Prognostic Nomogram of Predictors for Shunt-Dependent Hydrocephalus in Patients with Aneurysmal Subarachnoid Hemorrhage Receiving External Ventricular Drain Insertion: A Single-Center Experience and Narrative Review

Construction and verification of risk predicting models to evaluate the possibility of hydrocephalus following aneurysmal subarachnoid hemorrhage

BACKGROUND

Hydrocephalus following a ruptured aneurysm portends a poor prognosis. The authors aimed to establish a nomogram to predict the risk of hydrocephalus after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A total of 421 patients with aSAH who were diagnosed by digital subtraction angiography in The General Hospital of Northern Theater Command center from January 2020 to June 2021 were screened to establish the training cohort. An additional 135 patients who enrolled between July 2021 and May 2022 were used for the validation cohort. Variate difference analysis and stepwise logistic regression (model A) and univariate and multivariate logistic regressions (model B) were respectively used to construct two models. Then, the net reclassification improvement (NRI), integrated discrimination improvement (IDI), and receiver operating characteristic (ROC) curve were used to compare the predictive abilities of the two models. Finally, two nomograms were constructed and externally validated.

RESULTS

After screening, 556 patients were included. The area under the ROC curve of models A and B in the training cohort were respectively 0.884 (95 % confidence interval [CI]: 0.847-0.921) and 0.834 (95 % CI: 0.787-0.881). The prediction ability of the model A was superior to model B (NRI > 0, IDI > 0, p < 0.05). The C-index of models A and B was 0.8835 and 0.8392, respectively. Regarding clinical usefulness, the two models offered a net benefit with a threshold probability of between 0.12 and 1 in the decision curve analysis, suggesting that the two models can accurately predict hydrocephalus events.

CONCLUSIONS

Both models have good prediction accuracy. Compared with model B, model A has better discrimination and calibration. Further, the easy-to-use nomogram can help neurosurgeons to make rapid clinical decisions and apply early treatment measures in high-risk groups, which ultimately benefits patients.

Posthemorrhagic Hydrocephalus in Patients with Subarachnoid Hemorrhage Occurs Independently of CSF Osmolality

The molecular mechanisms underlying the development of posthemorrhagic hydrocephalus (PHH) remain incompletely understood. As the disease pathogenesis often cannot be attributed to visible cerebrospinal fluid (CSF) drainage obstructions, we here aimed to elucidate whether elevated CSF osmolality following subarachnoid hemorrhage (SAH) could potentiate the formation of ventricular fluid, and thereby contribute to the pathological CSF accumulation observed in PHH. The CSF osmolality was determined in 32 patients with acute SAH after external ventricular drainage (EVD) placement and again upon EVD removal and compared with the CSF osmolality from 14 healthy control subjects undergoing vascular clipping of an unruptured aneurism. However, we found no evidence of elevated CSF osmolality or electrolyte concentration in patients with SAH when compared to that of healthy control subjects. We detected no difference in CSF osmolality and electrolyte content in patients with successful EVD weaning versus those that were shunted due to PHH. Taken together, elevated CSF osmolality does not appear to underlie the development of PHH following SAH. The pathological CSF accumulation observed in this patient group must thus instead be attributed to other pathological alterations associated with the abnormal presence of blood within the CSF compartments following SAH.

Inflammatory Markers as Predictors of Shunt Dependency and Functional Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage

The mechanisms underlying post-hemorrhagic hydrocephalus (PHH) development following subarachnoid hemorrhage (SAH) are not fully understood, which complicates informed clinical decisions regarding the duration of external ventricular drain (EVD) treatment and prevents the prediction of shunt-dependency in the individual patient. The aim of this study was to identify potential inflammatory cerebrospinal fluid (CSF) biomarkers of PHH and, thus, shunt-dependency and functional outcome in patients with SAH. This study was a prospective observational study designed to evaluate inflammatory markers in ventricular CSF. In total, 31 Patients with SAH who required an EVD between June 2019 and September 2021 at the Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark, were included. CSF samples were collected twice from each patient and analyzed for 92 inflammatory markers via proximity extension assay (PEA), and the prognostic ability of the markers was investigated. In total, 12 patients developed PHH, while 19 were weaned from their EVD. Their 6-month functional outcome was determined with the modified Rankin Scale. Of the 92 analyzed inflammatory biomarkers, 79 were identified in the samples. Seven markers (SCF, OPG, LAP TGFβ1, Flt3L, FGF19, CST5, and CSF1) were found to be predictors of shunt dependency, and four markers (TNFα, CXCL5, CCL20, and IL8) were found to be predictors of functional outcome. In this study, we identified promising inflammatory biomarkers that are able to predict (i) the functional outcome in patients with SAH and (ii) the development of PHH and, thus, the shunt dependency of the individual patients. These inflammatory markers may have the potential to be employed as predictive biomarkers of shunt dependency and functional outcome following SAH and could, as such, be applied in the clinic.

Cerebrospinal fluid predictors of shunt-dependent hydrocephalus after hemorrhagic stroke: a systematic review and meta-analysis

Hydrocephalus is a common complication of hemorrhagic stroke and has been reported to contribute to poor neurological outcomes. Herein, we aimed to investigate the validity of cerebrospinal fluid (CSF) data in predicting shunt-dependent hydrocephalus (SDHC) in patients with hemorrhagic stroke. PubMed, CENTRAL, and Embase databases were searched for relevant studies published through July 31, 2021. The 16 studies with 1505 patient included those in which CSF data predicted risk for SDHC and reports on CSF parameters in patients in whom SDHC or hydrocephalus that was not shunt-dependent developed following hemorrhagic stroke. We appraised the study quality using Newcastle-Ottawa Scale and conducted a meta-analysis of the pooled estimates of the CSF predictors. The meta-analysis revealed three significant CSF predictors for shunt dependency, i.e., higher protein levels (mean difference [MD] = 32.09 mg/dL, 95% confidence interval [CI] = 25.48-38.70, I² = 0%), higher levels of transforming growth factor β1 (TGF-β1; MD = 0.52 ng/mL, 95% CI = 0.42-0.62, I² = 0%), and higher ferritin levels (MD = 108.87 µg/dL, 95% CI = 56.68-161.16, I² = 36%). The red blood cell count, lactate level, and glucose level in CSF were not significant in predicting SDHC in patients with hemorrhagic stroke. Therefore, higher protein, TGF-β1, and ferritin levels in CSF are significant predictors for SDHC in patients with hemorrhagic stroke. Measuring these CSF parameters would help in the early recognition of SDHC risk in clinical care.