Difference between tetraplegia and paraplegia. Quadriplegia: Quadriplegia refers to damage to the cervical spinal cord nerves in the spinal canal that results in impairment and loss of motor and sensory function below the injured segment. Quadriplegia results in functional impairment of the upper extremities, trunk, lower extremities and pelvis, but does not include damage to the brachial plexus or peripheral nerves outside the spinal canal. Paraplegia: Paraplegia is defined as impairment or loss of motor and sensory function following injury to the thoracic, lumbar or sacral (excluding cervical femoral) segments of the spinal cord within the spinal canal. In paraplegia, upper extremity function is not involved, but the trunk, lower extremities and pelvic organs can be involved to varying degrees depending on the injured segment.