Progressive Spinal Muscular Atrophy.
Synonym:—Progressive muscular atrophy of spinal origin.
Because of an atrophy of the anterior horns of the spinal cord, which involves the ganglionic cells, degenerative changes take place in the peripheries of the nerves, which directly affect the muscles to which the nerves are distributed. The cause of this is prolonged overwork in some cases, while in others, in which it may appear in childhood or early youth, there is a history of heredity.
Symptomatology:—The condition occurs most frequently in males, and is first discovered in the hands. It may affect both hands simultaneously, or attack one first and the other later. The hands become stiff and progressively weak, and lose their delicate co-ordinating power. The thumb is weak and assumes the same position as the other fingers, like that of an ape.
The muscles between the bones are atrophied, causing deep grooves to appear. Muscles of the arm are next affected, usually the deltoid first. Muscles of the leg or legs may be the next in order, the quadriceps femoris showing it as early as any. From this it attacks various groups, not especially those in contact, until the entire muscular structure may be involved. There are irregular fibrillary twitchings, and as the muscles atrophy there is a corresponding diminution in the reflexes, until they disappear entirely and a progressive loss of voluntary motion occurs. The atrophy may ultimately affect the diaphragm, when serious results and complications occur, with an especial tendency toward important and usually fatal lung changes or bronchitis. The condition extends over several years, being of slow progress.
Treatment: see Muscular Dystrophies.