Neurology: Vestibular Disease Flashcards
What is the purpose of the vestibular system?
- Maintain balance
- Maintain normal orientation relative to gravitational field
- Maintain position of the eyes, neck, trunk and limbs relative to position
How does the vestibular system work?
- 3 ducts orientated at right angles to each other
- Rotatoin of head makes more endolympg flow within one or more ducts
Vestibulocochlear nerve
* In connection with hair cells of each receptor
* Movement of fluid in semicircular ducts, bending hair cells- nerve impulse
What is the central vestibular system?
Brainstem
* 4 nuclei that receive information from nerve and pass message on to rest of brain and spinal cord
Cerebellum
* Inhibits vestibular nuclei
What are the clinical signs of vestibular disease?
- Ipsilateral head tilt
- If affects both sides- head sway
- Ataxia and wide-base stance
- Leaning and falling
- Less commonly tight circling
- Nystagmus- lesion on side of slower phase, vertical suggests central
What is a paradoxical head tilt
- Lesion on fluccononodula lobe or caudal cerebellar peduncel
- Head tilt contralateral to lesion
- Cerebellum inhibits ipsilateral vestribular nuclei
How can peripheral and central vestibular disease be distinguished?
- Proprioceptive defecits possible for central
- CN V-XII may be affected for central
- Vertical nystagmus with central
What most likely causes horner’s syndrome and facial nerve defecits?
Facial nerve defecits- peripheral disease
Horners- most commonly middle ear
What are most common causes of central vestibular disease?
- Cerebrovascular disease
- MUEs
- FIP
- Brain tumours
What are the most common causes of peripheral vestibular disease?
- Otitis media/interna
- Idiopathic
How can acute and chronic onset allow seperation of differentials
Acute likely to be idiopathic, cerebrovascular or trauma
Chronic- otitis, MUEs, FIP, tumours
What is cerebrovascular disease?
What can cause it?
Abnormality of brain caused by disruption of blood
* Stroke or CVA- clinical manifesation
* Infarct- area of necrotic tissue
* Ishaemic
* Haemorrhagic
How does cerebrovascular disease appear on MRI?
- Well-defined, sharply demarcated lesions with minimal to no mass effect
- Limited to the vascular territory of a main cerebral or perforating artery
- Hyperintense on T2WI and FLAIR
What are common concurrent disease of cerebrovascular diseases?
How is it treated?
- CKD
- Hypertension
- Cushings- hyperadrenocorticism
- PLE
- Neoplasia
Tx
* supportive/underlying disease
* Prognosis fair to good especially without concurrent medical conditions
What are the three types of menincoencephalomyelitis of unknown origin?
GME- granulomatous ME
NME- necrotising ME
NLE- necrotising leukoencephalitis
Pug, frenchy, chihua, montese
- What age of dogs are more commonly affected by granulomatous ME?
- What are the CS?
- What shows on MRI/CSF
- Young adults- 3-8
- Multifocal- causal fossa (vestibular/cerebellar), effect spinal cord
- MRI- multiple ill-defined hyperintensities, CSF- mononuclear pleocytsos
What breeds are predisposed to necrotising encephalitits?
What are the clinical signs?
Pug, chihuahua, yorkie
Seizures, blindness, altered behaviour, circling, depression
How are MUOs treated?
Immunosuppression
* Corticosteroids
±
* Cytosine arabinosine
* Leflunomide
* Ciclosporine
* Azathioprine
What are the neurological signs of FIP?
More commonly localise to cerebellomedullary region
* tetraparesis
* ataxia
* nystagmus
* loss of balance
How is FIP diagnosed?
- Very high serum titres of FCov Ab
- MRI- periventricular contrast enhancement
How can hypothyroidism be treated?
Levothyroxine
What antibiotic can cause central vestibular disease?
Metronidazole- uncommon
Central vestibar, seizures
Discontinue drug, diazepam causes faster improvement
How can diet cause central vestibular disease?
Thiamine deficiency
What brain tumours can cause central vestibular disease?
- Meningiomas- most common
- Tumours invading ear canal
What structures pass by the middle ear?
What signs can otitis media/interna therefore cause?
CN VII, CN VIII, sympathetic supply to eye
Signs
* facial paralysis
* peripheral vestibular signs
* Horners
* Pain on opening mouth
What is the most common cause of vestibular disease in dogs?
Idiopathic vestibular disease
- No central signs- proprioceptic defecity
- Vertical nystagmus
Acute onset- rolling, falling, vomiting, ataxia, head tild
Treat with ondansetron and maropitant
- What can cause facial nerve paralysis?
- What are the clinical signs?
- How is it treated?
- Idiopathic, middle ear disease, brain stem lesions (other signs)
- Drooping of face, widening of palpebral fissure, food/saliva may drop from side of mouth, palpebral reflux reduction
- Avoid dry eye- extent of recovery variable
How is deafness classified?
- Age- congenital, late
- Underlying cause- inherited, acquired
- Location- peripheral, central
- Sensorineural or conductive
What is the most common type of deafness?
Congenital sensorineural deafness
Dogs/cats with white pigmentation and blue eyes
What can cause acquired deafness?
- Chronic otitis
- Ototoxicity
- Noise trauma
- Presbycusis (old age)
- Anaesthesia associated
How can hearing be tested?
- Brainstem auditory evoked responses
- Otoacoustic emissions
