Shock, diaschisis and von Monakow.

The concept of shock apparently emerged in the middle of the 18th century (Whyett) as an occurrence observed experimentally after spinal cord transection, and identified as "shock" phenomenon one century later (Hall). The concept was extended (Brown-Séquard) and it was suggested that brain lesions caused functional rupture in regions distant from the injured one ("action à distance"). The term "diaschisis" (von Monakow), proposed as a new modality of shock, had its concept broadened, underpinned by observations of patients, aiming at distinguishing between symptoms of focal brain lesions and transitory effects they produced, attributable to depression of distant parts of the brain connected to the injured area. Presently, diaschisis is related mainly to cerebrovascular lesions and classified according to the connection fibers involved, as proposed by von Monakow. Depression of metabolism and blood flow in regions anatomically separated, but related by connections with the lesion, allows observing diaschisis with neuroimaging.