This article deals with the disorder known medically as anaesthesia, not with the techniques of using substances (anaesthetics) to prevent pain during treatment. Medically, anaesthesia involves the loss of sensation in the skin, causing an inability to experience touch, temperature changes or pain. Feeling in the skin consists of the coarse sense of touch, and the more subtle senses of pain and temperature. This information is carried by thin nerve tissue. There is also a fine sense of touch, and this information is carried by special (thick) sensory nerves. Muscles and joints also convey information to the brain about muscular tension, the state of the joints and degrees of movement. This information too is carried by the thick sensory nerves. The different sensory nerves are very close together in a nerve bundle which carries stimuli to the spinal column, thus all sorts of feeling deteriorate simultaneously in a nervous disorder. Irritation of the nerves also causes regular tingling and pain. Causes of such disorders include cuts, pressure on a nerve (carpal tunnel syndrome and slipped disc), and neuritis. In the spinal column the fibres carrying pain, temperature and coarse touch information run seperately from the fibres carrying information on fine touch and depth sensation. Thus disorders of the spinal column can also cause partial sensory disturbances. In syringomyelia for instance only pain, temperature and coarse touch appreciation are disturbed initially. Fine touch appreciation remains intact, so that the patient knows that he is holding a cigarette, for example, but not that it has burned completely away. Thus the condition can cause burns. Cervical myelopathy and Wernicke’s disease cause problems of fine touch and depth appreciation. The patient feels that he is walking on cotton wool, but muscular co-ordination is also disturbed, so that he cannot feel the condition and movement of his muscles and joints. In consequence walking and other activities become insecure and jerky. Other conditions of brain and/or spinal column that can lead to anaesthesia include tranverse lesion, multiple sclerosis and stroke. In these all sorts of sensory nerves are damaged, and all sensations are disturbed. Treatment varies considerably and depends entirely on the underlying condition.