Outcome of partially irradiated recurrent nonfunctioning pituitary macroadenoma by gamma knife radiosurgery.

BACKGROUND: Gamma knife treatment outcome of large pituitary tumors which are only partially irradiated secondary to immediate proximity to critical structures such as the optic apparatus have not been rigorously studied. MATERIALS AND METHODS: From July 2003 to December 2013, there were 41 cases of recurrent or residual nonfunctioning pituitary macroadenoma partially treated with gamma knife radiosurgery (GKRS) because the adenoma obscured part of the optic apparatus on planning SRS MR imaging. RESULTS: The follow up period after GKRS was 92.3 ± 5.6 months. The percentage of tumor coverage with the full dose was 88.5 ± 0.7%. Five of 43 (11.6%) patients experienced a transient visional decrease and one patient experienced a permanent visual field defect. During the follow up, two patients underwent transphenoidal surgery and one patient had a craniotomy due to tumor progression. Seven patients (16.2%) developed cortisol and thyroxine deficiencies. In multiple variant analyses, transient visual decline was correlated to the tumor volume (> 3.5 cc), percentage of tumor coverage (< 90%), the distance from the optic apparatus to the pituitary stalk (> 15 mm) and percentage of tumor above the orbital apex (65%). CONCLUSION: In the limited case of this cohort, we found that partially treated pituitary nonfunctioning macroadenoma yielded a high tumor control rate. However, visual decline as a result of tumor progression or radiation effect can occur in a minority of patients. The radiosurgical technique warrants further study to better define the long-term risk to benefit profile for its use in complex pituitary macroadenoma obscuring part of the optic apparatus.

Outcome of hearing preservation related to tumor morphologic analysis in acoustic neuromas treated by gamma knife radiosurgery.

BACKGROUND: Gamma Knife radiosurgery (GKRS) is an important part of the neurosurgical armamentarium in the treatment of acoustic neuromas. However, the treatment outcome related to the morphology of the tumor has not been rigorously studied. In this cohort, we evaluated the morphological features of the tumor in the tumor response and neurological outcomes after GKRS. MATERIAL AND METHODS: From July 2003 to December 2008, there were 93 cases of acoustic neuromas treated upfront with GKRS with 64 cases with serviceable hearing and 29 cases without serviceable hearing to fulfill the margin dose of 12Gy with at least follow up 5 years. RESULTS: The duration of symptom before GKRS in serviceable /no serviceable hearing was 7.9 ± 1.2 and 15.3 ± 3.1 months (p < 0.001) and associated no-hearing symptom was 70% and 35%, respectively (p < 0.001). There was 81.2% of hearing preservation after GKRS in serviceable hearing group including 27 cases of pear type (84%), 14 of linear type (70%), and 9 cases of sphere type (90%) (p < 0.01); however, there was no case of hearing improvement in the no-serviceable hearing group (0 of 29). There were 85% of patients with decreased tinnitus in serviceable hearing groups as compared to 61.5% of patients in no serviceable hearing group (p < 0.05). In multivariate analysis, the tumor morphology was highly correlated to hearing preservation rate (p < 0.01). CONCLUSION: In the limited case of this cohort, we found that the tumor morphology and timing of treatment was highly correlated to the rate of hearing preservation. The sphere type of tumor morphology was associated with the best chance of hearing preservation.

Multidisciplinary treatment of cavernous sinus dural arteriovenous fistulae with radiosurgery and embolization.

OBJECTIVE: With the advent of interventional neuroradiology and stereotactic radiosurgery, dural arteriovenous fistulae are less often managed with open surgery. We evaluated the outcome of dural arteriovenous fistulae of the cavernous sinus treated with a combination of radiosurgery and embolization. MATERIAL AND METHODS: Twenty dural arteriovenous fistulae located in the cavernous sinus were enrolled in our study. Fifteen patients received X-knife radiosurgery alone and 5 also required embolization, one before radiosurgery and 4 after radiosurgery. The mean volume of the lesions was 2.8 ml (range 0.2-12.6), the corresponding radiation volume was 6.5 ml (range 0.6-24.6), and the conformity index was 2.9 (range 1.8-5.3). The mean peripheral and maximum radiation dose was 17.8 Gy (range 17-20) and 28.3 Gy (range 19-37) Gy, respectively. The clinical and imaging data were analyzed. RESULTS: The mean follow up period was 29 months (23-39). Seventy-five percent (15/20) of patients receiving radiosurgery alone achieved a symptomatic cure and with additional embolization 90% (18/20) were cured. All patients achieved cure on imaging after radiosurgery alone or in combination with embolization. Abnormal imaging findings were observed in two patients after treatment, one had an intracerebral hemorrhage and the other radiation edema, but both were asymptomatic. CONCLUSION: With multidisciplinary treatment with combined radiosurgery and embolization, satisfactory results can be achieved for dural arteriovenous fistulae with a low complication rate. In patients with mild symptoms, radiosurgery is the initial treatment option. Embolization should be performed in patients with severe symptoms or who have failed radiosurgery.

A modified method to perform the frameless biopsy.

Neuronavigation is increasingly being used to assist in stereotactic neurosurgery due to its frameless property. In this study, we developed and assessed a modified method of performing stereotactic brain biopsies by combining the use of the Fisher stereotactic biopsy instrument, that was fixed on universal quick-lock holder, under infrared guidance of the BrainLab VectorVision Neuronavigation system. Eighteen patients received a frameless stereotactic procedure in this study, including 5 cases of brain biopsy, 2 cases of abscess aspiration, 10 cases of hematoma aspiration and one case of Ommaya reservoir implantation. All cases were on target and successful. In this paper, we present our technique, discuss the advantage and disadvantages of the method and review the literature.