Effects of Cerebellar Dysfunction Acquired as a Result of Tumor Therapy on the Functioning of the Saccadic System in Children

The cerebellum plays an important role in controlling saccadic eye movements and fixing gaze. Cerebellar lesions produce a variety of impairments to oculomotor behavior and associated psychophysiological processes. Such impairments have significant influences on the effectiveness of rehabilitation measures in patients treated for cerebellar tumors. The aims of the present work were to identify and objectively evaluate the effects of cerebellar dysfunction acquired as a result of tumor treatment on the characteristics of the oculomotor system in pediatric patients for subsequent development of diagnostic criteria and quantitative evaluation of the rehabilitation process. A total of 66 children aged 9–17 years took part in the study, all with tumor treatment-induced cerebellar dysfunction; 54 healthy children of the same age also took part. Three oculomotor tests were performed in which eye movements were recorded by videooculography. We found impairments to holding the gaze on visual objects, significant increases in hypermetric saccades, and difficulty with visual scanning in the patients. These dysfunctions of the oculomotor system inevitably led to impairments to a series of cognitive processes – visual perception, attention, memory, and reading. In addition, the phenomenon of hypermetric saccades should be regarded as a special case of cerebellar ataxia syndrome in the patients. These oculomotor impairments need to be considered for effective rehabilitation measures in this class of patients.