Initial Management of Children with Hypothalamic and Thalamic Tumors and the Modifying Role of Neurofibromatosis-1

Abstract

Diencephalic gliomas may be grouped into 2 clinical categories. Optic pathway/hypothalamus gliomas (OPG) arise primarily from a slower-growing juvenile pilocytic astrocytoma, and thalamic gliomas arise primarily from a fibrillary astrocytoma which can become clinically and histologically more aggressive. Children with OPG have an excellent long-term prognosis with a 10-year survival of over 85%. The major therapeutic challenge for these patients is to maximize their quality of life by preserving visual and endocrine function while minimizing treatment-related morbidity. Treatment is often initiated at diagnosis in infants and toddlers who have a major visual impairment or the diencephalic syndrome. The judicious application of chemotherapy may serve to forestall the need for radiotherapy or surgery. Children with neurofibromatosis-1 (NF-1) usually have a more indolent course. Tumors may grow more slowly or occasionally regress spontaneously. However, over 90% of children with OPG without NF-1 will require some form of therapy. Patients with thalamic gliomas present with a shorter history, often with hydrocephalus. Surgical intervention is often required to relieve intracranial pressure and establish the histologic identity of the tumor. Over 75% of these tumors will become locally aggressive. Current multimodality therapy is relatively ineffective. The bithalamic variant behaves similarly to a pontine glioma.

Optic pathway gliomas: a review

“…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.…”

“…3,28,48 In addition, Grill et al 23 found that the presentation depended on whether the patient had NF1. In their series, proptosis was significantly more frequent in patients with NF1 (21.5%) than in those without (5.5%), whereas patients without NF1 were more likely to present with nystagmus and hydrocephalus.…”

Brain tumors in the first three years of life: a review of twenty cases

“…In a recent study with 39 children younger than three years of age, the extension of tumor removal was the most important prognostic factor 10 . The only exception was the optic pathways gliomas 17 . Adjuvant chemotherapy can be indicated depending on the histological diagnosis and the amount of the surgical removal.…”

The role of early intra-operative MRI in partial resection of optic pathway/hypothalamic gliomas in children

“…Optic pathway/hypothalamic gliomas (OPHG) account for approximately 2-7% of intracranial tumours in the paediatric population, with 65% of these tumours found in children less than 5 years of age [2,11,16,24,28,33]. They comprise a broad spectrum of tumour sizes and localisations, and typically follow an unpredictable course.…”

“…They comprise a broad spectrum of tumour sizes and localisations, and typically follow an unpredictable course. Presentation tends to be due to compression of the optic pathways and diencephalon, but obstructive hydrocephalus is also a common feature [2,24]. Histologically, OPHGs are nearly always low-grade tumours, with pilocystic astrocytomas (WHO grade I) accounting for the majority, along with a proportion of pilomyxoid astrocytomas (WHO grade II) [5,7,9,11,17,22,30].…”