Brown-Séquard syndrome may be caused by injury to the spinal cord resulting from a spinal cord tumour, trauma [such as a fall or injury from gunshot or puncture to the cervical or thoracic spine], ischemia (obstruction of a blood vessel), or infectious or inflammatory diseases such as tuberculosis, or multiple sclerosis. In its pure form, it is rarely seen. The most common cause is penetrating trauma such as a gunshot wound or stab wound to the spinal cord.[citation needed] Decompression sickness may also be a cause of Brown-Séquard syndrome.[2]