Adjuvant Gamma Knife radiosurgery in non-functioning pituitary adenomas; low risk of long-term complications in selected patients.

Complete surgical removal of non-functioning pituitary adenomas is often not possible. This retrospective study aimed at evaluating the long-term outcome and complications of Gamma Knife (GK) radiosurgery adjuvant to pituitary microsurgery in selected patients with small tumour remnants treated 1994-2004. Thirteen men and ten women, median age 49 years, were identified. Prior to GK 15 patients had remaining pituitary function. Median size of the tumours was 1.1 cm(3). Median marginal dose was 20 Gy. Median follow-up with MR imaging was 78 and 97 months for clinical evaluation. Tumour growth control was 100%, irrespectively of growth hormone (GH) therapy for 72 months (n = 10). Only one recurrence was discovered outside radiation field and no new hypopituitarism was developed. This report suggests that in well-selected patients the long-term risk of complications is low and with careful surveillance GH insufficiency can be replaced. Lifelong follow-up is mandatory.

Combination of microsurgery and Gamma Knife surgery for the treatment of intracranial chondrosarcomas.

OBJECT: Intracranial chondrosarcomas have a high risk of recurrence after surgery. This retrospective study of patients with intracranial chondrosarcoma was conducted to determine the long-term results of microsurgery followed by Gamma Knife surgery (GKS) for residual tumor or recurrence. METHODS: The authors treated nine patients whose median age was 36 years. Seven patients had low-grade chondrosarcomas (LGCSs), whereas mesenchymal chondrosarcomas (MCSs) were diagnosed in two. Radiosurgery was performed in eight patients, whereas one patient declined further surgical intervention and tumor-volume reduction necessary for the GKS. The patients were followed up for 15 to 173 months (median 108 months) after diagnosis and 3 to 166 months (median 88 months) after GKS. Seven patients had residual tumor tissue after microsurgery, and two operations appeared radical. In the two latter cases, tumors recurred after 25 and 45 months. Thus, definite tumor control was not achieved after surgery alone in any patient, whereas the addition of radiosurgery allowed tumor control in all six patients with LGCSs. Two of these patients experienced an initial tumor regrowth after GKS; in both cases the recurrences were outside the prescribed radiation field. The patients underwent repeated GKS, and subsequent tumor control was observed. An MCS was diagnosed in the remaining two patients. Complications after microsurgery included diplopia, facial numbness, and paresis. After GKS, one patient had radiation necrosis, which required microsurgery, and two patients had new cranial nerve palsies. CONCLUSIONS: Tumor control after microsurgery alone was not achieved in any patient, whereas adjuvant radiosurgery provided local tumor control in six of eight GKS-treated patients. Tumor control was not achieved in the two patients with MCS. Similar to other treatments for intracranial chondrosarcoma, morbidity after micro- and radiosurgical combination therapy was high and included severe cranial nerve palsies.

Gamma knife surgery for dural arteriovenous shunts: 25 years of experience.

OBJECT: The aim of this study was to assess the clinical efficacy of gamma knife surgery (GKS) in the treatment of dural arteriovenous shunts (DAVSs). METHODS: From a database of more than 1600 patients with intracranial arteriovenous shunts that had been treated with GKS, the authors retrospectively and prospectively identified 53 patients with 58 DAVSs from the period between 1978 and 2003. Four patients were lost to follow-up evaluation and were excluded from the series. Thus, this study is based on the remaining 49 patients with 52 DAVSs. Thirty-six of the shunts drained into the cortical venous system, either directly or indirectly, and 22 of these were associated with intracranial hemorrhage on patient presentation. The mean prescription radiation dose was 22 Gy (range 10-28 Gy). All patients underwent a clinical follow-up examination. In 41 cases of DAVS a follow-up angiography study was performed. At the 2-year follow-up visit, 28 cases (68%) had angiographically proven obliteration of the shunt and in another 10 cases (24%) there was significant flow regression. Three shunts remained unchanged. There was one immediate minor complication related to the administration of radiation. Furthermore, one patient had a radiation-induced complication 10 years after treatment, although she recovered completely. There was one posterior fossa bleed 2 months after radiosurgery; a hematoma, as well as a lesion, was evacuated, and the patient recovered uneventfully. A second patient had an asymptomatic occipital hemorrhage approximately 6 months postradiosurgery. The clinical outcome after GKS was significantly better than that in patients with naturally progressing shunts (p < 0.01, chi-square test); figures on the latter have been reported previously. CONCLUSIONS: Gamma knife surgery is an effective treatment for DAVSs, with a low risk of complications. Major disadvantages of this therapy include the time elapsed before obliteration and the possibility that not all shunts will be obliterated. Cortical venous drainage from a DAVS, a risk factor for intracranial hemorrhage, is therefore a relative contraindication. Consequently, GKS can be used in the treatment of both benign DAVSs with subjectively intolerable bruit and aggressive DAVSs not responsive to endovascular treatment or surgery.

Gamma knife radiosurgery for pilocytic astrocytomas.

OBJECT: The authors report on the follow-up studies in patients treated at the Karolinska Hospital to evaluate the efficacy of gamma knife radiosurgery (GKS) for pilocytic astrocytoma. METHODS: Twelve male and seven female patients were treated (mean age 10.6 years [range 2-60 years]). Sixteen of these patients were children in whom GKS was performed to treat residual tumor after surgery. Most tumors were treated with a prescription dose of 10 to 12 Gy (range 9-20 Gy). The corresponding maximum dose varied between 22 and 30 Gy (range 10-50 Gy). The median clinical follow-up time was 7 years and mean clinical follow-up time 8.5 years. Median radiological follow-up time was 4.7 years and the mean radiological follow-up time was 5.9 years. Tumor control was achieved in all patients. In 85% of the cases a moderate tumor volume reduction was observed after GKS. This result occurred despite the low prescription dose administered. The radiological follow-up studies showed adverse radiation effects in 25% of patients with increasing contrast enhancement and some edema. These effects generally appeared within 7 months and resolved later. Cyst development occurred in two patients, which may have been treatment related. CONCLUSIONS: It appears that small pilocytic astrocytomas may be treated with low-prescription-dose GKS, resulting in satisfactory clinical outcomes and only minor side effects. There were a certain number of radiologically demonstrated side effects that appeared relatively early but subsequently resolved. This study should be regarded as a preliminary one because the number of patients is small and the follow-up period is short compared with the natural time course of the disease.