Hydrocephalus caused by unilateral foramen of Monro obstruction: A review on terminology.
BACKGROUND
Hydrocephalus caused by unilateral foramen of Monro (FM) obstruction has been referred to in literature by many different terminologies. Precise terminology describing hydrocephalus confined to just one lateral ventricle has a very important prognostic value and determines whether or not the patient can be shunt free after an endoscopic procedure.


METHODS
Aiming to define the best term for unilateral FM obstruction, 19 terms were employed on PubMed database (http://www.ncbi.nlm.nih.gov/pubmed) as quoted phrases.


RESULTS
A total of 194 articles were found. Four patterns of hydrocephalus were discriminated as a result of our research term query and were divided by types for didactic purpose. Type A - partial dilation of the lateral ventricle; Type B - pure unilateral obstruction of the FM; Type C - previously shunted patients with secondary obstruction of the FM; and Type D - asymmetric lateral ventricles with patent FM.


CONCLUSIONS
In unilateral FM obstruction hydrocephalus, an in-depth review on terminology application is critical to avoid mistakes that may compromise comparisons among different series. This terminology review suggests that Type B hydrocephalus, i.e., the hydrocephalus confined to just one lateral ventricle with no other sites of cerebrospinal fluid circulation blockage, are best described by the terms unilateral hydrocephalus (UH) and monoventricular hydrocephalus, the first being by far the most popular. Type A hydrocephalus is best represented in the literature by the terms uniloculated hydrocephalus and loculated ventricle; Type C hydrocephalus by the terms isolated lateral ventricle and isolated UH; and Type D hydrocephalus by the term asymmetric hydrocephalus.
Department of Surgical Specialties, Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil; Nervous System Electric Stimulation Laboratory (LabEEL) - Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
Flavio
F
Nigri
Department of Surgical Specialties, Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
Gabriel Neffa
GN
Gobbi
Department of Surgical Specialties, Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
Pedro Henrique
PH
da Costa Ferreira Pinto
Department of Surgical Specialties, Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
Elington Lannes
EL
Simões
Nervous System Electric Stimulation Laboratory (LabEEL) - Neurosurgery Teaching and Assistance Unit, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil; Physiological Sciences Department, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil.
Egas Moniz
EM
Caparelli-Daquer
Foramen of Monro; isolated lateral ventricle; monoventricular hydrocephalus; unilateral hydrocephalus