What do physicians know about normal pressure hydrocephalus and when did they know it? A survey of 284 physicians

Abstract

Normal pressure hydrocephalus (NPH) is a relatively new neurologic disorder first described by Salamon Hakim of Bogotá, Colombia, in 1965. NPH is characterized by three symptoms - impaired gait, incontinence and dementia - and an anatomic abnormality, i.e., enlargement of the cerebral ventricles, which can be seen on computerized tomographic or magnetic resonance imaging. Surprisingly, the intracranial pressure is normal. The first author of this article, a Yale Medical School faculty member, developed NPH over the decade from 1992 to 2002, during which it was erroneously diagnosed as cerebral atrophy and/or Parkinson's disease. On recognizing the lack of awareness of NPH by physicians, he initiated a survey to explore this problem. He interviewed 166 practicing physicians who graduated from 50 American and 33 foreign medical schools, using a one-page, 10-point questionnaire (Part I). Almost one-third of the physicians had never heard of NPH. One-fifth had learned of NPH in medical school, and about half learned of it after medical school. Because there were insufficient physicians surveyed from 1986 to 2005, we recruited 118 additional physicians from the 20 Yale Medical School graduating classes from 1986 through 2005 (Part II). Two-thirds of them had learned of NPH in medical school, and one-fourth during residency and fellowship. Seven percent had never heard of NPH. The significance of these studies is discussed.

Figure 1

Questionnaire for NPH survey (Part I). The questionnaires for Part I were identified by only a code number, e.g., 05-01, indicating the year and order in which the physician’s questionnaire was received for that year. Questionnaires for Part II included one additional question.

Figure 2

Learning about NPH in medical school 1935-2005. No physicians had learned of NPH in medical school before 1965, when NPH was first described, thus the percentage who learned of NPH in medical school was 0 percent. During the first decade thereafter, 9 percent learned about NPH in medical school. In the second decade, it increased to 63 percent. Although the percentage increased to 80 percent in the third and fourth decades, the slope decreased appreciably. The solid line shows the data for Part I. The dotted line shows data for Part II. Note that the curves for Part I and Part II are approximately parallel for the period from 1986 through 2005.