Ake Hansasuta

Multisession stereotactic radiosurgery for vestibular schwannomas: single-institution experience with 383 cases.

BACKGROUND Single-session stereotactic radiosurgery (SRS) treatment of vestibular schwannomas results in excellent tumor control. It is not known whether functional outcomes can be improved by fractionating the treatment over multiple sessions. OBJECTIVE To examine tumor control and complication rates after multisession SRS. METHODS Three hundred eighty-three patients treated with SRS from 1999 to 2007 at Stanford University Medical Center were retrospectively reviewed. Ninety percent were treated with 18 Gy in 3 sessions, targeting a median tumor volume of 1.1 cm3 (range, 0.02-19.8 cm3). RESULTS During a median follow-up duration of 3.6 years (range, 1-10 years), 10 tumors required additional treatment, resulting in 3- and 5-year Kaplan-Meier tumor control rates of 99% and 96%, respectively. Five-year tumor control rate was 98% for tumors < 3.4 cm3. Neurofibromatosis type 2–associated tumors were associated with worse tumor control (P = .02). Of the 200 evaluable patients with pre-SRS serviceable hearing (Gardner-Robertson grade 1 and 2), the crude rate of serviceable hearing preservation was 76%. Smaller tumor volume was associated with hearing preservation (P = .001). There was no case of post-SRS facial weakness. Eight patients (2%) developed trigeminal dysfunction, half of which was transient. CONCLUSION Multisession SRS treatment of vestibular schwannomas results in an excellent rate of tumor control. The hearing, trigeminal nerve, and facial nerve function preservation rates reported here are promising.

Human spinal arachnoid villi revisited: immunohistological study and review of the literature.

OBJECT Few have described the relationship between arachnoid protrusions (villi) and adjacent spinal radicular veins, and the descriptions that do exist are conflicting. Some authors have even denied the presence of spinal arachnoid villi, suggesting that they play no role in cerebrospinal fluid (CSF) absorption. METHODS To further elucidate these structures, laminectomies from C-2 inferiorly to S-2 were performed in 10 fresh human adult cadavers. Following removal of the laminae, the dural nerve sleeves were identified and the spinal nerves excised 1 cm lateral and medial to the intervertebral foramina. Samples were submitted for histological and immunohistological analysis. RESULTS The authors identified arachnoid villi in all specimens. The length of these structures was approximately 50 to 170 microm. Regionally, these villi were more concentrated in the lumbar region, but they were not present at every vertebral level, with observed skip zones. Occasionally, more than one villus was identified per vertebral level. The majority of villi were intimately related to an adjacent radicular vein. There was a direct relationship between the size of the adjacent radicular vein, and the presence and number of arachnoid villi. CONCLUSIONS Findings in the present study have demonstrated that arachnoid villi exist and are morphologically associated with radicular veins. These data support the theory that CSF absorption occurs not only intracranially but also along the spinal axis. Further animal studies are necessary to prove that CSF traverses these villi and is absorbed into the spinal venous system.

Cochlea Radiation Dose Correlates with Hearing Loss After Stereotactic Radiosurgery of Vestibular Schwannoma

OBJECTIVE For multisession radiosurgery, no published data relate the volume and dose of cochlear irradiation to quantified risk of hearing loss. We conducted a retrospective, dosimetric study to evaluate the relationship between hearing loss after stereotactic radiosurgery (SRS) and the dose-volume of irradiated cochlea. METHODS Cochlear dose data were retrospectively collected on consecutive patients who underwent SRS (18 Gy in 3 sessions) for vestibular schwannoma between 1999 and 2005 at Stanford University Hospital. Inclusion criteria included Gardner-Robertson (GR) grade I or II hearing prior to radiosurgical treatment, complete audiograms, and magnetic resonance imaging (MRI) follow-up. A cochlea dose-volume histogram was generated for each of the 94 patients who qualified for this study. RESULTS GR grade I-II hearing posttreatment was maintained in 74% of patients (70/94). Median time to last follow-up audiogram was 2.4 years (range 0.4-8.9) and to last MRI was 3.6 years (range 0.5-9.4). Each higher level of cochlear irradiation was associated with increased risk of hearing loss. Larger cochlear volume was associated with lower risk of hearing loss. Controlling for differences in cochlear volume among subjects, each additional mm(3) of cochlea receiving 10 to 16 Gy (single session equivalent doses of 6.6-10.1 Gy3) significantly increased the odds of hearing loss by approximately 5%. CONCLUSIONS Larger cochlear volume is associated with lower risk of hearing loss following trisession SRS for vestibular schwannoma. Controlling for this phenomenon, higher radiation dose and larger irradiated cochlear volume are significantly associated with higher risk of hearing loss. This study confirms and quantifies the risk of hearing loss following trisession SRS for vestibular schwannoma.

The clinical outcome of intracranial hemangioblastomas treated with linac-based stereotactic radiosurgery and radiotherapy.

Recent publications have reported stereotactic radiosurgery as an effective and safe treatment for intracranial hemangioblastomas. However, because of the low incidence of these particular tumors, reports on large patient number studies have not yet been available. The objective of this study was to analyze the clinical results of 14 patients with 56 intracranial hemangioblastomas treated with linear accelerator (linac)-based stereotactic radiosurgery (SRS) and radiotherapy (SRT) in the same institute. The median age of patients was 41 years (range, 28–73 years). Nine of the patients (64%) had von Hippel-Lindau disease. A total of 39 lesions (70%) were treated with CyberKnife (CK), and 17 lesions (30%) were treated with X-Knife. The median pretreatment volume was 0.26 cm3 (range, 0.026–20.4 cm3). The median marginal dose was 20 Gy (range, 10–32 Gy) in 1 fraction (range, 1–10 fractions). The median follow-up time was 24 months (range, 11–89 months). At the last follow-up, 47 tumors (84%) were stable, 7 (13%) decreased and 2 (4%) increased. The 1-, 2- and 6-year local control rates were 98%, 88% and 73%, respectively. No radiation complications were observed in this study. There was a trend toward local failure only in cystic tumors, but this trend was not found to be statistically significant. SRS/SRT achieved a high local control rate in intracranial hemangioblastomas without radiation-induced complications.

The Clinical Outcome of Hypofractionated Stereotactic Radiotherapy With CyberKnife Robotic Radiosurgery for Perioptic Pituitary Adenoma

Stereotactic radiation technique including single fraction radiosurgery and conventional fractionated stereotactic radiotherapy is widely reported as an effective treatment of pituitary adenomas. Because of the restricted radiation tolerance dose of the optic pathway, single fraction radiosurgery has been accepted for small tumor located far away from the optic apparatus, while fractionated stereotactic radiotherapy may be suitable for larger tumor located close to the optic pathway. More recently, hypofractionated stereotactic radiotherapy has become an alternative treatment option that provides high rate of tumor control and visual preservation for the perioptic lesions within 2 to 3 mm of the optic pathway. The objective of the study was to analyze the clinical outcomes of perioptic pituitary adenomas treated with hypofractionated stereotactic radiotherapy. From 2009 to 2012, 40 patients with perioptic pituitary adenoma were treated with CyberKnife robotic radiosurgery. The median tumor volume was 3.35 cm3 (range, 0.82-25.86 cm3). The median prescribed dose was 25 Gy (range, 20-28 Gy) in 5 fractions (range, 3-5). After the median follow-up time of 38.5 months (range, 14-71 months), 1 (2.5%) patient with prolactinoma had tumor enlargement, 31 (77.5%) were stable, and the remaining 8 (20%) tumors were smaller in size. No patient’s vision deteriorated after hypofractionated stereotactic radiotherapy. Hormone normalization was observed in 7 (54%) of 13 patients. No newly developed hypopituitarism was detected in our study. These data confirmed that hypofractionated stereotactic radiotherapy achieved high rates of tumor control and visual preservation. Because of the shorter duration of treatment, it may be preferable to use hypofractionated stereotactic radiotherapy over fractionated stereotactic radiotherapy for selected pituitary adenomas immediately adjacent to the optic apparatus.

Volumetric Analysis of Intracranial Arteriovenous Malformations Contoured for CyberKnife Radiosurgery With 3-Dimensional Rotational Angiography vs Computed Tomography/Magnetic Resonance Imaging

BACKGROUND Accurate target delineation has significant impact on brain arteriovenous malformation (AVM) obliteration, treatment success, and potential complications of stereotactic radiosurgery. OBJECTIVE We compare the nidal contouring of AVMs using fused images of contrasted computed tomography (CT) and magnetic resonance imaging (MRI) with matched images of 3-dimensional (3-D) cerebral angiography for CyberKnife radiosurgery (CKRS) treatment planning. METHODS Between May 2009 and April 2012, 3-D cerebral angiography was integrated into CKRS target planning for 30 consecutive patients. The AVM nidal target volumes were delineated using fused CT and MRI scans vs fused CT, MRI, and 3-D cerebral angiography for each patient. RESULTS The mean volume of the AVM nidus contoured with the addition of 3-D cerebral angiography to the CT/MRI fusion (9.09 cm(3), 95% confidence interval: 5.39 cm(3)-12.8 cm(3)) was statistically smaller than the mean volume contoured with CT/MRI fused scans alone (14.1 cm(3), 95% confidence interval: 9.16 cm(3)-19.1 cm(3)), with a mean volume difference of δ = 5.01 cm(3) (P = .001). Diffuse AVM nidus was associated with larger mean volume differences compared with a compact nidus (δ = 6.51 vs 2.11 cm(3), P = .02). The mean volume difference was not statistically associated with the patients sex (male δ = 5.61, female δ = 5.06, P = .84), previous hemorrhage status (yes δ = 5.69, no δ = 5.23, P = .86), or previous embolization status (yes δ = 6.80, no δ = 5.95, P = .11). CONCLUSION For brain AVMs treated with CKRS, the addition of 3-D cerebral angiography to CT/MRI fusions for diagnostic accuracy results in a statistically significant reduction in contoured nidal volume compared with standard CT/MRI fusion-based contouring.

Outcomes for Pituitary Adenoma Patients Treated with Linac- Based Stereotactic Radiosurgery and Radiotherapy: a Long Term Experience in Thailand.

BACKGROUND The study analyzed the long term clinical outcomes of pituitary adenoma cases treated with the first Thailand installation of a dedicated Linac-based stereotactic radiation machine (X-Knife). MATERIALS AND METHODS A retrospective review of 115 consecutive pituitary adenoma patients treated with X-Knife at the Faculty of Medicine, Ramathibodi Hospital, Bangkok, Thailand from 1997 to 2003 was performed. Stereotactic radiosurgery (SRS) was selected for 21 patients (18%) including those with small tumors (≤3 cm) located ≥5 mm. from the optic apparatus, whereas the remaining 94 patients (82%) were treated with fractionated stereotactic radiotherapy (FSRT). RESULTS With a median follow-up time of 62 months (range, 21-179), the six-year progression free survival was 95% (93% for SRS and 95% for FSRT). The overall hormone normalization at 3 and 5 years was 20% and 30%, respectively, with average time required for normalization of approximately 16 months for SRS and 20 months for FSRT. The incidence of new hypopituitarism was 10% in the SRS group and 9% in the FSRT group. Four patients (5%) developed optic neuropathy (1 in the SRS group and 3 in the FSRT group). CONCLUSIONS Linac-based SRS and FSRT achieved similar high local control rates with few complications in pituitary adenoma cases. However, further well designed, randomized comparative studies between SRS versus FSRT particularly focusing on hormone normalization rates are required.

Outcome of newly diagnosed high risk medulloblastoma treated with carboplatin, vincristine, cyclophosphamide and etoposide

Medulloblastoma is the most common malignant brain tumor among children. Although molecular study has been included in the new classification, in developing countries with limited resources the previous Chang staging system is still used. Therefore, treatment with postoperative radiation and chemotherapy remains the standard treatment. One common complication after treatment is ototoxicity, mainly due to radiation and cisplatinum. We report a revised chemotherapy protocol, replacing cisplatinum with carboplatin in newly diagnosed medulloblastoma cases. All 23 patients in this study had high risk medulloblastoma. Mean (SD) age was 9.5 ± 3.1 years. The 5-year progression free survival (PFS), 5-year overall survival (OS), and 10-year OS were 41.8 ± 12.2%, 60.0 ± 11.2%, and 48.0 ± 14.0 respectively. Most patients had grade 3-4 hematologic toxicity. Twelve patients had hearing tests, with 11 patients having grade 0 and 1 patient having grade 1 according to the Brock criteria.