Article
Conformal stereotactic radiosurgery for vestibular schwannoma
Behandlung vestibulärer Schwannome durch konformale stereotaktische Radiochirurgie
Search Medline for
Authors
Published: | April 23, 2004 |
---|
Outline
Text
Objective
To assess the feasibility of single isocenter conformal stereotactic radiosurgery for vestibular schwannoma.
Methods
From February 1998 to February 2002, 74 consecutive previously untreated patients (median age: 63 years, range: 26-81 years) with vestibular schwannoma (median volume: 1.74 cm3, range: 0.14-3.7 cm3) were prospectively treated. The median follow-up time is 24.3 months, with 42 patients having a follow-up of at least 24 months. In 33% of patients the vestibular schwannoma was located on the left side and in 67% on the right side. Twelve patients had only intrameatal growth and in 29 patients the vestibular schwannoma had brainstem contact. On initial presentation eleven patients complained about trigeminal neuralgia as the leading symptom, and 3 patients complained about a grade II facial nerve neuropathy according to House-Brackmann. Vertigo was the main complaint in ten and tinnitus in 26 patients. In all patients target delineation and treatment planning was based on CT and MRI image fusion. Patients were treated with the Novalis high-resolution bream shaper (m3 mMLC) using 6 to 11 static beams (28 patients) or 3 Dynamic Conformal Arcs (45 patients). In all patients the isocenter dose was limited to 13.5 Gy and at the periphery to 12 Gy resulting in a conformity index of 1.4 to 2.1 (median 1.7) and a homogeneity index of 1.15 according to the guidelines of the Radiation Therapy Oncology Group (RTOG).
Results
Deterioration in pre-treatment impaired hearing was noted in 16% patients. Improved hearing was found in 12%, and no change in 72% of patients. A temporary facial nerve weakness was observed in 1 patient with an intrameatal schwannoma. Temporary impairment of trigeminal neuropathy was seen in 8%, an improvement in 44% of the cases. Only 1 patient developed a temporary trigeminal neuropathy as a new complaint. Impaired dizzy-vertigo was observed in 20%, no change in 20% and improvement in 20% of patients. A decrease in tumour volume was found in 67% of patients and no patient has shown progression.
Conclusions
To date conformal stereotactic radiosurgery for vestibular schwannoma provided excellent local control and only minimal acute and late side effects.