title: Hydrocephalus secondary to obstruction of the lateral apertures in two dogs.
abstract: BACKGROUND
  Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described.
  
  
  METHODS
  The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients.
  
  
  CONCLUSIONS
  MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered.
authors: University of Georgia, Department of Small Animal Medicine and Surgery, Athens, Georgia, USA. mkent1@uga.edu.
authors: M
authors: M
authors: Kent
authors: Red Bank Veterinary Hospital, Tinton Falls, New Jersey, USA.
authors: E N
authors: EN
authors: Glass
authors: University of Georgia, Department of Small Animal Medicine and Surgery, Athens, Georgia, USA.
authors: A C
authors: AC
authors: Haley
authors: University of Georgia, Veterinary Biosciences and Diagnostic imaging, Athens, GA, USA.
authors: L S
authors: LS
authors: Shaikh
authors: University of Georgia, Department of Pathology, Athens, GA, USA.
authors: M
authors: M
authors: Sequel
authors: Athens Veterinary Diagnostic Laboratory, University of Georgia, Athens, GA, USA.
authors: U
authors: U
authors: Blas-Machado
authors: Upstate Veterinary Specialists, Latham, New York, USA.
authors: T M
authors: TM
authors: Bishop
authors: University of Georgia, Veterinary Biosciences and Diagnostic imaging, Athens, GA, USA.
authors: S P
authors: SP
authors: Holmes
authors: University of Georgia, Department of Small Animal Medicine and Surgery, Athens, Georgia, USA.
authors: S R
authors: SR
authors: Platt
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000000981:diagnostic imaging / Q000473:pathology; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D004285:Dogs; D006849:Hydrocephalus / Q000000981:diagnostic imaging / Q000662:veterinary*; D020547:Lateral Ventricles / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008297:Male; D013116:Spinal Cord / Q000000981:diagnostic imaging / Q000473:pathology
keywords: dogs; hydrocephalus; neurological dysfunction; ventricles