Synonyms.—Insular Sclerosis; Disseminated Sclerosis; Cerebro-Spinal Sclerosis.
Definition.—A disease characterized by the development of chronic inflammatory spots, or sclerotic patches of the central nervous system, and may occur either in the brain or cord, or brain and cord combined.
Etiology.—The specific or exciting cause is unknown. Among the predisposing- causes may be named age, it being a disease of early life, and rarely occurs after the age of forty. Hysteria, trauma, exposure, cold, and the infectious diseases may be causal factors. There is no preference for sex, if we except the neurotic state in certain females. Heredity is also a predisposing factor.
Pathology.—Prof. Taylor, an English authority, clearly describes the anatomical changes that take place. "The surface of the spinal cord, medulla oblongata, pons varolii, and base of the brain, present a number of irregular patches of pinkish-gray color, rather sharply outlined, and contrasting with the natural white color of the medulla, pons and crura. On section, the discoloration is found to extend inwards so far as to form deposits of a round or oval shape, ranging in size from that of a pea to that of a hazel-nut, generally harder than that of the normal nervous tissue, and even leathery or cartilaginous, sometimes projecting above the level of the section, sometimes sunken below it. Recent patches are dark gray, older patches more yellowish gray, and less translucent. They affect the white matter more than the gray matter; thus in the spinal cord the greater part of the cornea is unaffected, and in the cerebrum they are best seen on section of the hemispheres, which are dotted with gray areas, and the walls of the lateral ventricles are often invaded. They are not frequent in the cerebellum; but the sclerosis may invade the olfactory bulbs, and the spinal and cranial nerve-roots.
"Under the microscope the outline of the patch or nodule is much less distinctly marked than it appears to the naked eye. The nodule consists chiefly of fibrous or finely fibrillated tissue, developed by overgrowth of the neuroglia; within this area the nerve fibers have lost their myelin sheaths, but great numbers of axis cylinders persist. Nerve-cells are very little involved unless late in the disease. There may be some thickening- of the vessels, but it is rarely pronounced."
Symptoms.—The disease may begin insidiously, the patient simply noticing that he is growing weaker, tremulous, or spastic, or there may be a more rapid beginning, the patient behaving as though affected by hysteria. Thus the knees suddenly give way, or there is a sudden weakness of one arm or leg; this may soon improve temporarily, and then the same or another limb becomes paretic. When the disease is fully developed, however, there are three prominent and characteristic symptoms present:
1. Tremor of muscles on attempting motion.—The tremor is volitional, there being no abnormal movement when the patient is at rest; hence the term, intentional tremor. It is best noticed in the hand and arm in attempting to take hold of an object, the limb trembles or oscillates from side to side, or up and down, with regard to the object aimed at, the deviation often being quite marked. When standing, the body swings to and fro, and there is a nodding motion of the head. On attempting to walk, there is a trembling motion of the legs. The tendon reflexes are increased and ankle clonus may be present.
When the patient is quiet in bed or sitting in a chair with the back, head, and arms supported, there is an absence of tremors.
2. Syllabic or Scanning Speech.—In talking, the speech is at first only slow or drawling, but later each syllable is uttered slowly and distinctly, with a slight rising and falling inflection, and is known as scanning.
3. Nystagmus.—Oscillation of the eyeballs, when the eyes are fixed upon some object or when they are much turned to one side, being the result of voluntary movements as seen in the limbs. Optic-nerve atrophy is not infrequent. Sensory symptoms are not pronounced, and consist of tingling or numbness of the limbs and hyperesthetic areas that are transient in character. There is no atrophy of the muscles nor trophic changes. Vertigo is often present. The function of the bladder, rectum, and sexual organs may be retained, though involuntary expulsion or retention of urine is not uncommon.
There is generally impairment of the mental faculties, at first hysterical in character, but later maniacal tendencies may develop, or dementia result. Epileptiform or apoplectiform attacks may occur, though usually rare.
Diagnosis.—The diagnosis is usually easy after the disease is well established, the three characteristic symptoms, tremors, syllabic or scanning speech, and nystagmus, being easily recognized.
Prognosis.—The disease may extend over a period of years, from five to twenty, death occurring from some intercurrent disease. Death rarely occurs from a convulsion or apoplectiform attack. The prognosis as to cure is always unfavorable.
Treatment.—The treatment is mainly symptomatic, and along the same lines as other forms of sclerosis.