A retrospective chart review of all newly diagnosed tumors involving the optic chiasm from 1982-1996 was performed at British Columbia’s Children’s Hospital, Vancouver, Canada. Of 32 patients, 14 (10 male) had chiasmatic and 18 (9 male) chiasmatic/hypothalamic astrocytomas. Neurofibromatosis I was present in 10 (71%) of the chiasmatic group and none of the chiasmatic/hypothalamic patients. Clinical presentations of chiasmatic tumors were decreased visual acuity (9), symptomatic neoplasms elsewhere (4), hydrocephalus (3), developmental delay (2), and precocious puberty (2). The most common presenting symptoms of chiasmatic/hypothalamic tumors were reduced visual acuity (11), elevated intracranial pressure (8), and diencephalic syndrome (7).

The majority (13) of chiasmatic tumors was managed by surveillance only, for an average follow-up of 5.7 years (range 1.9-14.8 yrs), and none showed progression requiring treatment. Six of the 14 had second non-optic gliomas (2 in the septum pellucidum, 2 brain stem gliomas, 1 temporo-patietal and 1 thalamic glioma) treated by resection, irradiation or chemotherapy.

The majority (17) of chiasmatic/hypothalamic tumors had surgical resection, subtotal in 8, partial in 6, limited in 3; one had no surgery. The extent of resection showed no correlation with the time to tumor progression (average 18 months). Limited resections were associated with fewer complications related to hypothalamic dysfunction. Diabetes insipidus developed in 5 of 8 with subtotal resection, all 6 with partial resection, and none with limited resection or biopsy only. The syndrome of inappropriate antidiuretic hormone secretion developed in 7 overall. One patient died in the early postoperative period and 4 died during follow-up. If surgery is performed, it should be limited to a biopsy or decompression. [1]

COMMENT. Optic chiasmatic and optic chiasmatic/hypothalamic tumors are different in their clinical presentation and behavior. Neurofibromatosis I is a feature of only the optic chiasmatic tumors. Optic chiasmatic tumors are managed by observation and treatment is required mainly for associated non-optic tumors. In chiasmatic/hypothalamic tumors, radical resection should be avoided. Although radiotherapy is effective in preventing progression, it should be delayed as long as posible because of the risk of long-term complications. Chemotherapy as the first line of treatment for optic/hypothalamic tumors may delay the need for radiotherapy but it may not be effective in preventing progression.