Pattern Evoked Potential Latency as Indicator of Early and Delayed CNS Changes Due to Antileukemia Treatment in Children

Abstract

Central nervous system (CNS) irradiation and/or intrathecal antineoplastic drugs have strongly reduced meningeal involvement in young patients affected by acute lymphoblastic leukemia (ALL), but they have also produced adverse side effects: a) cranial irradiation has been implicated in the pathogenesis of early CNS defects (self-limited somnolence syndrome), b) the association of cranial irradiation (CI) with intrathecal methotrexate (IT-MTX) seems to give rise to late encephalopathies.White matter demyelination has been demonstrated in both early and late CNS side effects of ALL therapy. Pattern reversal visually evoked potentials (VEPs) were examined in children affected by ALL in order to test their usefulness in the detection of early and delayed side effects.Peak to peak amplitude and peak latency of the main positive component (high contrast check-reversal stimulation of different angular size: 80′, 40′, 20′ and 10′) were compared with those of a control group.The results suggest that: a) in patients without self limited somnolence syndrome and visual symptons increased VEP latency may occur 40–80 days after CI probably caused by early subclinical CNS changes involving optic pathways, b) delayed CNS changes (detected by neurological routine examination, EEG, and CAT scan) are correlated to increased VEP latency, even in the absence of visual symptons. The results, as a whole, show that pattern reversal VEPs are a useful diagnostic aid for screening CNS changes due to CI and IT-MTX in ALL patients.KeywordsAcute Lymphoblastic LeukemiaCranial IrradiationP100 LatencyProphylactic Cranial IrradiationIntrathecal MethotrexateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.