Abstract
BackgroundMagnetic resonance imaging (MRI) findings of canine brains with enlarged ventricles in asymptomatic dogs were compared to those in dogs with clinically relevant internal hydrocephalus, in order to determine the imaging findings indicative of a relevant increase in intraventricular pressure. Discrimination between clinically relevant hydrocephalus and ventriculomegaly based on MRI findings has not been established yet and is anything but trivial because of the wide variation in ventricular size in different dog breeds and individuals. The MRI scans of the brains of 67 dogs of various breeds, skull conformation and weight were reviewed retrospectively. Based on clinical and imaging findings, the dogs were divided into three groups: a normal group (n = 20), a group with clinically silent ventriculomegaly (n = 25) and a group with severe clinically relevant internal hydrocephalus (n = 22). In addition to the ventricle/brain-index, a number of potential subjective signs of increased intraventricular pressure were recorded and compared between the groups.ResultsThe ventricle/brain-index was significantly higher in dogs with relevant hydrocephalus (p < 0.001) and a threshold value of 0.6 was specified as a discriminator between internal hydrocephalus and ventriculomegaly. Other MR imaging findings associated with clinically relevant hydrocephalus were an elevation of the corpus callosum (p < 0.01), dorsoventral flattening of the interthalamic adhesion (p < 0.0001), periventricular edema (p < 0.0001), dilation of the olfactory recesses (p < 0.0001), thinning of the cortical sulci (p < 0.0001) and/or the subarachnoid space (p < 0.0027) and disruption of the internal capsule adjacent to the caudate nucleus (p < 0.0001).ConclusionA combination of the abovementioned criteria may support a diagnosis of hydrocephalus that requires treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0479-5) contains supplementary material, which is available to authorized users.
Highlights
Magnetic resonance imaging (MRI) findings of canine brains with enlarged ventricles in asymptomatic dogs were compared to those in dogs with clinically relevant internal hydrocephalus, in order to determine the imaging findings indicative of a relevant increase in intraventricular pressure
Animals Information regarding the breed, bodyweight, age, gender and indication for MRI/final diagnosis of all dogs are summarized in Additional file 1
The same applies for the presence of periventricular edema (p < 0.0001) and dilation of the olfactory recess(es) (p < 0.0001), both of which were only present in dogs with hydrocephalus
Summary
Magnetic resonance imaging (MRI) findings of canine brains with enlarged ventricles in asymptomatic dogs were compared to those in dogs with clinically relevant internal hydrocephalus, in order to determine the imaging findings indicative of a relevant increase in intraventricular pressure. Large ventricles are a common incidental finding in brachycephalic dog breeds [1,2,3,4] and have been referred to as “ventriculomegaly” to differentiate this finding from relevant internal hydrocephalus These dogs are considered to be asymptomatic and are not thought to have associated increased intraventricular pressure (IVP) [5,6,7]. Assessment of ventricular size alone is not helpful to evaluate whether neurological signs are a potential consequence of brain damage due to an existing high IVP and ventricular dilation This is of particular importance because inflammatory/infectious brain disease, which might be present in addition to ventricular enlargement and may lack other specific imaging findings, can remain undetected. Secondary ventriculomegaly is thought to sometimes be misdiagnosed as relevant internal hydrocephalus and interpreted to be the cause of clinical signs in dogs affected by inflammatory/infectious disorders
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