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Stage Information
There is no universally accepted staging system for visual pathway and
hypothalamic gliomas. They are low-grade astrocytomas that grow slowly and may
occur anywhere along the optic tracts. Visual pathway gliomas are found with
increased frequency in patients with neurofibromatosis. The major clinical
symptoms are visual. Tumors may also arise in the
hypothalamus; in large infiltrating lesions, distinctions between optic and
hypothalamic tumors are often artificial and of little clinical importance. In
infants and young children, hypothalamic gliomas may result in the diencephalic
syndrome, which is manifested by failure to thrive in an emaciated, seemingly
euphoric child. Such children may have little in the way of other neurologic
findings, but can have macrocephaly, intermittent lethargy, and visual
impairment.[1] Because the location of these tumors makes a surgical approach
difficult, biopsies are not always done. This is especially true in patients
with neurofibromatosis type 1 (NF-1).[2] Visual pathway and hypothalamic gliomas
usually spread contiguously, though subarachnoid dissemination has been
reported.[1,3] Evaluation should include neuro-ophthalmological testing to
carefully monitor the patient for the visual effects of tumor progression that
may not be evident using computed tomography or magnetic resonance imaging.
Visual-evoked responses have not, as yet, been shown to be more sensitive than
clinical examination in patients with visual pathway gliomas, even in young
children.
References
-
Perilongo G, Carollo C, Salviati L, et al.: Diencephalic syndrome and disseminated juvenile pilocytic astrocytomas of the hypothalamic-optic chiasm region. Cancer 80 (1): 142-6, 1997.
[PUBMED Abstract]
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Pollack IF, Mulvihill JJ: Special issues in the management of gliomas in children with neurofibromatosis 1. J Neurooncol 28 (2-3): 257-68, 1996 May-Jun.
[PUBMED Abstract]
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Mamelak AN, Prados MD, Obana WG, et al.: Treatment options and prognosis for multicentric juvenile pilocytic astrocytoma. J Neurosurg 81 (1): 24-30, 1994.
[PUBMED Abstract]
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