When Broca’s motor speech-area is primarily involved, the fits are preceded by difficulty in phonation, mumbling of words and incoherence, grinding of the teeth, &c., the fits then rapidly spreading to the parts responsible for the movements of the muscles of face and upper extremity.
When the fits arise from a post-central source of irritation, they are usually preceded by well-marked sensory auræ—tinglings, burning and painful sensations—again according to the region affected.
When preceded by sensations of taste and smell, the lesion is probably situated over the anterior part of the temporo-sphenoidal lobe.
When by visual impressions—flashes of light, &c.—the lesion is probably situated over the occipital lobe of the brain.
Pathology.
The pathological conditions responsible for the development of fits are various, resolving themselves, when fully investigated, into two main groups: those associated with meningeal changes only, and those accompanied by definite cortical scarring and tract degeneration.
In the event of osseous deficiency the scalp is usually more or less adherent to underlying structures, and the gap in the skull filled with dense fibrous tissue, which is itself adherent to the membranes of the brain and perhaps to the brain itself.
In the absence of osseous deficiency, the cerebral irritation is usually dependent on depressed fragments of bone, on subdural hæmatomata and cysts, and on meningeal thickening.
In the event of cerebral degenerative changes it may be presumed, whether there is a deficiency in the bone or not, that considerable matting of meninges and cortex is existent with pyramidal degeneration.
In the absence of evident signs of external injury, cases of focal epilepsy in the young require careful investigation, inquiry being made as to difficult labour, for, as Harvey Cushing points out, ‘When we consider the widespread lesions associated with those cases that later on are recognizable as Little’s disease, and that presumably an enormous number of children receive at birth some trifling injury which, from lack of symptoms, is overlooked, may it not be that many cases of so-called idiopathic epilepsy dating from childhood can be safely attributed to the effects of early traumatism?’