# Impact of Hemorrhage Extent on External Ventricular Drain-Associated Infections in Aneurysmal Subarachnoid Hemorrhage

## TL;DR

This study finds that the amount and location of brain bleeding in patients with aneurysmal subarachnoid hemorrhage increases the risk and speed of infection from external ventricular drains.

## Contribution

The study is the first to show that both the quantity and anatomical distribution of brain hemorrhage correlate with higher rates and earlier onset of EVD-associated infections.

## Key findings

- Larger subarachnoid blood clots (BNI grade 4) increase EVDAI risk by 6.66 times.
- Higher IVH scores correlate with increased EVDAI risk (odds ratio 1.33).
- EVDAI onset occurs earlier with greater hemorrhage extent and higher BNI grades.

## Abstract

External ventricular drain (EVD)–associated infections (EVDAI) remain a relevant complication of acute hydrocephalus treatment following aneurysmal subarachnoid hemorrhage (aSAH). Whether radiological quantity and anatomical distribution of subarachnoid and ventricular blood impact EVDAI rates has not been thoroughly studied to date.

This was a retrospective (2009–2023) analysis of patients with aSAH undergoing emergency ventriculostomy. Univariable and multivariable logistic regression analyses were used to assess the association between the Barrow Neurological Institute (BNI) grading scale for subarachnoid hemorrhage and the intraventricular hemorrhage (IVH) score for extent and anatomical distribution of intracerebral bleeding with EVDAI risk. Cox regression analysis was employed to investigate the relationship between hemorrhage extent and the timing of EVDAI onset.

One hundred and ninety-four patients with aSAH received 228 EVDs with a total of cumulative 2,258 EVD days. Overall EVDAI rates were 14% (27/194) per patient and 12% (27/228) per EVD. EVDAI was associated with a larger subarachnoid blood clot (BNI grade 4; odds ratio 6.66, 95% confidence interval 2.04–21.68; p = 0.002) and higher IVH scores (odds ratio 1.33, 95% confidence interval 1.05–1.69; p = 0.02). Intracerebral hemorrhage was more frequently localized in the posterior fossa in the EVDAI group (20% vs. 0%, p = 0.004). Multivariable analysis confirmed a positive independent correlation with larger blood clots. Cox regression demonstrated earlier EVDAI onset in association with higher BNI grades and IVH scores.

Both the quantity and radiological distribution of subarachnoid and ventricular blood positively correlate with EVD-associated nosocomial meningitis, eventually accelerating an earlier infection onset. These findings should help guide future research on EVDAI prevention in patients with aSAH.

The online version contains supplementary material available at 10.1007/s12028-025-02310-4.