This Week in Neurosurgery — Jul 9, 2026

Welcome to This Week in Neurosurgery. This week we are covering ten notable papers spanning CSF dynamics and hydrocephalus surgery, advances in vascular neurosurgery and aneurysm management, and modern paradigms in neuro-oncology and spine surgery. Let us dive in.

We begin our first theme with a focus on idiopathic normal pressure hydrocephalus, a condition where diagnostic precision and clear expectations for recovery are paramount. In a prospective comparative study published in Acta neurochirurgica, Lars-Kristian Eide and Lashkarivand investigated the safety of obtaining a cortical brain biopsy during shunt surgery [1]. Many centers hesitate to perform these biopsies due to fears of causing an intracranial hemorrhage. To address this, the investigators prospectively enrolled 588 patients undergoing shunt surgery for idiopathic normal pressure hydrocephalus at their institution, allocating 294 patients to shunt surgery with a cortical brain biopsy and another 294 to shunt surgery alone. Postoperative cranial computed tomography scans were performed to detect symptomatic hemorrhages as well as asymptomatic minor radiological hemorrhages or infarctions. Symptomatic intracranial hemorrhage occurred in only two of the 588 patients, representing a mere 0.3% of the entire cohort, with exactly one case occurring in each group. This resulted in a risk difference of zero percent. Asymptomatic minor radiological findings were observed in 6.3% of patients and were similarly distributed between the two groups. Furthermore, the rate of intracranial hemorrhage requiring surgical intervention within three months postoperatively was 3.6%, with no differences observed between those who received a biopsy and those who did not. The clinical implication of this large prospective trial is clear: adding a cortical brain biopsy during routine shunt surgery does not increase the risk of hemorrhagic complications. For centers looking to gather valuable tissue for pathological or research purposes, this procedure can be performed with a high degree of safety.

In a complementary study also focusing on normal pressure hydrocephalus, Scalia and colleagues published a multicenter prospective study in World neurosurgery examining the early cognitive, functional, and behavioral changes that occur just one month after ventriculoperitoneal shunt surgery [2]. While long-term outcomes and gait improvements are well-documented, early neuropsychological recovery has remained poorly understood. The authors prospectively evaluated 73 patients before surgery and at a one-month postoperative follow-up using a comprehensive neuropsychological battery. This battery assessed activities of daily living, global cognition, executive functions, processing speed, and apathy. At the one-month mark, the researchers observed significant improvements across multiple domains. Patients demonstrated enhanced functional autonomy, with significant improvements in both basic and instrumental activities of daily living. Global cognition, measured by the Mini-Mental State Examination, and visuoconstructive abilities, assessed via the Clock Drawing Test, also showed significant gains. Additionally, processing speed and apathy improved significantly. However, executive functions, as measured by the Frontal Assessment Battery, did not show a statistically significant change. This suggests a highly domain-specific early response to cerebrospinal fluid diversion. For the practicing neurosurgeon, these findings provide critical data for patient counseling. We can confidently tell patients and their families that noticeable improvements in daily functioning, processing speed, and motivation or apathy can occur as early as four weeks postoperatively, whereas recovery of executive functions may lag behind and require more time.

Turning to our second theme, advances in vascular neurosurgery, we look at how patient behaviors and modern devices influence aneurysm management. We begin with a multicenter cross-sectional study published in the Journal of clinical neuroscience by Costa and colleagues, which examined the association of smoking with high-risk characteristics for the rupture of unruptured intracranial aneurysms [6]. Smoking is a well-established risk factor for aneurysm growth and rupture, but this study sought to determine if smoking is directly linked to specific high-risk anatomical features. The researchers analyzed 1,180 patients harboring a total of 1,795 unruptured aneurysms, categorizing them into current, former, and never smokers. After adjusting for age, previous subarachnoid hemorrhage, and hypertension, the authors found that ever smokers had about a 60% increase in the odds of having a larger aneurysm, defined as 7 millimeters or greater, and a 29% increase in the odds of irregular morphology. When comparing current smokers specifically to never smokers, the associations were even more pronounced: current smokers had a 77% increase in the odds of having a larger aneurysm and a 57% increase in the odds of having multiple aneurysms. Most importantly, the study demonstrated a clear dose-dependent relationship. For every 10 pack-years of smoking in current smokers, the odds of having multiple aneurysms increased by 17%, and the odds of having a larger aneurysm increased by 14%. This dose-dependent correlation highlights that smoking does not just act as an independent trigger for rupture, but actively drives the development of dangerous anatomical features. This reinforces the absolute necessity of aggressive, structured smoking cessation counseling in the clinic, as every pack-year avoided directly mitigates the development of high-risk aneurysm characteristics.

Next, we look at how we treat these aneurysms once they are identified. Writing in Acta neurochirurgica, Jee and colleagues presented extended follow-up results from a single-center cohort evaluating the Surpass Evolve flow diverter [9]. This second-generation device was designed to improve procedural performance compared to earlier flow diverters. The investigators compared a prospective cohort of 67 patients treated with the Surpass Evolve to a retrospective control cohort of 53 patients treated with first-generation devices, specifically the Surpass Streamline and the Pipeline Embolization Device. At the last follow-up, complete aneurysm occlusion was achieved in 79.1% of the Surpass Evolve cohort. Crucially, the Surpass Evolve group experienced significantly fewer major strokes, at just 1.5% compared to over 13% in the control group. Aneurysm enlargement was also dramatically lower in the Surpass Evolve group, occurring in only 3.0% of patients compared to nearly 23% of historical controls. After adjusting for baseline variables using propensity score matching and multivariate regression, the use of the Surpass Evolve was independently associated with an 86% reduction in the odds of aneurysm enlargement. Furthermore, procedures using the Surpass Evolve had significantly shorter execution times and required balloon angioplasty less frequently. These findings indicate that the design refinements of second-generation flow diverters translate directly into safer procedures, shorter operative times, and superior long-term control of aneurysm volume, solidifying their role as a highly effective option for endovascular reconstruction.

In the realm of ischemic prevention, Wan and colleagues published a study in World neurosurgery investigating how to predict and prevent cerebral hyperperfusion syndrome after carotid artery stenting [5]. This syndrome is a rare but devastating complication, and we currently lack reliable, widely accessible tools to stratify patient risk. The authors conducted a prospective cohort study of 128 patients with severe symptomatic carotid stenosis of 70% or greater who underwent elective carotid artery stenting. All patients underwent preoperative magnetic resonance imaging to grade the T2-FLAIR hyperintense vessel sign, or HVS. Patients were stratified into low-risk, intermediate-risk, and high-risk groups based on their HVS grade, and managed with a tailored, risk-stratified perioperative protocol. This protocol included session-based staged angioplasty and tiered systolic blood pressure control. The overall 30-day incidence of symptomatic hyperperfusion syndrome was 6.3%, but it followed a strict stepwise progression across the risk groups: 0% in the low-risk group, 5.3% in the intermediate-risk group, and 24% in the high-risk group. Regression analysis revealed that an HVS grade of 2 or higher was associated with an almost seven-fold increase in the odds of developing hyperperfusion syndrome, while an incomplete circle of Willis increased the odds nearly four-fold. There were no differences in overall procedural complications compared to historical cohorts, and the overall hyperperfusion rate was numerically lower. This study demonstrates that preoperative T2-FLAIR HVS grading is a highly reliable and practical prognostic marker. Implementing an HVS-guided, risk-stratified management protocol allows neurosurgeons to identify high-risk patients preoperatively and apply aggressive blood pressure control and staged angioplasty to prevent this catastrophic complication.

Our third theme focuses on neuro-oncology, a field undergoing rapid technological evolution and facing complex systems-level challenges. We begin with a comprehensive review in the Journal of neuro-oncology by Faraj and colleagues, who outline the expanding frontiers of precision glioma surgery [10]. Diffuse gliomas present an ongoing surgical challenge due to their highly infiltrative nature and proximity to eloquent areas. The authors organize current and emerging technologies into two main clinical goals: optimizing tumor delineation and enhancing local therapeutic delivery. For tumor delineation, the gold standard remains awake craniotomy with direct electrical stimulation, which consistently increases resection rates while preserving function. This is increasingly combined with fluorescence-guided surgery using 5-ALA and fluorescein, intraoperative magnetic resonance imaging to correct for brain shift, and augmented reality navigation. Furthermore, emerging tissue characterization technologies like stimulated Raman histology, confocal laser endomicroscopy, and artificial intelligence-based platforms such as FastGlioma and DeepGlioma are enabling rapid, real-time molecular diagnoses in the operating room without the delays of conventional frozen sections. To bypass the blood-brain barrier, emerging local therapeutic delivery methods include low-frequency focused ultrasound, convection-enhanced delivery, and laser interstitial thermal therapy, which can disrupt the blood-brain barrier to allow therapeutic agents to penetrate the brain parenchyma. Additionally, technologies like intraoperative brachytherapy with Cesium-131 tiles deliver highly conformal radiation directly to the cavity at the time of resection. This review emphasizes that the future of glioma surgery lies in the deliberate, phase-organized integration of these complementary diagnostic and therapeutic tools to maximize resection and deliver targeted therapies directly to the tumor margin.

To see how intraoperative imaging technologies perform in real-world practice, we look at a study in Operative Neurosurgery by Biswas and colleagues, who evaluated the clinical utility of intraoperative ultrasound during endoscopic endonasal resection of pituitary adenomas [8]. As endoscopic techniques have advanced, smaller and more slender ultrasound probes have been developed to assist in tumor localization and residual detection. The authors retrospectively analyzed 79 cases involving 83 surgeries where intraoperative ultrasound was utilized. Gross total resection was achieved in 77.1% of cases, with an average residual volume of 2.9 cubic centimeters. Notably, the real-time feedback from the intraoperative ultrasound prevented the premature termination of surgery in 10 cases, directly enabling gross total resection in all 10. However, when compared to postoperative magnetic resonance imaging, the intraoperative ultrasound missed residual disease in 13 cases, representing about 16% of the cohort, with an average missed residual volume of 0.7 cubic centimeters. The lateral compartment of the cavernous sinus was the most common site where residual tumor eluded detection. While the specificity of the ultrasound in detecting residual disease was excellent at 98.5%, its sensitivity was quite low at 27.8%. The ability of the ultrasound to identify residual disease was significantly compromised in giant adenomas and in cases with extension into both the cavernous sinus and the suprasellar cistern. The take-home message for the skull base surgeon is that while intraoperative ultrasound is a highly valuable, cost-effective tool that can prevent early termination of a resection, its low sensitivity means we cannot rely on a negative ultrasound scan alone to confirm complete tumor clearance, particularly in large or anatomically complex adenomas.

In spinal oncology, determining which patients require surgical stabilization remains a challenge, particularly in the intermediate zone of the Spinal Instability Neoplastic Score, or SINS. Writing in World neurosurgery, Krystkiewicz and colleagues analyzed how this intermediate category, which spans scores from 7 to 12, is operationalized in real-world clinical practice [7]. The authors retrospectively reviewed 103 surgical cases of spinal metastases. Within the intermediate SINS cohort of 78 patients, 78% underwent instrumented stabilization, while 22% underwent decompression alone. Interestingly, the total SINS score did not differ between the stabilized and non-stabilized groups, with a median score of 10 in both, and the total score demonstrated poor discrimination with an area under the curve of only 0.52. Instead, the decision to perform instrumented stabilization was strongly associated with clinical factors: stabilized patients were significantly more likely to have a symptom duration of more than 14 days, a preserved neurological status represented by Frankel grade E, and a better functional status. Conversely, having three or more spinal metastases was associated with a lower likelihood of instrumentation. This study highlights that the intermediate SINS score represents a highly heterogeneous clinical gray zone. Rather than relying on rigid total SINS cutoffs, spine surgeons should make stabilization decisions based on an integrated, patient-specific clinical-radiological assessment.

Managing intracranial metastatic disease also requires precise risk stratification, particularly regarding the risk of intratumoral hemorrhage. In a retrospective study published in the Journal of neuro-oncology, Grossenbacher and colleagues analyzed 806 patients with brain metastases to identify specific risk factors for intratumoral hemorrhage and develop a predictive model [3]. Intratumoral hemorrhage occurred in nearly 12% of these patients. The researchers identified several independent risk factors for hemorrhage, including the presence of multiple brain metastases, which roughly doubled the risk, and antiplatelet therapy, which also roughly doubled the risk. Primary tumor histologies of melanoma and seminoma were associated with a five-fold and seven-fold increase in the risk of hemorrhage, respectively. Surprisingly, traditional bleeding risk factors, such as anticoagulation, cardiovascular risk factors, radiotherapy, chemotherapy, and anti-VEGF therapy, were not associated with an increased risk of hemorrhage. The authors developed a novel, brain metastasis-specific risk score using these factors, which demonstrated a significant discrimination with an area under the curve of 0.75, vastly outperforming the traditional cardiovascular HAS-BLED score, which had an area under the curve of only 0.54. This study demonstrates that bleeding in brain metastases is primarily driven by tumor-specific biology and antiplatelet therapy rather than systemic cardiovascular risk factors. Clinicians should abandon cardiovascular bleeding scores in this population and instead utilize tumor-specific characteristics and antiplatelet status to guide clinical decisions and discuss prognosis with patients.

Finally, we must examine how the organization of our healthcare delivery systems impacts the survival of our most vulnerable oncological patients. Ghaith and colleagues, writing in the Journal of neuro-oncology, evaluated the impact of care fragmentation on survival in over 42,000 patients with glioblastoma [4]. Care fragmentation was defined as receiving surgery and adjuvant therapy at different medical facilities, a scenario that affected 53% of the study population. The authors found that care fragmentation was associated with significant treatment delays, including longer times to initiate radiation and chemotherapy, and a higher rate of delayed adjuvant therapy beyond 42 days post-surgery. Patients who experienced care fragmentation had a shorter median overall survival of 14.6 months compared to 15.2 months for those with unified care, and fragmentation was independently associated with a small but statistically significant increase in the risk of death. Interestingly, subgroup analysis revealed that while care fragmentation was associated with worse survival at academic and integrated network facilities, it was actually associated with improved survival at community programs. This suggests that in the community setting, fragmentation may reflect purposeful, highly appropriate referrals to specialized academic centers. However, for patients treated within academic or integrated networks, care fragmentation represents a breakdown in coordination. Neurosurgeons and oncology teams must work together to build seamless care pathways, particularly when transitioning patients from surgical resection to adjuvant oncology, to minimize treatment delays and optimize survival outcomes.

If you only have time for one paper this week, make it the prospective comparative study by Lars-Kristian Eide and Lashkarivand in Acta neurochirurgica on the safety of cortical brain biopsies during shunt surgery [1]. This study provides high-quality, prospective evidence that performing a concomitant cortical biopsy does not increase the risk of symptomatic or asymptomatic hemorrhage, giving neurosurgeons the confidence to safely obtain tissue for histopathological or molecular analysis during routine shunt placement.

Here are the key takeaways from this week in Neurosurgery: First, performing a cortical brain biopsy during shunt surgery for idiopathic normal pressure hydrocephalus is safe and does not increase the risk of symptomatic or asymptomatic intracranial hemorrhage [1]. Second, patients undergoing ventriculoperitoneal shunt surgery for normal pressure hydrocephalus can expect early improvements in functional autonomy, processing speed, and apathy within one month, though executive functions may take longer to recover [2]. Third, the Surpass Evolve flow diverter offers superior safety and efficacy compared to earlier-generation devices, demonstrating high complete occlusion rates and significantly fewer major strokes and cases of aneurysm enlargement [9]. Fourth, when managing brain metastases, use tumor-specific risk factors—including multiplicity, melanoma or seminoma histology, and antiplatelet therapy—rather than standard cardiovascular bleeding scores to stratify intratumoral hemorrhage risk [3]. And finally, care fragmentation is highly prevalent in glioblastoma management and is independently associated with treatment delays and worse overall survival, highlighting the critical need for seamless care coordination between surgical and oncology centers [4].

That's your roundup for This Week in Neurosurgery. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.

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