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

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.