Vestibular disease

• Cause: disturbance of the central or peripheral vestibular system.
• May be secondary or idiopathic.
• Signs: ataxia, falling/rolling, leaning to one side, head tilt (unilateral) or wide excursion of the head from side to side (bilateral), circling, nystagmus.
• Diagnosis: signs.
• Treatment: depends on cause.
• Prognosis: reasonable to good, depending on cause.
  Follow the diagnostic tree on Vestibular disease.

• Ataxia.
• Falling/rolling.
• Leaning to one side.

• Head tilt (unilateral vestibular).
• Wide excusion of the head from side to side (bilateral vestibular).
• Nystagmus.

• Mean age for idiopathic disease is 4 years.

• Siamese Siamese and Burmese Burmese for congenital form.

Central vestibular disease

• Menigoencephalitis Meningomyelitis: bacterial and fungal:
  • Feline infectious peritonitis Feline infectious peritonitis.
  • Toxoplasmosis Toxoplasmosis.
  • Cryptococcocosis Cryptococcosis.
  • Bacterial.
  • Presumed immune-mediated.
• Neoplasia:
  • Lymphoma Lymphoma.
  • Meningioma Brain neoplasia.
  • Metastatic disease.
• Thiamine deficiency Thiamine deficiency.
• Cerebrovascular disease Cerebrovascular disease:
  • Brain infarct.
  • Brain hemorrhage Intracranial hemorrhage.
• Head trauma Head: trauma.
• Metronidazole toxicity Metronidazole.

Peripheral vestibular disease

• Otitis media Otitis media:
  • Extension of otitis externa Otitis externa.
  • Retrograde infection via eustachian tubes.
  • Hematogenous.
• Nasopharyngeal polyps Nasopharyngeal polyp.
• Idiopathic.
• Neoplasia.
• Congenital disease.
• Toxicity:
  • Aminoglycoside antibiotics.
  • Topical iodophors.
  • Chlorhexidine Chlorhexidine.
• Trauma:
  • Fracture of temporal bone.
  • Tympanic bulla damage.

• Acute onset over days.
• Signs may persist for weeks or months.

• Ataxia.
• Nystagmus.
• Head tilt.
• Wide excursion of the head from side to side.

• Ataxia/rolling.
• Head tilt.
• Wide excursion of the head from side to side. 
• Nystagmus.

• Ataxia.
• Wide base stance.
• Head tilt (to side of lesion with unilateral vestibular disorder      ), head tilt can be contralateral with lesion affecting the caudal cerebellar peduncle, fastigial nucleus and/or flocculonodular lobes of the cerebellum.
• Wide excursion of the head from side to side with bilateral peripheral or central vestibular disorder.
• Nystagmus (fast phase away from lesion):
  • May be detected by clinical examination.
  • May be detected by ophthalmoscopic examination only.
  • May only be abnormal positional nystagmus.
  • Vertical nystagmus and nystagmus that changes direction on changing position of the head can only be seen with central vestibular disorder.

• Leaning, rolling or falling to side of lesion.
• No postural weakness.
• Circling towards lesion.

• Mild hypertonia and hyperreflexia in limbs on side of lesion.
• Ventrally deviated eyeballs if head raised (strabismus).
• Horner's syndrome Horner's syndrome may be present with middle ear disease (tumor, otitis or polyps).
• Signs associated with central lesion, eg abnormal mentation, UMN  hemiparesis, general or reduced proprioceptive ataxia, deficits of cranial nerves V to XII (other than VII and VIII).

Radiography

• Skull radiography Radiography: skull (basic) may be useful in demonstrating otitis media   or nasopharyngeal polyps  .

Other

• Imaging techniques:
  • Computed tomography (CT) or magnetic resonance imaging (MRI) may be very useful for imaging central disease or otitis media  .
• Otoscopic and pharyngeal examination under general anesthesia:
  • Otitis externa Otitis externa with extension by rupture of tympanic membrane.
  • Tympanic membrane may appear discolored by fluid in middle ear.
  • Myringotomy Myringotomy with a 20-gauge spinal needle to obtain samples for cytology and culture if the tympanic membrane is intact, but bulging or of an abnormal color.
• Swabs:
  • Swabs for cytology and culture (aerobic, fungal and yeast) from the middle ear if the tympanic membrane is ruptured.
• CSF analysis  Cerebrospinal fluid: sampling (nucleated cell count Cerebrospinal fluid: cell count and differential, cytology Cerebrospinal fluid: cytology, total protein concentration, PCR for infectious titer PCR (Polymerase chain reaction)).

• Otitis media without vestibular involvement.

• Depends on cause

Idiopathic

• No evidence to suggest that any treatment affects outcome of disease.
• Meclizine (6.25 mg PO q12h) and/or diazepam Diazepam (1-2 mg PO q8h) are sometimes helpful in decreasing signs associated with acute vestibular disorder (nausea, anorexia, anxiety, and, in some instances, the severity of the head tilt and ataxia).

Otitis media

• Myringotomy Myringotomy (puncture of tympanic membrane (if intact) to relieve pressure and obtain fluid sample for diagnosis).
• Performed under general anesthesia.
• Clean external ear canal and then puncture tympanic membrane in ventrocaudal aspect with 22 guage spinal needle.
• Aspirate fluid sample and flush gently with 0.2-0.4 ml sterile saline.
• Treat with broad spectrum systemic antibiotics Therapeutics: antimicrobial drug for a minimum of 4-6 weeks. Choice of antibiotic is dictated by results of culture/sensitivity if available; if not amoxicillin/clavulanate Amoxicillin Clavulanate, cephalosporine or fluoroquinone are reasonable choices to consider.
  Delay topical therapy for 4-5 days if myringotomy performed.
• Surgical drainage and debridement via bulla osteotomy Bulla osteotomy if refractory to medical treatment.

Nasopharyngeal polyp

• Polyp should be removed Nasopharyngeal polyp removal.

• Good to reasonable depending on cause.
• Most idiopathic cases improve over several days and may continue to improve for up to 8 weeks.
• Good prognosis if underlying disease identified and treated eg otitis media, or nasopharyngeal polyp.
• Congenital cases may stabilize and occasionally signs regress then recur.

• Resolution of nystagmus over days to weeks. Reducing ataxia and head tilt.
  Many animals with on-going disease learn to accommodate and clinical signs may reduce with time.

• Underlying condition not diagnosed or treated adequately.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Negrin A, Cherubini G B, Lamb C et al (2010) Clinical signs, magnetic resonance imaging findings and outcome in 77 cats with vestibular disease: a retrospective study. J Feline Med Surg 12 (4), 291-299 PubMed.
• Rossmeisl J H Jr. (2010) Vestibular disease in dogs and cats. Vet Clin North Am Small Anim Pract 40 (1), 81-100 PubMed.
• Thomas W B (2000) Vestibular dysfunction. Vet Clin North Am Small Anim Pract 30 (1), 227-249 PubMed.
• LeCouteur R A & Vernau K M (1999) Feline vestibular disorders Part 1 - anatomy and clinical signs. J Feline Med Surg 1 (2), 71-80 PubMed.
• Vernau K M & LeCouteur R A (1999) Feline vestibular disorders Part 2 - diagnostic approach and differential diagnosis. J Feline Med Surg 1 (2), 81-8 PubMed.
• Schunk K L (1988) Disorders of the vestibular system. Vet Clin North Am 18 (3), 641-665 VetMedResource.
• Burke E E, Moise N S, de Lahunta A (1985) Review of idiopathic feline vestibular syndrome in 75 cats. JAVMA 187 (9), 941-3 PubMed.

Other sources of information

• de Lahunta A, Glass E (2009) Vestibular system - special proprioception. Veterinary Neuroanatomy and Clinical Neurology. 3rd edn. W B Saunders, Elsevier, St Louis, Missouri, pp 319-347.
• Munana K R (2004) Head tilt and nystagmus. In: BSAVA Manual of Canine and Feline Neurology. 3rd edn. S R Platt & N J Olby eds. BSAVA, pp 155-171.

Further Reading