Oculomotor Deficits after Chemotherapy in Childhood

Advances in the diagnosis and treatment of pediatric malignancies have substantially
increased the number of childhood cancer survivors. However, reports suggest that some
of the chemotherapy agents used for treatment can cross the blood brain barrier which may
lead to a host of neurological symptoms including oculomotor dysfunction. Whether chemotherapy
at young age causes oculomotor dysfunction later in life is unknown. Oculomotor
performance was assessed with traditional and novel methods in 23 adults (mean age 25.3
years, treatment age 10.2 years) treated with chemotherapy for a solid malignant tumor not
affecting the central nervous system. Their results were compared to those from 25 healthy,
age-matched controls (mean age 25.1 years). Correlation analysis was performed between
the subjective symptoms reported by the chemotherapy treated subjects (CTS) and oculomotor
performance. In CTS, the temporal control of the smooth pursuit velocity (velocity
accuracy) was markedly poorer (p<0.001) and the saccades had disproportionally shorter
amplitude than normal for the associated saccade peak velocity (main sequence) (p =
0.004), whereas smooth pursuit and saccade onset times were shorter (p = 0.004) in CTS
compared with controls. The CTS treated before 12 years of age manifested more severe
oculomotor deficits. CTS frequently reported subjective symptoms of visual disturbances
(70%), unsteadiness, light-headedness and that things around them were spinning or moving
(87%). Several subjective symptoms were significantly related to deficits in oculomotor
performance. To conclude, chemotherapy in childhood or adolescence can result in severe
oculomotor dysfunctions in adulthood. The revealed oculomotor dysfunctions were significantly
related to the subjects’ self-perception of visual disturbances, dizziness, light-headedness
and sensing unsteadiness. Assessments of oculomotor function may, thus, offer an
objective method to track and rate the level of neurological complications following
chemotherapy.