Tiny reviews – JVIM Sept/Oct 2017

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by Deena Tiches, DVM, DACVIM (Neurology)
Originally posted on the NeuroWebVet website; modified and reprinted with permission.

This issue of JVIM has three neurology articles.

 

Wireless EEG in the diagnosis of idiopathic epilepsy in dogs

The diagnosis of idiopathic epilepsy in dogs was improved when researchers in Canada, Germany, Finland and the US developed a wireless video EEG to be used in unsedated dogs. Eighty-one client-owned dogs were investigated for unusual behavior events. The events were described as a combination of tonic-clonic seizures, head bobbing or tremors, focal twitching/myoclonus/ spasticity (face, ears, head, neck, limbs), altered mentation, chasing/holding visible and invisible stimuli (lights, tail, “flies”), proprioceptive ataxia, and gastrointestinal upset. Diagnostic success was achieved in 72% of dogs. This technique was a reliable diagnostic tool to investigate the epileptic origin of behavioral events in dogs. Download article

Clinicopathologic and MRI features of FIP

The clinicopathologic features and MRI findings in 24 cats with histopathologically confirmed neurologic feline infectious peritonitis (FIP) was reported from research at the Royal Veterinary College, University of London. Twenty-four client-owned cats with histopathologic confirmation of neurologic FIP underwent imaging with a high-field MRI (1.5 Tesla). The clinical presentation of the 24 cases consisted of 3 distinct neurologic syndromes. Three cats presented with a T3-L3 myelopathy with no detectable brain involvement. Seven cats presented with central vestibular syndrome, including altered mental status, pronounced vestibular ataxia, and pathologic nystagmus. The remaining 14 cats presented with multifocal CNS disease with tetraparesis (14), obtundation (13), cervical hyperesthesia (6), decreased to absent menace response (6), decreased facial sensation (3), facial paresis (2), anisocoria (2), absent vestibulo-ocular reflex (2), and stupor (1). MRI abnormalities were detected in all 24 cats. Ventriculomegaly was detected in 20 (86.9%) of the 23 brains imaged. Contrast enhancement was detected after gadolinium administration in all 24 cats and was typically bilateral and symmetrical. Meningeal contrast enhancement was detected in 22 cats and was multifocal or generalized in 10, affecting the brainstem and cervical spinal cord in 5, the brainstem only in 2 and the spinal cord only in 2 cats. Ependymal contrast enhancement was present in 20 cats. Cerebrospinal fluid analysis was performed in 11 cats. Total protein concentration was increased in all 11 (mean, 9.4 g/L; median, 3.6 g/L; range, 0.85-28.8 g/L) as was total nucleated cell count (mean, 196/μL; median, 171/μL; range, 15-479/μL). Neutrophilic pleocytosis was present in 7 cats, lymphocytic pleocytosis in 2, and mixed pleocytosis in 2 cats. Cerebrospinal fluid analysis by polymerase chain reaction for feline coronavirus antigen was performed in 5 cats and was positive in all 5. Immunohistochemistry was performed on brain tissue in 10 cats; all showed positive intracellular staining for the feline coronavirus antigen. Neurologic FIP typically causes diffuse vasculitis affecting the brain and spinal cord, but rarely, cats may present with neurologic deficits suggestive of a more localized disease process. Given the difficulties distinguishing feline enteric coronavirus and the FIP virus to reach a definitive antemortem diagnosis of FIP is difficult. However, the results of this case series suggest that MRI of the brain can be a sensitive means of lesion detection in cats presented with neurologic FIP, with MRI findings reflecting leptomeningeal and ependymal vasculitis, secondary ventriculomegaly, and mass effect. Download article

Relationship of brachycephaly and hydrocephalus in Persian cats

Cat breeders began to observe a frequent occurrence of internal hydrocephalus in Persian cats with extreme brachycephalic head morphology. This led Dr. MJ Schmidt and colleagues to investigate a possible relationship among the grade of brachycephaly, ventricular dilatation, and skull dysmorphologies in Persian cats. The brachycephalic morphology of this modern “peke-face” Persian, named after the flat-faced Pekingese dog, accentuates childlike skull characteristics as it produces large round eyes and a flat face with a large forehead. This phenotype has become popular, although high grades of brachycephaly can be associated with severe health problems in Persians. The grade of brachycephaly was determined on skull models based on CT datasets for 92 Persian cats and 12 domestic short hair (DSH) cats. Compared to both DSH and doll-face Persians, a grossly reduced cranial length and increased width and height was noted in the peke-face Persians. When viewed from the front, the width of the braincase (cranial width) almost reached the lateral borders of the orbits in fourteen cats. The skull was dorsally round and dome-shaped and showed frontal bossing in all peke-face cats. The frontal sinus was small or absent in all peke-face cats. The nasal bone was found to be notably short. Eight peke-face Persians showed osseous defects in the parietal and frontal bones. Thirty-eight peke-face cats showed a prognathic mandible. The occlusal pattern of the canines and incisors was aberrant in twelve cats. Retrograde growing conchae were found in 24 cats, leading to obstruction of the ventral nasal passage. None of these findings were seen in doll-face Persians. Midsagittal MR-images revealed a displacement of the turbinates toward, or into, the cranial cavity. In peke-face Persians, the rostral aspect of the brain was compressed leading to a more circular brain shape in sagittal views. Olfactory bulbs were ventrally and laterally shifted. The corpus callosum was round, separated from the fornix, and dorsally displaced in eighteen peke-face Persians Thirty-eight cats showed cerebellar deviation into the foramen magnum, which was also seen in twelve of the doll-face Persians. In five kittens, almost half of the cerebellum herniated into the vertebral canal. Dimensions of the lateral ventricles were subjectively increased in 29 peke-face Persians. All doll-face Persians showed subjectively normal ventricular dimensions. Ventricular enlargement (ventricle-brain ratio) (P < 0.0001) and cerebellar herniation (P < 0.001) were clearly associated with the peke-face morphology. The results of this study show that the increasing emphasis on a brachycephalic phenotype can have a correlating negative impact on general skull and brain morphology in Persian cats. Download article