A new non-craniotomy model of subarachnoid hemorrhage in the pig: a pilot study

Subarachnoid hemorrhage (SAH) from rupture of an intracranial arterial aneurysm is a devastating disease affecting young people, with serious lifelong disability or death as a frequent outcome. Large animal models that exhibit all the cardinal clinical features of human SAH are highly warranted. In this pilot study we aimed to develop a non-craniotomy model of SAH in pigs suitable for acute intervention studies. Six Norwegian Landrace pigs received advanced invasive hemodynamic and intracranial pressure (ICP) monitoring. The subarachnoid space, confirmed by a clear cerebrospinal fluid (CSF) tap, was reached by advancing a needle below the ocular bulb through the superior orbital fissure and into the interpeduncular cistern. SAH was induced by injecting 15 mL of autologous arterial blood into the subarachnoid space. Macro- and microanatomical investigations of the pig brain showed a typical blood distribution consistent with human aneurysmal SAH (aSAH) autopsy data. Immediately after SAH induction ICP sharply increased with a concomitant reduction in cerebral perfusion pressure (CPP). ICP returned to near normal values after 30 min, but increased subsequently during the experimental period. Signs of brain edema were confirmed by light microscopy post-mortem. None of the animals died during the experimental period. This new transorbital injection model of SAH in the pig mimics human aSAH and may be suitable for acute intervention studies. However, the model is technically challenging and needs further validation.