FAINTING.

By George L. Engel '34, M.D. Second Edition. Springfield, Illinois:Charles C Thomas, 1962. 196 pp $7.50.

The author in his introduction pays tribute to earlier investigators of syncope, mentioning W. R. Gowers, Sir Thomas Lewis and Soma Weiss, whom he identifies as having stimulated his own interest in the subject.

He defines syncope as a brief loss of consciousness, often preceded by giddiness, faintness and weakness, a symptom only of some other basic difficulty which has led to a reduced cerebral metabolism associated with a reduced blood supply or to a lack of oxygen. The effects of various reflexes and of hypoglycemia, as well as other changes on this metabolism, are also considered, and in a later chapter he speculates on the loss of awareness of one's surroundings, as seen in hysteria, as differing from syncope because of the lack of changes in the oxygen or blood supply to the brain. He also differentiates fainting from epilepsy, narcolepsy, and catalepsy.

Separate chapters are given to the most frequent causes of fainting, as the vasopressor syndrome, quoting Darwin as believing that fright associated with an inability to flee leads to a collapse of the vaso-motor apparatus with a fall in blood pressure reducing the blood supply to the brain, and suggesting the probability that if muscular activity is begun with the onset of the premonitory symptoms that fainting may be avoided.

Cardiac disorders which in various ways may lead to a reduced blood supply to the brain are well covered and documented.

Pulmonary disorders with their "various disturbed reflexes are discussed, and there is a good explanation of the mechanism of the valsalva maneuver, as well as the syncope associated with spasmodic coughing with urination and defecation.

Fainting due to cerebral disorders is found m Chapter V, considering that associated with the obstruction or spasm of the various cerebral blood vessels and with other cerebral pathology. Evidence is presented in favor of the argument that transient spasm of the cerebral vessels may produce symptoms among which is syncope.

Carotid sinus and other reflexes affecting the vaso-motor control centers in the brain stem and in higher cerebral centers, as well as a consideration of the effects of changes in cerebral metabolism, finish the chapter.

This is an interesting summary of what is known of the mechanism of fainting and is well worth reading.