Focal Symptoms.—These result in part from destruction of a portion of the brain, and partly froin pressure of the tumor on adjacent or remote portions of the cerebrum (direct focal symptoms, pressure symptoms, and remote pressure symptoms). The symptoms may be those of irri tation or of paralysis. Irritative symptoms are particularly frequent in the facial muscles and in the extremities, and consist in tremor, choreic and athetoid movements, cortical epilepsy and hemiplegic convulsions. They are usually the forerunners of the actual palsy. Irritative symp toms in the organs of special sense may also precede loss of the respective function.
It is obvious that focal sytnptoms may be produced by circumscribed disease of the brain other than a neoplasm; hence the follouing para graphs apply to all forms of cerebral disease. We shall not attempt to give a detailed description of focal symptoms and refer the reader for that purpose to the books of Bruns, Cowers, Oppenheim and others.
1. Central Convolutions (motor area).—Hemiplegia of one arm, one leg, or one-half of the face; the paralysis can only spread from one cortical field to another, as shown in Fig. 50. Thus, for example, paraly sis affecting one leg cannot extend to the face without involving the arm. Frequent onset with cortical epilepsy; not rarely parresthesia in the extremities, especially before the convulsive attacks. Accurate focal diagnoses can be made by noting the progress as indicated by each successive attack or the gradual extension of the paralysis. Ocular symptoms (conjugate deviation, strabisnius) are very common in irrita tive conditions affecting the surface of the brain.
2. Frontal Lobe.—Motor aphasia in diseases of the posterior portion of the third frontal convolution of the left hemisphere (Broca's region); hence diseases of the central convolutions on the left side are practically always accompanied by disturbances of the speech, either partial or total aphasia. Other disturbances characteristic of disease of the frontal lobe (diminished intelligence, a tendency to crack jokes—so called frontal ataxia) cannot very well be recognised in the child. IIenti plegia from pressure on the motor tracts is sometimes a remote symptom.
3. Temporal Lobes.—Sensory aphasia from lesion of the first convolu tion of the left temporal lolx, (Wernicke); auditory disturbances which, however, are marked only in bilateral lesions; possibly' disturbances of smell and taste (centres in the uncus gyri hippocampi?) Among remote effects, symptoins of irritation of the motor region; hernianopsia.
Marked disturbances of all the functions of speech are found in lesions affecting the island of Reit.
4. Occipital Lobe.—Crossecl homonymous hemiartopsia without hernianopic pupillary reaction; sometimes symptoms of optic nerve irritation (flashes of light). In rare eases optic aphasia and alexia; and, finally, psychic blindness, usually in bilateral lesions.
5. Basal Ganglia (corpus striatum, lenticular nucleus, optic thala mus).—Sometimes uithout symptoms; usually the effects of remote pressure on the internal capsule with gradual development of a simple hemiplegia, often accompanied by irritative symptoms in the extremi ties. In tumore of the optic thalamus contralateral athetosis, disturbances of sensation and unilateral facial paralysis should be mentioned. Tumors in the centrum ovale may be present for a long time without focal symptoms; later, there may be symptoms of irritation or paralysis, the nature of which will depend on the nearest motor or sensory' tract.
6. Corpora Quadrigemina.—Ocular palsies (particularly of the exter nal oculomotor and trochlear nerves) of unequal intensity on tbe two sides, which are not involved at the same titne; often associated. Cere bellar ataxia; often tremor of the arnis; unilateral deafness; possibly heminanopsia.
7. Cros Cerebri.—Alternating hemiplegia, i.e., paralysis of the oculo motor on the diseased side and of the facial, extremities and hypoglossus on the opposite side, often with tremor of the extremities (syndrome de &medal). Later the oculomotor on the opposite side also becomes involved.
S. Pons.—Alternating hemiplegia as follows: facial, abdueens, trifacial, either on both sides or only on the side of the tumor; crossed paralysis of the extremities; sometimes also involvement of the cranial nerve centres in the medulla (pressure). Often associated ocular palsies. Sometimes the cranial palsies first spread to the other side (of the abdu eens for instance) and the extremities are not involved until later; rarely disease of the auditory nerve.