XIXth century pre-Jacksonian concepts of epileptogenesis.

By the beginning of the XIXth Century the old belief that epilepsy was due to demonic possession or to malevolent influences emanating from a variety of sources had largely given way to an acceptance that the disorder was a physical illness which arose in the brain, though in some not very precisely defined way. No even reasonably satisfactory hypotheses about epileptogenesis were available till Marshall Hall (1790-1857), from 1836 onwards, popularised the concept of reflex action which had earlier been described by Robert Whytt (1714-1776) under the name 'sympathy'. Marshall Hall interpreted epilepsy as due to abnormal irritability in the afferent limb or central section of what later came to be called the reflex arc, loss of consciousness in the seizures being the result of secondary cerebral venous congestion. This concept of epileptogenesis was refined by Brown-Séquard, who in 1858 ascribed a more important role to overt or occult peripheral afferent nerve irritability, considered that the central element of the relevant reflex mechanism involved the medulla oblongata, and believed that reflex cerebral vasospasm, rather than cerebral venous congestion, caused loss of consciousness in the seizures. Almost contemporaneously, Schroeder van der Kolk placed considerably greater emphasis on the medullary element in causing the increased excitability of the reflex arc that produced epileptic seizures. These ideas of exaggerated reflex activity as the mechanism of epilepsy were made redundant by the work of Hughlings Jackson (1837-1911), who from 1860 onwards demonstrated that epilepsy arose in the cerebrum itself, rather than from altered function at lower levels of the nervous system.