A group of disorders of unknown origin. Certain cells in the neurological system's MOTOR nerves degenerate and die. Upper and lower motor neurones may be affected but sensory cells retain their normal functions. Three types of MND are identified: amyotrophic lateral sclerosis (AML – 50 per cent of patients); progressive muscular atrophy (25 per cent), in which the prognosis is better than for AML; and bulbar palsy (25 per cent). Men are affected more than women, and the disorder affects about seven people in every 100,000. Those affected develop progressive weakness and wasting of their muscles. The diagnosis is confirmed with various tests including the measurement of electrical activity in muscles (electromyography), muscle BIOPSY, blood tests and imaging of the spine. There is no specific treatment: patients need physical and psychological support with aids to help them overcome disabilities.