Gamma Knife Radiosurgery For Non-malignant Skull Base Tumors. Analysis Of Demographics And Early Results.

Abid Muhammed Saleem1, AZHAR RASHID2, MA Sattar1, Mohammed Ali Memon1, Naveed Ahmed.1

1Pakistan Gamma knife and Stereotactic Radiosurgery Center, Neurospinal and medical institute, Karachi,Pakistan 2Pakistan Gamma KNife & Stereotactic Radiosurgery Center, Neurospinal & Medical Institute

Keywords: gamma knife, brain tumor, skull base, outcome, radiosurgery

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      Total resection of skull base tumors is difficult and involves significant risks to the neural and vascular structures of the skull base including those within cavernous sinus, the petrous apex, C.P. angle and jugular bulb. Gamma knife radiosurgery (GKRS) has evolved as a primary or adjuvant treatment option for these patients. The aim of the present study is to review the cases of GKRS for misc. non malignant skull base tumors, analyze the demographics and describe the early results.
      From May 2008 through Oct. 2009 a total of 518 patients underwent Gamma knife Radiosurgery (GKRS) at the Pakistan Gamma Knife and Stereotactic Radiosurgery center with Leksell Gamma knife 4C. During this interval 217 miscellaneous non malignant extra-axial skull base tumors were treated with GKRS. There were one twenty five males and ninety- two females. Fifty-five percent patients received radiosurgery as the first line of treatment for their disease while 45% had previous operations or radiotherapy. The median Karnofsky Performance Score of the patients was 80(range 60 -100). The various entities included vestibular schwannomas(n=50) meningiomas (n=69), pituitary adenomas(n=51), craniopharyngiomas(n=24), chordoma(n=1) schwannomas of trigeminal, facial and glossopharyngeal nerves (n=9),and Glomus Jugulare tumors(n=9) Hemangioblastomas (n=3),and Chondrosarcoma (n=1). The patients referred to our center were initially reviewed by two neurosurgeons with experience in both microsurgery and radiosurgery. Most of the tumors were diagnosed on neuroimaging characteristics in conjunction with neurological examination. For most patients tumor controlling doses are similar for a wide spectrum of these benign tumors with the exception of pituitary tumors. The patients are being followed up with MRI at 3, 6 and 12 months and then yearly.
      Our preliminary results are very encouraging. We were able to achieve complete resolution in cases of solid craniopharyngiomas at one year median follow up. The vestibular schwannomas are showing central hypodensities and regression with excellent facial nerve preservation. Remarkable shrinkage is noticed in trigeminal schwannomas. Meningiomas respond with central necrosis and volumetric shrinkage. Pituitary adenomas showed growth arrest.
      Gamma Knife radiosurgery is recommended as primary treatment option in the management of skull base tumors without significant mass effect and as an adjuvant management after partial resection of large tumors.


Project Roles:

A. Saleem (), A. RASHID (), M. Sattar (), M. Memon (), N. Ahmed. ()