In 1891, Hans Chiari described a group of congenital hindbrain anomalies, which were eventually named after him. He classified these malformations into three types (Chiari malformations I, II, and III), and four years later added the Chiari IV malformation. However, numerous reports across the literature do not seem to fit Chiari's original descriptions of these malformations, so researchers have been encouraged to propose new classifications to encompass these variants (e.g., Chiari 0, Chiari1.5, and Chiari 3.5 malformations). Moreover, there is a continued misunderstanding and misuse of the term "Chiari IV malformation." Therefore, the current review intended to describe anatomical, pathophysiological, and clinical aspects of the newer classifications with clarifications of the Chiari malformations. We reviewed available literature about Chiari malformations and their variants using "PubMed" and "Google Scholar." We also looked into the term Chiari IV, clarifying its original description and citing examples where the term has been used erroneously. References in the reviewed articles were searched manually. Variants of the originally described Chiari malformations are termed Chiari 0, Chiari 1.5, and Chiari 3.5. Each has distinct anatomical characteristics and some of these are extremely rare and incompatible with life (e.g. Chiari 3.5). Chiari IV malformation has been further clarified. Some physicians might be unfamiliar with the newer classifications of Chiari malformations because these conditions are rare or even unique. Furthermore, care is needed in using the term "Chiari IV malformation", which must be consistent with Chiari's original description, i.e. an occipital encephalocele containing supratentorial contents. Clin. Anat. 31:314-322, 2018. © 2018 Wiley Periodicals, Inc.

Background. Waterpipe smoking in young individuals is increasing with limited studies addressing its respiratory health effects. The aim of the study was to determine the effect of waterpipe smoking on young adults’ lung functions. Spirometric parameters were compared between waterpipe smokers and nonsmokers. Methods. A comparative cross-sectional study of university students, including males and females, was conducted. An interviewer-administered questionnaire was used to record students’ characteristics. The spirometry test was performed to assess students’ lung functions; we recorded the forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, peak expiratory flow (PEF), and forced expiratory flow between 25 and 75% of FVC (FEF25–75%). Results. A total of 300 apparently healthy students (150 waterpipe smokers and 150 nonsmokers) were included in the study. Waterpipe smokers showed significantly lower values in FEV1, FEV1/FVC ratio, PEF, and FEF25–75% compared to the nonsmoker group (P<0.05 to P<0.001). The subgroup analysis on female students (50 WP smokers and 50 nonsmokers) showed a significant decrease in FEV1/FVC ratio, PEF, and FEF25–75% parameters (P<0.001). Conclusion. Waterpipe smoking is associated with reduced spirometric parameters in healthy young adults with relatively limited smoking years.