A periodic variation of the size of the pupils is associated with the periodic respiration. The pupils are of ordinary size or at most only slightly contracted during the respiratory pause, while, synchronously with the beginning of respiration they slowly and widely dilate. With the cessation of breathing both pupils return to their former size quicker than they dilated, to repeat this play with the next respiratory phase.
Intense light (luring the respiratory pause produces an observable, although not the maximum reflex contraction; but, during the progress of the respirations, it does not prevent the increasing dilatation of the pupils. Pinching any part of the body does not induce such a dilatation of the pupils as would disturb the periodic changes in the size of the pupils (Thiemieh).
The pulse rate also is influenced by the periodic respiration; from the beginning of the first inspiration to the end of the pause it constantly decreases.
Sensory disturbances form an essential part of the symptom-complex. An early sign of this, even before pronounced lethargy ensues, is dimin ished frequency of winking, which depends upon lessened sensibility of the cornea.
From the beginning the psychic change as a rule is of a depressant nature; at any rate a stage of excitation precedes it much selclomer than e.g. in cerebrospinal meningitis. Usually there is deep coma for clays, but occasionally it may set in only a few hours before death. Again in other cases it may occur early and may persist for weeks until the end.
Headache continues even in the presence of marked somnolence and betrays itself occasionally by tossing, painful sighing, or by abrupt, shrill cries; this so-called "eri hydrocephalique" is however neither a constant nor a po.sitive symptom, as it occurs also in other conditions of cerebral irritation.
Constipation, which is a quite constant symptom, though somewhat oftener absent in artificially nourished infants, may be due in part to insufficient ingestion of food (which is evidenced by extreme emaciation and shrivelling of the patient); in part it has a centric origin as has the boat-shaped abdomen.
Vomiting, which was mentioned as a frequent early symptom, is certainly centric. It only remains to emphasize that the vomiting by no means always has the projectile character, which is held to be char acteristic of cerebral enaesis, and that conversely, this type itself fre quently occurs in gastric diseases, e.g. in spastic contraction of the pylorus.
Of changes in the skin perspiring and erythematous patches espe cially if these appear after lightly touching or gently stroking the skin, deserve attention as being signs of vasomotor disturbances. The patches described above were named by Trousseau "Caches eerebrales."
Disturbances of function of the cranial nerves, paralysis of the facial, hypoglossal and oculomotor nerves in varied combinations and sequence, usually occur comparatively late as a result of the basal exudate. This holds also for the pupillary disturbances which, at least in tile later stages, belong to the most constant symptoms: inequality of the pupils (anisocoria), slow and incomplete reaction to light, later complete reflex rigidity of the pupil: the pupils may at this time be strikingly dilated as well as extremely contracted (Schlafpupillen). Pinching any part of the body then no longer excites dilatation (Parrot).
Recently Squires has asserted that, on the fourth or fifth day of the disease, there occurs a constant mydriasis on bending the head backward, a constant tnyosis on bending it forward. There is as yet no corroborative evidence on this probably important symptom.
Besides optic neuritis, which is rather infrequent and not very valuable for diagnostic purposes, the occurrence of tubercles in the choroid should be particularly mentioned. Its positive recognition, which is not a. simple matter (Sehmidt-Rimpler), may be decisive in suspected cases; owing to its infrequency its diagnostic value is decidedly limited.
Lumbar puncture, which discloses to us, on onc hand the existence of pressure in the cerebrospinal canal, and the state of the ecrebrospinal fluid on the other, is the most reliable method we possess for positively establishing the diagnosis of tuberculous meningitis.
The pressure symptoms, which Pfaundler especially has studied, show a certain definite dependence upon the age of the patient, the chief localization of the meninges] process, and especially the stage of the disease. The pressure, normally averaging 20-25 mm. Hg., rises during the disease to 48-52 rum., and declines again to normal with the appear ance of cerebral paralyses. Of course, decided variations occur in individual cases; still at the height of the disease increased intraeranial pressure can always be cleteeted. The increase of alburninoids, diminu tion of reducing substances, etc., are of subordinate diagnostic value. The following points are more important:— 1. The cerebrospinal fluid, which is altered by inflammation, on standing, precipitates a fine fibrinous roagulum resembling a spider web; which on agitation is loosened from the walls of the tube and rolls itself up into small floccules. As the same thing occurs in some nontuber culons serous meningitides, it is differentially diagnostic only as against functional disease, but not against other forms of meningitis.