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Melanocytomas are rare tumors of the central nervous system that are believed to arise from leptomeningeal melanocytes. A young girl presented with a contrast-enhancing cystic mass in the temporal horn of the left lateral ventricle. Microsurgical resection of a black-colored vascular tumor supplied by the anterior choroidal artery was performed. Appropriate immunohistochemical staining and electron microscope evaluations were used to confirm the pathological diagnosis. The patient made an excellent recovery; follow-up imaging revealed no recurrent or residual tumor. This is the first documented primary occurrence of a melanocytoma in an intraventricular location. The intraventricular occurrence of this tumor suggests that melanocytes may migrate into the choroidal fissure and may infrequently undergo neoplastic proliferation in that location. This case contains implications for the differential diagnosis of intraventricular tumors.

✓ The authors report on two patients who underwent radiosurgery for torsion spasm and evaluate the efficiency of gamma knife radiosurgery (GKS) as an alternative treatment.

The first patient was a 33-year-old woman with severe right-sided lower-limb torsion dystonia. The second patient was a 20-year-old man with right-sided upper-limb torsion dystonia. The target was located at the anterior portion of the ventrolateral nucleus. The maximum doses were 150 Gy and 145 Gy, respectively. Double isocenters with a 4-mm collimator were used. Follow up lasted for 18 months and 8 months, respectively. Both patients had excellent clinical improvement 2 to 3 months after GKS, respectively.

The authors believe that GKS may be a safe and efficient treatment for torsion spasm.

Object.The purpose of this study was to evaluate the effect on tumor growth and symptom relief in patients with jugular foramen schwannomas after undergoing gamma knife radiosurgery (GKS).

Methods.Between November 1993 and December 2000, 27 patients were treated for jugular foramen schwannomas. The results of GKS in these cases are reviewed. Twelve patients had undergone previous tumor resection and the others underwent GKS as their primary treatment. The mean tumor volume was 13.5 cm³(range 4.7–35.7 cm³). The mean margin dose was 14.6 Gy (range 9.8–20 Gy). The mean maximum dose was 32.6 Gy (range 25.4–50 Gy). The prescription isodose was 35 to 55%. Twenty-five patients were followed for a mean period of 38.7 months (range 9–90 months). Tumors shrank in 11 patients, remained stable in 13, and enlarged in one patient who underwent a second GKS procedure. Sixteen patients improved and nine remained at their pre-GKS clinical status. No patient developed new cranial nerve deficits after GKS.

Conclusions.The follow-up results indicate that GKS is a safe and effective primary or adjuvant treatment method for the control of jugular foramen schwannomas.

Object.The authors sought to evaluate the effect of gamma knife radiosurgery (GKS) on growth hormone (GH)—producing pituitary adenoma growth and endocrinological response.

Methods.From 1993 to 1997, 79 patients with GH-producing pituitary adenomas were treated with GKS. Seventysix patients had acromegaly. Sixty-eight patients were treated with GKS as the primary procedure. The tumor margin was covered with a 50 to 90% isodose and the margin dose was 18 to 35 Gy (mean 31.3 Gy). The dose to the visual pathways was less than 10 Gy except in one case. Sixty-eight patients (86%) were followed for 6 to 52 months. Growth hormone levels declined with improvement in acromegaly in all cases in the first 6 months after GKS. Normalization of the hormone levels was achieved in 23 (40%) of 58 patients who had been followed for 12 months and in 96% of cases for more than 24 months (43 of 45), or more than 36 months (25 of 26), respectively. With the reduction of GH hormone levels, 12 of 21 patients with hyperglycemia regained a normal blood glucose level (p < 0.001). The tumor shrank in 30 (52%) of 58 patients who had been followed for 12 months (p < 0.01), 39 (87%) of 45 patients for more than 2 years (p = 0.02), and 24 (92%) of 26 patients for more than 36 months. In the remainder of patients tumor growth ceased.

Conclusions.Gamma knife radiosurgery for GH-producing adenomas showed promising results both in hormonal control and tumor shrinkage. A margin dose of more than 30 Gy would seem to be effective in improving the clinical status, reducing high blood glucose levels, and normalizing hypertension.

Object.The authors analyzed the outcome of 53 patients with cavernous hemangiomas who underwent gamma knife radiosurgery (GKS) and evaluated the benefit of the treatment.

Methods.From 1994 to 1995, 57 patients were treated with GKS for cavernous hemangiomas. The mean margin dose to the lesions was 20.3 Gy (range 14.5–25.2 Gy) and the prescription isodose was 50 to 80%. The mean follow-up period was 4.2 years. Four patients were lost to follow up. In 18 of 28 patients whose chief complaint was seizures, there was a decrease in seizure frequency. Five of 23 patients with hemorrhage suffered rebleeding 4 to 39 months after GKS. Seventeen patients in whom the hemangiomas were located at the frontal or parietal lobe had neurological disability and in five this was severe. Two patients underwent resection of their hemangioma after GKS. Three experienced visual problems. Follow-up imaging demonstrated shrinkage of the lesion in 19 patients.

Conclusions.A higher margin dose (> 16 Gy) may be associated with a reduction in the incidence of rebleeding after GKS. Higher dosage and severe brain edema after GKS may decrease the frequency and intensity of seizures at least temporarily. Gamma knife radiosurgery may play a role in protection against hemorrhage and in reduction of the rate of seizure in selected cases with the appropriate dose.

Object.The authors evaluated the long-term efficacy of gamma knife surgery (GKS) in patients with trigeminal schwannomas.

Methods.Fifty-six patients, 31 women and 25 men (mean age 42 years), underwent GKS for trigeminal schwannomas. Fourteen had previously undergone surgery, and GKS was the primary treatment in the remaining 42 patients. The mean target volume was 8.7 cm³(range 0.8–33 cm³); the mean maximum dose was 27 Gy (range 20–40 Gy); the mean tumor margin dose was 13.3 Gy (range 10–15 Gy); and the mean follow-up period was 68 months (range 27–114 months).

Disappearance of the tumor occurred in seven patients. An obvious decrease in tumor volume was observed in 41 patients, four tumors remained unchanged, and four tumors progressed at 5, 26, 30, and 60 months, respectively. One patient with disease progression died of tumor progression at 36 months after GKS. The tumor growth control rate in this group was 93% (52 of 56 cases).

Mild numbness or diplopia was relieved completely in 14 patients. Improvement of other neurological deficits was demonstrated in 25 patients. Trigeminal nerve dysfunction was either unchanged or slightly worse in 13 patients after GKS. Four patients experienced mild symptom deterioration related to tumor progression.

Conclusions.Radiosurgery proved to be an effective treatment for small- and medium-sized trigeminal schwannomas. Some larger tumors are also suitable for radiosurgery if there is no significant brainstem compression.