Value of magnetic resonance imaging (MRI) for the diagnosis of peripheral vestibular disorders

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

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.

Review of diagnostic imaging of ear diseases in the dog and cat

Diagnostic imaging techniques (conventional radiography, computed tomography and magnetic resonance imaging) are an essential tool in the diagnostic work-up of ear diseases. Conventional radiography is commonly used, but often lacks sensitivity. Computed tomography (CT) and magnetic resonance (MR) are complementary imaging studies of the middle ear, labyrinth, internal auditory canal and their contents. CT provides excellent images of bony structures and is indicated where osseous changes are of greatest diagnostic importance. MR is superior in imaging soft tissue components including intralabyrinthine fluid. Therefore, more than one of these imaging techniques may be required in order to make a diagnosis.

Results of magnetic resonance imaging in dogs with vestibular disorders: 85 cases (1996-1999)

OBJECTIVE

To determine results of magnetic resonance (MR) imaging in dogs with vestibular disorders (VD) and correlate results of MR imaging with clinical findings.

DESIGN

Retrospective study.

ANIMALS

85 dogs.

PROCEDURE

Information on signalment, clinical signs, and presumptive lesion location was obtained from the medical records, and MR images were reviewed.

RESULTS

27 dogs had peripheral VD, 37 had central VD, and 21 had paradoxical VD. Of the 27 dogs with peripheral VD, 11 (41%) had MR imaging abnormalities involving the ipsilateral tympanic bulla compatible with otitis media (6 also had abnormalities involving the petrous portion of the ipsilateral temporal bone compatible with otitis interna), 7 (26%) had MR imaging abnormalities compatible with middle ear neoplasia, 2(7%) had an ipsilateral cerebellopontine angle lesion, and 7 (26%) did not have MR imaging abnormalities. All dogs with central and paradoxical VD had abnormalities evident on MR images. Of the 37 dogs with central VD, 13 (35%) had an extra-axial lesion, 6 (16%) had an intra-axial lesion, and 18 (49%) had multiple intra-axial lesions. In 23 (62%) dogs with central VD, lesions on MR images corresponded with location suspected on the basis of clinical signs. Of the 21 dogs with paradoxical VD, 12 (57%) had an extra-axial lesion, 5 (24%) had an intra-axial lesion, and 4 (19%) had multiple intra-axial lesions. Location of lesions on MR images agreed with location suspected on the basis of clinical signs in 19 (90%) dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that MR imaging may be helpful in the diagnosis and treatment of VD in dogs.

Presumed vestibular hemorrhage secondary to warfarin

Hemorrhage secondary to anticoagulant therapy is well documented. We report a patient who presented with acute vertigo and unilateral deafness while on warfarin and was found to have a probable hemorrhage in the labyrinth, identified on MRI.