Twenty-seven of the 1560 patients treated by radiosurgery during the period 1984-1993 had acoustic neurinomas. Four cases were excluded from this study because they had a follow-up of less than 2 years. There were 24 neurinomas treated in 23 patients as one patient had a bilateral tumour. Seven patients underwent radiosurgery for a recurrent tumour (already operated on once or twice), while it was the first treatment for 16 patients. The tumour volume ranged from 1.99 cm3 to 18.30 cm3, and the patient follow-up was from 2 to 8 years. To determine the target on CT/NMR for linear accelerator stereotactic irradiation, the Greitz-Bergström non-invasive head fixation device was used. It was again adopted for subsequent serial imaging, and for repeat radiosurgery when necessary. The total peripheral tumour dose ranged from 12 to 45 Gy. In 9 patients there was a reduction in tumour volume varying from 39 to 100%, while 14 of the neurinomas appeared stable after an average follow-up of 3 years. In one patient there was an increase in size of the tumour. Variable morphological changes were present in 66% of the neurinomas treated. Radiosurgery is indicated as an alternative to microsurgery for inoperable patients and for those who refuse surgery, for recurrent tumours, and as a post-operative complementary treatment for partially removed tumours. A gradual approach to radiosurgery, depending on tumour response, allows a greater efficacy with minimal risk. In the present series no complications were observed. Hearing was preserved at almost the same level as that prior to radiosurgery in all patients.

A total of 114 patients with benign and malignant intracranial tumors were treated by Valentino at the Flaminia Radiosurgical Center using a Philips 6-MeV linear accelerator between 1987 and 1995. The tumor locations break down as follows: 36 in the cerebral hemispheres, 14 in the region of the hypothalamus/optic chiasm, 21 in the III ventricle/pineal region, 3 in the basal ganglia, 27 in the posterior fossa, 13 in the brain stem. Seventy-nine patients had multivariate/combined treatment consisting of surgery or biopsy followed by chemotherapy, radiotherapy and/or radiosurgery. Thirty-five were not operated on or biopsied but were treated primarily by radiosurgery, which was associated with chemotherapy and conventional radiotherapy. The short- and long-term results were evaluated separately for each pathology in an attempt to derive guidelines for future treatment. For tumors of the pineal region, we are of the opinion that radiosurgery is the treatment of choice in children and that more than one-third of patients can be cured by this means. The remaining patients require surgery and/or chemotherapy in addition. For medulloblastomas radiosurgery may be useful to control local recurrence if coupled with chemotherapy. In the case of ependymomas, partly because of the extreme malignancy of the lesions in our series, radiosurgery did not succeed in controlling local recurrence. We fear that limiting treatment to radiosurgery, rather than prescribing conventional radiotherapy when indicated, could permit CNS seeding. For craniopharyngiomas radiosurgery proved useful for controlling solid remnants. In glial tumors radiosurgery helped either to "sterilize" the tumor bed after removal or to treat remnants of the lesions in critical areas; for diffuse brain stem gliomas it should be considered the treatment of choice.

Of 812 patients with intracranial tumours treated by radiosurgery during the period 1984-1990, 129 had meningiomas. Of these latter, 72 had middle fossa meningiomas. Patients with meningiomas treated by us since March 1990 are not included in this report since we established the investigative principle of a minimum of 30 months follow-up. Seventeen of the 72 patients were treated after incomplete surgical resection, and 21 for tumour regrowth. In 34 patients, radiosurgery was the primary treatment. The tumour volume was calculated by the ellipsoid method. It ranged from 0.588-76.346 ml. Radiosurgery was performed using the non-invasive stereotactic fixation head device (Greitz-Bergström) adapted to the Fixster frame, and dynamic irradiation performed with the linear accelerator, using especially designed collimators. The total tumour dose for each patient ranged from 15-45 Gy. The minimum follow-up was 2 1/2 years and the maximum 8 years. In 50 patients there was tumour shrinkage ranging from 24-91% of the initial tumour volume. Shrinkage was associated with central tumour necrosis in 11 of these 50 patients. In 18 patients the tumour volume remained stable. In 2 patients there was tumour progression and in 2 there was regrowth after initial reduction of tumour volume. There were no significant treatment complications. Radiosurgery is preferable to re-operation in recurrent meningiomas and indicated after incomplete surgical removal. In high risk patients, as well as in "unresectable" meningiomas, it is an obvious alternative to microsurgery.

Between 1984 and 1991 86 patients with single cerebral metastases underwent linear accelerator radiosurgery using the atraumatic and reproducible Greitz-Bergström head-fixation device. Routine one-month follow-up documented disappearance of the tumour in 16 patients, with resolution of the oedema and ventricular shift. Shrinkage of the metastasis occurred in 51 patients. In 9 patients the tumour remained stable, in 7 there was progression of tumour size. Among the patients showing shrinkage of the tumour or unchanged tumour volume, repeated radiosurgery resulted in disappearance of the metastasis in 5 and further shrinkage in 28. In 14 patients routine stereotactic CT follow-up study led to the detection of a new metastasis, again treated with excellent results. Local recurrence occurred in 2 patients and radiation necrosis in the target area in 5 patients. Radiosurgery thus proves to be an appropriate alternative to surgery. The versatility of our non-invasive and painless method permits CT staging (which we consider essential) without hospitalization of the patient.

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