In some of these severe cases, inflam matory in nature, there is often a marked remission of all symptoms, including the regaining of consciousness, a lessening of the spastic condition of the muscles, and a decided improvement of the gen eral condition. This change for the better is too often a deceptive one, and is followed by a return of the same grave symptoms noted above preceding death. In cases of simple non-tubercular basilar meningitis the improvement may be real and the patient slowly recover, and after some months the recovery may be a per fect one. It is more common, however, that some permanent mental or physical defect is left as the result of the effusion, and such patients are a long time in re covering from the very marked emacia tion which always is present and in some cases is extreme.
The course of the disease may be ex tremely variable, and the duration from a few days to many months. In such cases the characteristic hydrocephalic head may develop, and the case very much resemble one of chronic hydro-. cephalus. This variability in this dis ease we must assume to be directly de pendent upon the grade and extent of the primary inflammation, which in certain cases runs a subacute or almost chronic course which may finally end in more or less perfect recovery. Even in the most favorable case, when effusion has taken place into the ventricles, it is extremely rare that this effusion wholly disappears. The clinical and post-mor tem evidence is strongly in favor of the view that when effusion once occurs it is, at best, only permanently limited in the favorable cases, the brain gradually accustoming itself to the changed con ditions, while the majority of the cases show a tendency toward progressive in crease of the ventricular accumulation.
When tubercular meningitis is the primary condition, the same prodromal symptoms are usually noticed as have been above noted as ushering in non tubercular meningitis. At times the on set is very acute, but it is more apt to be gradual, with slowly-rising temperature, which does not commonly run so high as the temperature-curve of typhoid fever, nor does it often exhibit the very marked remittency usually observed in that dis ease. Irregularity of the pulse, some changes in the respiration-rhythm, re traction of the abdomen, irregularly contracted pupils, slow and irregular lateral movements of the eyeballs and unilateral or bilateral flushing of the face, the lathe meningique, gradually de velop. A violent convulsion, followed
by hemiplegia with involvement of the face, may be the next symptom, and it may or may not be preceded by twitch ings of the facial and orbital muscles. In many cases amaurosis, ptosis, strabis mus, or facial paralysis alone may be noticed after a convulsion. Drowsiness may be present from the beginning of the illness, but coma comes on early or late, according to the severity of the case, and the clinical picture is one of coma slowly ending in death.
The symptoms attending the course of other conditions producing acute hydro cephalus, and non-inflammatory in na ture, naturally depend upon the nature of the obstruction to the venous circula tion and the manner of its occurrence. In cases arising from enlargement of the bronchial glands the cerebral effusion may accumulate very slowly and be un suspected until the ease is far advanced, when prominence of the fontanelles with absence of pulsation, some increase in the size of the cranium, coupled with gradual on-coming stupor, tremors, con vulsive seizures, or some form of paraly sis may direct attention to the cerebral condition. The clinical course of these cases, which are fortunately of rare oc currence, is extremely variable, and the same may be said of the symptoms pre sented before actual dropsy of the ven tricles occurs, and evidences of intracere bral pressure become manifest, so that such forms of the disease, while they may develop acutely, approach very closely and often run into chronic hydro cephalus. In all cases of acute hydro cephalus the changes in the shape and size of the skull may be very slight, and if the disease occurs after the ossification of the cranial bones, such changes can not be detected by measurements.
Etiology.—Any cause which operates by obstructing the venous circulation within the cranial cavity may cause an acute effusion of serum into the ven tricles or elsewhere within the skull. Thus, intracranial tumors, enlarged bronchial glands, retropharyngeal ab scess, and intracranial hmmorrhage are all causes of more or less acute hydro cephalus.
Adult internal hydrocephalus, apart from acute meningitis, is almost always due to subtentorial tumor, and is, indeed, a very common consequence of such a tumor. The tumor causes the hydro cephalus by (a) compressing the veins of Galen, (t) compressing the outlet from the lateral ventricles, or (c) compressing both. William Gordon (Lancet, Jan. 9, '97).