The vestibular system and hearing

Question 1

If animals have left ear infection, which way would they fall?

Answer 1

• To the left as has lost the resting tone on the left

Question 2

What does the central vestibular system include?

Answer 2

• 4 nuclei on each side of brainstem (medulla)
• Vestibulocerebellum (ventral part of the cerebellum) -flocculonodular lobe

Question 3

What is seen with eyes with ear problems?

Answer 3

• Ears connected to eyes
• Will have pathological nystagmus
• Eye drop - positional ventral strabismus

Question 4

Whats the difference between peripheral + central vestibular syndrome?

Answer 4

• Peripheral vestibular syndrome
  -Falling over to one side … with no other findings
  -Falling over to one side plus facial paralysis (ipsi)
  -Falling over to one side plus Horner’s (ipsi)
  -Both facial and Horner’s (ipsi)
• Central vestibular syndrome
  -Falling over to one side … plus pretty much any other finding and often many, many other findings

Question 5

Whayt are signs that have to be central vestibular?

Answer 5

• Vertical nystagmus
• Changing nystagmus
• Paradoxical vestibular syndrome (side of head tilt disagrees with other deficits)

Question 6

What is paradoxical vestibular syndrome?

Answer 6

• Central vestibular problem
• Head tilt on opposite side of lesion
• In Ventral cerebellum

Question 7

What are differentials for peripheral vestibular disease?

Answer 7

• Otitis media – interna
• Ototoxic drugs / solutions
• Congenital vestibular syndrome
• Hypothyroid
• Idiopathic vestibular disease
• Ear neoplasms (invading in)

Question 8

What are differentials for central vestibular disease?

Answer 8

• Cerebrovascular (ischemic CVAs)
• MUE (dog), FIP (cat)
• Metronidazole
• (Hypothyroid)
• Brain Tumors
• Thiamine deficiency
• Lysosomal storage diseases

Question 9

What artery is most affected by stroke?

Answer 9

• Rostral cerebellar artery - haemorrhage / ischaemia
  =paradoxical vestibular syndrome

Question 10

How are ischaemic strokes treated?

Answer 10

• Supportive
• Treat underlying disease
• Anticoagulant for future?

Question 11

What can cause meningo-encephalo-myelitis of unknown origin?

Answer 11

• GME - granulomatous meningoencephalitis
  -Female>male, young adults (3-8y/o), terriers +toys
  -multifocal
• NE - necrotizing encephalitis
  -pug, chihuahua, yorkie
  -1-2y/o, forebrain only
• same Tx but worse prognosis

Question 12

What is Dx + Tx of MUO?

Answer 12

• Dx = MRI + CSF support inflammation
  -Rule out infections, NO HISTOLOGY
• Tx = Steroids + cyclosporine, cytosine, leflunomide

Question 13

What is seen with FIP?

Answer 13

• 30% of FIP cases = CNS involvement
• Iritis, anterior uveitis, chorioretinitis
• Neutrophilia, hyperglobulinaemia = blood
• CSF tap = neutrophilic pleocytosis

Question 14

What should be done with metronidazole neurotoxicity?

Answer 14

• Discontinue immediately
• More rapid recovery with diazepam

Question 15

What occurs with thiamine deficiency?

Answer 15

• From all-fish diets
• Central vestibular
• Mydriasis, absent PLR + blind
• Seizures

Question 15

What does otitis media-interna cause?

Answer 15

• Peripheral vestibular disease +/or CN VII +/or Horners
• Ear pain + pain on jaw opening
• Otitis externa in most cases

Question 16

What does idiopathic vestibular syndrome cause?

Answer 16

• Only peripheral = no proprioceptive deficits
• Concurrent facial paralysis
• Normal MRI
• Old - Geriatric dogs
• Peracute + improves in 2-3days, resolve sin 2-3weeks

Question 17

How is deafness classified?

Answer 17

• Age of onset - inherited, acquired, geriatric
• Underlying cause - inherited / acquired
• Location of defect - central / peripheral
• Conductive
• Sensorineural

Question 18

What animals are predisposed to deafness?

Answer 18

• Being white / merle / piebald with BLUE Eyes

Question 19

What is a BAER hearing test?

Answer 19

• Done for breeding purposes
• Useful for unilateral deafness