Spinal arachnoid cyst without neural tube defect.

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-old girl with lumbar intradural arachnoid cyst with progressive weakness of the lower limbs. There was full recovery after fenestration of the cyst.