Treatment of Right Parietal Parasagittal Meningioma
Complete surgical resection with removal of the dural attachment is the treatment of choice for symptomatic right parietal parasagittal meningiomas, with the goal of achieving Simpson grade I or II resection to minimize recurrence risk. 1, 2
Initial Clinical Assessment
Document baseline neurological status immediately, focusing on:
- Left-sided motor weakness (given right parietal location affecting motor cortex) 2
- Sensory deficits in left hemibody 2
- Seizure activity (occurs in up to 30% of meningiomas) 2
- Signs of increased intracranial pressure (headache, papilledema) 2
- Visual field defects 2
Diagnostic Imaging Requirements
MRI with contrast must be performed within 2 weeks prior to any intervention as the gold standard for treatment planning. 1, 2 Look for:
- Homogeneous dural-based enhancement with characteristic "dural tail sign" 1, 2
- Degree of peritumoral edema 2
- Relationship to superior sagittal sinus (critical for surgical planning) 2
- Mass effect and cortical buckling 2
- Relationship to eloquent motor cortex 2
Consider somatostatin receptor (SSTR) PET imaging when tumor extension is unclear or for complex cases, as it provides superior detection sensitivity compared to conventional MRI. 1
Treatment Algorithm Based on Clinical Presentation
For Symptomatic Meningiomas (Most Common Presentation)
Proceed directly to surgical resection if the tumor is accessible with acceptable surgical risk. 1, 2 The extent of resection directly correlates with recurrence rates. 2
Initiate dexamethasone preoperatively to reduce peritumoral edema, especially in patients with neurological deficits. 2
Start antiepileptic medication if seizures are present or suspected. 2
For Asymptomatic Small Meningiomas (<30 mm)
Observation with serial MRI surveillance is appropriate, particularly if:
- Patient has advanced age or significant comorbidities 1
- Tumor is located in eloquent, deep, or brainstem areas 1
Surgery should be considered even for asymptomatic lesions if accessible and potential neurological consequences exist. 1
Surgical Approach and Technique
Critical surgical principles for parasagittal meningiomas to minimize the 5-14% risk of venous infarction and eloquent cortical damage: 3
- Do not cross the superior sagittal sinus during craniotomy 3
- Avoid falx resection 3
- Use motor evoked potentials (MEPs) intraoperatively to prevent damage to eloquent motor cortex 3
- Consider preoperative embolization selectively to reduce intraoperative bleeding 4, 3
- Utilize image-guided neuronavigation for surgical planning 1
Aim for Simpson grade I or II resection (complete removal with dural attachment), as this directly correlates with lower recurrence rates. 2 However, subtotal resection is acceptable when complete removal would risk venous infarction or motor deficit. 4, 3
Alternative Primary Treatment: Stereotactic Radiosurgery
SRS as primary therapy is recommended for smaller tumors (<3 cm diameter, <7.5 cc volume) with patent sagittal sinuses, achieving 93% 5-year tumor control. 5, 6
SRS prescription dose typically ranges 12-15 Gy in a single fraction for WHO grade 1 meningiomas. 5
SRS should be considered instead of surgery for:
- Tumors in eloquent areas with unacceptable surgical risk 1
- Patients with significant medical comorbidities 1
- Smaller tumor volumes (<7.5 cc) 6
Critical caveat: SRS is not recommended for asymptomatic meningiomas that are surgically accessible. 1
Adjuvant Treatment Based on Histopathology
WHO Grade 1 (Benign) - 75-80% of Cases
Observation with MRI surveillance every 6-12 months after complete resection. 1, 2
WHO Grade 2 (Atypical) - 15-20% of Cases
External beam radiation therapy (EBRT) is indicated after subtotal resection. 1, 2
Consider planned second-stage radiosurgery soon after initial subtotal resection for any residual tumor nodule or neoplastic dural remnant. 6
WHO Grade 3 (Malignant) - 1-5% of Cases
EBRT is indicated after surgery regardless of extent of resection. 1
High-Risk Features Requiring Aggressive Management
Superior sagittal sinus invasion and WHO grade 2/3 are independently associated with tumor progression requiring salvage therapy (OR: 8.22 and 7.58 respectively). 7
80% of patients with WHO grade 2/3 tumors with sinus invasion require salvage treatment, compared to only 13.6% of WHO grade 1 tumors without sinus invasion. 7
Additional high-risk features include:
- Brain invasion (OR: 6.93) 7
- Peritumoral edema (OR: 2.81) 7
- Sagittal sinus occlusion (OR: 4.86) 7
- Non-spherical shape (OR: 3.89) 7
Advanced Treatment for Recurrent/Refractory Disease
Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor ligands shows promising results for treatment-refractory meningiomas. 5, 1
SSTR PET imaging must be performed prior to PRRT to confirm target expression. 5, 1
PRRT regimen: 4 treatment cycles of 7.4 GBq spaced 8±2 weeks apart, with amino acid infusion for nephroprotection. 5
Critical Pitfalls to Avoid
Do not delay surgical consultation in patients with progressive disabling symptoms. 2
Do not underestimate surgical complexity of parasagittal/falcine meningiomas due to:
- Potential superior sagittal sinus involvement 2
- Risk of venous infarction (up to 14% of cases) 3
- Need for specialized neurosurgical expertise 2
Do not assume all enhancing dural-based lesions are meningiomas - brain metastases, gliomas, and primary CNS lymphoma can mimic meningiomas. 8
Recognize that recurrence rates for completely resected benign meningiomas can reach 20% within 25 years, necessitating long-term surveillance. 1
Multimodality Management Strategy
For larger tumors (>3 cm) with progressive neurological deficits: Perform initial resection followed by planned second-stage radiosurgery for residual tumor. 6 This approach may enhance long-term tumor control, reduce need for multiple resections, and maintain functional status. 6
40% of parasagittal meningiomas require salvage treatment regardless of primary treatment modality, emphasizing the importance of close surveillance. 7