A posterior midline cutaneous lesion known as a faun tail nevus or aberrant lumbar hypertrichosis is significant to doctors because it may serve as a cutaneous signal for an underlying spinal cord and spine abnormalities. We describe a 17-year-old child who, since infancy, has had excessive hair development over his lumbosacral area. The lower spinal cord was affected by a related spinal abnormality. Clinical evidence was used to make the diagnosis. The patient presented with complaints of asymmetric monoparesis which on clinical examination and radiological investigations was found to be cauda equina syndrome secondary to spina bifida occulta. This case is reported for its clinical importance as patients with spina bifida occulta may show late deterioration.