Mania—of a violent type—usually develops within a short time of the accident—a few hours or days. Its development is probably dependent on an acute cerebral œdema—the result of a most severe grade of vaso-motor depression—and it is often, though not necessarily, associated with extensive cerebral injury. There is marked engorgement of the cerebral venous system, and considerable increase of cerebro-spinal fluid, both on the surface of the brain and in the ventricular spaces.
When insanity develops at a later date, of whatever variety, it is probably dependent on definite pathological changes. Ll. Powell, Duret, and others, after investigating the conditions, came to the conclusion that the injury was comparatively superficial—subdural cysts and hæmatomata, pachymeningitis, osteosclerosis, ossification of the dura mater, &c. They also maintain—an opinion that I also hold—that the nervous phenomena are, in most cases, due to reflex meningeal irritation.
Ll. Powell reports on 67 cases submitted to operation, with the following results:—
In 41 there was mental recovery.
In 12 there was marked mental improvement.
In 5 there was slight mental improvement.
In 4 there was no change.
Death resulted in 5 cases.
The results obtained by surgical treatment are largely dependent on the time that has elapsed since the accident. Lapse of time is no bar to operation, but the sooner this procedure is carried out the better for the patient.