Oculomotor Schwannomas: A Systematic Review and Report of Two Pediatric Cases Treated with Fractionated Cyberknife Stereotactic Radiotherapy.

OBJECTIVE: Pediatric oculomotor nerve schwannomas are rare and challenging lesions due to the high morbidity associated with surgical intervention and their proximity to critical structures limiting the opportunity for stereotactic radiosurgery. We aim to report and review the novel use of fractionated Cyberknife (Accuray, Inc., Sunnyvale, California, USA) stereotactic radiotherapy in pediatric patients with oculomotor schwannomas. METHODS: A systematic review of PubMed, Embase, and Cochrane was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two patients, ages 8 and 10 years, with tumor volumes of 0.1 cm3 and 0.2 cm3, respectively, were treated with fractionated Cyberknife radiotherapy at our institution. A total dose of 45-50 Gy was administered over 25 fractions (1.8-2.0 Gy per fraction) to the 82%-84% isodose line. Serial magnetic resonance imaging was obtained for long-term follow-up (56-58 months). RESULTS: We found 14 articles published between 1982 and 2018 that reported a total of 18 pediatric patients with intracranial oculomotor schwannomas. No previously described cases of pediatric intracranial oculomotor schwannomas were treated with radiation therapy. In both of our patients, radiographic tumor control was achieved at a mean follow-up of 57 months, with 1 patient displaying a decrease in tumor volume. Neither patient exhibited any worsening of their presenting symptoms, nor did either patient develop any new neurocognitive deficits following treatment. CONCLUSIONS: Fractionated Cyberknife radiotherapy is an effective and well-tolerated treatment option for intracranial oculomotor nerve schwannomas with excellent tumor control rates, similar to surgical and radiosurgical techniques, while sparing critical surrounding structures.

Parasellar Schwannomas: Extradural vs Extra-Intradural Surgical Approach.

BACKGROUND: Schwannomas of the parasellar region may arise from the trigeminal, oculomotor, trochlear, and abducens nerves. OBJECTIVE: To define the tumor origin, location, and dural relationship (extradural vs extra-intradural vs cisternal) on preoperative magnetic resonance imaging (MRI), in order to plan the best surgical approach (purely extradural vs extra-intradural). METHODS: Twenty-four patients with parasellar schwannomas who underwent surgery were retrospectively analyzed. Twenty arose from the trigeminal nerve (7 intracavernous and 13 within the Meckel's cave), 3 from the oculomotor nerve, and 1 from the abducens nerve. The preoperative identification of the tumor location (extradural vs extra-intradural vs cisternal) and the nerve of origin was defined on MR sequences. All patients were operated on through a pterional approach (extradural or extra-intradural route). RESULTS: The tumor location was correctly defined on MRI in 22 out of 24 cases (92%) and the nerve of origin in 22 (92%). An extradural approach without intradural exploration was performed in all 5 intracavernous trigeminal schwannomas, in 11 out of 13 of the Meckel's cave, and in 2 schwannomas of the oculomotor nerve. Two schwannomas of the Meckel's cave with transgression of the medial dural wall, 1 of the oculomotor nerve, and the abducens nerve schwannoma required an extra-intradural approach. Complete tumor resection was obtained in 19 out of 24 cases (80%). CONCLUSION: The pterional extradural approach is sufficient for Dolenc type I and II trigeminal schwannomas, excepting for those transgressing the inner dural layer. Schwannomas of the oculomotor and abducens nerves with cisternal location require an extradural-intradural approach.

Rare presentation of intracranial vascular blowout after tumor resection and radiation therapy.

A middle-aged patient presented with a rapidly growing right dural-based extra-axial posterior clinoid mass extending to the right cavernous sinus that was surgically resected. Histological examination showed solid growth of primitive neuroectodermal tumor arising from the third nerve. Following surgical resection, the patient was further managed by radiation and chemotherapy. Two years later the patient developed new intracranial hemorrhage in the area adjacent to the previous surgical cavity. A cerebral angiogram showed contrast extravasation at the junction of the posterior communicating artery (Pcom) and the right posterior cerebral artery (PCA), with an expanding pseudoaneurysm. This was managed with N-butyl cyanoacrylate embolization. Autopsy showed microscopic recurrence of tumor into the PCA/PCom region with invasion of the wall of the Pcom. This case report illustrates the concept of vascular blowout in intracranial cerebral vasculature. It appears that, in the presence of risk factors that contribute to weakening of vessel walls (surgery, radiation, tumor recurrence), a blowout can occur intracranially.

Stereotactic radiotherapy for intracranial nonacoustic schwannomas including facial nerve schwannoma.

PURPOSE: Although the effectiveness of stereotactic radiosurgery for nonacoustic schwannomas is currently being assessed, there have been few studies on the efficacy of stereotactic radiotherapy (SRT) for these tumors. We investigated the long-term outcome of SRT for nonacoustic intracranial nerve schwannomas. METHODS AND MATERIALS: Seventeen patients were treated between July 1994 and December 2006. Of these patients, 7 had schwannomas located in the jugular foramen, 5 in the trigeminal nerve, 4 in the facial nerve, and 1 in the oculomotor nerve. Radiotherapy was used as an initial treatment without surgery in 10 patients (59%) and after initial subtotal resection in the remaining patients. The tumor volume ranged from 0.3 to 31.3 mL (mean, 8.2 mL). The treatment dose was 40 to 54 Gy in 20 to 26 fractions. The median follow-up period was 59.5 months (range, 7.4-122.6 months). Local control was defined as stable or decreased tumor size on follow-up magnetic resonance imaging. RESULTS: Tumor size was decreased in 3 patients, stable in 13, and increased in 1 after SRT. Regarding neurologic symptoms, 8 patients (47%) had improvement and 9 patients were unchanged. One patient had an increase in tumor size and received microsurgical resection at 32 months after irradiation. No patient had worsening of pre-existing neurologic symptoms or development of new cranial nerve deficits at the last follow-up. CONCLUSIONS: SRT is an effective alternative to surgical resection for patients with nonacoustic intracranial nerve schwannomas with respect to not only long-term local tumor control but also neuro-functional preservation.

Proptosis y oftalmoplejía de aparición brusca / Proptosis and ophthalmoplegia with sudden onset

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Fractionated radiation therapy in the treatment of intracranial meningiomas: local control, functional efficacy, and tolerance in 91 patients.

PURPOSE: To evaluate efficacy and tolerance of external fractionated radiation therapy (RT) in the treatment of intracranial meningiomas. METHODS AND MATERIALS: From January 1981 to September 1993, 91 patients with intracranial meningiomas were treated with fractionated RT. Indications were as follows: (a) incomplete surgical resection, 29 patients; (b) tumor recurrences without considering the amount of the second resection, if performed, 14 patients; (c) completely excised angioblastic, aggressive benign, and anaplastic tumors, 8 patients; (d) medically inoperable and basilar tumors where operation would involve considerable danger or permanent neurological damage, 44 patients. Most patients were irradiated with 6 to 9 MV photon beams. A three- to four-field technique with coned-down portals was used. Doses were calculated on the 95% isodose and were given 5 days a week for a median total dose of 52 Gy (1.80 Gy/fraction). RESULTS: Median follow-up from radiation therapy was 40 months. Acute tolerance was excellent, but there were six late delayed injuries. Tumor recurrences occurred in six cases. Six patients died from their tumor or RT complications, 19 from nontumoral reasons. Three, 5- and 10-year survival rates were 82, 71, and 40%, respectively. The most significant prognostic factor was age: 5-year survival rate was 86% for patients less than 65 years and 37% for patients more than 65. However, there were no differences in recurrence-free survival rates between patients younger than 65 and the oldest ones. Of 60 symptomatic patients with neurological deficits, 43 had neurological improvement (72%), beginning in some cases within 15 to 20 days after starting RT. CONCLUSION: These results reassess the role of fractionated RT in the treatment of meningiomas, and stress on its efficacy, especially on cranial nerves palsies, without severe toxicity in most cases.