Leukoencephalopathy after CNS prophylaxis for acute lymphoblastic leukaemia

A 16 year old boy with epilepsy and learning difficulties is reported. At 3 years of age he was diagnosed with common acute lymphoblastic leukaemia, and received therapy according to the UK protocol, UKALL VIII. This included prophylactic CNS radiotherapy and chemotherapy. He did not develop CNS leukaemia, and complete remission was achieved. At age 7, he began to experience lethargy and learning difficulties, especially problems with hand-writing, concentration and memory. Furthermore, he began experiencing atypical absence seizures, which were provoked by concentration at times of tiredness. EEG showed bilateral non-specific abnormalities, with some epileptiform features. Over the following 9 years, several anti-epileptic drugs were prescribed. Although with the changes in therapy initial remissions have been achieved, the seizures have, each time, continued to relapse. At age 12, EEG was very abnormal, showing frequent generalized slow or sharp waves. At age 13, MRI revealed multiple discrete small high-intensity lesions in the subcortical white matter of both hemispheres. Problems with lethargy, concentration and memory persist and although multiple anti-epileptic drugs have been prescribed, seizures continue to occur almost daily.