Fig. 78. A Diagrammatic Illustration (after Luciani) to explain the Symptoms observed in Cerebellar Abscess Formation. P., Pyramidal fibres; C.A., Right cerebellar abscess; R., Reinforcing fibres from right cerebellum to left cortex; B.g., Basal ganglia; E.R., External rectus; N., Nucleus for sixth nerve; D.P.T., Direct pyramidal tract; C.P.T., Crossed pyramidal tract.
Retraction of the head and neck. Retraction of the head and neck, stiffness of the nuchal muscles, and even opisthotonos, may be observed. The existence of these symptoms is always suggestive of meningeal infection, but an abscess of considerable size, even when situated in the anterior part of the lateral lobe of the cerebellum, may so exercise pressure in the downward direction as to cork up that part of the cerebellum which normally extends into the mouth of the foramen magnum. The neighbouring upper cervical nerves may then be irritated or compressed.
Yawning. Frequent purposeless yawning is said to be pathognomonic of cerebellar disease (see [p. 165]).
Attitude in bed. More commonly the patient lies curled up in bed in the position of cerebral irritation, perhaps more frequently with the sound side upwards.
(c) Frontal abscess. The abscess is usually dependent on long-continued suppuration in the frontal sinus, with deficient drainage and spread of disease to the surrounding bone. The abscess may be situated in close relation to the focus of the disease, but, more commonly, it occupies a more posterior position, so much so that direct pressure is exercised on the corona radiata proceeding from the pre-Rolandic or motor area. It would appear also that definite localizing symptoms do not arise until the abscess has attained considerable size. The general symptoms peculiar to all cases of brain abscess are perhaps less definite when the abscess is frontal in position. Thus, although headache may be localized to the frontal region, and although optic neuritis may be present, yet vomiting, alterations in pulse-rate and in respiratory rhythm are less marked than usual.
The localizing symptoms are often reasonably definite, so much so that but little difficulty may be experienced in arriving at a diagnosis.
In the earlier stages of the abscess formation motor irritation may predominate, with the development of fits of the Jacksonian type, the lower and more anterior motor areas being first and mainly affected. More commonly, however, attention will be directed towards the nature of the trouble by paresis or paralysis of the opposite side of the body. In this case also the lower motor areas—those responsible for the opposite side of the face and upper extremity (also the motor speech-area on the left side of the brain)—are first and chiefly involved. In some cases—more especially when the abscess is of considerable size—definite hemiplegia may result.
In cases of frontal abscess, the mental condition of the patient demands special consideration. Some definite degree of moral perversion will usually be noticed, the patient—presuming that he is in a conscious condition—making himself as objectionable as possible. He will upset his food, disarrange his bedclothes, disobey orders, and even pass his urine and fæces in his bed though well aware of his wrong-doing. When questioned he answers with suspicion, when examined he demands to know the why and the wherefore of the various details of the investigation. An ophthalmoscopic examination is especially difficult to carry out in a satisfactory manner. In a case recently under my care—one in which a frontal abscess was drained three times before a cure was obtained—these curious mental perversions were observed each time, and the patient subsequently acknowledged that he had performed the various acts wittingly, but was unable to deny himself the opportunity of irritating those around him.
It has been stated that these mental changes are only to be observed when the abscess involves the left frontal lobe. In my own experience no such lateral differentiation has been noticed.