Olfactory Groove Meningiomas (OGMs) are benign brain tumors that arise from the meninges — the protective layers covering the brain — in the front part of the skull base. Although usually slow-growing, they can reach a large size before causing symptoms due to their deep location and gradual pressure on the frontal lobes, olfactory and optic nerves. Surgical removal is the primary treatment, and with modern microsurgical and endoscopic techniques, most patients achieve excellent outcomes and preserved function.
Symptoms
Early symptoms may be subtle and progress slowly:
- Loss or reduction of smell (anosmia) — often the first symptom
- Progressive vision changes (blurred or double vision)
- Personality or behavioral changes due to frontal lobe compression
- Headache and fatigue
- Memory or concentration difficulties
- Seizures in some patients
- In rare, advanced cases: Cushing reflex (high blood pressure, irregular pulse) or endocrine changes from pressure on nearby structures
If the tumor grows large, it can obstruct cerebrospinal fluid (CSF) flow and lead to hydrocephalus, causing increased intracranial pressure and worsening symptoms.
Diagnosis
Imaging Studies
- MRI brain with contrast: The gold standard — shows a well-circumscribed, dural-based mass with enhancement along the skull base
- CT scan: Defines bony involvement or hyperostosis of the skull base
- 3D reconstruction or neuronavigation imaging: Used for pre-surgical planning to understand anatomy and relation to optic nerves, frontal lobes, and vascular structures
Differential Diagnosis
OGMs must be distinguished from other anterior skull base lesions such as:
- Frontal lobe gliomas
- Esthesioneuroblastomas
- Planum sphenoidale or tuberculum sellae meningiomas
Accurate localization determines the safest surgical route.
Treatment Options
1. Microsurgical Resection
The goal of surgery is complete tumor removal with preservation of brain and optic structures. Approaches are selected based on tumor size and extension:
- Bifrontal craniotomy: Traditional approach for large or bilateral tumors
- Unilateral subfrontal or pterional approach: For smaller or asymmetric tumors
- Endoscopic endonasal approach (EEA): Minimally invasive option for midline OGMs extending toward the nasal cavity
Modern techniques use neuronavigation, intraoperative monitoring, and microsurgical instruments to minimize brain retraction and protect olfactory and visual pathways.
2. Endoscopic Endonasal Surgery (EEA)
- Performed through the nose and sinuses without external incisions
- Ideal for midline, smaller, or anteriorly located tumors
- Allows early decompression of the optic nerves and reduced hospital stay
- Requires experience in skull base reconstruction to prevent CSF leaks
3. Radiosurgery / Fractionated Radiotherapy
- Used for residual or recurrent tumor after surgery
- Suitable for small, asymptomatic tumors in patients unfit for open surgery
- Controls tumor growth effectively but does not remove mass effect
Risks & Complications
- Loss of smell (often permanent if both olfactory tracts are involved)
- CSF leakage (managed with endoscopic repair if occurs)
- Infection or meningitis (rare with modern aseptic techniques)
- Visual changes or transient swelling of the optic nerves
- Personality or memory changes (usually temporary)
Complete removal is achieved in most cases, with low recurrence rates.
Recovery & Prognosis
- Hospital stay: 5–10 days, depending on surgical approach
- Recovery period: 4–6 weeks for most patients
- Postoperative MRI: Performed at 3 months to confirm complete resection
- Smell function: May recover partially if one olfactory tract is preserved
- Vision and cognitive function: Often improve as pressure is relieved
- Long-term follow-up: MRI scans every 6–12 months initially, then yearly
With total excision, recurrence is <10%, and most patients resume normal life activities.
Patient Advisory
Olfactory Groove Meningioma surgery requires precise skull base expertise to balance complete tumor removal with preservation of function. Each case is unique — surgical planning depends on tumor size, extension, and patient-specific anatomy. Modern microsurgical and endoscopic techniques offer excellent outcomes with minimal morbidity when performed by experienced neurosurgical teams. Do not rely solely on online information; consult your neurosurgeon for an individualized evaluation and treatment plan.