Chronic disease that hardens the skin and fixes it to underlying structures. Swelling and collagen buildup lead to loss of elasticity. The cause is unknown. It usually begins at age 25–55, more often in women, with severe inflammation of underlying tissue and stiffness, pain, and skin tautness and thickening. Systemic problems that may arise years later include fever, trouble in breathing, fibrous tissue in the lungs, inflammation of heart muscle or membranes, gastrointestinal disorders, and kidney malfunction. Calcium deposits build up under the skin. The disease may finally stabilize or gradually regress. Steroids may help, and physical medicine and rehabilitation with heat, massage, and passive exercise (movement of the limbs by the therapist) help prevent limb fixation and deformity.
Learn more about scleroderma with a free trial on Britannica.com.
Disease of the brain and spinal cord in which gradual, patchy destruction of the myelin sheath of nerve fibres causes interruption or disordered transmission of nerve impulses. Its early symptoms may include limb weakness or trembling, visual problems, sensory disturbances, unsteady walking, and defective bladder control, which come and go irregularly. Attacks grow more severe, and some symptoms become permanent, sometimes with eventual complete paralysis. Average survival from onset is about 25 years, but a rare acute form progresses over months. The cause remains uncertain and treatment unsatisfactory. Corticosteroids may ease symptoms. MS may be due to a delayed immune response that attacks the myelin sheaths; suggested causes include various common viruses. Dietary causes have also been suggested.
Learn more about multiple sclerosis with a free trial on Britannica.com.
Degenerative nervous-system disorder causing muscle wasting and paralysis. The disease usually occurs after age 40, more often in men. Most victims die within two to five years from respiratory muscle atrophy. ALS affects motor neurons; the muscles they control become weak and atrophied, with debility usually beginning in the hands and creeping slowly up to the shoulders. The lower limbs become weak and spastic. Variants include progressive muscular atrophy and progressive bulbar palsy. In 1993 the defective gene that accounts for 5–10percnt of cases was discovered; it produces an ineffective version of an enzyme that neutralizes free radicals, which destroy motor neurons.
Learn more about amyotrophic lateral sclerosis (ALS) with a free trial on Britannica.com.