Browse

You are looking at 1 - 4 of 4 items for

  • By Author: Sheehan, Jason x
  • By Author: Patterson, Greg x
Clear All
Restricted access

Ayhan Kanat

Restricted access

Chun Po Yen, Jason Sheehan, Greg Patterson and Ladislau Steiner

Object

Although considered benign tumors, neurocytomas have various biological behaviors, histological patterns, and clinical courses. In the last 15 years, fractionated radiotherapy and radiosurgery in addition to microsurgery have been used in their management. In this study, the authors present their experience using Gamma Knife surgery (GKS) in the treatment of these tumors.

Methods

Between 1989 and 2004, the authors performed GKS in seven patients with a total of nine neurocytomas. Three patients harbored five recurrent tumors after a gross-total resection, three had progression of previous partially resected tumors, and one had undergone a tumor biopsy only. The mean tumor volume at the time of GKS ranged from 1.4 to 19.8 cm3 (mean 6.0 cm3). A mean peripheral dose of 16 Gy was prescribed to the tumor margin with the median isodose configuration of 32.5%.

Results

After a mean follow-up period of 60 months, four of the nine tumors treated disappeared and four shrank significantly. Because of secondary hemorrhage, an accurate tumor volume could not be determined in one. Four patients were asymptomatic during the follow-up period, and the condition of the patient who had residual hemiparesis from a previous transcortical resection of the tumor was stable. Additionally, the patient who experienced tumor hemorrhage required a shunt revision, and another patient died of sepsis due to a shunt infection.

Conclusions

Based on this limited experience, GKS seems to be an appropriate management alternative. It offers control over the tumor with the benefits of minimal invasiveness and low morbidity rates. Recurrence, however, is not unusual following both microsurgery and GKS. Open-ended follow-up imaging is required to detect early recurrence and determine the need for retreatment.

Restricted access

Chun Po Yen, Jason Sheehan, Melita Steiner, Greg Patterson and Ladislau Steiner

Object

Focal tumors, a distinct subgroup of which is composed of brainstem gliomas, may have an indolent clinical course. In the past, their management involved monitoring of open-ended imaging studies and shunt placement if cerebrospinal fluid diversion was required. Nonetheless, their treatment remains a significant challenge for neurosurgeons. Gamma Knife surgery (GKS) has recently been tried as an alternative to surgical extirpation. In the present study the authors assess clinical and imaging results in 20 patients who harbored focal brainstem gliomas treated with GKS between 1990 and 2001.

Methods

There were 10 male and 10 female patients with a mean age of 19.1 years. Sixteen tumors were located in the midbrain, three in the pons, and one in the medulla oblongata. The mean tumor volume at the time of GKS was 2.5 cm3. In 10 cases a tumor specimen was obtained either by open surgery or stereotactic biopsy, securing the diagnosis of pilocytic astrocytoma in five patients and nonpilocytic astrocytoma in five others. In the remaining 10 cases, the diagnosis was based on clinical and neuroimaging findings. The prescription Gamma Knife dose varied between 10 and 18 Gy, except in three patients who were receiving a boost to a site in which external-beam radiation was previously delivered. An average of four isocenters were utilized per GKS.

Patients were followed up for a mean of 78.0 months. The tumors disappeared in four patients and shrank in 12 patients. Of these patients, one experienced transitory extrapyramidal symptoms and fluctuating impairment of consciousness (from somnolence to coma) for 6 months. Another patient whose tumor disappeared 3 years following GKS died of stroke 8 years postoperatively. The rest of the patients either remained stable or improved clinically. Tumor progression occurred in four patients; of these four, one patient developed hydrocephalus requiring a ventriculoperitoneal shunt, two showed neurological deterioration, and one 4-year-old boy died of tumor progression.

Conclusions

Gamma Knife surgery may be an effective primary treatment or adjunct to open surgery for focal brainstem gliomas.

Restricted access

Chun Po Yen, Jason Sheehan, Greg Patterson and Ladislau Steiner

Object

The authors review imaging and clinical outcomes in patients with metastatic brainstem tumors treated using Gamma Knife surgery (GKS).

Methods

Between March 1989 and March 2005, 53 patients (24 men and 29 women) with metastatic brainstem lesions underwent GKS. The metastatic deposits were located in the midbrain in eight patients, the pons in 42, and the medulla oblongata in three. Lung cancer was the most common primary malignancy, followed by breast cancer, melanoma, and renal cell carcinoma. The mean volume of the metastatic deposits at the time of treatment was 2.8 cm3 (range 0.05–21 cm3). The prescription doses varied from 9 to 25 Gy (mean 17.6 Gy).

Imaging follow-up studies were not completed in 16 patients, because of the short-term survival in 11 and patient refusal in five. Of the remaining 37 patients, who underwent an imaging follow-up evaluation at a mean of 9.8 months (range 1–25 months), the tumors disappeared in seven, shrank in 22, remained unchanged in three, and grew in five. All but one of 18 patients with asymptomatic brainstem deposits remained free of symptoms. In 35 patients with symptomatic brainstem deposits, neurological symptoms improved in 21, remained stable in 11, and worsened in three. At the time of this study, 10 patients were alive, and their survival ranged from 3 to 52 months after treatment. Thirty-four patients died of extracranial disease, three of the progressing metastatic brainstem lesion, and six of additional progressing intracranial deposits in other parts of the brain. The overall median survival period was 11 months after GKS. In terms of survival, the absence of active extracranial disease was the only favorable prognostic factor. Neither previous whole-brain radiation therapy nor a single brainstem metastasis was statistically related to the duration of survival.

Conclusions

Compared with allowing a metastatic brainstem lesion to take its natural course, GKS prolongs survival. The risks associated with such treatment are low. The severity of systemic diseases largely determines the prognosis of metastases to the brainstem.