Olfactory groove meningioma presenting solely with visual impairment: illustrative case.

backgroundOlfactory groove meningiomas (OGMs) are rare intracranial tumors that arise from the anterior cranial fossa. Because of their slow-growing and insidious nature, OGMs often go undetected until they reach considerable size, making them among the largest CNS tumors at diagnosis. Common presenting symptoms include headache, anosmia, personality changes, and visual impairment; however, these can be subtle and easily overlooked. OBSERVATIONS: The authors present the case of a female in her 70s who presented with a 5-week history of progressive visual deterioration, initially affecting the right eye. Notably, she exhibited no other common neurological symptoms. Imaging revealed a giant OGM measuring > 6 cm, with mass effect, midline shift, and encasement of both internal carotid arteries. The patient underwent a bifrontal craniotomy and subtotal tumor resection, achieving approximately 80%-90% removal. LESSONS: The patient's visual acuity and field improved over the following weeks. This case underscores the stealthy and potentially dangerous growth of OGMs, particularly when classical symptoms are absent. It highlights the importance of early imaging in unexplained visual loss and the role of a multidisciplinary approach in managing complex skull base tumors. Greater awareness of atypical presentations may aid in earlier diagnosis and improved outcomes. https://thejns.org/doi/10.3171/CASE25657.