Skull base meningioma treatment
Treatment of skull base lesions is complex and usually requires a multidisciplinary approach. In meningioma, which is the most common tumor entity in this region, resection is considered to be the most important therapeutic step to avoid meningioma recurrence. However, resection of skull base lesions with orbital or optic nerve involvement poses a challenge due to their anatomical structure and their proximity to eloquent areas.
Therefore the main goal of surgery should be to achieve the maximum extent of resection while preserving neurological function. In the postoperative course, medical and radiotherapeutic strategies may then be successfully used to treat possible tumor residues. Methods to safely improve the extent of resection in skull base lesions therefore are desirable.
The advances in endoscopy have revolutionized the management of sinonasal and skull base lesions. Many complex cancers that traditionally required open approaches are now amenable to purely endoscopic endonasal resection, providing less invasive surgery with lower morbidity but with comparable oncologic outcomes in terms of survival rates 1).
Skull base lesions are challenging to treat and may be managed using several approaches each with its own advantages and limitations. In selected cases, a modular, combined, multiportal approach could overcome the limits of a single approach and respond well to the needs of the patient.
Neuronavigation, which displays 3-dimensional reconstructions of lesion, vessels, nerves and fiber tracts during surgery and makes use of image fusion techniques, is an important tool in the neurosurgical management of skull base lesions 2).
Efforts to achieve a radical resection with a dural margin are not suitable in many cases of skull base meningiomas, because of the neurovascular structures around the tumors.
Stereotactic radiosurgery (SRS) is associated with superior local control of asymptomatic, skull-based meningiomas as compared to active surveillance and does so with low morbidity rates. SRS should be offered as an alternative to active surveillance as the initial management of asymptomatic skull base meningiomas. Active surveillance policies do not currently specify the optimal time to intervention when meningioma growth is noted. The results indicate that if active surveillance is the initial management of choice, SRS should be recommended when radiologic tumor progression is noted and prior to clinical progression 3).
Gamma knife radiosurgery
see Gamma Knife radiosurgery for meningioma
Gamma knife radiosurgery (GKRS) is well established in the management of inaccessible, recurrent, or residual benign skull base meningiomas. Most series report clinical outcome parameters and complications in the short intermediate period after radiosurgery.
The long-term control is comparable to that obtained with conventionally-fractionated radiotherapy, while the toxicity rate is very limited 4).
GKRS offers a highly durable rate of tumor control for World Health Organization grade 1 meningioma, with an acceptably low incidence of neurological deficits. The Karnofsky Performance Scale at the time of radiosurgery serves as a reliable long-term predictor of overall outcome 5).