The clinical phenomena vary according to the case, the seat of the abscess and the stage of the disease. We distinguish: (1) the initial stage; (2) the stage in which the abscess is well developed, and (3) the terminal stage. In addition there is in many cases a latent stage, which occurs between the first and second and must be inferred chiefly from the. history (Macewen, Oppenheim).
The initial stage is characterized by headache, vomiting, chills and general prostration, with fever of variable degree. These symptoms may easily be overlooked in the presence of a head injury or a suppura tive otitis, which in themselves produce the picture of severe illness. Tbe initial stage may last from 1 to 6 days. It is followed by a period of latency during which either all symptoms are entirely absent ("pure latency") or the patient ma3; be in comparatively good health, oc casionally interrupted by headache, fever, a tendency to drowsiness or sudden chills ("impure latency," Oppenheirn, Huguenin). Optic neu ritis may also be present. Leaving out a few exceptional cases, this period rarely lasts longer than a few months. The active or manifest stage of tile disease either follow-s directly upon the initial stage or may be separated from it by the latent period. It is during this stage that the physician often sees his patient for the first time. The general symptoms of the first stage are still present in more or less characteristic form and, in addition, other signs referable to the seat of the disease make their appearance. The headache, which is usually less intense than during the initial stage, is often referred to a definite part of the head and thus affords some clue to the seat of the brain abscess, al though great caution is necessary in this respect in the ease. of children. It is increased by anything which tends to raise the blood pressure (contraction of the abdominal muscles or coughing). Sometimes per cussion of the skull elicits distinctly localized pain. Vomiting is more marked in cerebellar abscess and often follows a change to the erect posture. Convulsions are more frequent in children than in adults. The pulse rate is distinctly reduced and may fall as low as 30 to 60 beats in the minute (Maeewen, Baginsky, Gluck). The pulse is usually
irregular and intermittent. Cases are observed, however, especially in children, in which the entire active stage of the disease is marked by increased pulse frequency. Respiration may be slowed in cerebellar abscess, and Cheyne-Stokes breathing is occasionally observed. The temperature is usually normal and often subnormal, an important point in the differential diagnosis from suppurative meningitis ancl sinus phlebitis. Psy-chic changes which often occur are interesting. They consist in loss of memory, inability to concentrate, sluggish re action to stimuli. In smaller children there may be stupor and delir ium, with violent headache as the dominant symptom. In addition to these general symptoms many, but by no means all cases exhibit focal symptoms which afford a clue to the seat of the abscess. It is characteristic of brain abscess that the abscess may attain a consider able size before it produces any localized symptoms. The reason of this lies in the slow growth of the abscess, the gradual encroachment on the brain substance, and the fact that the more delicate portions of the brain, the internal capsule and the medulla oblongata, are rarely the seat of abscess. Small multiple abscesses particularly of the metas tatic variety rarely cause paralytic symptoms.
The focal symptoms inay be due directly to the seat of the abscess or to pressure on distant portions of the brain. Abscesses in the tem poral lobe, which must be thought of after disease of the middle ear, are characterized by word deafness (the words are heard but their mean ing is not understood) and loss of hearing in the opposite ear. In addi tion to these symptoms, which are difficult to elicit in children, we have as the result of pressure on the internal capsule paralysis of the facial nerve or the extremities on the opposite side, and from pressure on the oculomotor, which runs along the base of the brain, paralysis of that nerve on the same side (rarely' of the internal muscles of the eye). When the abscess is on tile left side, a purely motor aphasia from pressure on the third frontal convolution is present. Abscesses situated in the.