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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
Traumatic peripheral vestibular diseases
Trauma to middle or inner ear
26
Toxic peripheral vestibular diseases
Aminoglycosides Chlorhexidine
27
Anomalous peripheral vestibular diseases
Congenital vestibular disease (most common cause in dogs)
28
Metabolic peripheral vestibular diseases
Hypothyroidism
29
Neoplastic peripheral vestibular diseases
Tumours of the middle and inner ear
30
Pathogenesis of otitis media/interna
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
Clinical signs of otitis media/interna
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
Diagnosis of otitis media/interna
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
Treatment of otitis media/interna
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
Prognosis of otitis media/interna
Good for resolution of infection, although neurological damafe may persist due to irreversible damage of neural structures
35
Pathogenesis of idiopathic vestibular disease
Cause not determined, potentially various
36
Epidemiology of idiopathic vestibular disease
Common in dogs and cats Most common cause in dogs Typically older dogs so sometimes called canine geriatric vestibular disease
37
Clinical signs of idiopathic vestibular disease
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
Diagnosis of idiopathic vestibular disease
Exclusion of other causes MRI contrast enhancement of CN VIII
39
Treatment of idiopathic vestibular disease
No treatment is recommended other than supportive care
40
Prognosis of idiopathic vestibular disease
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
Middle ear polyps
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
Diagnosis of polyps
Visualisation (with or without otoscope) Imaging (CT, MRI)
43
Treatment of polyps
Traction-avulsion vs central bulla osteotomy vs TECA +/- antibiotics and corticosteroids Recurrence depends on technique (14-50% traction avulsion, 2% VBO)
44
Ototoxic medication causing disease
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
Neurodiagnostic investigation (especially when central vestibular syndrome suspected)
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
Pathogenesis of cerebrovascular accident (CVA)
Ischaemic (>70%): - endocrine - renal - cardiac - neoplasia - sepsis - parasitic - hypertension Haemorrhagic (<30%): - neoplasia - coagulopathy - parasitic - malformations - trauma - hypertension - vasculitis
47
Signs of cerebrovascular accident (CVA)
SIgns of central vestibular disease Peracute/acute onset Minimal progression/gradual movement
48
Diagnosis of cerebrovascular accident (CVA)
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
Treatment of cerebrovascular accident (CVA)
If concurrent disease identified then treat that Symptomatic (nursing, anti-emetics, physiotherapy)
50
Prognosis of cerebrovascular accident (CVA)
Good if no concurrent disease found Ischaemic disease has better prognosis than haemorrhagic
51
Metronidazole toxicity - central vestibular disease
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
Thiamine deficiency - central vestibular disease
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
FIP - central vestibular disease
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
Diagnosis of FIP - central vestibular disease
PCR on CSF, free fluid, or tissue Immunohistochemistry MRI CSF: increase in microprotein and leocytosis
55
Treatment of FIP - central vestibular disease
Remdesivir IV Adenosine nucleoside analogue 80-90% response - good prognosis
56
Hypothyroidism - central vestibular disease
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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