Facial nerve preservation and tumor control after gamma knife radiosurgery of unilateral acoustic tumors

To assess the long-term risk of facial nerve dysfunction after unilateral acoustic tumor stereotactic radiosurgery, we retrospectively analyzed our initial experience in 98 unilateral acoustic tumor patients who were evaluated at least 2 years after treatment. This observation interval permits an analysis of both the risk of onset and the potential for recovery of facial nerve function. The overall risk of developing any degree of delayed transient or permanent postoperative facial neuropathy was 21.4% (21 of 98 patients). Only one patient undergoing radiosurgery alone had poor residual facial nerve dysfunction worse than House-Brackmann grade III. Normal facial nerve function (House-Brackmann grade 1) was preserved in 95% of patients with small tumors (10 mm or less petrous-pons dimension) and in 90% of patients who had useful hearing and normal facial function preoperatively. Normal facial function was preserved in all patients with intracanalicular acoustic tumors. The risk of delayed facial neuropathy was reduced by performing radiosurgery when tumors were small (1000 mm(3) or less), by enclosing the tumor within the 50% isodose volume, by using multiple small radiation isocenters, and by detailed identification of the tumor volume using stereotactic magnetic resonance imaging.     

Adjuvant stereotactic radiosurgery for anaplastic ependymoma

OBJECT: The purpose of this retrospective study is to evaluate the role of stereotactic radiosurgery using the Gamma Knife as an adjuvant to other modalities used in the treatment of malignant ependymomas of both children and adults and to assess its efficacy in terms of tumor control and overall survival. METHOD: Between 1987 and 1998, 22 patients in the age range of 1.5-65 years (mean age 22. 3) with progressive anaplastic ependymoma were treated by stereotactic radiosurgery using the 201 source Co-60 Leksell Gamma Knife at the University of Pittsburgh. The irradiated tumor volume varied from 0.84 to 36.8 cm(3) (mean 13.7). The median dose delivered to the tumor margin was 16.1 Gy (range 10-20), and the mean maximal dose was 32.2 Gy (range 20-40). The disease-free survival, the tumor control rate and the overall survival were recorded to evaluate the efficacy of radiosurgery. The median follow-up from radiosurgery was 21 months (range 4-84). RESULTS: Median survival after radiosurgery was 2.2 years (46.6 +/- 12.1% 5-year actuarial). Median survival from the initial diagnosis was 10. 1 years (50.3 +/- 12.5% at 5 years, 37.7 +/- 14.4% at 10 years). Reduction or stabilization of the treated tumor was seen in 16 out of 22 (68%) patients. Forty-one percent of the patients eventually developed delayed distant cerebral recurrence outside the treated volume. The 5-year actuarial rates for local control and cranial control at any location were 62.3 +/- 13.6% and 32.4 +/- 10.8%, respectively. No complication occurred as a side effect of radiosurgery. CONCLUSION: For patients with locally recurrent or progressive anaplastic ependymomas, Gamma Knife stereotactic radiosurgery proved to be safe and effective as a salvage adjuvant therapy to achieve local tumor control and improve survival.     

The radiobiology of radiosurgery

Radiosurgery is the precise and complete destruction of a chosen target containing healthy or pathological cells, without significant concomitant or late radiation damage to adjacent cells. This article discusses briefly the many uses of radiobiology and considers variables in the treatment, such as dose rate, dose homogeneity, and the issue of possible pharmacological radioprotection for radiosurgery. Comparisons between radiosurgery and fractionation are also made.     

Image-guided stereotactic management of non-AIDS-related cerebral infection.

Every neurosurgeon can appreciate Dandy's recognition that the drainage of brain abscesses causes trauma to the delicate parenchyma. Over the years, brain surgery has evolved toward management of problems by using less and less invasive techniques and thus gaining ever lower morbidity. Clearly, the advent of better imaging techniques has improved the outcome in patients afflicted with intracerebral infections. The combination of stereotaxy with these imaging techniques is contributing a "zero mortality" in the treatment of these infections. In our series of 29 consecutive patients with non-AIDS-related infections, no patient died as a direct result of a stereotactic surgical procedure. Two patients (7%) had new neurologic deficits after surgery. The only patient left with a permanent disability had a kidney allograft and subacute bacterial endocarditis. His condition deteriorated 6 hours after aspiration of a sterile abscess, when an intra-abscess hematoma was diagnosed and evacuated. In retrospect, this complication may have been avoided by less vigorous aspiration. Three of the four patients with nonviral infections who died were iatrogenically immunosuppressed for their organ transplants. These patients are difficult to treat, and given the current popularity of transplantation procedures, neurosurgeons will face more and more opportunistic infections. In general, the patients with abscesses did well. On the other hand, nonoperative mortality was extremely high for patients with viral encephalitides. This high mortality may have resulted from a delay in diagnosis and treatment or from the unavailability of highly effective antiviral agents at the time the biopsies were performed. The importance of early diagnosis and treatment of infection cannot be overemphasized. T.H. Flewett's warning about the management of HSE applies to the management of all cerebral infections: "It seems clear from everybody's published results [in the papers already given] if we wait to do biopsy until the clinical indications are unmistakable, we have waited so long that the patient, if he survives, will be left a severe neurological cripple." Because it is relatively noninvasive, stereotactic neurosurgery has been used increasingly to diagnose brain masses in patients with AIDS. We recommend its use for establishing diagnoses in all suspected cases of cerebral infection. We agree with Rosenblum et al: Empiric treatment of brain infections should be regarded as "radical." Such treatment should be reserved for patients who have an identifiable source of infection and causative organism or for patients who are clinically too unstable to undergo surgery.(ABSTRACT TRUNCATED AT 400 WORDS)     

Radiosurgery for childhood intracranial arteriovenous malformations

OBJECTIVE: The optimal management of intracranial arteriovenous malformations (AVMs) in children remains controversial. Children with intracranial AVMs present a special challenge in therapeutic decision-making because of the early recognition of their future life-long risks of hemorrhage if they are treated conservatively. The goals of radiosurgery are to achieve complete AVM obliteration and to preserve neurological function. We present long-term outcomes for a series of children treated using radiosurgery. METHODS: The findings for 53 consecutive children who underwent at least 36 months of imaging follow-up monitoring after radiosurgery were reviewed. The median age at the time of treatment was 12 years (range, 2-17 yr). Thirty-one children (58%) presented after their first intracranial hemorrhaging episodes, two (4%) after their second hemorrhaging episodes, and one (2%) after five hemorrhaging episodes. Nineteen children (36%) presented with unruptured AVMs, and a total of 25 children (47%) exhibited neurological deficits. AVMs were graded as Spetzler-Martin Grade I (2%), Grade II (23%), Grade III (36%), Grade IV (9%), or Grade VI (30%). The median AVM volume was 1.7 ml (range, 0.11-10.2 ml). The median marginal dose was 20 Gy (range, 15-25 Gy). RESULTS: Results were stratified according to AVM volumes (Group 1, < or =3 ml; Group 2, >3 ml to < or =10 ml; Group 3, >10 ml). Twenty-eight patients (80%) in Group 1 and 11 (64.7%) in Group 2 achieved complete obliteration. The only patient in Group 3 did not achieve obliteration. Complications included brainstem edema (n = 1) and transient pulmonary edema (n = 1). Four patients experienced hemorrhaging episodes, 30, 40, 84, and 96 months after radiosurgery. Multivariate logistic regression analysis demonstrated that only volume was significantly correlated with obliteration rates (P = 0.0109). CONCLUSION: Radiosurgery is safe and efficacious for selected children with AVMs. The obliteration rates and the attendant low morbidity rates suggest a primary role for stereotactic radiosurgery for pediatric AVMs.     

The role of stereotactic cyst aspiration for glial and metastatic brain tumors

OBJECTIVE: To evaluate the role of stereotactic cyst aspiration in the context of multimodality management of cystic glial and metastatic tumors, we retrospectively reviewed our experience with 38 patients during a 10-year interval. METHODS: All 38 patients had one or more computed tomography or magnetic resonance imaging guided stereotactic cyst aspirations. Twenty-seven patients had glial neoplasms and 11 had metastatic brain tumors. Twenty-two patients underwent cyst aspiration as the initial treatment modality while 15 patients had cyst aspiration following previous treatments. RESULTS: In the immediate postoperative period, 19 of the 27 (70%) patients with gliomas and nine of the 11 (82%) patients with metastatic tumors experienced symptomatic improvement. No procedure-related morbidity was encountered. Twelve patients (31.5%) eventually required a catheter-reservoir system. Thirty-seven percent of patients with cystic glial neoplasms and 18% of patients with metastatic tumors had delayed cytoreductive surgery by craniotomy subsequent to stereotactic cyst aspiration. Reduction in tumor volume following aspiration facilitated Gamma knife radiosurgery in seven patients. CONCLUSION: Single stereotactic aspiration is a low risk procedure that provides immediate relief of symptoms in patients with cystic brain tumors. It appears to be valuable together with the use of other therapeutic strategies.