DIABETES INSIPIDUS.
Probably diabetes insipidus is purely an extra-renal disease, and clue more to some train of nervous disturbances than to any direct renal irritation. Sir W. Roberts, who collected 120 examples, found that out of 42 cases, cerebral diseases or blows on the head were credited in 19 as being the cause of the polyuria. This is probably due to disturbance of the fourth ventricle. In three cases the af fection was hereditary. In a large proportion of cases no cause could be assigned for the onset of the symptoms. In some of the traumatic cases the thirst and diuresis appeared with great severity on the day of the accident, in others they occurred later.
Dr. Matthews Duncan has related the case of a woman who had received a severe blow on the .back of her head, and shortly after observed a great thirst and diuresis. These symptoms continued for fourteen years, at the end of which time she came under observation. The quantity of urine ranged from twenty to thirty pints daily. She enjoyed fair health and was the mother of four healthy children.
quantity of urine is usually greater than in saccharine diabetes. Fifteen, twenty, and even forty pints are fre quently mentioned as being the daily amount excreted. One little girl under Sir W. Roberts' care passed rather more than one-third her own weight of urine daily for some weeks. The specific gravity is 1.003 to 1.007. The urine is limpid, colorless, and contains an excess of urea. The phosphates are sometimes increased (ride Phosphaturia).
The thirst is intense and insatiable; thus Dr. Willis' patient drank two bucketfuls daily. The urine, however, does not correspond to the amount imbibed, for when fluids are curtailed the diuresis con tinues and dehydration of the tissues results.
Fair health is recorded is many cases, but besides the tormenting thirst there are usually marked signs of constitutional disturbance. The temper is capricious, the patient sleepless, the bodily and men tal strength is diminished, the sexual powers become weakened, the skin is hot and dry ; there is emaciation, and lumbar pains are com plained of. Frequency of micturition is, of course, increased. The patient usually succumbs to some intercurrent disease of the brain or to phthisis.
Prognosis.—Cases are recorded of persons who have been polyuric from twenty-four to fifty years. But these are usually congenital cases ; the traumatic variety generally lasts only a few weeks or months.
Out of 77 cases of all kinds collected by Roberts, 16 were re corded as complete recoveries, 14 ended fatally, and the remaining 47 were still in progress when reported, though in some considerable amelioration had taken place. In the 16 recoveries the duration of the polyuria was comparatively short. * Morbid Anatomy and Causation.—Our knowledge of the morbid changes noticeable in diabetes insipidus is slight. In some in stances marked changes about the base of the brain, such as tuber culosis (Roberts, Dickinson), were discovered and in one there was a sarcomatous tumor in the region of the sella turcica (Fazio). In others, the neighborhood of the fourth ventricle was affected, by gummy in Ralfe's case, by gliosarcoma in a case recorded by Mosler. In one case the abdominal sympathetic was affected by malignant in vasion. In most, visible changes had occurred in the urinary tract, but it is probable that these were secondary. Phthisical changes as a cause or consequence were found in several. The immediate anatomical cause for the polyuria is probably an impairment of the vasomotor nerves of the kidney permitting the rapid transudation of urine.
By what means the disturbance is excited, whether it be clue to disease or traumatism of the base of the brain, especially of the fourth ventricle (Bernard), or of other parts of the nervous system, or to disease or injury of the solar plexus, is at present uncertain. It is undeniable that a large proportion of the cases followed injuries to the nervous centres, and in six cases (Roberts) palpable disease of the brain was found after death. Probably polyuria is merely a symptom of many nervous disorders.
Treatment.—Our therapeutic efforts, in the absence of specific knowledge of the cause or causes, are directed against the prominent symptoms—the thirst and diuresis. Enforced abstinence from fluids has nearly always proved unsuccessful, most distressing, and in one case at least positively harmful. f Among the remedies most strongly recommended is valerianate of zinc. It is administered in pills, in gradually increasing doses, until a daily dose of twenty grains is reached (Bayer). Good results from the exhibition of belladonna and ergot, or ergot alone, and of dilute nitromuriatic acid in drachm doses, have been obtained, also from the application of the constant galvanic current to the loins and hypochondria (Seidel, Kiilz, Althaus).