To describe trends in the usage of neurological eponyms over time.

Eponyms are common across medicine, particularly within neurology. The use of eponyms has been discouraged because they are not descriptive and can lead to confusion, particularly in cases when the same eponym is applied to different phenomena.

A representative list of ­neurological eponyms was obtained from various sources including two clinical neurology textbooks and Wikipedia. Eponyms referring to diseases and physical exam maneuvers or findings were included. Neuroanatomical eponyms were excluded. For the subset of eponyms with a corresponding non-eponymous term, usage over time was tracked using Google Ngram for the years 1900-2008. Google Ngram provides the frequency of a given word’s usage as a proportion of all words in a given year within a large corpus of books and scientific publications as indexed by Google.

An initial list of 110 candidate eponyms was obtained, of which 19 (17.2%) had corresponding non-eponymous terms. Analysis of Ngram outputs for these terms revealed that the overall use of both eponymous and non-eponymous terms increased over the course of the 20^th century. The ratio of the usage of eponymous to non-eponymous terms increased most significantly from 1900 to 1930, with another notable rise in usage seen between 1970 and 1990. Between 2000 and 2008, the ratio decreased.

This descriptive study found that the overall usage of both eponymous and non-eponymous neurological terms increased from 1900 to 2000. The rate of eponym usage relative to corresponding non-eponymous terms generally increased across the 20^th century, with a decrease over the most recent years studied (2000-2008). We hypothesize that the decrease in the ratio magnitude observed in the 21th century reflects an increased awareness about the limitations - and attendant intentional avoidance - of eponymous terms in our field.