SPASM (Lat. spasmus, from Gk. σπασμός, spasmos, σπασμα, spasma, spasm, from σπᾶν, span, to draw, rend). Involuntary and sudden muscular contraction, due to central nerve disturbance, to peripheral irritation, or to reflex conditions from irritation of other parts. There are two kinds of spasm: tonic and clonic. Tonic spasm is a prolonged involuntary rigidity of a muscle or a group of muscles. Such spasm occurs at the beginning of an epileptic attack, during hysteria major, tetanus, angina pectoris, and meningitis. It also occurs in the muscles of the calves of the legs in swimmers, attended with pain, when it is called cramp (q.v.). Clonic spasm is an involuntary contracting and relaxing of groups of muscles, causing twitching, jerking, and rolling movements and contortions. It is the common convulsion, or fit. Such a spasm occurs in epilepsy, hysteria major, uræmia, chorea, hydrophobia, and in some cases of indigestion and worms. In asthma (q.v.) there is spasm of the muscles controlling the bronchial tubes, as also in whooping cough (q.v.), together with hyperæsthesia. Spasm occurs also in colic.

The treatment of spasm consists of the use of antispasmodics such as asafœtida, galbanum, musk, sumbul, valerian, belladonna, cannabis indica, opium, the bromides, and stramonium, and the administration by inhalation of choloroform or amyl nitrite, or by outward application of heat in a prolonged hot bath.