This rare condition occurs when certain nerve cells die. These are the motor neurons that run from the brain to the muscles and control the muscles’ movements. The affected muscles cannot be stimulated and used, and they gradually waste away. The affected part of the body becomes increasingly weak. The disease can cause difficulty in swallowing, breathing, walking, or any other muscle powered activity. Thus it can interfere with virtually any of the body’s physical functions.Motor neuron disease occurs most often in people over 40. Little is known about its cause, and it cannot be cured. Treatment is directed at easing symptoms and helping you to remain relatively mobile and independent. In most cases death occurs within two to ten years of the onset of the disease.