5 Parasagittal Meningioma

Remi Nader

Fig. 5.1 (A) Axial and (B) coronal T1-weighted magnetic resonance images (MRIs) with contrast showing parafalcine dural-based lesion in the parietooccipital lobe. (C) Sagittal T1-weighted MRI showing the tumor. (D) Magnetic resonance venography showing patency of the superior sagittal sinus at the site of the tumor.

Clinical Presentation

A 69-year-old healthy woman presents with episodic headaches and dizziness.

There is no deficit on examination, and there are no other symptoms.

Her family physician obtained the following study (magnetic resonance imaging [MRI] scan shown in Fig. 5.1).
She has seen a neurosurgeon who told her that she had nothing to worry about and the mass seen in the MRI scan can be observed.
She comes to see you for a second opinion.

Questions

Outline a management plan for this particular patient. She asks you, “Is the other neurosurgeon right?” What do you tell her?
What are your indications for surgery?
If the patient is demanding to have surgery, how do you approach this situation?
What is the most serious potential surgical complication specific to this case, and how do you avoid it and manage it if it were to occur?
If you decide to operate and have a residual mass post-operatively, how do you manage it?
What are some adjuvant treatments for meningioma?
What are the outcomes of these treatments?

Answers

Outline a management plan for this particular patient.

This is likely an incidental meningioma. You may get magnetic resonance angiography (MRA)/MR venography (MRV) and MR spectroscopy to evaluate vasculature and tumor type. Then you need to have a discussion with the patient about the diff erent options: observation, surgery, and radiosurgery. A discussion about potential risks of surgery and radiosurgery and benefits of each option is in order.

You may mention that the other neurosurgeon’s view is a valid option.1

This may not be the only option available to manage this condition.^1–3
What are your indications for surgery?
- Uncertain diagnosis
- Increase in size more than 1 cm in a year or any other change in radiologic features such as extensive edema
- Symptomatic patient
- Location of tumor (operative difficulty)
- Patient’s wishes (controversial)²
If the patient is demanding to have surgery, how do you approach this situation?
- Patient autonomy is important and should be respected.
- However, one must take into account any other potential prohibitive factors such as age, other medical problems (none in this case), psychosocial situation, etc.
- If there are some doubts about the benefits of surgery, then these should be clearly explained to the patient.¹
- If the patient seems to have an unreasonable behavior or expectations, a psychological evaluation may help.
What is the most serious potential surgical complication specific to this case, and how do you avoid and manage it?
- The risk of venous sinus injury, which may lead to profuse hemorrhage, air embolism, or venous infarction
- Avoidance is achieved by
  - – Obtaining detailed preoperative venous imaging (MRV or venogram)
  - – Assistance with neuronavigation
  - – Attention during opening not to injure the sinus while drilling the skull
- Attention during tumor resection not to apply any extensive retraction on the sinus or large draining veins and to avoid sinus occlusion
- Be prepared and have a strategy to repair the sinus and to treat a potential air embolus (have graft ready, precordial Doppler probe, warn anesthesia to monitor PCO₂, etc.).^3,4
If you decide to operate and have a residual mass post-operatively, how do you manage it?
- Observation with serial MRI is an option with an increase in size warranting further treatment.
- Stereotactic radiosurgery is another option, depending on the size of the residual mass and pathology.^5,6
What are some adjuvant treatments for meningioma?
- Radiation therapy
  - – Shown to arrest the growth of some tumors
  - – Good for residual or recurrent tumors
  - – Good for malignant pathologies
- Other nonsurgical therapies
  - – Restricted to recurrence or incomplete resections
  - – Tamoxifen
  - – Mifepristone (RU-486)
  - – Trapidil — platelet-derived growth factor antagonist^6,7
What are the outcomes of these treatments?
- Radiosurgery shows tumor control rates of 84–100%.
- Complications of radiosurgery are mainly related to edema and include seizure, cranial nerve deficits (trigeminal symptoms, oculomotor palsy, dysphasia, hearing loss), hemiparesis, headache, mental status changes, and imbalance.
- Permanent morbidity secondary to gamma knife surgery occurs in 5.7% of cases.^6,8