Craniotomy without flap replacement for ruptured intracranial aneurysms to reduce ischemic brain injury: a preliminary safety and feasibility analysis

Cortical and subcortical brain ischemia following aneurysmal subarachnoid hemorrhage (aSAH) remains a central challenge in improving patient outcome. Generally the bone flap is replaced after surgical clipping and no decompression is practiced in endovascularly treated patients. The aim of this preliminary safety and feasibility study is to clarify whether a first-line decompression would improve brain perfusion and salvage more tissue at risk in patients who developed delayed vasospasm. In addition, we assessed whether the risks involved with a second surgery to replace the bone flap would affect patient outcome.

We retrospectively analyzed patients with aSAH who underwent surgical clipping and developed cerebral vasospasm from 2009 to 2012 at our institution. We selected cases where the bone flap was not replaced at initial surgery and needed a second procedure for bone flap replacement. Primary end points were new delayed ischemic neurological deficits (DINDs), the extent of brain infarctions, and patient functional outcome. Secondary end points were hazards of the second procedure for bone replacement.

We identified six patients in whom the surgeon chose not to replace the bone flap. In four patients, this was a pterional bone flap (standard), and in two patients it was a larger frontotemporoparietal flap. Despite the limited extent of the craniotomy, only one patient (16 %) required additional decompression. Two patients (33%) developed DINDs and five patients (83 %) showed delayed cerebral infarctions on computed tomography. Of those, three patients showed good outcome (Glasgow Outcome Scale score >4 and modified Rankin Scale score <3). No complications or new neurological deficits occurred during the second surgery for bone replacement.

To date, no standardized criteria exist to decide whether the bone flap should be removed or replaced at initial surgery. Our single-center experience in a limited number of patients reveals a pattern with respect to initial clinical parameters and imaging findings that might be a first step in developing standardized decision parameters. This may prevent secondary surgery for decompression in deleterious conditions during the vasospasm phase. Based on these findings, we have developed a protocol for a prospective study that will further investigate the benefits of this management.