Recovery of stance and gait ataxia in children with acute surgical lesions

Introduction: A previous study of our group in adolescents and young adults with chronic surgical cerebellar lesions has shown that recovery depends on lesion site. If lesions affected the cerebellar nuclei recovery was worse compared to lesions affecting the cerebellar cortex alone. In a prospective study in children we were interested if motor impairment is already different in acute surgical lesions affecting the cerebellar nuclei or not. Severity of ataxia of stance and gait were assessed 3 and 12 months following surgery.

Methods: Twelve children and adolescents with cerebellar tumours (6 male, 6 female, mean age 11yrs., range 6–17yrs.) and 14 healthy subjects (6 male, 8 female, mean age 12yrs., range 6–18yrs.) were included in the study. Six children presented with pilocytic astrocytoma, two with medulloblastoma, and one each from glioblastoma, ependymoma, dermoid cyst and AV-malformation. Static and dynamic posturography was used to assess ataxia of stance. Automatic postural reflexes of the lower limb were recorded. Gait ataxia was assessed during treadmill walking with the help of an ultrasound system (Zebris). Gait conditions included normal and tandem gait, with eyes open and eyes closed. In all patients high-resolution brain MRIs were acquired to define affected cerebellar nuclei and lobules.

Results: Three months following surgery many patients fell during dynamic posturography. Disorders were most severe in the condition where platform movement was sway-referenced and eyes closed (revealing vestibulocerebellar dysfunction). Tandem gait was not possible in a subset of children. Duration of long latency postural responses was increased. Ataxia of stance and gait was less severe one year after surgery. Both 3 months and 1 year after surgery, children with permanent lesions of the fastigial nuclei were more severely affected compared to children with no or temporary lesions due to edema.

Conclusions: Lesion side appears to be critical for the severity of cerebellar signs already at the acute stage following surgery of cerebellar tumours during childhood. Ataxia of stance and gait is more marked when the fastigial nuclei are permanently affected. Both in children with and without permanent lesions of the cerebellar nuclei show motor recovery. Recovery, however, is less complete if the nuclei are affected.

Supported by DFG TI 239/5–2, IFORES D/107–20780 und D/107–20530