endpoint following SRS ( p = 0.52). Considering surgical associated side effects, only 2/10 patients of the resection + SRS group reached a favorable endpoint ( p < 0.001). Patients of SRS group, who are > 34 years old ( p = 0.02), have larger tumors (> 4 mL, 0.04), internal auditory canal (IAC) segment tumor involvement ( p = 0.01) were more likely to reach an unfavorable endpoint. Resection + SRS group patients did not show such a difference. Conclusion While resection is still needed for larger tumors, SRS offers better clinical and radiological outcomes compared to resection followed by SRS for facial schwannomas. Younger age, smaller tumors, and non-IAC situated tumors are factors that portend a favorable outcome.

Hemifacial spasm: a neurosurgical perspective.

Hemifacial spasm (HFS) causes both physical and psychological disabilities that significantly impact quality of life. Medical management with serial botulinum toxin injections provides transient spasm relief and is widely reported as highly effective, as compared to no treatment. While there is an excellent potential for disease cure with microvascular decompression (MVD) surgery, utilization rates remain very low in North America (approximately 10%) and many patients are not adequately informed of this surgical option. Although the majority of MVD neurosurgeons maintain a low annual case volume, excellent safety and success rates can be achieved with attention to technical nuances and anatomical appreciation of the target facial root exit zone. Attention to better informing patients and optimizing surgical outcomes should lead to a greater role for neurosurgery in the treatment and cure of HFS.

A novel method for quantitative evaluation of motor evoked potential monitoring during cerebrovascular surgeries.

Transcranial motor evoked potential (MEP) monitoring, intended to assess cerebral cortical ischemia, may produce false negative results when the stimulation inadvertently activates the deep, subcortical motor pathways. This study examined hand MEP onset latency as a potential means to differentiate superficial versus deep stimulus penetration in surgical patients monitored for cerebral ischemia. Intraoperative MEP data were prospectively collected from 40 patients treated for intracranial aneurysm or carotid stenosis. Onset latencies of hand MEP responses were measured over a range of stimulation intensities from both the contralateral and ipsilateral hand (crossover responses). At the threshold for superficial, cortical stimulation of the contralateral hand, the MEP latency was 26.9 ± 0.4 ms. MEP onset latencies measurements became shorter as stimulation intensities were increased. At the maximum intensity (when crossover response was usually generated), the contralateral hand MEP latency of 22.5 ± 0.3 ms was significantly shorter than at threshold stimulation (p < 0.001). Latency-stimulus intensity plots best fit a 3 parameter hyperbolic decay function (r2 = 0.85 ± 0.02) and revealed a narrow window of acceptable MEP stimuli to obtain superficial cortical activation. Our analysis refutes the utility of the crossover response in reliably gauging depth of activation. Additionally, we found that differentiation between long and short MEP onset latency times may serve as a dependable marker for depth of stimulation. Attention to hand MEP onset latency may reduce inadvertent stimulation of the deep corticospinal tract pathways and avoid false negative MEP recordings during cerebrovascular surgeries.

Adverse radiation effects in volume-staged radiosurgery for large arteriovenous malformations: a multiinstitutional study.

OBJECTIVE: The optimal treatment paradigm for large arteriovenous malformations (AVMs) is controversial. One approach is volume-staged stereotactic radiosurgery (VS-SRS). The authors previously reported efficacy of VS-SRS for large AVMs in a multiinstitutional cohort; here they focus on risk of symptomatic adverse radiation effects (AREs). METHODS: This is a multicentered retrospective review of patients treated with a planned prospective volume staging approach to stereotactically treat the entire nidus of an AVM, with volume stages separated by intervals of 3-6 months. A total of 9 radiosurgical centers treated 257 patients with VS-SRS between 1991 and 2016. The authors evaluated permanent, transient, and total ARE events that were symptomatic. RESULTS: Patients received 2-4 total volume stages. The median age was 33 years at the time of the first SRS volume stage, and the median follow-up was 5.7 years after VS-SRS. The median total AVM nidus volume was 23.25 cm3 (range 7.7-94.4 cm3), with a median margin dose per stage of 17 Gy (range 12-20 Gy). A total of 64 patients (25%) experienced an ARE, of which 19 were permanent. Rather than volume, maximal linear dimension in the Z (craniocaudal) dimension was associated with toxicity; a threshold length of 3.28 cm was associated with an ARE, with a 72.5% sensitivity and a 58.3% specificity. In addition, parietal lobe involvement for superficial lesions and temporal lobe involvement for deep lesions were associated with an ARE. CONCLUSIONS: Size remains the dominant predictor of toxicity following SRS, but overall rates of AREs were lower than anticipated based on baseline features, suggesting that dose and size were relatively dissociated through volume staging. Further techniques need to be assessed to optimize outcomes.

Effect of Anatomic Segment Involvement on Stereotactic Radiosurgery for Facial Nerve Schwannomas: An International Multicenter Cohort Study.

BACKGROUND: Facial nerve schwannomas are rare, challenging tumors to manage due to their nerve of origin. Functional outcomes after stereotactic radiosurgery (SRS) are incompletely defined. OBJECTIVE: To analyze the effect of facial nerve segment involvement on functional outcome for these tumors. METHODS: Patients who underwent single-session SRS for facial nerve schwannomas with at least 3 mo follow-up at 11 participating centers were included. Preoperative and treatment variables were recorded. Outcome measures included radiological tumor response and neurological function. RESULTS: A total of 63 patients (34 females) were included in the present study. In total, 75% had preoperative facial weakness. Mean tumor volume and margin dose were 2.0 ± 2.4 cm3 and 12.2 ± 0.54 Gy, respectively. Mean radiological follow-up was 45.5 ± 38.9 mo. Progression-free survival at 2, 5, and 10 yr was 98.1%, 87.2%, and 87.2%, respectively. The cumulative proportion of patients with regressing tumors at 2, 5, and 10 yr was 43.1%, 63.6%, and 63.6%, respectively. The number of involved facial nerve segments significantly predicted tumor progression (P = .04). Facial nerve function was stable or improved in 57 patients (90%). Patients with involvement of the labyrinthine segment of the facial nerve were significantly more likely to have an improvement in facial nerve function after SRS (P = .03). Hearing worsened in at least 6% of patients. Otherwise, adverse radiation effects included facial twitching (3 patients), facial numbness (2 patients), and dizziness (2 patients). CONCLUSION: SRS for facial nerve schwannomas is effective and spares facial nerve function in most patients. Some patients may have functional improvement after treatment, particularly if the labyrinthine segment is involved.

Earlier radiosurgery leads to better pain relief and less medication usage for trigeminal neuralgia patients: an international multicenter study.

OBJECTIVE: Trigeminal neuralgia (TN) is a chronic pain condition that is difficult to control with conservative management. Furthermore, disabling medication-related side effects are common. This study examined how stereotactic radiosurgery (SRS) affects pain outcomes and medication dependence based on the latency period between diagnosis and radiosurgery. METHODS: The authors conducted a retrospective analysis of patients with type I TN at 12 Gamma Knife treatment centers. SRS was the primary surgical intervention in all patients. Patient demographics, disease characteristics, treatment plans, medication histories, and outcomes were reviewed. RESULTS: Overall, 404 patients were included. The mean patient age at SRS was 70 years, and 60% of the population was female. The most common indication for SRS was pain refractory to medications (81%). The median maximum radiation dose was 80 Gy (range 50-95 Gy), and the mean follow-up duration was 32 months. The mean number of medications between baseline (pre-SRS) and the last follow-up decreased from 1.98 to 0.90 (p < 0.0001), respectively, and this significant reduction was observed across all medication categories. Patients who received SRS within 4 years of their initial diagnosis achieved significantly faster pain relief than those who underwent treatment after 4 years (median 21 vs 30 days, p = 0.041). The 90-day pain relief rate for those who received SRS ≤ 4 years after their diagnosis was 83.8% compared with 73.7% in patients who received SRS > 4 years after their diagnosis. The maximum radiation dose was the strongest predictor of a durable pain response (OR 1.091, p = 0.003). Early intervention (OR 1.785, p = 0.007) and higher maximum radiation dose (OR 1.150, p < 0.0001) were also significant predictors of being pain free (a Barrow Neurological Institute pain intensity score of I-IIIA) at the last follow-up visit. New sensory symptoms of any kind were seen in 98 patients (24.3%) after SRS. Higher maximum radiation dose trended toward predicting new sensory deficits but was nonsignificant (p = 0.075). CONCLUSIONS: TN patients managed with SRS within 4 years of diagnosis experienced a shorter interval to pain relief with low risk. SRS also yielded significant decreases in adjunct medication utilization. Radiosurgery should be considered earlier in the course of treatment for TN.

Using strength-duration analysis to identify the afferent limb of the lateral spread response in hemifacial spasm patients during microvascular decompression surgery.

Strength-duration analysis has been used to identify excitability differences between motor and sensory axons in human peripheral mixed nerves. The trigeminal and facial nerves have both been suggested to play a role in mediating the lateral spread response (LSR) in patients with hemifacial spasm (HFS). We sought to investigate this hypothesis by analyzing strength-duration properties of spasm side mentalis M wave and o. oculi LSR in 22 patients undergoing microvascular decompression surgery for HFS. Simultaneous recordings of mentalis M wave and o. oculi LSR prior to dural opening were collected following marginal mandibular facial nerve branch stimulation. Threshold responses were observed at stimulus pulse widths from 0.05 to 1.0 ms and the chronaxie and rheobase calculated from charge versus stimulus pulse width plots. The mean chronaxie (±SEM) of mentalis M wave was 0.34 ± 0.03 ms and 0.33 ± 0.04 ms for the LSR (p = 0.42, one-tailed t-test). The rheobase for the M wave (8.0 ± 1.0 mA) was found to be significantly different than the LSR rheobase (5.7 ± 0.7 mA; p = 0.03, one-tailed t-test) likely due to differences in the threshold amplitudes of the M wave versus the LSR. These results are highly suggestive of the facial nerve and not the trigeminal nerve in mediating the LSR.

Stereotactic Radiosurgery for Cavernous Sinus Versus Noncavernous Sinus Dural Arteriovenous Fistulas: Outcomes and Outcome Predictors.

BACKGROUND: Dural arteriovenous fistulas (DAVFs) can be categorized based on location. OBJECTIVE: To compare stereotactic radiosurgery (SRS) outcomes between cavernous sinus (CS) and non-CS DAVFs and to identify respective outcome predictors. METHODS: This is a retrospective study of DAVFs treated with SRS between 1988 and 2016 at 10 institutions. Patients' variables, DAVF characters, and SRS parameters were included for analyses. Favorable clinical outcome was defined as angiography-confirmed obliteration without radiological radiation-induced changes (RIC) or post-SRS hemorrhage. Other outcomes were DAVFs obliteration and adverse events (including RIC, symptomatic RIC, and post-SRS hemorrhage). RESULTS: The overall study cohort comprised 131 patients, including 20 patients with CS DAVFs (15%) and 111 patients with non-CS DAVFs (85%). Rates of favorable clinical outcome were comparable between the 2 groups (45% vs 37%, P = .824). Obliteration rate after SRS was higher in the CS DAVFs group, even adjusted for baseline difference (OR = 4.189, P = .044). Predictors of favorable clinical outcome included higher maximum dose (P = .014) for CS DAVFs. Symptomatic improvement was associated with obliteration in non-CS DAVFs (P = .005), but symptoms improved regardless of whether obliteration was confirmed in CS DAVFs. Non-CS DAVFs patients with adverse events after SRS were more likely to be male (P = .020), multiple arterial feeding fistulas (P = .018), and lower maximum dose (P = .041). CONCLUSION: After SRS, CS DAVFs are more likely to obliterate than non-CS ones. Because these 2 groups have different total predictors for clinical and radiologic outcomes after SRS, they should be considered as different entities.

A Proposed Grading Scale for Predicting Outcomes After Stereotactic Radiosurgery for Dural Arteriovenous Fistulas.

BACKGROUND: There are presently no grading scales that specifically address the outcomes of cranial dural arteriovenous fistula (dAVF) after stereotactic radiosurgery (SRS). OBJECTIVE: To design a practical grading system that would predict outcomes after SRS for cranial dAVFs. METHODS: From the International Radiosurgery Research Foundation (University of Pittsburgh [41 patients], University of Pennsylvania [6 patients], University of Sherbrooke [2 patients], University of Manitoba [1 patient], West Virginia University [2 patients], University of Puerto Rico [1 patient], Beaumont Health System 1 [patient], Na Homolce Hospital [13 patients], the University of Virginia [48 patients], and Yale University [6 patients]) centers, 120 patients with dAVF treated with SRS were included in the study. The factors predicting favorable outcome (obliteration without post-SRS hemorrhage) after SRS were assessed using logistic regression analysis. These factors were pooled with the factors that were found to be predictive of obliteration from 7 studies with 736 patients after a systematic review of literature. These were entered into stepwise multiple regression and the best-fit model was identified. RESULTS: Based on the predictive model, 3 factors emerged to develop an SRS scoring system: cortical venous reflux (CVR), prior intracerebral hemorrhage (ICH), and noncavernous sinus location. Class I (score of 0-1 points) predicted the best favorable outcome of 80%. Class II patients (2 points score) had an intermediate favorable outcome of 57%, and class III (score 3 points) had the least favorable outcome at 37%. The ROC analysis showed better predictability to prevailing grading systems (AUC = 0.69; P = .04). Kaplan-Meier analysis showed statistically significant difference between the 3 subclasses of the proposed grading system for post-SRS dAVF obliteration (P = .001). CONCLUSION: The proposed dAVF grading system incorporates angiographic, anatomic, and clinical parameters and improves the prediction of the outcomes following SRS for dAVF as compared to the existing scoring systems.

Dose response and architecture in volume staged radiosurgery for large arteriovenous malformations: A multi-institutional study.

BACKGROUND: Optimal treatment paradigm for large arteriovenous malformations (AVMs) is controversial. Volume-staged stereotactic radiosurgery (VS-SRS) provides an effective option for these high-risk lesions, but optimizing treatment for these recalcitrant and rare lesions has proven difficult. METHODS: This is a multi-centered retrospective review of patients treated with a planned prospective volume staging approach to stereotactically treat the entire nidus of an AVM with volume stages separated by intervals of 3-6 months. A total of 9 radiosurgical centers treated 257 patients with VS-SRS between 1991 and 2016. We evaluated near complete response (nCR), obliteration, cure, and overall survival. RESULTS: With a median age of 33 years old at the time of first SRS volume stage, patients received 2-4 total volume stages and a median follow up of 5.7 years after VS-SRS. The median total AVM nidus volume was 23.25 cc (range: 7.7-94.4 cc) with a median margin dose per stage of 17 Gy (range: 12-20 Gy). Total AVM volume, margin dose per stage, compact nidus, lack of prior embolization, and lack of thalamic location involvement were all associated with improved outcomes. Dose >/= 17.5 Gy was strongly associated with improved rates of nCR, obliteration, and cure. With dose >/= 17.5 Gy, 5- and 10-year cure rates were 33.7% and 76.8% in evaluable patients compared to 23.7% and 34.7% of patients with 17 Gy and 6.4% and 20.6% with <17 Gy per volume-stage (p = 0.004). Obliteration rates in diffuse nidus architecture with <17 Gy were particularly poor with none achieving obliteration compared to 32.3% with doses >/= 17 Gy at 5 years (p = 0.007). Comparatively, lesions with a compact nidus architecture exhibited obliteration rates at 5 years were 10.7% vs 9.3% vs 26.6% for dose >17 Gy vs 17 Gy vs >/=17.5 Gy. CONCLUSION: VS-SRS is an option for upfront treatment of large AVMs. Higher dose was associated with improved rates of nCR, obliteration, and cure suggesting that larger volumetric responses may facilitate salvage therapy and optimize the chance for cure.

Hemorrhage risk of cerebral dural arteriovenous fistulas following Gamma Knife radiosurgery in a multicenter international consortium.

OBJECTIVE: The authors performed a study to evaluate the hemorrhagic rates of cerebral dural arteriovenous fistulas (dAVFs) and the risk factors of hemorrhage following Gamma Knife radiosurgery (GKRS). METHODS: Data from a cohort of patients undergoing GKRS for cerebral dAVFs were compiled from the International Radiosurgery Research Foundation. The annual posttreatment hemorrhage rate was calculated as the number of hemorrhages divided by the patient-years at risk. Risk factors for dAVF hemorrhage prior to GKRS and during the latency period after radiosurgery were evaluated in a multivariate analysis. RESULTS: A total of 147 patients with dAVFs were treated with GKRS. Thirty-six patients (24.5%) presented with hemorrhage. dAVFs that had any cortical venous drainage (CVD) (OR = 3.8, p = 0.003) or convexity or torcula location (OR = 3.3, p = 0.017) were more likely to present with hemorrhage in multivariate analysis. Half of the patients had prior treatment (49.7%). Post-GRKS hemorrhage occurred in 4 patients, with an overall annual risk of 0.84% during the latency period. The annual risks of post-GKRS hemorrhage for Borden type 2-3 dAVFs and Borden type 2-3 hemorrhagic dAVFs were 1.45% and 0.93%, respectively. No hemorrhage occurred after radiological confirmation of obliteration. Independent predictors of hemorrhage following GKRS included nonhemorrhagic neural deficit presentation (HR = 21.6, p = 0.027) and increasing number of past endovascular treatments (HR = 1.81, p = 0.036). CONCLUSIONS: Patients have similar rates of hemorrhage before and after radiosurgery until obliteration is achieved. dAVFs that have any CVD or are located in the convexity or torcula were more likely to present with hemorrhage. Patients presenting with nonhemorrhagic neural deficits and a history of endovascular treatments had higher risks of post-GKRS hemorrhage.

A Propensity Score-Matched Cohort Analysis of Outcomes After Stereotactic Radiosurgery in Older versus Younger Patients with Dural Arteriovenous Fistula: An International Multicenter Study.

OBJECTIVE: This study aims to evaluate the outcomes of Gamma Knife stereotactic radiosurgery (SRS) for dural arteriovenous fistulas (dAVFs) in older patients (≥65 years) compared with younger patients (age <65 years). METHODS: Two groups with a total of 96 patients were selected from a database of 133 patients with dAVF from 9 international medical centers with a minimum 6 months follow-up. A 1:2 propensity matching was performed by nearest-neighbor matching criteria based on sex, Borden grade, maximum radiation dose given, and location. The older cohort consisted of 32 patients and the younger cohort consisted of 64 patients. The mean overall follow-up in the combined cohort was 42.4 months (range, 6-210 months). RESULTS: In the older cohort, a transverse sinus location was found to significantly predict dAVF obliteration (P = 0.01). The post-SRS actuarial 3-year and 5-year obliteration rates were 47.7% and 78%, respectively. There were no cases of post-SRS hemorrhage. In the younger cohort, the cavernous sinus location was found to significantly predict obliteration (P = 0.005). The 3-year and 5-year actuarial obliteration rates were 56% and 70%, respectively. Five patients (7.8%) hemorrhaged after SRS. Margin dose ≥25 Gy was predictive of unfavorable outcome. The obliteration rate (P = 0.3), post-SRS hemorrhage rate (P = 0.16), and persistent symptoms after SRS (P = 0.83) were not statistically different between the 2 groups. CONCLUSIONS: SRS achieves obliteration in most older patients with dAVF, with an acceptable rate of complication. There was no increased risk of postradiosurgery complications in the older cohort compared with the younger patients.

A history of the Jannetta procedure.

Peter Jannetta was a neurosurgery resident when he proposed the neurovascular compression theory. He built upon the astute observations of Dandy, Gardner, and others who, in the era before the operating microscope, had successfully ventured into the posterior fossa. In 1965, Jannetta performed cranial nerve microdissections for dental students and identified the trigeminal portio intermedia. He proposed that preservation of these sensory fibers may avoid complete facial numbness, and together with Robert Rand developed a subtemporal transtentorial approach for selective rhizotomy for trigeminal neuralgia (TN). Such rash surgery, using an operating microscope, was then forbidden at their University of California, Los Angeles center, so they collaborated with John Alksne to perform the first surgery at Harbor General Hospital. Upon visualizing the trigeminal nerve root, Jannetta was surprised to see a pulsating superior cerebellar artery compressing the nerve and said "That's the cause of the tic." He also hypothesized that alleviating the observed vascular cross-compression may be curative.A few months later, while assessing a patient with hemifacial spasm, Jannetta had the epiphany that this was the same disease process as TN, but instead affecting the facial nerve. The patient consented to what would become Jannetta's first microvascular decompression procedure. The senior faculty members who had forbidden such surgery were away, so the supervising neurosurgeon, Paul Crandall, granted the approval to perform the surgery and assisted. Via a retromastoid approach with the patient in the sitting position and using the operating microscope, Jannetta identified and alleviated the culprit neurovascular compression, with a cure resulting.Jannetta presented his neurovascular compression theory and operative findings to the neurosurgical patriarchy of the time. Elders of the field were generally not inclined to accept the bold speculations of an untested neurosurgeon, and were often determined to discredit the new "cure" of the old diseases. Over decades of refining his surgical technique, documenting the outcomes, and enduring the skepticism he often faced, Jannetta's theory and his microvascular decompression procedure withstood critical analysis and have become recognized as one the great discoveries and advances in neurosurgery and medicine.

Geographic Disparities in the Surgical Management of Hemifacial Spasm in Canada.

BACKGROUND: We aimed to interrogate the Canadian Institute for Health Information (CIHI) database in order to determine the geographic distribution and outcomes of microvascular decompression (MVD) for the treatment of hemifacial spasm (HFS). METHODS: The CIHI database was searched from 2004 to 2017 for relevant diagnostic and procedure codes. A new database was populated with the following categories: year, institution, province, number of interventions per year, and mean length of stay. Descriptive statistics were generated. Provincial utilization rates of MVD for HFS were calculated. RESULTS: During the period 2004-17, we identified 671 MVDs performed for HFS at 20 centers across Canada. During the study period, 286 MVDs (42.6%) were performed at one center in Manitoba. Another 131 (19.5%) and 72 (10.7%) were performed at one center in British Columbia and Ontario, respectively. The remaining 182 (27.1%) MVDs for HFS were performed at 17 centers across the rest of Canada where the mean number of cases performed per year was 1.1 (SD=0.9, range 0.2-2.9). When out-of-province cases were re-allocated to place of residence, the adjusted provincial utilization of MVD for HFS ranged between 0.5 and 6.1 patients per million per year. CONCLUSIONS: Microvascular decompression for HFS is performed relatively rarely and there is a tremendous geographic variation in utilization across Canada. Although most of these surgeries are performed by a few surgeons, more than half of Canadian centers perform an average of less than 1 case per year. Further examination of the impact of these discrepancies appears warranted.

Disparités géographiques dans la prise en charge chirurgicale du spasme hémifacial au Canada. CONTEXTE: Nous avons voulu interroger la base de données de l'Institut canadien d'information sur la santé (ICIS) afin de déterminer la répartition géographique et les résultats de la décompression vasculaire microchirurgicale (DVMC) dans le traitement du spasme hémifacial. MÉTHODES: Notre recherche a porté sur les années 2004 à 2017 et visait, au moyen de la base de données de l'ICIS, à repérer des diagnostics et des codes d'acte pertinents. Une nouvelle base de données a été ensuite alimentée en fonction des catégories suivantes : l'année de l'intervention, l'établissement concerné, la province, le nombre d'interventions par année et la durée moyenne de séjour des patients. C'est à partir de cette nouvelle base de données que des statistiques descriptives ont été produites. À cet égard, nous avons calculé les taux provinciaux d'utilisation de la DVMC pour traiter le spasme hémifacial. RÉSULTATS: Au cours de la période allant de 2004 à 2017, nous avons identifié 671 interventions de DVMC dans 20 établissements de santé situés partout au Canada. Durant cette période d'étude, 286 interventions de DVMC (42,6 %) ont été réalisées dans un seul établissement du Manitoba tandis que 131 autres (19,5 %) et 72 autres (10,7 %) ont été respectivement réalisées dans un seul établissement de la Colombie-Britannique et de l'Ontario. Quant aux 182 (27,1 %) autres interventions, elles ont été réalisées dans 17 établissements du reste du pays où le nombre moyen d'interventions par année était de 1,1 (σ = 0,9; étendue = 0,2 ­ 2,9). Une fois réassignés les cas de patients provenant d'autres provinces, et ce, en fonction de leurs lieux de résidence, l'utilisation ajustée par province de la DVMC variait, sur une base annuelle, de 0,5 à 6,1 patients par million. CONCLUSIONS: Les interventions de DVMC pour traiter le spasme hémifacial sont réalisées peu fréquemment. Il existe aussi une énorme variation géographique au Canada quant à l'utilisation de cette technique chirurgicale. Bien que la plupart de ces interventions soient effectuées par quelques chirurgiens, plus de la moitié des établissements de santé canadiens concernés effectuent en moyenne moins d'une intervention par année. Un examen plus approfondi de l'impact de ces écarts semble ainsi se justifier.

Evaluation of stereotactic radiosurgery for cerebral dural arteriovenous fistulas in a multicenter international consortium.

OBJECTIVE: In this multicenter study, the authors reviewed the results obtained in patients who underwent Gamma Knife radiosurgery (GKRS) for dural arteriovenous fistulas (dAVFs) and determined predictors of outcome. METHODS: Data from a cohort of 114 patients who underwent GKRS for cerebral dAVFs were compiled from the International Gamma Knife Research Foundation. Favorable outcome was defined as dAVF obliteration and no posttreatment hemorrhage or permanent symptomatic radiation-induced complications. Patient and dAVF characteristics were assessed to determine predictors of outcome in a multivariate logistic regression analysis; dAVF-free obliteration was calculated in a competing-risk survival analysis; and Youden indices were used to determine optimal radiosurgical dose. RESULTS: A mean margin dose of 21.8 Gy was delivered. The mean follow-up duration was 4 years (range 0.5-18 years). The overall obliteration rate was 68.4%. The postradiosurgery actuarial rates of obliteration at 3, 5, 7, and 10 years were 41.3%, 61.1%, 70.1%, and 82.0%, respectively. Post-GRKS hemorrhage occurred in 4 patients (annual risk of 0.9%). Radiation-induced imaging changes occurred in 10.4% of patients; 5.2% were symptomatic, and 3.5% had permanent deficits. Favorable outcome was achieved in 63.2% of patients. Patients with middle fossa and tentorial dAVFs (OR 2.4, p = 0.048) and those receiving a margin dose greater than 23 Gy (OR 2.6, p = 0.030) were less likely to achieve a favorable outcome. Commonly used grading scales (e.g., Borden and Cognard) were not predictive of outcome. Female sex (OR 1.7, p = 0.03), absent venous ectasia (OR 3.4, p < 0.001), and cavernous carotid location (OR 2.1, p = 0.019) were predictors of GKRS-induced dAVF obliteration. CONCLUSIONS: GKRS for cerebral dAVFs achieved obliteration and avoided permanent complications in the majority of patients. Those with cavernous carotid location and no venous ectasia were more likely to have fistula obliteration following radiosurgery. Commonly used grading scales were not reliable predictors of outcome following radiosurgery.

Stereotactic Radiosurgery for Trigeminal Neuralgia in Patients With Multiple Sclerosis: A Multicenter Study.

BACKGROUND: Facial pain response (PR) to various surgical interventions in patients with multiple sclerosis (MS)-related trigeminal neuralgia (TN) is much less optimal. No large patient series regarding stereotactic radiosurgery (SRS) has been published. OBJECTIVE: To evaluate the clinical outcomes of MS-related TN treated with SRS. METHODS: This is a retrospective cohort study. A total of 263 patients contributed by 9 member tertiary referral Gamma Knife centers (2 in Canada and 7 in USA) of the International Gamma Knife Research Consortium (IGKRF) constituted this study. RESULTS: The median latency period of PR after SRS was 1 mo. Reasonable pain control (Barrow Neurological Institute [BNI] Pain Scores I-IIIb) was achieved in 232 patients (88.2%). The median maintenance period from SRS was 14.1 months (range, 10 days to 10 years). The actuarial reasonable pain control maintenance rates at 1 yr, 2 yr, and 4 yr were 54%, 35%, and 24%, respectively. There was a correlation between the status of achieving BNI-I and the maintenance of facial pain recurrence-free rate. The median recurrence-free rate was 36 mo and 12.2 mo in patients achieving BNI-I and BNI > I, respectively (P = .046). Among 210 patients with known status of post-SRS complications, the new-onset of facial numbness (BNI-I or II) after SRS occurred in 21 patients (10%). CONCLUSION: In this largest series SRS offers a reasonable benefit to risk profile for patients who have exhausted medical management. More favorable initial response to SRS may predict a long-lasting pain control.

Stereotactic Radiosurgery for Intracranial Ependymomas: An International Multicenter Study.

BACKGROUND: Stereotactic radiosurgery (SRS) is a potentially important option for intracranial ependymoma patients. OBJECTIVE: To analyze the outcomes of intracranial ependymoma patients who underwent SRS as a part of multimodality management. METHODS: Seven centers participating in the International Gamma Knife Research Foundation identified 89 intracranial ependymoma patients who underwent SRS (113 tumors). The median patient age was 16.3 yr (2.9-80). All patients underwent previous surgical resection and radiation therapy (RT) of their ependymomas and 40 underwent previous chemotherapy. Grade 2 ependymomas were present in 42 patients (52 tumors) and grade 3 ependymomas in 48 patients (61 tumors). The median tumor volume was 2.2 cc (0.03-36.8) and the median margin dose was 15 Gy (9-24). RESULTS: Forty-seven (53%) patients were alive and 42 (47%) patients died at the last follow-up. The overall survival after SRS was 86% at 1 yr, 50% at 3 yr, and 44% at 5 yr. Smaller total tumor volume was associated with longer overall survival (P = .006). Twenty-two patients (grade 2: n = 9, grade 3: n = 13) developed additional recurrent ependymomas in the craniospinal axis. The progression-free survival after SRS was 71% at 1 yr, 56% at 3 yr, and 48% at 5 yr. Adult age, female sex, and smaller tumor volume indicated significantly better progression-free survival. Symptomatic adverse radiation effects were seen in 7 patients (8%). CONCLUSION: SRS provides another management option for residual or recurrent progressive intracranial ependymoma patients who have failed initial surgery and RT.

Microsurgical rhizotomy for trigeminal neuralgia in MS patients: technique, patient satisfaction, and clinical outcomes.

OBJECTIVEPatients with multiple sclerosis (MS)-associated trigeminal neuralgia (TN) have higher recurrence and retreatment rates than non-MS patients. The optimal management strategy and role for microsurgical rhizotomy (MSR) for MS-TN remains to be determined. The aim of this study was to report time to treatment failure (TTF) and pain scores following MSR compared to percutaneous and Gamma Knife procedures.METHODSTime to treatment failure was analyzed after MSR (n = 14) versus prior procedures (n = 53) among MS-TN patients. Kaplan-Meier curves and log-rank test were utilized to compare TTF after MSR versus prior procedures using the same cohort of patients as their own control group. Subsequent analysis compared TTF after MSR to TTF after 93 other procedures among a second cohort of 18 MS-TN patients not undergoing MSR. BNI pain scores were compared between MSR and other procedures among the MS-TN cohort using a chi-square test.RESULTSTTF was significantly longer after MSR than after other procedures in the MSR cohort (median TTF 79 vs 10 months, respectively, p < 0.0001). Similarly, TTF was longer after MSR than after prior procedures in the non-MSR cohort (median TTF 79 vs 13 months, respectively, p < 0.001). MSR resulted in a higher proportion of excellent pain scores when compared to other procedures in the non-MSR cohort (77% vs 29%, p < 0.001). Probability of treatment survival was higher after MSR than after other procedures at all time points (3, 6, 12, 24, 36, and 48 months). There were no deaths or major complications after MSR.CONCLUSIONSTTF was significantly longer following MSR compared to prior procedures in MS-TN patients. Additionally, a higher proportion of patients achieved excellent BNI pain scores after MSR.