Sequential quantitative EEG analysis in acute lymphocytic leukemia of children

The mystery of electroencephalography in acute lymphoblastic leukemia

The aim of the study was to evaluate changes in electroencephalogram (EEG) recordings during the course of acute lymphoblastic leukemia (ALL) in children. The study group consisted of 48 children with ALL who underwent a total of 72 EEGs at various stages of the disease. The medical files were reviewed for pertinent clinical data, and the EEGs were evaluated for changes in brain activity. Abnormal background activity was noted in 52.2% of the EEGs done at 1-10 days of therapy, in 43.5% of those done at 10-60 days, and only 4.3% of those done at later stages (p=0.037). These findings, together with earlier reports, suggest that early-stage ALL, even before treatment, may be associated with excessive slow EEG activity, which improves over time. The EEG changes, by themselves, are not an indication of central nervous system leukemia or a predictor of later seizures or other central nervous system involvement.

On the origin of EEG-slowing and encephalopathy during induction treatment of acute lymphoblastic leukemia

BACKGROUND

Neurological complications and EEG slowing frequently occur in children undergoing induction treatment for acute lymphoblastic leukemia (ALL). Disease-related factors and treatment-related toxicity are believed to play causative roles. We wanted to elucidate the etiology further by serial EEG examinations and parallel CSF amino acid analyses.

PROCEDURE

Twenty-nine children participated in the study. EEG examinations with quantitative computerized analysis were scheduled on day 1, 10, 29, and 59 of protocol I of BFM-ALL 90 and 95 Study Protocols. CSF analysis for amino acids was carried out on day 1, 15, 29, 45, and 59.

RESULTS

A total of 21 of 25 available EEGs showed slight-to-moderate slowing already at diagnosis. The abundance of slow waves was significantly correlated to the white blood count and the CSF glutamine concentration. The EEGs significantly worsened during the first 10 days of treatment with prednisone, VCR, daunorubicin, and intrathecal methotrexate. The following treatment including asparaginase (ASP) gave rise to depletion of CSF from asparagine and a rise of aspartate; glutamine, and glutamate did not follow this pattern. The EEGs remained abnormal, but did not worsen further; the CSF amino acid changes were not related to the EEG. During the subsequent consolidation treatment, the EEGs normalized despite administration of cyclophosphamide, cytara bine, intrathecal methotrexate, and mercaptopurin.

CONCLUSIONS

The greater part of EEG changes observed in the early treatment of ALL is due to disease-related factors. Treatment with prednisone, vincristine, and to a much lesser degree asparaginase aggravates the pre-existing encephalopathy. Depletion of CSF from asparagine does not give rise to additional changes. In the second month, the EEG normalizes despite ongoing treatment with different cytotoxic drugs.

Initial electroencephalographic findings in children with acute lymphoblastic leukaemia

Electroencephalography (EEG) was performed on 66 children with acute lymphoblastic leukaemia, 45 before treatment and 21 during the first 5 days of chemotherapy. The patients, aged 7 months to 16 years, 33 boys and 33 girls, had been admitted to the Department of Paediatrics, University of Oulu, between March 1976 and January 1987. The EEG findings were compared with those in 66 age and sex-matched control children chosen at random from the local population. The patients had significantly more frequent and more severe disturbances in background activity (p less than 0.001) than the controls and increased slow waves in the occipital (p less than 0.001) and temporal regions (p less than 0.01). The patients who had received chemotherapy before the EEG recording had EEG disturbances significantly more frequently than the other patients (p less than 0.01), but the latter still had EEG abnormalities significantly more frequently than their matched controls, although they did not have severe changes (grade 3). The results suggest that chemotherapy increases EEG changes during the early days of induction therapy and possibly induces long-term disturbances in brain function. The associations between EEG changes and clinical findings were also analysed and the results show that a long duration of leukaemic symptoms or an aggressive disease may lead to EEG abnormalities.

Prospective neurophysiological study in children treated for acute lymphoblastic leukaemia: serial EEG during treatment and long-term follow up with evoked potentials

In 79 children treated for acute lymphoblastic leukaemia according to protocol ALL-BFM 81, serial EEG examinations were performed before, during and after therapy. Diffuse changes of the background activity were observed in 64% of the children at the time of diagnosis. During induction and reinduction treatment with vincristine and L-asparaginase, and with some delay after CNS irradiation, a marked slowing developed in up to 65% of patients. Children who had not been irradiated showed transient disturbances during treatment with medium-dose-methotrexate. Reinduction induced more abnormal EEGs in the children who had been irradiated. At the end of maintenance therapy, only slight EEG changes were found. No differences between the irradiated and non-irradiated group were then seen. Children with CNS leukaemia or seizures differed from those with an uncomplicated treatment in that they more often showed focal and persistent disturbances. In 39 patients who stayed in first remission for at least 18 months after the termination of treatment, a follow up investigation was performed. From the EEG examination, including power spectral analysis, no differences were found between irradiated and non-irradiated patients. Slowing of the dominant frequency was seen in the patients with more severe leukaemia and in those whose EEG had been markedly abnormal at diagnosis. The visually evoked potentials were normal in all groups of patients. In the brainstem auditory evoked potential, a prolongation of the latency of wave I and a decrease of the I-V interval was found in irradiated patients. We conclude that the diffuse EEG changes frequently emerging during treatment are reversible. Persistent or lateralized changes can indicate a neurological complication.(ABSTRACT TRUNCATED AT 250 WORDS)