The History of the Kernohan Notch Revisited

The history of false localizing signs is intimately linked to the birth of modern neurology and the unraveling of the mysteries of localization through neurological examination at the end of the 19th century. This phenomenon has attracted much attention but has not been properly explained, even in the authoritative handbooks such as that by Oppenheim. A scholarly article written by Kernohan and Woltman in 1929 is considered to be a landmark in the history of neurology and neurosurgery in that it provided the definitive answer and an exhaustive explanation of the problem, leading some neurologists to conclude that the localization of a lesion is not an exact science. However, despite the professional manner in which Kernohan and Woltman presented their case, they did not offer an explanation. In another article published 2 years earlier in 1927, Groeneveld and Schaltenbrand provided a pathophysiological and anatomical explanation of the phenomenon, described in detail. Although Kernohan and Woltman themselves refer to that previous article, it was this article that provided the first logical, clear, indubitable explanation of the phenomenon that we today refer to as the Kernohan notch.