Abstract
Collapse of the lateral cerebral ventricles after ventriculo-peritoneal drainage is a fatal complication in dogs with internal hydrocephalus. It occurs due to excessive outflow of cerebrospinal fluid into the peritoneal cavity (overshunting). In most shunt systems, one-way valves with different pressure settings regulate flow into the distal catheter to avoid overshunting. The rationale for the choice of an appropriate opening pressure is a setting at the upper limit of normal intracranial pressure in dogs. However, physiological intraventricular pressure in normal dogs vary between 5 and 12 mm Hg. Furthermore, we hypothesise that intraventricular pressure in hydrocephalic dogs might differ from pressure in normal dogs and we also consider that normotensive hydrocephalus exists in dogs, as in humans. In order to evaluate intraventricular pressure in hydrocephalic dogs, twenty-three client owned dogs with newly diagnosed communicating internal hydrocephalus were examined before implantation of a ventriculo-peritoneal shunt using a single use piezo-resistive strain-gauge sensor (MicroSensor ICP probe). Ventricular volume and brain volume were measured before surgery, based on magnetic resonance images. Total ventricular volume was calculated and expressed in relation to the total volume of the brain, including the cerebrum, cerebellum, and brainstem (ventricle-brain index). Multiple logistic regression analysis was performed to assess the influence of the covariates “age”, “gender”, “duration of clinical signs”, “body weight”, and “ventricle-brain index” on intraventricular pressure. The mean cerebrospinal fluid pressure in the hydrocephalic dogs was 8.8 mm Hg (standard deviation 4.22), ranging from 3–18 mm Hg. The covariates “age”, (P = 0.782), “gender” (P = 0.162), “body weight”, (P = 0.065), or ventricle-brain index (P = 0.27)” were not correlated with intraventricular pressure. The duration of clinical signs before surgery, however, was correlated with intraventricular pressure (P< 0.0001). Dogs with internal hydrocephalus do not necessarily have increased intraventricular pressure. Normotensive communicating hydrocephalus exists in dogs.
Highlights
Internal hydrocephalus is a common malformation of the central nervous system in dogs [1,2,3], characterised by the accumulation of cerebrospinal fluid (CSF) in the cerebral ventricles
Other terms used in the classification of hydrocephalus in humans are “hypertensive” and “normotensive” to classify cases of hydrocephalus in which intraventricular pressure (IVP) is increased or normal
They act like on-off switches, opening when the IVP exceeds the valve’s opening pressure, allowing egress of CSF until IVP falls below the opening pressure
Summary
Internal hydrocephalus is a common malformation of the central nervous system in dogs [1,2,3], characterised by the accumulation of cerebrospinal fluid (CSF) in the cerebral ventricles. If the preselected opening pressure does not adequately improve the clinical symptoms, modern systems allow the opening pressure to be gradually altered externally using a special magnetic adjusting device [21] These shunt systems and the necessary equipment are extremely cost intensive, which limits their use in companion animals. The reduction of ventricular volume and associated improvement of clinical signs in a large cohort of operated dogs was somewhat variable [18] This raises the question whether the selected opening pressure may not adequately address the requirements in each individual animal, and a valve with a lower pressure may be needed to reduce ventricular volume. We hypothesise that IVP varies in hydrocephalic dogs, and that IVP is not necessarily increased in all dogs with hydrocephalus
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
