"Hamlet," Act II.
THE MECHANISM OF THE FIT
The brain consists of cells of grey matter, grouped together to form centres for thought, action or sensation, and white matter, consisting of nerve strands, which act as lines of communication between different parts of brain and body. The wrinkled surface (cortex) of the brain, is covered with grey matter, which dips into the fissures. There are also islands of grey matter embedded in the white.
The front part of the brain is supposed, with some probability, to be the seat of intelligence, while a ribbon three inches wide stretched over the head from ear to ear would roughly cover the Rolandic area, in which are contained the motor cells through which impulse is translated to action. These motor cells are controlled by inhibitory cells, which act as brakes and release nerve energy in a gentle stream; otherwise our movements would be convulsive in their violence, and life would be impossible through inability usefully to direct our energy.
That is how inhibition acts physically; mentally it is the power to restrain impulses until reason has suggested the wisest course.
Irritation of the cortex, especially the motor area, causes convulsions, and experiment has shown that epilepsy may be due to a disease or instability of certain inhibitory cells of the cortex. The motor cells of epileptics are restrained, with some difficulty, by these cells in normal times. When irritation from any cause throws additional strain on the motor cells, the defective brakes fail, and the uncontrolled energy, instead of flowing in a gentle stream through the usual channels, bursts forth in a tidal wave through other areas of the brain, causes unconsciousness, and exhausts itself in those violent convulsions of the limbs which we term a fit.
The Primary Cause of epilepsy is an inherent instability of the nervous system.
Secondary Causes are factors which cause the first fit in a person with predisposing nervous instability; later, the brain gets the fit habit, and attacks recur independently of the secondary cause. In most cases no secondary causes can be discovered, and the disease is then termed idiopathic, for want of an explanation.
Injuries to the brain may cause epilepsy, and many cases date from birth, a difficult labour having caused a minute injury to the brain.