Clinical signs, magnetic resonance imaging findings and outcome in 77 cats with vestibular disease: a retrospective study

Abstract

Medical records of 77 cats that had clinical signs of vestibular disease and magnetic resonance imaging (MRI) of the head were reviewed retrospectively. The aetiological, clinical and MRI characteristics were described and evaluated for a relationship with patient outcome. Forty cats (52%) had signs of central vestibular dysfunction (CVD), which was part of a multifocal disease in 17 cats (43%). The most frequent causes of CVD were inflammatory conditions (18 cats; 45%), including bacterial inflammation as an intracranial extension of otitis interna (five cats; 13%), feline infectious peritonitis (three cats; 8%) and toxoplasmosis (two cats; 5%). Neoplasia (12 cats; 30%) and vascular disease (four cats; 10%) were respectively the second and the third most frequent causes of CVD. Thiamine deficiency was diagnosed in one cat based on MRI findings and improvement following vitamin B(1) supplementation. Of 37 cats (48%) with peripheral vestibular dysfunction (PVD), idiopathic vestibular syndrome (IVS) was suspected in 16 (43%) and otitis media/interna was suspected in 16 (43%). Within the group of cats with evident MRI lesions, the location of the imaged lesions agreed with the clinical classification of vestibular dysfunction in 52/55 (95%) cats. Most of the cats (nine cases; 56%) with presumed IVS had rapid and complete recovery of their clinical signs. As most of these cats presented with progressive clinical signs over 3 weeks they were classified as having 'atypical' IVS to differentiate them from cats with the typical non-progressive IVS. No underlying systemic diseases were documented in any of these cases. Statistically significant predictors of survival included neurolocalisation (central or peripheral vestibular system), age and gender. No difference in survival was observed between cats with presumed idiopathic peripheral syndrome and cats with otitis media/interna.

Fig 1

Transverse MR images of histologically confirmed pyogranulomatous meningitis in a cat with multifocal neurological signs (CVD and forebrain). In T1-weighted images there is a midline shift to the left and obliteration of the right lateral ventricle compatible with a mass effect. Marked thickening, enhancement following administration of contrast medium and hyperintensity on T2-weighted images is evident affecting the pachymeninges over the right temporal lobe. Left side of the picture corresponds to right side of the cranium.

Fig 2

Transverse MR images of a cat with central vestibular signs on the left side, as a result of meningoencephalitis due to intracranial extension of otitis. Tissue in the dorsal part of the left tympanic cavity is associated with a diffuse meningeal lesion on the left/dorsal aspect of the cerebellum (arrows) characterised by hypointensity on T1-weighted images, enhancement of a peripheral narrow rim of tissue following administration of contrast medium (T₁+C) and hyperintensity on T2-weighted images. Left side of the picture corresponds to right side of the cranium.

Fig 3

Transverse MR images of a cat with peripheral vestibular signs on the right side associated with chronic otitis media/interna with intracranial extension. The right tympanic bulla is diffusely thickened (arrow) and filled with tissue characterised by isointensity on T1-weighted images, uneven peripheral enhancement following administration of contrast medium (T₁+C) and hyperintensity on T2-weighted images. The perilymph in the right inner ear has slightly increased signal intensity in T1-weighted images and reduced signal in T2-weighted images. Contrast accumulation on the right/ventral aspect of the brainstem is compatible with meningitis. Left side of the picture corresponds to right side of the cranium.

Fig 4

Transverse MR images of a large meningioma impinging on the right temporal lobe in a cat with multifocal central nervous system (CNS) localisation (CVD and forebrain). The mass (m) is characterised by isointensity on T1-weighted images, moderate heterogeneous enhancement following administration of contrast medium (T₁+C) and heterogeneous intensity on T2-weighted images. The medial aspect of the mass is delineated by CSF compatible with an extra-axial origin of the mass. The temporal bone adjacent to the lateral aspect of the mass is slightly thickened (arrowhead) suggestive of hyperostosis. The left lateral ventricle is dilated. The thalamic lesion observed in this cat may explain the vestibular signs considering the thalamic functioning as a relay station of afferent vestibular inputs to cortex. Left side of the picture corresponds to right side of the cranium.

Fig 5

Transverse MR images of acute haemorrhage in a cat with central vestibular signs on the right side. A focal lesion in the region of the right vestibular nuclei (arrow) is hyperintense on both T1- and T2-weighted images. Left side of the picture corresponds to right side of the cranium.

Fig 6

Transverse MR images of aural neoplasia in a cat with left peripheral vestibular signs. A large mass (m) obliterates the left tympanic bulla and is characterised by isointensity on T1-weighted images, peripheral enhancement following administration of contrast medium (T₁+C) and heterogeneous intensity on T2-weighted images. There is a fluid air interface evident in the right tympanic cavity (arrow) (cat was in dorsal recumbency). Left side of the picture corresponds to right side of the cranium.