Background Aneurysmatic subarachnoidal haemorrhage (SAH) induces cerebrospinal (CSF) circulation disruption with multiple pathways. Sterile inflammation increases the CSF production and SAH itself blocks the absorption of CSF at microscopical and macroscopical level. Organization of blood in subarachnoidal space induces fibrosis and further disturbs normal CSF circulation which is seen as need of permanent shunt to normalise intracranial pressure.

Methods We hypothesized that by actively removing SAH via minimally invasive active external ventricular drainage (EVD) while actively exchanging CSF we can reduce pathological outcome of blood in subarachnoidal space. This might reduce shunt dependency of SAH patients. We identified patients with high probably of shunt dependency with CHESS score 6> which predicts 75% shunt dependency. We gathered data from three US and EU centers . 15 SAH patients were recognized to have CHESS score 6 or higher, with 3 months follow-up and which aneurysms were endovascularly treated. All the patients suffered from acute hydrocephalus and received active EVD with where subarachnoid space where irrigated and drained passively. 7 patients received tPA in irrigation fluid with daily doses of 1,5-3mg. The rest of the patients irrigated with ringer acetate or NaCl solutions alone.

Results Active EVD allows accelerated removal of SAH. Shunt dependency was seen in 2 (13,3%) patients in 3 months follow-up. This was less than excepted (11 patients) with CHESS score prediction (75%). None of the patients suffered from mortality or morbidity related to CSF exchange.

Conclusions Active CSF exchange is possible via active EVD and this accelerated SAH removal. This might reduce shunt dependency after SAH. Prospective trials are needed to confirm our preliminary findings.

Disclosures B. Rezai Jahromi: 1; C; IRRAS. 2; C; IRRAS, Neurovascular Innovations, Helsinki Surgical Instruments. F. Göhre: None. M. Niemelä: None. P. Tanskanen: None. J. Siironen: None. N. Brandmeir: 2; C; IRRAS.