Symptomatic arachnoid cysts of the spine are rare lesions in the pediatric
age group. Although most commonly occurring in association with neural tube
defects, such as myelomeningocele and diastematomyelia, in some cases the
cysts appear in children without spinal anomalies. We describe a 12-month-o
ld girl with lumbar intradural arachnoid cyst with progressive weakness of
the lower limbs. There was full recovery after fenestration of the cyst.