Spinal cord cyst. Coloured magnetic resonance imaging (MRI) scan of a sagittal section through the cervical spine (neck) of a 13-year-old child, showing a syringomyelia cavity (dark, lower centre). Syringomyelia is a term used to describe a disorder in which a cavity or cyst forms within the spinal cord. A cyst is a fluid-filled sac. As it grows the cyst destroys tissue and compresses nerve fibres. This causes weakness of the limbs, pain and the loss of perception of extremes of temperature. Severe cases can lead to paralysis. The cyst may form due to an anatomical abnormality, or after trauma or infection. Treatment is with draining of the cyst, or surgical removal. Although in both cases the cyst may reform.