Observations on the course of 59 children who experienced 109 distinct episodes of CNS involvement by leukemia showed that:
1. This complication may be associated with all types of acute and subacute leukemia.
2. There is no single or combination of diagnostic criteria. Manifestations of increased CSF pressure, such as vomiting, headache, and papilledema are the most frequent clinical findings. However, it should be emphasized that CNS involvement may be associated with normal CSF findings.
3. CNS involvement may be present at the onset of leukemia or can occur at any time during the course.
4. Approximately 26 per cent of children with leukemia develop CNS involvement.
5. CNS involvement may occur when the disease is under apparently good therapeutic control as well as during relapse.
6. There is no relationship between the agents which had been previously used to treat the systemic disease and the later development of CNS involvement. However, the onset of CNS symptoms was less frequent when the systemic disease was under treatment with steroids.
7. The development of CNS involvement does not appear to shorten the survival time of patients with leukemia when treatment for CNS involvement is given.