Optic Chiasm Astrocytomas of Childhood

Abstract

We presented our experience from 1975 to 1994 with emphasis on the long term follow-up of children with optic chiasm astrocytomas in part I. In part II we describe the surgical management of 20 patients with the diagnosis of an astrocytoma of the optic chiasm confirmed by biopsy. These patients underwent surgery by the senior author between 1988 and 1994. The patients and the tumors in this series are comparable in age, sex, and presentation and imaging characteristics to other series. Surgery was undertaken with the intent to reduce tumor volume and mass effect and in certain cases to confirm the diagnosis. The patients’ mean age at the time of surgery was 81 (range 18–216) months. The surgical approaches used were pterional in 11 patients, transorbital/subfrontal in 8, and subfrontal in 1 patient. Greater than 50% of the tumor was resected in 8 patients, less than 50% was resected in 9, and biopsy only was achieved in 3 patients. Larger tumors were more likely to have magnetic resonance imaging documented debulking of tumor. Permanent morbidity included mild visual loss, diabetes insipidus, mild hemiparesis, and panhypopituitarism in 1 patient each. There was no surgical mortality. The likelihood of resecting greater than 50% of the tumor was higher in those with a diameter greater than 25 mm. The indications for craniotomy are (1) to debulk symptomatic tumors greater than 50 mm in diameter which are exophytic or cystic; (2) to relieve obstruction at the foramen of Monro, and (3) for diagnostic biopsy.

The role of surgery in optic pathway/hypothalamic gliomas in children

“…12,13,22,41 However, we do not consider that gross-total resection of OPHG is a feasible concept because the involvement of the neighboring structures means that hypothalamic damage and blindness would be inevitable should this be aggressively pursued. 28,40 Neurosurgery for Secondary Effects of the Tumor or Treatment. Neurosurgery may be required to treat hydrocephalus, to treat the vascular complications of treatment (such as moyamoya disease) and potentially to decompress the optic pathways in cases of progressive visual failure due to progressive cystic disease compressing the optic pathways.…”

“…The dangers of aggressive neurosurgical tumor excision have been highlighted in other series, with high rates of surgery-related complications, including hypothalamic damage and endocrine deficit. 28,40 In this series, the neurosurgeon aimed to limit the operative risks by leaving a rim of tumor around the base, performing a predominantly central debulking of the exophytic component of the tumor. Through this approach, none of our surgical cohort of patients showed signs of hypothalamic or visual injury as a direct consequence of surgery.…”

Optic pathway gliomas: a review

“…Therefore, contemporary indications for surgery include single nerve involvement causing progressive, disfiguring proptosis, blindness, or both, or exophytic chiasm tumors causing mass effect or hydrocephalus. 2,5,54,55 Surgery is contraindicated in patients with infiltrative tumors. Although authors of numerous case reports have described spontaneous regression of OPG after surgical debulking or biopsy without additional postoperative adjuvant therapy, 25,28,54,55,84,85 it is unclear whether spontaneous regression might have occurred without any treatment at all, which has also been well-reported.…”

“…2,5,54,55 Surgery is contraindicated in patients with infiltrative tumors. Although authors of numerous case reports have described spontaneous regression of OPG after surgical debulking or biopsy without additional postoperative adjuvant therapy, 25,28,54,55,84,85 it is unclear whether spontaneous regression might have occurred without any treatment at all, which has also been well-reported. 63,66 In 2006, Ahn et al 2 retrospectively reviewed a series of 33 patients with OPGs who had undergone surgery over a 17-year period.…”

“…3,28,48,56,64,75,79 When associated with NF1, the tumors are more often benign, can be multifocal and bilateral, 12,15 and are usually found within the optic nerves 74,83 but can occur anywhere along the optic pathway, from the optic nerves to the visual cortex. 54 Chiasmatic gliomas are rarely associated with NF1, often have a more aggressive course, present with diencephalic syndrome (hypersomnia and cachexia), and typically progress. 25,74,83 Overall, 25% of OPGs are confined to the optic disc and nerve, whereas 40-75% involve the chiasm.…”