The deposit of miliary tubercles in the pia mater, with little or no accompanying meningitis, is met with in rare instances. The tubercles are few in number, but vary in dimensions, being sometimes united together in masses of considerable size, which are frequently encysted. Beyond thickening and opacity of the membrane, their presence seems to excite but little inflammatory reaction, but they are generally accompanied by ventricular effusion which by its pressure gives rise to characteristic symptoms.
The principal lesions found in other organs of the body consist of tubercle in various stages of development, caseous matter, diseases of the bones, etc. Miliary granulations are chiefly seen in the lungs, peritoneum, intestinal mucous membrane, pleura, spleen, liver, and kidneys. The bronchial and mesenteric glands often contain caseous masses, some of which are broken down and suppurating. The testicles sometimes present the same appearances. In adults, the most frequent lesion which is found external to the brain is pulmonary tuberculosis in a more or less advanced stage. Tubercles are also sometimes present in the eye. Angel Money11 states that out of 44 examinations made at the Hospital for Sick Children, London, the meninges were the seat of gray granulations in 42. The choroid (one or both) showed tubercles 14 times (right 3, left 5, both 6), and 11 times there were undoubted evidences of optic neuritis. Twice the choroid was affected with tubercle when the meninges were free; in one of these instances there was a mass of crude tubercle in the cerebellum; in the other, although there were tubercles in the belly and chest, there were none in the head. So that 12 times in 42 cases of tubercles in the meninges there were tubercles in the choroid—i.e. about 31 per cent.
11 “On the Frequent Association of Choroidal and Meningeal Tubercle,” Lancet, Nov. 10, 1883.
DIAGNOSIS.—In many cases tubercular meningitis offers but little difficulty in the diagnosis. Although the symptoms, taken singly, are not pathognomonic, yet their combination and succession, together with their relation to the age, previous health, and antecedents of the patient, are usually sufficient to lead us to a correct opinion. The prodromic period of altered disposition (irritability of temper or apathetic indifference), headache, constipation, vomiting, and emaciation, followed by irregularity and slowness of the pulse, sighing respiration, sluggishness and irregularity of the pupils; the progress from somnolence to unconsciousness and coma; the sudden lamentable cry; the convulsions and paralysis; the return of rapid pulse and respiration in the last stage,—are characteristic of no other disease. Our chief embarrassment arises during the insidious approach of the malady, before its distinctive features are visible or when some important symptom is absent. Its real nature is then apt to be overlooked, and, in fact, in some cases it is impossible to decide whether the symptoms are indicative of commencing cerebral disease, or, on the other hand, are owing to typhoid fever, to a simple gastro-intestinal irritation from error in diet, to worms in the alimentary canal, to overwork in school, or to some other cause. Under these circumstances the physician should decline giving a positive opinion until more definite signs make their appearance. It must be remembered that very important symptoms may be absent in cases which are otherwise well marked. In all doubtful cases the family history should, if possible, be obtained, especially whether one or both parents or other near relatives have been consumptive or have shown symptoms of scrofula or tuberculosis in any form, and whether the patient himself has signs of pulmonary tuberculosis, of enlarged or suppurating glands, or obstinate skin eruptions. The presence or history of those conditions would add greatly to the probability of tubercular meningitis.
The diseases for which tubercular meningitis is most liable to be mistaken are acute simple meningitis, typhoid fever, acute gastro-intestinal affections, eclampsia of infants and children, worms in the intestines or stomach, the hydrencephaloid disease of Marshall Hall, and cerebro-spinal meningitis.
Acute meningitis is distinguished from the tubercular disease by its sudden invasion without prodromatous stage, by the acuteness and intensity of the symptoms, the severity of the headache, the activity of the delirium, the greater elevation of the temperature, and by its brief duration, which rarely exceeds one week. In those exceptional cases of tubercular meningitis in which the prodromal period is absent or not observed and the course is unusually rapid, it would be perhaps impossible to distinguish between the two diseases. A family history of tubercle, or the discovery of the granulations in the choroid by ophthalmoscopic examination, might save us from error under such circumstances. The great rarity of idiopathic simple meningitis should be remembered. Meningitis from disease of the ear sometimes resembles the tubercular affection, but the history of the attack, usually beginning with local pain and otorrhœa, will in most cases prevent any confusion between the two forms of disease.
The early period of typhoid often bears considerable resemblance to that of tubercular meningitis. Headache, languor, restlessness, and mild delirium are common to both. Typhoid can be distinguished by the coated tongue, the diarrhœa, the enlargement of the spleen, the tympanites, abdominal tenderness and gurgling, the eruption, and, above all, by the characteristic temperature-curve, which, if accurately observed, is conclusive. The course of typhoid fever is comparatively uniform, while that of tubercular meningitis is often extremely irregular. It should not be forgotten that the two diseases may coexist.
The presence of worms in the alimentary canal may cause symptoms somewhat like those of tubercular meningitis, and the symptoms of the latter disease are occasionally erroneously attributed to those parasites. The administration of an anthelmintic, which should never be omitted in doubtful cases, will clear up all uncertainty.
Cerebro-spinal meningitis is usually an epidemic, and therefore not likely to be confounded with the tubercular disease. In sporadic cases it can be recognized by its sudden onset and acute character, by the eruption, and by the prominence of the spinal symptoms.
The so-called hydrencephaloid disease of Marshall Hall is a condition of exhaustion and marasmus belonging to infancy, caused by insufficient or unsuitable nourishment, by diarrhœa, and by the injudicious depletive treatment so much in vogue in former times, when the affection was much more common than at present. Some of its symptoms, such as sighing respiration, stupor, pallor, and dilated pupils, bear a certain resemblance to those of tubercular meningitis, though it would be more easily confounded with chronic hydrocephalus. The absence of constipation, headache, convulsions, and vomiting, and the favorable results of suitable nourishment and stimulants, serve to distinguish it from cerebral disease.