Coloured magnetic resonance imaging (MRI) scan of the neck of a patient with a slipped, or herniated, intervertebral disc. the blocks down centre left are the bones (vertebrae) of the spine. The intervertebral disc (purple and pink) at centre is protruding into the spinal canal (brown). This puts pressure on the nerves running along the canal and can result in severe pain and paralysis. Treatment is with physiotherapy and anti-inflammatory drugs, although surgery may be needed in severe cases.