Crista Galli Pneumatization Complicating Olfactory Groove Meningioma Resection: A Case Report.

Pneumatization of the crista galli (PCG) is an anatomic variant of the osseous skull base. Olfactory groove meningiomas (OGMs) arise in the vicinity of the crista galli, and PCG may be an obstacle to complete resection from a preferred unilateral approach. A 22-year-old male presented with symptoms of chronic frontal headaches and was found to harbor a 4cm OGM. Preoperative imaging workup also revealed the presence of a very large PCG with a height of 27mm above the floor of the anterior fossa. Given the presence of PCG, we elected to adjust our conventional approach of a unilateral pterional/subfrontal craniotomy to a modified bilateral frontal craniotomy, which was a combination of a large right-sided pterional and a small left-sided frontolateral osteotomy, sparing the midline. This allowed excellent access to the floor of the anterior fossa, allowing us to achieve a favorable Simpson 2 resection. Apart from iatrogenic anosmia, the patient had an uneventful recovery. The preoperative work-up of OGM patients should include dedicated CT imaging of the skull base to assess potential variations in the aeration status of the paranasal sinuses and ethmoidal cells. This is of great clinical relevance as it allows for the detection of variations such as a PCG. This can prompt an adjustment of the operative strategy to minimize the risk of postoperative cerebrospinal fluid (CSF) leak and meningitis.