Measurement of balance in survivors of acute lymphoblastic leukemia in childhood

Survivors of acute lymphoblastic leukemia (ALL) in childhood have been identified with balance problems. The goals of this study were to objectively quantify these observations by measuring the displacement and velocity of the body centre of pressure, a measure of 'sway'. The subjects included 79 ALL survivors who were at least 1 year post-treatment for ALL and 83 age-matched controls. Testing was carried out using various static balance tests designed to challenge central nervous system maintenance of balance and postural control. Patients were different from controls, across all age groups, in the more difficult task in which they were required to balance over a narrow base of support. However this did not reach statistical significance. When they were asked to perform this task with their eyes closed 32% of the patients tested, as opposed to 2% of controls, were unable to complete the task (significant at P<0.01, chi(2)). The youngest group of patients (children aged 5-7 years) presented consistently with lower (or similar) displacement and lower velocity measures. This phenomenon has been observed in healthy children, however, in patients, these trends were magnified and beyond the normal age range in healthy children. The velocity values were significantly different from the other patient groups (normalized values for velocity; P<0.01). These observations then manifested as higher sway values when patients were challenged with a difficult task with their eyes closed. We propose that survivors of childhood ALL have delayed motor development compared to age-matched controls giving rise to impairment in balance and postural control. It is possible that these impairments are a consequence of intensive multi-agent chemotherapy and cranial irradiation.