Hawkes, Maximiliano A.

Abstract Objective. Modern stereotactic neurosurgery increasingly relies on bilateral and multi-trajectory workflows (e.g. deep brain stimulation (DBS), stereoelectroencephalography (sEEG)), which can exceed the reach and flexibility of conventional frame-based systems. Building on our skull-mounted Navinetics D1 platform, we present a stereotactic frame (Navinetics E1) intended to expand the reachable work envelope, enable independent bilateral targeting, and preserve mechanical accuracy and patient comfort. Approach. We designed the Navinetics E1 stereotactic frame using a center-of-arc architecture with five degrees of freedom per hemisphere ( X, Y, Z , Arc, Collar) and two operating modes: Double Arm (independent left/right arms for simultaneous bilateral targeting) and Single Arm (mechanically coupled arms). The system was designed in CAD and fabricated via carbon fiber-reinforced polylactic acid (PLA-CF) additive manufacturing. Collision-aware MATLAB simulations quantified work volume and admissible approach directions. Mechanical targeting accuracy was evaluated on a ground truth fixture (GTF) platform, with mixed-effects modeling to assess target- and trajectory-dependent effects. Operative feasibility was assessed through an intraoperative entry-point replication test relative to the D1 system. Main results. Compared to the D1, the E1 frame significantly expanded key geometric ranges, including, most notably, 0°–360° Collar rotation and posterior Y -axis reach, thereby increasing the work volume and trajectory range by factors of 3.39 and 8.42, respectively. Mean GTF targeting deviation was 0.78 ± 0.38 mm in Single Arm mode and 1.23 ± 0.36 mm (right) and 1.65 ± 0.47 mm (left) in Double Arm mode. Entry-point replication across 17 clinical cases achieved 76.5% success in overlapping the reference points, providing preliminary evidence of feasibility under real operative conditions. Significance. The E1 frame extends a compact skull-mounted platform to support broader stereotactic reach and trajectory while enabling independent bilateral workflows. These features may reduce intraoperative reconfiguration for complex DBS and sEEG cases. Future work will focus on increasing structural stiffness, improving angular readout/setting, and developing MRI-compatible implementations.

Objectives: Elevated intracranial pressure (ICP) remains a challenge and immediate danger in patients with acute brain injury. Current literature supports the use of a single hyperosmolar agent to reduce ICP. However, the efficacy and safety of overlapping hyperosmolar agents have not been evaluated. The objectives of this study are to analyze the ICP lowering effects and evaluate the safety profile of overlapping hyperosmolar therapy. Materials and Methods: This single-center, retrospective study included adults (≥18 y) admitted to the Neurosciences Intensive Care Unit between May 2018 and September 2024 with acute brain injury leading to intracranial hypertension refractory to a single hyperosmolar agent and an ICP monitor. They received overlapping doses of mannitol and hypertonic sodium approximately every 3 hours. We evaluated the impact of overlapping hyperosmolar therapy on ICP. Safety outcomes included acute kidney injury incidence, electrolyte disturbances, and volume status changes. Results: Forty-six patients were included in this study with a median (IQR) age of 46.5 (35.9, 62.4) years. Median (IQR) dose of mannitol was 40.1 (34.6, 50.0) g, while median (IQR) dose of hypertonic sodium was 120 (90, 125) mEq. About 86% of patients experienced a decrease in ICP after initiation of overlapping hyperosmolar therapy. Six acute kidney injuries occurred, and 7 patients experienced pulmonary edema. Median (IQR) peak sodium, chloride, and osmolar gap values were 149 (144, 155) mEq/L, 115 (111, 119) mEq/L, and 5.7 (0.7, 9.0) mOsm/kg. Conclusions: Overlapping hyperosmolar therapy may provide a transient ICP reduction without excessive adverse effects in patients with refractory ICP to a single hyperosmolar agent.

Abstract Background and aims Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by recurrent thunderclap headaches and reversible multifocal cerebral arterial narrowing. Although prognosis is generally favorable, a subset of patients develops cerebrovascular complications that may drive long-term disability; this study aims to identify factors associated with these complications. Methods We retrospectively reviewed 348 patients with probable or definite RCVS evaluated at Mayo Clinic between 2010-2023. Diagnostic criteria were adapted from RCVS2 and ICHD-3. The primary outcome was a composite of ischemic stroke, non-aneurysmal subarachnoid hemorrhage, and intracerebral hemorrhage; secondary outcome was poor functional status (modified Rankin Scale ≥2 within one year). Univariable and multivariable logistic regression identified predictors of these outcomes. Results Cerebrovascular complications occurred in 37.6% of patients and were the strongest determinant of poor functional outcome (aOR 5.05, 95% CI 2.04–12.51). On multivariable analysis, older age (aOR per year 1.02, 95% CI 1.00–1.04) and angiographically visible vasoconstriction (aOR 3.14, 95% CI 1.85–5.33) were independently associated with higher risk of cerebrovascular complications, whereas male sex (aOR 0.55, 95% CI 0.30–0.99), thunderclap headache at presentation (aOR 0.30, 95% CI 0.11–0.86), and sexual activity as a trigger (aOR 0.19, 95% CI 0.08–0.42) were associated with lower risk of these complications. Conclusions Cerebrovascular complications are common and strongly predict disability. Angiographic vasoconstriction and older age identify patients at higher risk, whereas thunderclap headache and sexual activity as a trigger mark a more benign phenotype. These findings may guide early risk stratification and help tailored monitoring strategies. Conflict of interest Name of author: nothing to disclose.

Background Resuming anticoagulation in patients with mechanical heart valves after intracranial hemorrhage presents a clinical dilemma. The optimal timing must balance the risk of thromboembolism against hemorrhagic expansion. Prior studies have addressed this issue, but most were limited by small sample sizes. This systematic review and meta‐analysis aimed to determine the optimal timing for anticoagulation resumption in this population. Methods We conducted a systematic review and meta‐analysis using PubMed, Embase, Web of Science, and Scopus from database inception to August 23, 2024. The target population included adults with intracranial hemorrhage who required anticoagulation for mechanical heart valves. Results Thirteen studies involving 788 patients were included: 12 retrospective and 1 prospective observational study. While off anticoagulation, 32 patients developed ischemic stroke, with a pooled event rate of 5.23% (95% CI, 3.80–7.20%) and negligible heterogeneity ( I 2 = 0%). The pooled average time to stroke was 8.08 days (95% CI, 1.99–14.18). After anticoagulation resumption, 73 patients experienced hemorrhagic recurrence, corresponding to a pooled event rate of 10.95%, with nonsignificant heterogeneity ( I 2 = 40.4%). Conclusions Withholding anticoagulation for up to 7 days after intracranial hemorrhage in patients with mechanical heart valves appears relatively safe. Hemorrhagic recurrence after resumption was more common than ischemic stroke during interruption. However, the included studies were observational and carried serious or critical risk of bias. Prospective multicenter studies, and ideally randomized trials, are needed to provide more definitive evidence.

BACKGROUND AND OBJECTIVES: External ventricular drain (EVD) placement is the most commonly performed bedside emergent neurosurgical procedure. However, catheter misplacement occurs in approximately 25% of cases, potentially resulting in neurological injury or the need for repositioning, highlighting the need for safer and more accurate placement techniques. This review aims to (1) summarize technological innovations developed to enhance the accuracy and safety of bedside EVD placement, (2) evaluate their reported benefits and limitations, and (3) identify key barriers to their clinical implementation in critical care settings. METHODS: We conducted a systematic review of PubMed, Embase, and Scopus combining terms related to EVD placement and assistive technologies. All the studies evaluated EVD placement using simulations, phantoms, cadavers, and patient procedures conducted at the bedside and in the operating room. RESULTS: We identified 3898 records, and 76 studies met the inclusion criteria. Of these, 30 studies compared stereotactic systems, ultrasound guidance, frameless neuronavigation, and augmented or mixed reality technologies to the freehand technique. These studies consistently reported improved accuracy with advanced systems although complication rates and procedural times were variably reported. An additional 35 and 12 studies evaluated nonimmersive and immersive technologies, respectively, in noncomparative settings. Most of these demonstrated high first-pass success and mean tip deviations under 3 mm. Variability in the definitions of accuracy and procedural metrics limited data synthesis, but the overall findings suggest a promising trajectory for technology-assisted EVD placement. CONCLUSION: Assistive technologies for EVD placement show potential to improve accuracy and safety over the freehand technique. These early successes signal potential to improve bedside neurosurgical care. Realizing this promise will require future studies to standardize accuracy metrics, report time, and safety outcomes consistently and validate performance in real-world critical care settings.

OBJECTIVE Achieving submillimetric accuracy in stereotactic neurosurgery remains critical for safely targeting deep brain structures. Current workflows rely on intraoperative CT to register stereotactic frames to preoperative imaging, but this introduces additional radiation exposure, cost, and workflow complexity. Three-dimensional surface scanning (3DSS) potentially offers a fast radiation-free alternative capable of capturing detailed craniofacial anatomy and frame geometry. Therefore, the aim of this cadaveric study was to evaluate the feasibility, accuracy, and navigational compatibility of integrating 3DSS into stereotactic workflows as a potential replacement for intraoperative CT. METHODS A human cadaveric head was imaged with both thin-slice CT and structured-light 3DSS after mounting stereotactic frame components. CT, 3DSS, and computer-aided design (CAD) models were registered using a multistep point cloud alignment pipeline involving the fast point feature histogram, the random sample consensus method, and the iterative closest point algorithm. Accuracy was assessed using surface deviation error, root mean square error (RMSE), and fiducial registration error within a commercial neuronavigation platform. RESULTS Fusion of the 3D facial scan with CT provided a mean surface deviation error of approximately 0.4 mm. Registration of the 3DSS-derived N-bar localizer to its CAD reference model produced a frame alignment RMSE of 1.3 mm. Within the navigation system, the 3DSS-based workflow achieved a mean fiducial registration error of 0.14 mm (range 0.02–0.20 mm), outperforming the conventional CT-based method (mean error 0.20 mm, range 0.09–0.40 mm). CONCLUSIONS The 3DSS-based method enabled precise submillimetric stereotactic registration without the need for intraoperative CT, reducing radiation exposure and operative complexity. This workflow is fully compatible with existing navigation systems and could serve as a practical radiation-free alternative in stereotactic neurosurgery. Future work will focus on automating frame detection, incorporating artificial intelligence–driven fusion methods, and validating this approach in live surgical settings.