[Radiotherapy of chiasmal gliomas in children]

Chiasmal gliomas are rare tumors occurring predominantly in children. Their treatment consists of surgery, radiotherapy and chemotherapy. Surgical removal can usually be only partial, and radiotherapy frequently follows. There are supporters of radiotherapy, as well as opponents. The author has been engaged in problems of optimal treatment of this entity for more than 10 years. He offers a review of knowledge provided by literature concerning radiotherapy of this disease in children. In the past he was enthusiastic for radiotherapy. Nevertheless after passing the Postgraduate course in paediatric neurosurgery in Bonn (1989), where J.F. Hirsch demonstrated very pessimistic progressive long-term harmful sequellae of irradiation of the developing child's brain, the author has re-evaluated his attitude to this therapy. The short history and basic physical principles of radiotherapy are reviewed. Some new trends of this therapy are also mentioned (hyperbaric oxygenation, radiosensitizing agents, hyperthermia etc.). Great attention is paid to the deleterious adverse effects of radiotherapy and to the possible technical parameters enabling to avoid them (optional daily fractions, optimal total dose, limiting age in infants etc.). Harmful effects of radiotherapy are reviewed in detail. The most frequent are chronic sequellae: brain atrophy, radiation-induced brain necrosis, progressive intellectual deterioration, growth retardation, panhypopituitarism, galactorea, learning disabilities, moya-moya syndrome, radiation-induced secondary brain tumors (especially gliomas). Risks of radiotherapy combined with chemotherapy are also emphasized. Nevertheless radiotherapy has remained an important therapeutical measure in the treatment of chiasmal gliomas in children with progressive disease in cases when surgery and chemotherapy have failed.