Hani Ridwan

Background/Objectives: Chronic subdural hematoma (cSDH) is an increasingly prevalent neurosurgical condition in the aging population. Burr hole craniotomy (BHC) with irrigation and postoperative drainage represents the evidence-based standard of care, yet recurrence rates remain substantial. Twist drill craniostomy (TDC), a minimally invasive bedside procedure performed under local anesthesia, offers theoretical advantages for frail patients but has been largely abandoned due to concerns regarding incomplete evacuation and recurrence. This study aimed to identify the predictors of a successful TDC outcome and to compare the recurrence rates between TDC and BHC. Methods: We performed a retrospective cohort study of consecutive patients undergoing surgical treatment for radiologically confirmed cSDH at RWTH Aachen University Hospital between 2015 and 2023. Hematoma morphology was classified using an extended CT-based architecture system and grouped into homogeneous, organized, sedimented, or subacute categories. The primary endpoint was recurrence requiring surgical reintervention. Multivariable logistic regression was used to identify independent predictors of recurrence among patients discharged after definitive TDC. Propensity score matching was performed to compare recurrence rates between TDC and BHC while adjusting for baseline demographic, clinical, and radiographic differences. Results: Among 178 patients initially treated with TDC, 56 (31.5%) were discharged without conversion to BHC. Late recurrence occurred in 26 of 56 patients (46.4%) treated definitively with TDC. In multivariable analysis, homogeneous hematoma architecture was the only independent predictor of recurrence (adjusted OR 4.48, 95% CI 1.10–22.07, p = 0.037). Propensity score matching yielded 48 well-balanced pairs of TDC and BHC patients. Recurrence rates remained significantly higher after TDC compared with BHC (42.6% vs. 17.0%, p = 0.012), as confirmed by conditional logistic regression (adjusted OR 3.20, 95% CI 1.17–8.73). Conclusions: Twist drill craniostomy may provide definitive treatment in carefully selected patients but is associated with substantially higher recurrence rates than burr hole craniotomy, particularly in homogeneous hematomas. Burr hole evacuation remains the preferred standard approach, while optimized drainage protocols and architecture-guided selection may define a limited role for TDC in high-risk patients.

Objective: Chronic subdural hematoma (cSDH) is a common neurosurgical condition with rising incidence in the aging population. Recurrence after surgical evacuation remains frequent, affecting up to one third of patients. Prior studies have proposed an association between ABO blood type and recurrence risk, though the findings are inconsistent. This study aimed to determine whether ABO blood group independently predicts cSDH recurrence after adjusting for clinical and radiological risk factors and to contextualize these findings in the context of previously published studies. Methods: We conducted a retrospective cohort study of all consecutive patients surgically treated for cSDH at University Hospital RWTH Aachen between 2015 and 2023. Clinical, laboratory, and imaging data, including hematoma volume, laterality, and architecture, were extracted from medical records. The primary outcome was recurrence requiring reintervention. Associations between ABO blood type and recurrence were assessed using chi-square tests and multivariable logistic regression. A random-effects meta-analysis was performed to integrate our findings with all identified prior studies reporting recurrence stratified by blood type. Results: Of 630 treated patients, 488 with documented ABO blood type and recurrence status were included. Recurrence occurred in 31.1% of these patients. ABO distribution matched European population frequencies. Univariate analysis showed no association between blood type and recurrence (p = 0.434). Adjusted models likewise showed no significant differences between type A and type B (OR 1.43, 95% CI 0.67–3.00), type AB (OR 2.35, 95% CI 0.74–7.24), and type O (OR 0.95, 95% CI 0.57–1.58). Hematoma architecture remained strongly associated with recurrence (p < 0.001). A meta-analysis of available studies similarly demonstrated no association between any ABO blood type and recurrence, with pooled odds ratios near unity across comparisons. Conclusions: ABO blood type was not associated with cSDH recurrence in our cohort, and pooled evidence from previously published studies confirms the absence of a meaningful effect. Hematoma architecture and volume remain the most important predictors of recurrence. Based on these results, blood type should not influence postoperative surveillance or counseling, and future work should focus on modifiable biological and imaging-based determinants of recurrence.

Background: Young children requiring neurosurgical care frequently undergo repeated neuroimaging. Whereas CT involves exposure to ionizing radiation, conventional MRI is time-consuming and often necessitates sedation in non-cooperative children. To address these limitations, ultrafast cranial MRI (UF-MRI) based on T2-HASTE sequences was implemented at our institution in 2019 for selected indications. The aim of this study was to evaluate the real-world implementation of UF-MRI in children younger than six years of age. Methods: We retrospectively analyzed cranial MRI examinations consisting exclusively of ultrafast sequences performed between July 2019 and December 2024 in children younger than six years. Clinical settings, diagnostic adequacy, immediate consequences for patient management, and the impact on MRI and CT utilization were systematically assessed. Results: A total of 404 UF-MRI examinations were performed in 198 inpatients and outpatients (mean age: 2 years 2 months) without the need for dedicated anesthesia team support solely for imaging. Only one examination (0.2%) required same-day repetition after mild oral sedation. In 20 patients (5.0%), UF-MRI was supplemented by conventional MRI under anesthesia, most commonly for preoperative planning. Immediate clinical consequences included no change in management in 54.5% of examinations, early follow-up in 22.8%, shunt valve adjustment in 11.6%, neurosurgical intervention in 7.7%, and other measures in 5.0%. UF-MRI accounted for 24.5% of all cranial MRI examinations in this age group and was associated with a 41% reduction in CT utilization compared with the corresponding period prior to UF-MRI implementation. Conclusions: In routine clinical practice, UF-MRI provides rapid, clinically sufficient neuroimaging in young children without the need for sedation or exposure to ionizing radiation. Its implementation significantly streamlines imaging workflows, optimizes resources utilization, reduces the need for CT, and supports timely clinical decision-making, underscoring its value as a complementary imaging modality in pediatric neuroimaging.

Purpose: To evaluate the potential of Photon-Counting Detector CT Angiography (PCD-CTA) for the assessment of carotid and subclavian artery stents compared to digital subtraction angiography (DSA) and Duplex ultrasound (DUS). Methods: This study is a single-center, retrospective analysis of consecutive patients treated with a stent for high grade stenosis of the extra-cranial carotid and the subclavian artery between April 2023 and May 2024. Polyenergetic images (PE), iodine and virtual monoenergetic images were performed at different keV levels (40 and 80) and with two body vascular reconstruction kernels (Bv56 and 72) with and without iterative metal artifact reduction. Three independent readers assessed image quality using a 5-point Likert scale and region of interest analysis. A blinded, independent reading was performed to determine in-stent vessel stenosis. Results: A total of 19 patients (64.3 ± 10.3 (mean patient age in years ± SD); 9 women) with carotid or subclavian artery stents and available DSA, DUS and PCD-CTA were analyzed. Virtual monoenergetic images (VMI) reconstructed with Bv56 at 40 keV, PE and IOD reconstructed with Bv56 scored higher and achieved higher SNRs and CNRs in the in-stent vessel lumen compared with Bv72 reconstructions (p < 0.001). In 2/19 cases with elevated flow velocities (>250 cm/s) in the in-stent vessel lumen, the subsequently performed PCD-CTA and DSA could rule out a high-grade stenosis. Conclusion: PCD-CTA with spectral reconstructions allows a reliable non-invasive assessment of the in-stent vessel lumen in patients after carotid artery or subclavian artery stenting.

Purpose: To evaluate the potential of Photon-Counting Detector CT Angiography (PCD-CTA) for the post-interventional assessment of intracranial aneurysms treated with coil-embolization or clipping, compared to digital subtraction angiography (DSA). Methods: Retrospective analysis of consecutive patients treated with coils or clips between April 2023 and May 2024, who underwent PCD-CTA and, if necessary, DSA as part of their clinical routine. Polyenergetic images and spectral reconstructions were performed at different kiloelectron volt (keV) levels (40, 80 and 120) and with reconstruction kernels: Quantitative (Qr56 and Qr72) and Head vessel (Hv56 and Hv72), both with and without iterative metal artifact reduction (iMAR). Three independent readers assessed image quality using a 5-point Likert scale and region of interest analysis. A blinded, independent reading was performed to determine the presence of aneurysm remnants and intracranial vessel stenosis in the parent vessel. Results: A total of 21 patients (mean age 58 ± 14 years; range 36–74; 18 women) with intracranial, saccular aneurysms treated with either clipping (17/21) or coiling (4/21) were included. Reconstructions using smooth kernels (Hv56, Qr56) at a low keV level (40 keV) yielded increased signal- and contrast-to-noise ratios compared to sharper kernels (Hv72, Qr72) and higher keV levels (80 and 120 keV) (p < 0.001). Unexpectedly, reconstructions with iMAR negatively impacted evaluation, with only 6/21 diagnostic images at the clip site. The sensitivity of PCD-CTA for detecting aneurysm remnants was 100% (7 of 7 aneurysm clip/coil site), while specificity was 89% for patients with clips (8/9). A 100% negative predictive value was observed for all readers regarding aneurysm remnants. Conclusion: Photon-Counting CT-Angiography demonstrated adequate diagnostic value in most patients with intracranial clips. However, while coil artifacts were reduced, spectral reconstructions and iMAR were not sufficient to fully minimize these artifacts.

Purpose: Bacterial contamination has been reported to occur during angiographies, although data on its frequency and relevance are limited. The purpose of our study was to determine whether angiographic materials such as catheters and guide wires remain sterile during angiographies. We sought to differentiate between different materials, and to detect the frequency, the extent and the spectrum of bacterial contamination. Methods: We prospectively collected 698 fluid or material samples from 100 neuroangiographies. Per angiography we analyzed proximal ends and distal tips of catheters and guide wires, and fluid samples from the water container (working bowl) in which materials were stored during the angiography. We analyzed the frequency and extent of contamination and determined the bacterial spectrum. Results: The majority of samples (51.4%) were contaminated. There was no angiography that showed no contamination (0%). The highest proportion of contaminated samples was found in the fluid from the working bowl after completion of the examination (92.9%). Catheters and wires were contaminated in 34.1–49.2% of samples. Contamination of the samples increased with longer duration of the angiographic procedures. Most of the bacterial species were environmental or skin contaminants (86.2%). Conclusion: Bacterial contamination during diagnostic neuroangiographies or interventions is a frequent finding although its clinical significance is believed to be small. Bacterial contamination increases with longer duration of angiographic procedures.

Background/Objectives: Chronic subdural hematoma (cSDH) is a common disease of growing significance due to the increasing use of antithrombotic drugs and population aging. There exists conflicting observational evidence that previous treatment with angiotensin-converting enzyme (ACE) inhibitors reduces the rate of cSDH recurrence. This study assesses the hypothesis that ACE inhibitors may affect recurrence rates by altering hematoma membrane formation. Methods: All patients with chronic subdural hematoma who were operated upon in a single university hospital between 2015 and 2020 were considered for inclusion. Hematomas were classified according to their structural appearance in computed tomography (CT) imaging into one of eight subtypes. Patients’ own medication, prior to hospitalization for cSDH treatment, was noted, and the use of ACI-inhibitors was identified. Results: Of the included 398 patients, 142 (35.9%) were treated with ACE inhibitors before admission for cSDH treatment. Of these, 115 patients (81.0%) received ramipril, 13 received patients lisinopril (11.3%), and 11 patients (9.6%) received enalapril. Reflecting cardiovascular comorbidity, patients on ACE inhibitors were more often simultaneously treated with antithrombotics (63.4% vs. 42.6%; p ≤ 0.001). Hematomas with homogenous hypodense (OR 11.739, 95%CI 2.570 to 53.612; p = 0.001), homogenous isodense (OR 12.204, 95%CI 2.669 to 55.798; p < 0.001), and homogenous hyperdense (OR 9.472, 95%CI 1.718 to 52.217; p < 0.001) architectures, as well as the prior use of ACE inhibitors (OR 2.026, 95%CI 1.214 to 3.384; p = 0.007), were independently associated with cSDH recurrence. Conclusions: Once corrected for hematoma architecture, type of surgery, and use of antithrombotic medication, preoperative use of ACE inhibitors was associated with a twofold increase in the likelihood of hematoma recurrence.

(1) Background: Bacterial contamination has been shown to occur during angiographies, although data on its frequency and relevance are sparse. Our aim was to evaluate the incidence of bacterial contamination of syringes used under sterile conditions during neuroangiographies. We sought to differentiate between contamination of the outside of the syringes and the inside and to detect the frequency, extent and germ spectrum of bacterial contamination. (2) Methods: We prospectively collected 600 samples from 100 neuroangiographies. Per angiography, fluid samples from the three routinely used syringes as well as the syringes themselves were analyzed. We analyzed the frequency and extent of contamination and determined the germ spectrum. (3) Results: The majority of samples (56.9%) were contaminated. There was no angiography that showed no contamination (0%). The outer surfaces of the syringes were contaminated significantly more frequently and to a higher extent than the inner surfaces. Both the frequency and extent of contamination of the samples increased with longer duration of angiographic procedures. Most of the bacterial species were environmental or skin germs (87.7%). (4) Conclusions: Bacterial contamination is a frequent finding during neuroangiographies, although its clinical significance is believed to be small. Bacterial contamination increases with longer duration of angiographic procedures.

Background: Cerebral autoregulation (CA) can be impaired in patients with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The Pressure Reactivity Index (PRx, correlation of blood pressure and intracranial pressure) and Oxygen Reactivity Index (ORx, correlation of cerebral perfusion pressure and brain tissue oxygenation, PbtO₂) are both believed to estimate CA. We hypothesized that CA could be poorer in hypoperfused territories during DCI and that ORx and PRx may not be equally effective in detecting such local variances. Methods: ORx and PRx were compared daily in 76 patients with aSAH with or without DCI until the time of DCI diagnosis. The ICP/PbtO₂-probes of DCI patients were retrospectively stratified by being in or outside areas of hypoperfusion via CT perfusion image, resulting in three groups: DCI + /probe + (DCI patients, probe located inside the hypoperfused area), DCI + /probe−  (probe outside the hypoperfused area), DCI−  (no DCI). Results: PRx and ORx were not correlated (r = − 0.01, p = 0.56). Mean ORx but not PRx was highest when the probe was located in a hypoperfused area (ORx DCI + /probe + 0.28 ± 0.13 vs. DCI + /probe−  0.18 ± 0.15, p < 0.05; PRx DCI + /probe + 0.12 ± 0.17 vs. DCI + /probe−  0.06 ± 0.20, p = 0.35). PRx detected poorer autoregulation during the early phase with relatively higher ICP (days 1–3 after hemorrhage) but did not differentiate the three groups on the following days when ICP was lower on average. ORx was higher in the DCI + /probe + group than in the other two groups from day 3 onward. ORx and PRx did not differ between patients with DCI, whose probe was located elsewhere, and patients without DCI (ORx DCI + /probe−  0.18 ± 0.15 vs. DCI−  0.20 ± 0.14; p = 0.50; PRx DCI + /probe−  0.06 ± 0.20 vs. DCI−  0.08 ± 0.17, p = 0.35). Conclusions: PRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx. Further research should investigate their robustness to detect DCI and to serve as a basis for autoregulation-targeted treatment after aSAH.