The effect of temporary CSF diversion modality on shunt-dependency following aneurysmal subarachnoid hemorrhage: A nationwide assessment

Background: Aneurysmal subarachnoid hemorrhage (aSAH) carries a high economic cost and clinical morbidity in the United States. Beyond prolonged admissions and poor post-injury functional status, there is an additional cost of chronic shunt-dependent hydrocephalus for many aSAH patients. Adjuvant lumbar drain (LD) placement has been hypothesized to promote clearance of subarachnoid blood from the cisternal space, with an ultimate effect of decreasing shunt placement rates. In this nationwide database study, we aim to evaluate outcomes associated with different forms of temporary bedside cerebrospinal fluid (CSF) diversion in the aSAH patient cohort.

Methods: Inpatient admissions were queried from the National Inpatient Sample (NIS; 2016-2020). Inclusion criteria included adult patients presenting with non-traumatic SAH that underwent treatment with either non-elective clip ligation or coil embolization of their underlying aneurysms and received either an external ventricular drain (EVD), lumbar drain (LD), or both (EVD + LD) for temporary CSF diversion during that admission. Outcome variables evaluated included inpatient mortality, bacterial meningitis, length of stay, discharge disposition, and need for shunt placement.

Results: A total of 5505 admissions met inclusion criteria, of which 18.42 % required permanent CSF diversion. The majority of patients received EVD alone (4842, 87.96 %). The remaining patients were split between LD alone (366, 6.65 %) or EVD + LD placement (297, 5.4 %). Patients receiving LD alone tended to be healthier, with lower rates of extreme APR-DRG subclass, Elixhauser Comorbidity Index (ECI), and NIS SAH Severity Score (NIS-SSS). Patients in the EVD + LD cohort had higher rates of shunt placement (OR 1.624, p = 0.0009) and higher rates of bacterial meningitis (OR 8.715, p < 0.0001), even when controlling for APR-DRG illness severity and ECI.

Conclusion: Our study found higher rates of permanent CSF diversion, longer lengths of stay, and higher rates of bacterial meningitis in patients receiving both EVD and LD placement. Due to limitations inherent to nationwide database studies, these results should be interpreted cautiously. Further studies are needed to clarify whether adjuvant temporary CSF diversion with LD placement in the aSAH cohort for intent of minimizing chronic shunt-dependence is efficacious.