Comparison
Features | Olfactory groove meningiomas | Planum sphenoidale (PSM) | Tuberculum sellae meningiomas (TSM) |
% of all intracranial meningioma | 10% | 5% | 10% |
Site of origin | Frontosphenoid suture | Anterior to the limbus sphenoidale | Posterior to the limbus sphenoidale: Tuberculum sella, limbus sphenoidale, chiasmatic sulcus, diaphragma |
Main blood supply | Anterior and post ethmoidal | Post-ethmoidal | |
Olfactory nerves | Lateral | Inferior | |
Optic apparatus | Inferolateral | Superolateral | |
Displacement of chiasm | Depression | Depression | Elevation |
Visual field deficit | Inferior | Inferior | Bitemporal |
Anterior cerebral arteries | Posterosuperior | Posterosuperior | Posterosuperior |
Clinical features | Initially present with disturbances in olfaction and as they enlarge posteriorly, they may affect vision. | Initially present with visual dysfunction and as they grow larger, they can affect olfaction |
- Planum sphenoidale and tuberculum sellae meningiomas
- Between 5 and 10 % of intracranial meningioma
- Arbitrarily, the tumours originating are termed PSMs, whereas those originating posteriorly to the limbus are called TSMs.
Clinical features
- Progressive painless visual loss
- Most common presentation.
- Can be
- Unilateral or bilateral
- Homonymous or bitemporal hemi-anopsia.
- Endocrinological dysfunction
- For larger-sized tumours
- Due to compression of the pituitary stalk or the gland itself.
- Less common modes of presentation include persistent headache or seizures.
Investigation
- Ophthalmological evaluation
- Visual acuity
- Visual field testing
- Fundoscopic examination to look for primary optic atrophy
- ENT evaluation
- Endoscopic approach is being considered.
- Full pituitary hormonal and biochemical profile
- To detect any preoperative endocrine dysfunction
- MRI of the brain
- Study sella and suprasellar region to delineate tumor extension, especially its lateral extension, encasement of vessels, displacement of the pituitary stalk, and presence of brain edema
- CT with thin slice axial and coronal reconstruction
- For endonasal approach
- To evaluate extent of hyperostosis and study endo- nasal anatomy is very helpful.
Management
Observation
- Indication
- Small
- Asymptomatic
Surgery
- Indication
- Growing tumour
- Deteriorating vision
- Rare worsening headaches
- Less likely indicated for deteriorating pituitary function
- Aim
- Prevent further visual deterioration
- Surgical options
- The transcranial approach to TSM
- Lateral (pterional, frontolateral/subfrontal, supraorbital)
- Bilateral (usually reserved for larger-sized tumors > 4 cm)
- Bilateral subfrontal approach
- Bilateral transbasal interhemispheric +/- lamina terminalis
- Unilateral
- Unilateral subfrontal approach
- Unilateral subfrontal + orbital osteotomy
- Pterional transsylvian approach +/- orbitozygomatic
- The pterional approach allows to deal with further extensions into the interpeduncular cistern and around the internal carotid artery, but will likely involve a degree of manipulation of the ipsilateral optic nerve and the area medial to the nerve could be a blind spot.
- Supraorbital mini-craniotomy (keyhole)
- Medial (interhemispheric frontobasal or superior)
- The anterior interhemispheric approach rather than subfrontal can preserve olfaction more readily and avoid manipulations of the optic nerves, but a retroclival extension, especially with a prefixed chiasm, is a blind spot.
- Uni- or bilateral?
- Bilateral subfrontal
- Preservation of blood supply improved
- Transection of SSS has risk of venous infarction
- Risk of anosmia
- Risk of CSF leak due to frontal sinus opening
- Unilateral subfrontal
- Less morbidity and adequate results
- Ipsi- or contralateral to worsened vision?
- Non-dominant approach
- Ipsilateral for early decompression of ON
- Contralateral for better visualization of inferomed ON, but worse visualization of lateral affected ON
- Side of vascular encasement
- Indication
- Soft tumour (seen as hyperintensity on T2 MRI)
- Lesions that are small or extending into the sphenoid sinus with absence of vascular encasement on MRI and not extending laterally to the carotid may be considered for extended endoscopic endonasal approaches
- Pros
- More direct access to tumour
- Via a transcribiform, transplanum, transtubercular, and transclival corridors, it allows access to the entire central anterior skull base.
- Early tumour devascularization and effective decompression
- Complete removal of tumour, involved bone and dural attachment
- Tumour dissection along arachnoid planes with no brain retraction
- Preservation of optic vascularity
- No manipulatkon of CN2
- Sellar/sphenoid extension of tumour can be accessed easiy
- No blind spots from carotid to carotid
- Less chance for olfactory nerve injury
- Minimal or no brain retraction is required.
- Better cosmetic result.
- Cons
- Tumour size is controversial
- Essential if the tumour is confined within two optical canal then you can operate.
- Optic canal involvement can be done if
- Not invaded the canal
- Is in the optical canal but pushing it laterally
- If the vasculature is involved (if tumour is soft you can do it, if not then hard)
- Approximation
- Adherence
- Encasement
- CSF Leak management
- Steep learning curve.
- Technique
Microsurgical
Endoscopic
Radiotherapy
SRS
- Generally not used as it can
- Damage optic nerve
- Cause delayed panhypopituitarism
- Indication
- Only used in residual tumour in cavernous sinus or next to carotid
Fractionated radiosurgery
- Indication
- Patients with severe comorbidities where surgery can carry a very high operative risk, fractionated radiosurgery may be considered as the primary option.
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