The efficacy of radiosurgery for neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS) remains debatable. We retrospectively analyzed radiosurgical outcomes for NF2-associated VS compared to sporadic VS using our database of 422 consecutive VS patients. Twenty-five patients with 30 NF2-associated VSs with a mean follow-up of 121 months were identified. NF2-associated VSs exhibited excellent tumor control (10-year cumulative rate, 92% vs. 92% in sporadic VSs; p = 0.945) and worse overall survival (73% vs. 97%; p = 0.005), mainly due to tumor progression other than the treated VSs. The presence of NF2 was not associated with failed tumor control via multivariate Cox proportional hazard analyses. No difference in radiation-induced adverse events (RAEs) was confirmed between cohorts, and prescription dose (hazard ratio 8.30, 95% confidence interval 3.19–21.62, p < 0.001) was confirmed as a risk for cranial nerve injuries via multivariate analysis. Further analysis after propensity score matching using age, volume, and sex as covariates showed that NF2-associated VSs exhibited excellent local control (100% vs. 93%; p = 0.240) and worse overall survival (67% vs. 100%; p = 0.002) with no significant difference in RAEs. Excellent long-term tumor control and minimal invasiveness may make radiosurgery a favorable therapeutic option for NF2 patients with small to medium VS, preferably with non-functional hearing or deafness in combination with postoperative tumor growth or progressive non-operated tumors, or with functional hearing by patients’ wish.

Stereotactic frame-based brain tumor biopsy (SFB) is a potent diagnostic tool considering its minimal invasiveness, though its diagnostic power and safety for brainstem lesions remain to be discussed. Here, we aimed to examine the usefulness of SFB for brainstem tumors. Twenty-two patients with brainstem tumors underwent 23 SFBs at our institution during 2002–2021. We retrospectively analyzed patient characteristics, tumor pathology, surgical procedures, and outcomes, including surgery-related complications and the diagnostic value. Seven (32%) tumors were located from the midbrain to the pons, eleven (50%) in the pons only, and four (18%) from the pons to the medulla oblongata. The target lesions were in the middle cerebellar peduncles in sixteen procedures (70%), the cerebellum in four (17%), the inferior cerebellar peduncles in two (9%), and the superior cerebellar peduncles in one (4%). A definitive diagnosis was made in 21 patients (95%) at the first SFB. The diagnoses were glioma in seventeen (77%) cases, primary central nervous system lymphoma in four (18%), and a metastatic brain tumor in one (5%). The postoperative complications (cranial nerve palsy in three [13%] cases, ataxia in one [4%]) were all transient. SFB for brainstem tumors yields a high diagnostic rate with a low risk of morbidity.

Intracranial atherosclerosis (ICAS) involves diverse histologies and several remodeling patterns. Ring finger protein 213 (RNF213) c.14576G>A variant (rs112735431), recently reported to be associated with ICAS, may be linked with negative remodeling (outer diameter - reducing morphological alteration) of intracranial arteries. This study investigated the outer diameter of atherosclerotic middle cerebral artery (MCA). Patients with unilateral atherosclerotic MCA stenosis/occlusion were enrolled in this single-hospital-based case-control study at The University of Tokyo Hospital. The patients were divided into two groups by the presence of RNF213 c.14576G>A (variant group and wild-type group) and the outer diameter of the MCA was measured with high-resolution magnetic resonance imaging. Twenty-eight patients with the wild type and 19 patients with the variant type were included. The outer diameter of the stenotic side MCA was smaller in the variant group than in the wild-type group (P = 8.3 × 10-6). The outer diameter of the normal side MCA was also smaller in the variant group than in the wild-type group (P = 5.2 × 10-3). The ratio of stenotic side to normal side was also smaller in the variant group than in the wild-type group (P = 1.5 × 10-5). This study indicates that RNF213 c.14576G>A is associated with negative remodeling of ICAS.

OBJECTIVE: In Gamma Knife radiosurgery (GKS) for arteriovenous malformations (AVMs), CT angiography (CTA), MRI, and digital subtraction angiography (DSA) are generally used to define the nidus. Although the AVM angioarchitecture can be visualized with superior resolution using rotational angiography (RA), the efficacy of integrating RA into the GKS treatment planning process has not been elucidated.METHODS: Using data collected from 25 consecutive patients with AVMs who were treated with GKS at the authors’ institution, two neurosurgeons independently created treatment plans for each patient before and after RA integration. For all patients, MR angiography, contrasted T1 imaging, CTA, DSA, and RA were performed before treatment. The prescription isodose volume before (PIV_B) and after (PIV_A) RA integration was measured. For reference purposes, a reference target volume (RTV) for each nidus was determined by two other physicians independent of the planning surgeons, and the RTV covered by the PIV (RTV_PIV) was established. The undertreated volume ratio (UVR), overtreated volume ratio (OVR), and Paddick’s conformal index (CI), which were calculated as RTV_PIV/RTV, RTV_PIV/PIV, and (RTV_PIV)²/(RTV × PIV), respectively, were measured by each neurosurgeon before and after RA integration, and the surgeons’ values at each point were averaged. Wilcoxon signed-rank tests were used to compare the values obtained before and after RA integration. The percentage change from before to after RA integration was calculated for the average UVR (%ΔUVRave), OVR (%ΔOVRave), and CI (%ΔCIave) in each patient, as ([value after RA integration]/[value before RA integration] − 1) × 100. The relationships between prior histories and these percentage change values were examined using Wilcoxon signed-rank tests.RESULTS: The average values obtained by the two surgeons for the median UVR, OVR, and CI were 0.854, 0.445, and 0.367 before RA integration and 0.882, 0.478, and 0.463 after RA integration, respectively. All variables significantly improved after compared with before RA integration (UVR, p = 0.009; OVR, p < 0.001; CI, p < 0.001). Prior hemorrhage was significantly associated with larger %ΔOVR_ave (median 20.8% vs 7.2%; p = 0.023) and %ΔCI_ave (median 33.9% vs 13.8%; p = 0.014), but not %ΔUVR_ave (median 4.7% vs 4.0%; p = 0.449).CONCLUSIONS: Integrating RA into GKS treatment planning may permit better dose planning owing to clearer visualization of the nidus and, as such, may reduce undertreatment and waste irradiation. Further studies examining whether the observed RA-related improvement in dose planning also improves the radiosurgical outcome are needed.

Stereotactic radiosurgery (SRS) is known to provide excellent tumor control with functional preservation for vestibular schwannomas (VS), but its efficacy in the other major intracranial schwannomas including trigeminal (TS), facial (FS), and jugular foramen schwannomas (JFS) has not been established yet due to their rarity. We retrospectively analyzed data of 514 consecutive patients who had intracranial schwannomas (460 VS, 22 TS, 7 FS, and 25 JFS) and underwent SRS. The 5- and 10-year tumor control rates were 97% and 94% for VS, 100% and 100% for TS, 80% and 80% for FS, and 100% and 80% for JFS. Radiation-induced complications included one hydrocephalus for TS (4.5%), no cases for FS (0%), and one hydrocephalus and one lower palsy for JFS (8.0%). Through matched cohort analysis between patients with VS and each of the non-VS, we found no statistical difference in tumor control and radiation-induced adverse events. SRS seems to provide long-term tumor control with functional preservation for TS, FS and JFS and the efficacies are similar to VS.