Olfactory Groove Meningioma Presenting Solely with Visual Impairment: An Atypical Case

Olfactory groove meningiomas (OGMs) are rare intracranial tumours that arise from the anterior cranial fossa, typically originating at the cribriform plate, planum sphenoidale, or fronto sphenoidal suture. Due to their slow-growing and insidious nature, OGMs often go undetected until they reach considerable size, making them among the largest central nervous system (CNS) tumours at diagnosis. Common presenting symptoms include headache, anosmia, personality changes, and visual impairment; however, these can be subtle and easily overlooked. We present the case of a female in her early 70s who presented with an isolated 5-week history of progressive visual deterioration, initially affecting the right eye. Notably, she exhibited no other common neurological symptoms such as headache, seizures, or personality change. Imaging via CT and MRI revealed a giant olfactory groove meningioma measuring over 6 cm, with mass effect, midline shift, and encasement of both internal carotid arteries. The patient underwent a bifrontal craniotomy and subtotal tumour resection, achieving approximately 80-90% removal. Critical neurovascular structures, including the right optic nerve and anterior cerebral arteries (ACA), were successfully preserved. Histopathological analysis confirmed a WHO Grade II atypical meningioma with brain invasion but a low Ki-67 proliferation index. Given the incomplete resection and tumour grade, adjuvant postoperative radiotherapy was recommended to reduce recurrence risk. The patient’s post-operative course was favourable, with notable improvement in visual acuity and field 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 tumours. Greater awareness of atypical presentations may aid in earlier diagnosis and improved outcomes.