AIM: To evaluate the relationship between optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in patients with acute ICP elevation controlled through external ventricular drainage (EVD). MATERIAL and METHODS: In this prospective observational study, simultaneous measurements of right and left ONSD, ICP, and cerebral perfusion pressure (CPP) were recorded in 46 adult patients undergoing EVD. Two patients were excluded due to ophthalmic pathology and missing data, resulting in a final cohort of N = 44 patients. After we obtained the baseline measurements, 5 mL of cerebrospinal fluid (CSF) were drained, and the measurements were repeated 2 minutes (min) later. RESULTS: CSF drainage led to significant reductions in both ICP and bilateral ONSD (p = .001 for all), while CPP significantly increased (p = .038). We identified an ONSD cut-off of 5.35 mm for detecting ICP values >= 15 mmHg, and this cut-off had 53% sensitivity and 86% specificity (Youden index: 0.395). However, we could not determine a reliable cut-off for detecting ICP values >= 20 mmHg (p = .076). CONCLUSION: When ICP is controlled through EVD, the linear relationship between ONSD and ICP observed during acute pressure elevations may be disrupted, particularly at higher ICP values (>= 20 mmHg). Although we identified a cut-off ONSD value of 5.35 mm for detecting ICP values >= 15 mmHg, the low sensitivity of this cut-off significantly limits its clinical utility. Additionally, since no reliable cut-off could be established for ICP values >= 20 mmHg, ONSD may have limited value for monitoring pressure following CSF drainage.
ABSTRACT:AIM: To establish a nomogram model of Ki-67-positive grade 4 diffuse gliomas that can predict the survival rate of patients and has certain guiding values that are useful in treatment. MATERIAL and METHODS: Data from 146 patients with Ki-67-positive grade 4 diffuse gliomas was retrospectively obtained and analyzed using the R software. Statistically significant indicators were identified via Cox regression analysis and used to establish the nomogram. The nomogram was corrected using the C-index, area under the curve (AUC), calibration curve, and decision curve analyses (DCA). Finally, the model was externally validated using the Chinese Glioma Genome Atlas database. RESULTS: Age, treatment, and IDH status were significant. The models had a C-index of 0.743, and the time-dependent receiver operating characteristic curve had an AUC of 0.832 at 3 months and 0.829 at 6 months, indicating good discriminatory ability. Finally, a nomogram was constructed and validated using the validation and DCA curves. CONCLUSION: Age, treatment, and IDH were independent prognostic factors in patients with Ki-67-positive grade 4 diffuse gliomas. The constructed model can accurately assess the disease-specific survival rates of these patients and help inform treatment options.
ABSTRACT:AIM: To determine hemispheric asymmetries in major white matter tracts using diffusion tensor imaging (DTI) metrics and morphometric measurements, as comprehensive multitract analyses remain limited. MATERIAL and METHODS: Diffusion MRI data from 102 healthy adults enrolled in the Human Connectome Project (HCP) were analyzed using DSI Studio to reconstruct 17 major white- matter tracts bilaterally. For each tract, diffusion metrics (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD], axial diffusivity [AD], quantitative anisotropy [QA], isotropic value [ISO], restricted diffusion imaging [RDI], and normalized RDI [nrdı]) and morphometric parameters (fiber count, mean length, trunk volume, branch volume, total volume, and termination region areas) were quantified. Paired t-tests compared left-right hemispheric differences. Multiple comparison corrections were performed with the Benjamini-Krieger-Yekutieli procedure, and effect sizes were reported as Cohen's d. RESULTS: Significant hemispheric asymmetries were observed in most tracts. FA was significantly higher in the left hemisphere (p<0.001) for the arcuate fasciculus (AF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), and uncinate fasciculus (UF). Mean diffusivity (MD) demonstrated left dominance in the UF and SLF2-3 (p=0.009). QA was predominantly left- lateralized across multiple tracts, including AF, IFOF, ILF, and frontal aslant tract (FAT) (p<0.01, Cohen's d: 0.42 to 1.17), except for the vertical occipital fasciculus (VOF), where rightward dominance was noted (Cohen's d: -0.55). Tract-trunk-branch volumes were predominantly left-lateralized in frontal lobe pathways such as AF, SLF1, SLF2, FAT, and UF (p<0.01). Rightward dominance was observed in SLF3, parietal aslant tract (PAT), IFOF, ILF, and middle longitudinal fasciculus (MLF) (p<0.05). Similar asymmetries were observed in termination region areas, fiber counts, and fiber lengths (p<0.001). CONCLUSION: Widespread hemispheric asymmetries were observed across multiple pathways. Such asymmetry may reflect distinct hemispheric functional specialization and the neurological basis of lateralized functions.
ABSTRACT:AIM: To present a single-center experience with posterior C1-C2 fixation for atlantoaxial instability, emphasizing an anatomy-driven approach to C2 anchorage selection, construct strategy, complications, and clinical outcomes. MATERIAL and METHODS: We retrospectively reviewed 45 patients who underwent posterior C1-C2 fixation between June 2020 and January 2026. Constructs were categorized as pedicle, hybrid, bilateral laminar, planned C2 omission (C1-C3 extension), or transarticular fixation. Demographics, etiology, operative variables, complications, reoperations, mechanical failure, and fusion were analyzed. Exploratory categorical comparisons were performed using Fisher's exact test. Fusion was evaluated using postoperative computed tomography (CT) obtained ≥6 months postoperatively and was defined as osseous bridging without implant loosening. RESULTS: The mean patient age was 47.8 ± 20.1 years, and 25 patients (55.6%) were women. Etiologies included trauma (31.1%), basilar invagination (22.2%), Chiari malformation (15.6%), os odontoideum (8.9%), atlantoaxial subluxation (8.9%), tumor (8.9%), and other causes (4.4%). Construct types included pedicle fixation in 31 patients (68.9%), hybrid constructs in 5 (11.1%), bilateral laminar fixation in 5 (11.1%), planned C2 omission in 3 (6.7%), and transarticular fixation in 1 patient (2.2%). The median follow-up duration was 6.3 months (IQR, 1.2-22.3 months). CT-based fusion assessment was available for 26 patients at a median follow- up of 19.5 months, and fusion was observed in 20 patients (76.9%). Radiographic mechanical abnormalities were identified in 7 patients (15.6%), including 6 (13.3%) who underwent revision surgery. Construct strategy was not significantly associated with either mechanical abnormalities or CT-confirmed fusion. Mechanical abnormalities were significantly more frequent in patients with os odontoideum or nontraumatic atlantoaxial subluxation than in those with other etiologies (p < 0.001). CONCLUSION: An anatomy-driven escalation strategy for C2 anchorage selection provided a practical framework for managing variable craniovertebral anatomy during freehand posterior atlantoaxial fixation. Hybrid constructs, bilateral laminar fixation, and planned C2 omission served as feasible alternatives when pedicle fixation was limited by anatomical constraints or pathology.
