Minimally invasive keyhole removal is possible for many skull base Meningiomas
Meningiomas arising in the skull base near the pituitary often cause visual loss or double vision.
The optimal treatment for many symptomatic meningiomas arising near the pituitary gland is maximal surgical removal. Fortunately, most tuberculum sella or planum meningiomas that result in visual loss, can be removed through a minimally invasive supraorbital or endoscopic endonasal keyhole approach, while preserving pituitary gland function. However, many invasive skull base meningiomas, extending into the areas of the optic canals, cavernous sinus or Meckel’s cave regions can only be partially removed and may need additional therapy such as focused radiation.
At the Pacific Neuroscience Institute, we have one of the world’s largest experiences treating all such parasellar meningiomas with keyhole and endoscopic approaches as well as treating residual, recurrent and atypical meningiomas. By incorporating cutting edge technology and instrumentation with proven surgical experience, we make meningioma surgery safer, less invasive and more effective.
Meningiomas are the most common benign brain tumor although up to 10% can exhibit more aggressive growth patterns. Meningiomas are classified by the World Health Organization into 3 grades based on their growth pattern and histology: Grade I (typical – 90%), Grade II (atypical – 6-9%) and Grade III (anaplastic 1-3%). These tumors arise from arachnoidal cap cells in the brain coverings (meninges). They are more common in women than men and can occur in all ages but are typically seen in middle-aged and older adults. They may arise from any meningeal surface and are typically attached to the dura (outer layer of the meninges) but can also occur in the cerebral ventricles.
Meningiomas of the midline skull base that arise near the pituitary gland include planum sphenoidale, tuberculum sella, clinoidal, optic canal, cavernous sinus, Meckel’s cave and petroclival meningiomas. Some highly invasive and extensive meningiomas may extend into multiple compartments and into the sella itself, surrounding the pituitary gland.
Midline meningiomas of the skull base that arise above the pituitary gland (tuberculum sellae), or in front of the pituitary gland (planum sphenoidale), typically cause progressive visual loss from optic nerve and optic chiasm compression. They may also cause headache, double vision and loss of pituitary function.
Meningiomas that extend into the cavernous sinus may cause double vision (diplopia) and those that extend into the region called Meckel’s cave (below the cavernous sinus), may cause facial numbness or tingling. Some large petroclival meningiomas that arise in front of the brain stem, may cause double vision, loss of vision, facial numbness and difficulty walking, difficulty swallowing, urinary incontinence and headache.
Meningiomas are best diagnosed by an MRI of the brain with gadolinium, or by a CT scan of the brain with contrast. For midline skull base meningiomas adjacent to the pituitary gland, a focused MRI of the pituitary region, or orbits is often indicated to obtain better anatomical detail of a meningioma. Other tests may also be needed such as angiography (a CT angiogram or an MR angiogram), visual field tests, and pituitary hormonal tests.
Meningioma Surgery: Symptomatic tuberculum sellae or planum sphenoidale meningiomas are typically treated by surgical removal through either a supraorbital eyebrow or an endoscopic endonasal approach.
Our Center Director, Dr. Daniel Kelly has been one of the pioneers in removing tuberculum sellae meningiomas through an endoscopic endonasal approach and comparing this approach to the supraorbital approach. The advantage of the endonasal approach over a transcranial approach is that brain retraction is not necessary and manipulation of the optic nerves and chiasm is minimized. However, for larger tumors (over 3 cms) or those that extend far off the midline, the supraorbital eyebrow approach is an excellent minimally invasive alternative. With either approach, vision typically improves and pituitary hormonal function is usually preserved. For some larger meningiomas in this region, a more conventional pterional (fronto-temporal) craniotomy may be needed.
For invasive parasellar meningiomas that involve the cavernous sinus, Meckel’s cave, sella and/or petroclival region, endoscopic endonasal tumor debulking and bony decompression is a reasonable treatment option that we often use and often follow with focused stereotactic radiotherapy.
Radiosurgery (SRS) or Stereotactic Radiotherapy (SRT): Meningiomas of the cavernous sinus, Meckel’s cave, sella tursica and petroclival region cannot be completely removed in over 50% of cases. For meningiomas of the tuberculum sellae or planum sphenoidalea, complete tumor removal rates are significantly higher.
With incomplete removal or if a tumor re-grows stereotactic radiotherapy (SRT) or Stereotactic Radiosurgery (SRS), are often needed to halt further tumor growth. The tumor control rate with SRS or SRT is quite high with over 90% of patients having no further tumor growth. Complications of SRS or SRT such as visual loss or brain injury are rare.