Page 823 - Clinical Small Animal Internal Medicine

72 Vestibular Disease 791

Idiopathic resolution of infection due to permanent nerve damage,
VetBooks.ir older dogs. The history is often an acute onset of head including deafness.
Canine idiopathic vestibular disease is common in
tilt, nystagmus (fast phase away from the head tilt),
ataxia/falling/rolling, drooling/nausea, inappetence, Inflammatory
Nasopharyngeal Polyps
and vomiting. The severity can be quite variable, from A polyp is a fleshy mass composed of granulation tissue
mild to extreme. There is no specific treatment, but covered with respiratory epithelium, that originates from
symptomatic therapy with antinausea/antiemetic medi­ the lining of either the auditory tube or the middle ear.
cations for apparent nausea, fluid support to maintain The primary etiology is unknown, but viral and/or chronic
hydration until they are eating, +/− diazepam (GABA inflammatory processes are suspected to play a role. They
modulator acting centrally to suppress vestibular are most common in cats 1–5 years of age but have been
responses) can help the patient feel better during recovery. documented in much older cats as well, with an equal dis­
Appropriate recumbent care is necessary in nonambu­ tribution in males and females. Polyps can also lead to sec­
latory patients, especially since they will often lie only ondary infection or inflammation of the middle and inner
on one side. Improvement can be quick (hours) but ear, and therefore, patients may present with vestibular
more commonly takes 1–3 weeks and often there is a signs. Since the mass can also grow into the pharyngeal
residual head tilt. Signs are exacerbated in the dark area, signs of sneezing and gagging may be the presenting
since visual compensation is the primary means for clinical complaint. Polyp removal is typically via traction
improved function. It is uncommon, but possible, for or surgical approach (ventral bullae osteotomy) but recur­
idiopathic vestibular disease to recur. However, rence is possible. Rarely dogs are affected.
repeated events should encourage diagnostic testing to
exclude other causes. Cholesteatoma
Feline idiopathic vestibular syndrome can occur in A cholesteatoma is a nonneoplastic concretion of keratin
cats of any age and affects outdoor cats more fre­ debris, keratinizing epithelium, and epidermoid cystic
quently. It appears to be more common in the summer structure(s) that is thought to be a rare sequela of chronic
and fall months in the northeastern United States, inflammation and is reported infrequently in dogs with
although this timing is not appreciated in other parts otitis media. The cholesteatoma results in bullae expan­
of the country. Clinical signs are similar to canine sion and secondary osteolysis. Patients often present for
idiopathic disease, but vomiting is less common. pain on opening the mouth, pain on palpation of the ear,
Diagnosis is based on exclusion of other causes of +/− peripheral vestibular signs. Surgical intervention is
peripheral vestibular disease. Cats also spontaneously necessary, so it should not be mistaken for primary infec­
recover within a few weeks. tious otitis and managed medically. There are imaging
characteristics that can help differentiate it from primary
Infectious infectious otitis which should prompt surgical interven­
Otitis Media/Interna tion. Risk of recurrence after surgery is high. Monitoring
Ascending infection via the auditory tube can result in with advanced imaging every 6–12 months should be
otitis media/interna in the absence of otitis externa. considered.
Otoscopic exam may not be conclusive in these cases
unless there are obvious changes to the tympanic mem­ Neoplasia
brane (bulging, rupture). Otitis externa is often present Any neoplastic process adjacent to the vestibular anatomy
without concurrent otitis media/interna. Therefore, (such as squamous cell carcinoma, adenocarcinoma, oste­
definitive diagnosis of otitis media/interna typically osarcoma, fibrosarcoma, chondrosarcoma) can potentially
requires advanced imaging. This may not be practical in result in peripheral vestibular signs. The mass may track
all cases. Cats with otitis media may also have evidence along the skull base where cranial nerves exit their respec­
of Horner’s syndrome as the sympathetic fibers pass tive foramina, resulting in one or more of the following in
through the bullae in this species. Since the facial nerve addition to vestibular signs: facial paralysis, change in
travels near the horizontal external ear canal and by the voice, stridor, difficulty swallowing, and tongue deviation
bulla, severe and chronic ear disease may also result in or dimpling/contracture. If there are no changes in menta­
signs of facial paresis/paralysis if the periauricular tissues tion and no proprioceptive deficits or paresis, localization
are involved. Depending on the severity of the problem, to the peripheral vestibular system would still be suspected
treatment may involve medical or surgical management. (i.e., the process has not yet invaded the cranial vault to any
Typically, the outcome is better for surgical management appreciable degree on exam). Advanced imaging and
with antibiotic/antifungal therapy based on culture and cytology/biopsy would be needed to determine the extent
sensitivity results. Clinical signs may still be present after of the disease, treatment options, and prognosis.