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SA Neurology > Vestibular disease > Flashcards

Vestibular disease Flashcards

1
Q

Anatomy of the vestibular system

A

Peripheral part:
- sensory receptors (in the vestibular apparatus)
- vestibulocochlear nerve CNVIII

Central part:
- Brainstem - vestibular nuclei
- (cerebellum, thalamus, cranial cervical spine)

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2
Q

Function of the vestibular system

A

Maintain an animals balance and orientation wrt gravity

Including maintaing position of eyes, trunk, and limbs

It also controls eye movements in relation to movements of the head

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3
Q

Clinical signs of unilateral vestibular dysfunction

A

Imbalance
Abnormal head, limb/body, and eye position
Abnormal eye movements

Head tilt towards the lesion (unless paradoxical)

Ataxia with a wide based stance, circling, leaning, falling, or rolling towards a lesion

Strabismus (often positional), nystagmus

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4
Q

Clinical signs of bilateral vestibular dysfunction

A

Wide excursions of the head from side to side and a lack of physiological nystagmus

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5
Q

Neurological exam findings in central vestibular disease (brainstem and cerebellum)

A

Mentation: may be affected

Head tilt: ipsilateral or contralateral

Gait: vestibular ataxia, can present paresis, proprioceptive ataxia, dysmetria

Postural reaction deficits: may be ppresent on the side of the lesion

Nystagmus: pure vertical, horizontal, rotatory. Can change direction with change of head position

Intention tremor: with cerebellar lesion

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6
Q

Neurological exam findings in peripheral vestibular disease (inner ear and CN VIII)

A

Mentation: normal

Head tilt: ipsilateral

Gait: vestibular ataxia, no paresis

Postural reaction deficits: normal

Nystagmus: VII, sympathetic innervation of the eye (Horner’s)

Intention tremor: no

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7
Q

Types of nystagmus

A

Horizontal, rotatory, or vertical

Spontaneous or positional

Jerk or pendular

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8
Q

Spontaneous nystagmus

A

observed when head in normal position

Due to different stimulation of the vestibular system

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9
Q

Postional nystagmus

A

Elicited by moving the head in an unusual position i.e. either by lifting the head or by lying the animal on its back

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10
Q

Jerk nystagmus

A

Has a slow and rapid phase

Typically observed in vestibular disorders

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11
Q

Pendular nystagmus

A

Sinusoidal

Typically observed in cerebellar disorders

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12
Q

Circling

A

Seen in vestibular and fore brain diseases.

CIrcles are usually narrow in vestibular diseases, compared with wide compulsive circles in forebrain diseases.

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13
Q

Paradoxical vestibular disease

A

The head tilt is paradoxical

Cerebellar lesion (caudal cerebellar peduncle and flocculonodular lobe)

Sometimes other cerebellar signs

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14
Q

Vascular central vestibular diseases

A

Infarction, haemorrhage

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15
Q

Infectious/inflammatory central vestibular diseases

A

Meningoencephalitis (MUO)

Empyaema, Toxoplasma/neospora, FIP

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16
Q

Idiopathic central vestibular diseases

A

Arachnoid cysts

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17
Q

Traumatic central vestibular diseases

A

Head trauma

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18
Q

Toxic central vestibular diseases

A

Metronidazole

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19
Q

Anomalous central vestibular diseases

A

Congenital malformation

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20
Q

Neoplastic central vestibular diseases

A

Brain tumours - primary or metastatic

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21
Q

Nutritional central vestibular diseases

A

Thiamine deficiency

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22
Q

Degenerative central vestibular diseases

A

Lysosomal storage disorders

Neurodegenerative diseases

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23
Q

Infectious/inflammatory peripheral vestibular diseases

A

Otitis media/interna

Nasopharyngeal polyps

24
Q

Idiopathic peripheral vestibular diseases

A

Idiopathic vestibular disease

25
Q

Traumatic peripheral vestibular diseases

A

Trauma to middle or inner ear

26
Q

Toxic peripheral vestibular diseases

A

Aminoglycosides
Chlorhexidine

27
Q

Anomalous peripheral vestibular diseases

A

Congenital vestibular disease (most common cause in dogs)

28
Q

Metabolic peripheral vestibular diseases

A

Hypothyroidism

29
Q

Neoplastic peripheral vestibular diseases

A

Tumours of the middle and inner ear

30
Q

Pathogenesis of otitis media/interna

A

Infeciton of the middle/inner ear, most commonly as an extension of otitis externa

Staphylococcus intermedius and Pseudomonas are the most common organisms

Can also occur by ascent from the oral cavity through auditory tube or by haematogenous spread

31
Q

Clinical signs of otitis media/interna

A

Vestibular signs (peripheral)

Facial nerve paralysis and/or Horner’s syndrome can be seen due to close association of CN VII nd the sympathetic nerve with the petrous temporal bone

32
Q

Diagnosis of otitis media/interna

A

Otoscopic exam: tympanic membrane often ruptured

X-ray/MRI/CT: to visualise the tympanic bullae

Myringotomy: to obtain some fluid for cytology or culture - needle through tympanic membrane to aspirate

33
Q

Treatment of otitis media/interna

A

Systemic antibiotics ideally on results of culture, for 4-6 weeks (amoxycillin/clavulanate, cephalosporin, or fluoroquinolone)

Bulla osteotomy can be needed if unresponsive to medical treatment

34
Q

Prognosis of otitis media/interna

A

Good for resolution of infection, although neurological damafe may persist due to irreversible damage of neural structures

35
Q

Pathogenesis of idiopathic vestibular disease

A

Cause not determined, potentially various

36
Q

Epidemiology of idiopathic vestibular disease

A

Common in dogs and cats

Most common cause in dogs

Typically older dogs so sometimes called canine geriatric vestibular disease

37
Q

Clinical signs of idiopathic vestibular disease

A

Peripheral vestibular dysfunction

Signs usually unilateral and severe

Peracute onset

Vomiting is common at the initial stage of the disease

Horner’s syndrome can be seen in dogs but not in cats

In cats can get facial paralysis

38
Q

Diagnosis of idiopathic vestibular disease

A

Exclusion of other causes

MRI contrast enhancement of CN VIII

39
Q

Treatment of idiopathic vestibular disease

A

No treatment is recommended other than supportive care

40
Q

Prognosis of idiopathic vestibular disease

A

Usually good

Spontaneous improvement typically seen within 2-3 days

Complete resolutions takes 2-4 weeks and in some cases may be prolonged for months

Mild head tilt may persist

Can re-occur

41
Q

Middle ear polyps

A

Cats of all ages (often young, and male)

Middle ear localisation, Horner’s common

May show respiratory signs

Sub-acute onset, progressive signs of vestibular disease

42
Q

Diagnosis of polyps

A

Visualisation (with or without otoscope)

Imaging (CT, MRI)

43
Q

Treatment of polyps

A

Traction-avulsion vs central bulla osteotomy vs TECA

+/- antibiotics and corticosteroids

Recurrence depends on technique (14-50% traction avulsion, 2% VBO)

44
Q

Ototoxic medication causing disease

A

Causes: animoglycosides, tetracyclines, cisplatin, chlorhexidine, loopdiuretics, propylene glycol

Signs of peripheral vestibular disease

Peracute/acute onsest

Progressive

Diagnose on clinical signs and history

Treatment: stop medications

Prognosis good for recovery of vestibular signs but poor for hearing

45
Q

Neurodiagnostic investigation (especially when central vestibular syndrome suspected)

A

Routine haem and biochem (metabolic, inflammatory, infectious disease)

ACTH stimulation: Cushing’s disease and chronic renal failure - hypertension

T4/TSH testing: hypothyroidism

Toxoplasma/neospora serology

Coagulation testing

Angiostrogylus vasorum testing: haemorrhagic stroke

Urinalysis: protein losing enteropathy can predispose ischaemic stroke (loss of anticoagulant factors)

Systemic blood pressure: persistent hypertension

CT/MRI: structural abnormalities

46
Q

Pathogenesis of cerebrovascular accident (CVA)

A

Ischaemic (>70%):
- endocrine
- renal
- cardiac
- neoplasia
- sepsis
- parasitic
- hypertension

Haemorrhagic (<30%):
- neoplasia
- coagulopathy
- parasitic
- malformations
- trauma
- hypertension
- vasculitis

47
Q

Signs of cerebrovascular accident (CVA)

A

SIgns of central vestibular disease

Peracute/acute onset

Minimal progression/gradual movement

48
Q

Diagnosis of cerebrovascular accident (CVA)

A

Confirm clinical suspicion
- MRI (ischaemic: T2W hyperintense, sharly marginated, mainly GM, lesions confined to vascular territory of affected vessel.; Haemorrhagic: mass lesion, intensities vary with time)
- CSF (exclusion of other causes

Look for concurrent disease process:
- CBC, biochemistry, UA
- BP
- imaging (chest/abdomen)
- endocrine testing if clinically appropriate

49
Q

Treatment of cerebrovascular accident (CVA)

A

If concurrent disease identified then treat that

Symptomatic (nursing, anti-emetics, physiotherapy)

50
Q

Prognosis of cerebrovascular accident (CVA)

A

Good if no concurrent disease found

Ischaemic disease has better prognosis than haemorrhagic

51
Q

Metronidazole toxicity - central vestibular disease

A

Dogs and cats treated with high doses of metronidazole for at least a month can develop signs of neurotoxicity, usually presenting as central vestibular syndrome

Can happen at lower doses in shorter time

Resolution of signs after discontinuation of therapy takes 3-5 days, may be quicker is diazepam given orally

Cerebellovestibular ataxia, head tilt, nystagmus, seizures

52
Q

Thiamine deficiency - central vestibular disease

A

In cats, females overrepresented

Encelopathy, including the medial vestibnular nuclei

Impaired energy metabolism

Bilateral, central vestibular signs. Subacute/acute onset. Wax- and-waning

Diagnose with brain MRI - symmetrical hyperintense leions in specific nuclei. Serum testing can reveal low thiamine levels but ranges poorly defined.

Treat by injecting vitamin B1 (thiamine), and correcting diet

Prognosis is good - reversible in most cases

53
Q

FIP - central vestibular disease

A

Signs sometimes multifocal/diffuse. Subacute/acute onset. Progressive

CNS form often associated with ocular form and non-effusive form

Immune-complex mediated development of vasculitis

54
Q

Diagnosis of FIP - central vestibular disease

A

PCR on CSF, free fluid, or tissue

Immunohistochemistry

MRI

CSF: increase in microprotein and leocytosis

55
Q

Treatment of FIP - central vestibular disease

A

Remdesivir IV

Adenosine nucleoside analogue

80-90% response - good prognosis

56
Q

Hypothyroidism - central vestibular disease

A

Central and peripheral signs

Subacute/acute onset. Progressive

Central disease can be related to CVA

Abnormal axonal function and transport/polyneuropathy; abnormal lipid metabolism and arteriosclerosis; myxoedematous compression

Diagnosis: T4/TSH

Treatment: Levothyroxine

Prognosis: good, reversible

SA Neurology (11 decks)

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