Electroencephalogram-based objective assessment of surgical skill remains underexplored in neurosurgical training. We investigated whether electroencephalogram spectral features can discriminate surgical expertise during microvascular anastomosis training and identify neural markers associated with task performance. We conducted a prospective observational study in 29 right-handed male participants (neurosurgeons, residents, and medical students) performing a 10-minute interrupted anastomosis on a 1.0-mm hydrophilic tube under an operating microscope. Electroencephalogram under the 10-20 system was recorded during the task, segmented into 3 procedural phases (needle insertion, knot tying, thread cutting), and epoched into 2-second windows. Participants were stratified post hoc into Skilled (≥6 units) and Less-skilled (≤5 units) groups based on task throughput. Power spectral density from 4 to 22 Hz was summarized into 6 frequency bands across 7 regions of interest, yielding 42 features per epoch. Classification models were trained using a nested cross-validation framework with a leave-one-subject-out outer loop, and epoch-level predictions of Skilled-class probability were aggregated into subject-level scores, from which phase-specific area under the receiver operating characteristic curve values were calculated. A total of 7,201 artifact-free epochs (76.3%) were included. Subject-level discrimination performance varied by phase, with area under the receiver operating characteristic curve values of 0.736 for needle insertion, 0.678 for knot tying, and 0.788 for thread cutting. Feature attribution and group-level analyses consistently revealed increased frontal alpha power and reduced midline theta power in Skilled participants, particularly during needle insertion and thread cutting. These findings support the feasibility of electroencephalogram-based objective assessment of microsurgical expertise and identify candidate neural markers of proficiency.

Although vestibular schwannomas are common, benign intracranial tumors with similar histopathology originating from other nerves are rare. For non-vestibular schwannomas, surgery remains standard treatment, albeit associated with morbidities. Radiotherapy offers a safe and effective alternative treatment modality. Nevertheless, the previous publication had a limited follow-up period and included outcomes from both stereotactic radiosurgery and radiotherapy. To investigate our long-term results, a retrospective chart review was conducted in patients who received stereotactic radiotherapy for non-vestibular schwannomas using hypo- or conventional fractionated regimen, from 2000 to 2020, with a minimum follow-up of 24 months. Treatment failure was defined as a ≥20% tumor growth, necessitating additional treatment. Radiation-induced sequelae were also observed. During the study period, 66 patients underwent stereotactic radiotherapy for non-vestibular schwannomas. After excluding non-eligible cases, 57 patients were analyzed. The tumor's median volume was 6.5 milliliters (interquartile range 2.85-11.04). Hypofractionated stereotactic radiotherapy, delivered in 3, 5, or 10 sessions, was used in 53 patients, while 4 patients received 25-day conventional fractionated stereotactic radiotherapy. With a median follow-up of 121 months (interquartile range 54-159), tumor control was achieved in 55 subjects (96.5%), with surgical resection necessary in 2 patients after radiation. The actuarial control rates were 100%, 97%, and 92% at 5, 10, and 15 years, respectively. Tumor shrinkage was observed in 27 individuals (47.37%). Regarding complications, one patient reported worsening of facial numbness after radiation. With extended follow-up compared to prior reports, our long-term outcomes support the efficacy and safety of hypo- and conventional fractionated stereotactic radiotherapy for non-vestibular schwannomas.

Anterior skull base meningiomas are often supplied by ethmoidal arteries branching from the ophthalmic artery. Preoperative embolization can reduce intraoperative bleeding and facilitate safer resection; however, its use is limited by the risk of visual complications. This study evaluates the safety, effectiveness, and technical considerations of embolization via the ophthalmic artery using n-butyl-2-cyanoacrylate (n-BCA). This retrospective study included patients with meningiomas who underwent preoperative embolization via the ophthalmic artery between 2017 and 2025. Demographics, clinical characteristics, technical details, surgical outcomes, and complications were analyzed. Five patients (median age of 58 years) underwent embolization. Two meningiomas were at the olfactory groove, two at the planum sphenoidale, and one at the sphenoid ridge (median diameter of 41.9 mm). Unilateral embolization was performed in four patients; one underwent bilateral embolization. The working angle was set at an anterior oblique and cranial position to optimize visualization of the central retinal and ethmoidal arteries. The microcatheter was advanced beyond the central retinal artery to cannulate the ethmoidal artery and to position it near the tumor. N-BCA, heated to 80°C, was used at concentrations ranging from 20% to 33%. All patients showed reduced tumor blush without neurological complications, including vision loss or impairment. Simpson grade II-III resection was achieved in all patients, with a median intraoperative blood loss of 350 mL. One patient demonstrated postoperative improvement in the visual field defects. Embolization via the ophthalmic artery can be safely performed to facilitate the resection of skull base meningiomas using standardized techniques and n-BCA.

The cerebrospinal fluid tap test is commonly used to select shunt candidates in idiopathic normal pressure hydrocephalus; however, it is invasive and has limited predictive value, as a substantial proportion of patients who tested positive on tap test do not improve after shunt surgery. This limitation highlights the need for noninvasive imaging markers to support preoperative decision-making. We retrospectively analyzed 80 patients with ventriculomegaly evaluated at a single center between 2014 and 2022, including 40 patients with idiopathic normal pressure hydrocephalus who tested positive on tap test and underwent shunt surgery, and 40 control patients with ventriculomegaly without idiopathic normal pressure hydrocephalus. Shunt responsiveness was defined as an improvement of at least 1 point on the idiopathic normal pressure hydrocephalus grading scale at 6-12 months. Evans index, z-Evans index, callosal angle, disproportionately enlarged subarachnoid-space hydrocephalus, and the coronal hydrocephalic index (Eo index = z-Evans index/Evans index) were measured on magnetic resonance imaging. Among patients who underwent shunt surgery, 28/40 (70%) demonstrated clinical improvement. In univariate analyses within the shunted subgroup, Evans index and z-Evans index were not associated with shunt responsiveness, whereas callosal angle, disproportionately enlarged subarachnoid-space hydrocephalus, and the coronal hydrocephalic index were significant discriminators. The discriminative performance of the coronal hydrocephalic index was comparable to callosal angle and was complementary to disproportionately enlarged subarachnoid-space hydrocephalus. In the full ventriculomegaly cohort, the coronal hydrocephalic index also discriminated patients with idiopathic normal pressure hydrocephalus who were shunt-responsive from others who were not. Receiver operating characteristic analyses were used to derive within-sample cut-off values for scenario-based clinical decision support. The coronal hydrocephalic index is a simple, noninvasive magnetic resonance imaging-derived parameter that may support stratification of shunt responsiveness in patients with idiopathic normal pressure hydrocephalus, and requires external validation in independent cohorts before broader clinical application.

Seizures following aneurysmal subarachnoid hemorrhage are clinically significant complications that may adversely affect neurological outcomes. Clazosentan sodium has been shown to reduce cerebral vasospasm and delayed cerebral ischemia; however, seizure occurrence during acute hospitalization in patients treated with clazosentan has not been well characterized. This multicenter retrospective cohort study included patients with aneurysmal subarachnoid hemorrhage who underwent surgical clipping or endovascular coiling and received clazosentan sodium for vasospasm prevention. Patients were followed from aneurysmal subarachnoid hemorrhage onset to hospital discharge. Early seizures were defined as acute symptomatic seizures occurring within 7 days of onset, and late seizures defined as seizures occurring on or after day 8; since follow-up was limited to hospitalization, late seizures were classified as in-hospital late seizures. Among 264 patients, early seizures occurred in eight patients (3.0%) and in-hospital late seizures in 4 (1.5%). The incidences of angiographic vasospasm and delayed cerebral ischemia were 17.0% and 16.0%, respectively. All patients received clazosentan therapy, and no non-clazosentan-treated control group was included. Although the incidences of seizures during hospitalization were relatively low compared with prior reports, differences in definitions, follow-up duration, and study design limit direct comparison. Given the single-arm design and limited observation period, causal relationships could not be inferred. These findings provide descriptive data on seizure occurrence during acute hospitalization in the contemporary era of vasospasm prevention, and should be interpreted as hypothesis-generating.

Cytotoxic lesions of the corpus callosum are increasingly recognized after aneurysmal subarachnoid hemorrhage, but their prognostic value for shunt-dependent chronic hydrocephalus remains uncertain. We conducted a two-center retrospective cohort study of consecutive patients with aneurysmal subarachnoid hemorrhage who underwent brain magnetic resonance imaging within 7 days of onset. Cytotoxic lesions of the corpus callosum were defined as diffusion restriction with corresponding apparent diffusion coefficient reduction and were classified as none, small-type, or large-type using prespecified morphological criteria. The primary outcome was shunt-dependent chronic hydrocephalus, and the secondary outcome was unfavorable functional outcome (modified Rankin Scale score 3-6 at discharge or at approximately day 60). Associations were evaluated using prespecified multivariable logistic regression. As a sensitivity analysis, binary intraventricular hemorrhage was replaced by the Graeb score to account for quantitative intraventricular hemorrhage burden. Among 230 patients, 68 (29.6%) had cytotoxic lesions of the corpus callosum (small-type, 44 [19.1%]; large-type, 24 [10.4%]), and 62 (27.0%) developed shunt-dependent chronic hydrocephalus. After adjustment, small-type cytotoxic lesions of the corpus callosum (vs none) were associated with shunt-dependent chronic hydrocephalus (adjusted odds ratio 2.99, 95% confidence interval 1.31-6.83; p = 0.009) and unfavorable functional outcome (adjusted odds ratio 4.85, 95% confidence interval 1.79-13.93; p = 0.002). For large-type cytotoxic lesions of the corpus callosum, point estimates for both outcomes were elevated, but the 95% confidence interval included 1.0. Modified Fisher grade and Graeb score differed significantly across cytotoxic lesion of the corpus callosum subtypes (both p < 0.001). Early cytotoxic lesion of the corpus callosum assessment, particularly identification of small-type lesions, was associated with shunt-dependent chronic hydrocephalus and unfavorable outcome after aneurysmal subarachnoid hemorrhage.

Debulking surgery is a treatment option for optic hypothalamic pilocytic astrocytoma. This study aimed to clarify the changes in magnetic resonance imaging following debulking surgery. We retrospectively reviewed the clinical and magnetic resonance imaging data of patients with optic hypothalamic pilocytic astrocytoma who underwent debulking surgery at Tohoku University Neurosurgery between January 2008 and August 2024. Tumor volume was measured using two-dimensional contrast-enhanced T1-weighted images before surgery, immediately postoperatively, up to 6 months, and beyond 6 months after surgery. These volumes were designated as V1, V2, V3, and V4 (mL), respectively. Time intervals from the day of surgery to the days when V2, V3, and V4 were assessed were defined as T2, T3, and T4 (days). An increase in tumor volume of 140% or greater compared with V2 was classified as enlargement according to the Response Assessment in Neuro-Oncology criteria 2.0. Nineteen debulking surgeries were performed on 10 patients. The median extent of resection was 55.6%. In nine of 14 surgeries without immediate adjuvant therapy, the ratio V3/V2 exceeded 140%. Despite this enlargement, no neurological deficits developed in these patients between T2 and T3. 5 patients were monitored without additional treatment, and 3 exhibited spontaneous tumor volume reductions by T4. In conclusion, early tumor enlargement commonly occurs within 6 months following debulking surgery for optic hypothalamic pilocytic astrocytoma; however, this enlargement can be transient in some cases. These findings suggest that a watchful waiting approach is a viable option for asymptomatic early enlargement after debulking surgery for OHPA.

Cervical kyphosis after an intradural spinal tumor is a significant complication, especially for high cervical tumors that require a C2 laminectomy. This study presents our new surgical approach: a C2 laminoplasty with reconstruction of the cervical deep extensor muscles. We investigated whether the C2 reconstruction technique contributes to maintaining cervical alignment.

Consecutive adult patients (≥18 years) who underwent the C2 reconstruction technique for intradural high cervical tumors between 2015 and 2024 were included. The preoperative and postoperative C2/7 angles were compared.

A total of 21 patients (median age 50 years, interquartile range 44-75 years; 10 men) were included. Histological diagnoses included 11 intramedullary and 10 intradural extramedullary tumors, with schwannoma (29%) and ependymoma (24%) being the 2 most frequent tumors. The tumor center was located between C1 and C3 in 90% of patients, and the median tumor size was 29 mm. The C2 spinous processes were split in the midline from the C2 lamina without detaching the attached muscles. At the end of surgery, the C2 lamina was fixed, and the bilateral C2 spinous processes were sutured back to the C2 lamina along with their attached muscles. The pre- and postoperative C2/7 angles did not significantly differ (11.5 vs 10.6°, p = 0.65). No patients had cervical kyphosis that required instrumented fusion at the median follow-up of 37 months (interquartile range 14-63 months).

For patients with cervical spinal tumors, the reconstruction of the C2 deep extensor muscles may contribute to maintaining cervical alignment.