Arteriovenous malformations and radiosurgery
Douglas Kondziolka, Hideyuki Kano, and L. Dade Lunsford
Kim J. Burchiel
Ajay Niranjan, Ahmed Kashkoush, Hideyuki Kano, Edward A. Monaco III, John C. Flickinger, and L. Dade Lunsford
Seizures are the second-most common presenting symptom in patients with lobar arteriovenous malformations (AVMs). However, few studies have assessed the long-term effect of stereotactic radiosurgery (SRS) on seizure control. The authors of this study assess the outcome of SRS for these patients to identify prognostic factors associated with seizure control.
Patients with AVM who presented with a history of seizure and underwent SRS at the authors’ institution between 1987 and 2012 were retrospectively assessed. The total cohort included 155 patients with a mean follow-up of 86 months (range 6–295 months). Primary outcomes assessed were seizure frequency, antiepileptic drug regimen, and seizure freedom for 6 months prior to last follow-up.
Seizure-free status was achieved in 108 patients (70%), with an additional 23 patients (15%) reporting improved seizure frequency as compared to their pre-SRS status. The median time to seizure-free status was estimated to be 12 months (95% CI 0–27 months) as evaluated via Kaplan-Meier survival analysis. The mean seizure frequency prior to SRS was 14.2 (95% CI 5.4–23.1) episodes per year. Although not all patients tried, the proportion of patients successfully weaned off all antiepileptic drugs was 18% (28/155 patients). On multivariate logistic regression, focal impaired awareness seizure type (also known as complex partial seizures) and superficial venous drainage were significantly associated with a decreased odds ratio for seizure-free status at last follow-up (OR 0.37 [95% CI 0.15–0.92] for focal impaired awareness seizures; OR 0.36 [95% CI 0.16–0.81] for superficial venous drainage). The effects of superficial venous drainage on seizure outcome were nonsignificant when excluding patients with < 2 years of follow-up. AVM obliteration did not correlate with long-term seizure freedom (p = 0.202, chi-square test).
This study suggests that SRS improves long-term seizure control and increases the likelihood of being medication free, independently of AVM obliteration. Patients with focal impaired awareness seizures were less likely to obtain long-term seizure relief.
Gillian Harrison, Hideyuki Kano, L. Dade Lunsford, John C. Flickinger, and Douglas Kondziolka
The reported tumor control rates for meningiomas after stereotactic radiosurgery (SRS) are high; however, early imaging assessment of tumor volumes may not accurately predict the eventual tumor response. The objective in this study was to quantitatively evaluate the volumetric responses of meningiomas after SRS and to determine whether early volume responses are predictive of longer-term tumor control.
The authors performed a retrospective review of 252 patients (median age 56 years, range 14–87 years) who underwent Gamma Knife radiosurgery between 2002 and 2010. All patients had evaluable pre- and postoperative T1-weighted contrast-enhanced MRIs. The median baseline tumor volume was 3.5 cm3 (range 0.2–33.8 cm3) and the median follow-up was 19.5 months (range 0.1–104.6 months). Follow-up tumor volumes were compared with baseline volumes. Tumor volume percent change and the tumor volume rate of change were compared at 3-month intervals. Eventual tumor responses were classified as progressed for > 15% volume change, regressed for ≤ 15% change, and stable for ± 15% of baseline volume at time of last follow-up. Volumetric data were compared with the final tumor status by using univariable and multivariable logistic regression.
Tumor volume regression (median decrease of −40.2%) was demonstrated in 168 (67%) patients, tumor stabilization (median change of −2.7%) in 67 (26%) patients, and delayed tumor progression (median increase of 104%) in 17 (7%) patients (p < 0.001). Tumors that eventually regressed had an average volume reduction of −18.2% at 3 months. Tumors that eventually progressed all demonstrated volume increase by 6 months. Transient progression was observed in 15 tumors before eventual decrease, and transient regression was noted in 6 tumors before eventual volume increase.
The volume response of meningiomas after SRS is dynamic, and early imaging estimations of the tumor volume may not correlate with the final tumor response. However, tumors that ultimately regressed tended to respond in the first 3 months, whereas tumors that ultimately progressed showed progression within 6 months.
Jason Sheehan and Chun Po Yen
Mohamed Samy Elhammady and Roberto C. Heros
Relationship between tinnitus and surgical options for vestibular schwannomas
Douglas Kondziolka and Hideyuki Kano
Stephen Johnson, Hideyuki Kano, Andrew Faramand, Ajay Niranjan, John C. Flickinger, and L. Dade Lunsford
Optimizing outcomes in the management of patients with vestibular schwannomas (VSs) requires consideration of the patient’s goals. Earlier recognition of VS by imaging has led to an evolution in management. Stereotactic radiosurgery (SRS) has emerged as a frequently used strategy designed to reduce management risks, obtain long-term tumor control, and preserve current neurological function. The authors analyzed features that impact hearing preservation rates in patients with serviceable hearing prior to SRS.
The study included 307 patients who had serviceable hearing (Gardner-Robertson hearing scale [GR] grade 1 or 2, speech discrimination score ≥ 50%, pure tone average ≤ 50 dB) at the time of SRS. The authors evaluated parameters that included age, tumor volume, hearing status, disequilibrium, tinnitus, Koos class, sex, and tumor margin dose. The Pittsburgh Hearing Prediction Score (PHPS) was evaluated as a method to predict long-term hearing outcomes in these cases.
At a median of 7.6 years after SRS (range 1–23 years), tumor control was achieved in 95% of patients. The overall serviceable hearing preservation rate was 77.8% at 3 years, 68.8% at 5 years, and 51.8% at 10 years. The PHPS assigns a total of 5 points based on patient age (1 point if < 45 years, 2 points if 45–59 years, and 3 points if ≥ 60 years), tumor volume (0 points if < 1.2 cm3, 1 point if ≥ 1.2 cm3), and GR grade (0 points if grade 1 hearing, 1 point if grade 2 hearing) The serviceable hearing preservation rate was 92.3% at 10 years in patients whose score total was 1. In contrast, none of the patients whose PHPS was 5 maintained serviceable hearing at 10 years (p < 0.001).
SRS resulted in a high rate of long-term tumor control and cranial nerve preservation. The PHPS helped to predict long-term hearing preservation rates in patients who underwent SRS when they still had serviceable hearing. The best long-term hearing preservation rates were found in younger patients with smaller tumor volumes.