vertigo (see DM) Flashcards
what modulates normal balance
continuous interaction between vestibular, proprioceptive and visual mechanisms which are all modulated by the CNS
what is vertigo
a sensation of dizziness or abnormal motion resulting from a disorder of the sense of balance
how do environmental factors affect balance control (sensory pathway)
environmental interaction -> visual, vestibular and somatosensation systems provide info about the body position -> compare, select and combine sense -> determination of body position
if there is a lesion in the Thalamo-Cortical Structure what is the presentation (vestibular)
conscious illusion of spinning
if there is a lesion in the occulomotar nuclei what is the presentation (vestibular)
nustagmus
if there is a lesion in the spinal chord what is the presentation (vestibular)
lateropulsion (tendancy to veer to one side)
if there is a lesion in the cerebellum what is the presentation (vestibular)
gait ataxia
if there is a lesion in the autonomic medullary centres what is the presentation (vestibular)
autonomic symtpoms e.g. sweating, vomiting
what is vestibular compensation
a process that allows the brain to regain balance control and minimise dizziness symptoms when there is damage to one of the vestibular organs - due to ON/OFF tonic signaling from the vestibular organs
what changes are seen in the brains of ballet dancers (vestibular)
through spotting, the brain has adapted to suppress activity in the cerebrum and cerebellum associated with vestibular function
examples of general medical causes of vertigo (6)
- Anaemia
- postural Hypotension
- Carotid Sinus Syndrome
- Dysrhythmia
- Hypoglycaemia
- Hyperventillation
examples of neurological causes of vertigo (8)
- Epilepsy
- Migraine
- Syncope
- Psychogenic
- Multiple Sclerosis
- Cerebral Ischaemia
- Infective disorders
- Tumours
otological causes of vertigo (10)
- Menière’s Disease
- Post Traumatic Syndrome
- Positional Nystagmus
- Vestibular Neuronitis
- Infection
- Otosclerosis and Paget’s Disease
- Vascular accidents
- Tumours
- Auto-immune disorders
- Drug intoxication
what are the 3 most common peripheral vestibular causes of vertigo
- Benign Paroxysmal Positional Vertigo (BPPV)
- Menière’s disease (or syndrome)
- Vestibular Neuronitis
how does alcohol cause vertigo
the endolymph becomes less viscous with the consumption of alcohol, this allows the hair cells to move more easily within the ear, which sends the signal to the brain and results in exaggerated and overcompensated movements of body
what is “true vertigo” a disease of
the semicircular canals and their CNS connections - has accompanying symptoms of gait unsteadiness, nausea, vomiting etc.
what is the commonest cause for single attack of vertigo
vestibular neuronitis
what is the commonest cause for recurrent spontaneous vertigo
migraine
what is the commonest cause for positional vertigo
BPPV
what does a vertigo attack that lasts seconds indicate the cause could be
vestibular paroxsysms, cardiac arrythmias, BPPV
what does a vertigo attack that lasts hours indicate the cause could be
meniere’s disease, migraine
what does a vertigo attack that lasts days indicate the cause could be
vestibular neuronitis, brainstem/cerebellar stroke
how to distinguish BPPV from other positional causes e.g. orthostatic hypotension
BPPV arises from a specific reorientation of the head e.g. rolling over in bed or turning the head, rather than a change in head position e.g. sitting to standing
what does vertigo + red eyes, skin rashes arthritis etc. indicate
autoimmune inner-ear disease
what does vertigo + diplopia, dysarthria, numbness, paresis etc. indicate
posterior fossa lesion (incl. ischaemia) or basilar migraine
what is romberg’s test
asking the patient to stand up with their feet together and to close their eyes -> A positive Romberg means that the patient shows a tendency to actually fall
what does a +ve romberg’s test indicate
dorsal column or severe afferent polyneuropathy
what is unterberger’s test and what will a +ve result show
involves asking the patient to step up and down on the spot with eyes closed;
+ve result - In unilateral vestibular lesions the patient rotates towards the hypoactive side
what is first degree nystagmus
Nystagmus with gaze deviation in the direction of the fast phase - i.e. it only occurs when the gaze is deviated
what is second degree nystagmus
nystagmus when looking at a fixed spot straight ahead
what are frenzel glasses
help to visualise nystagmus - magnifies the eyes and making it easier to see subtle movement and also preventing the patient from using ocular fixation to prevent nystagmus occurring
what do saccades in the eyes indicate
central lesion (brain) -> pursuit is normal in vestibular disorders
how does the vestibulo-ocular reflex stabilise the eyes during head movement
generates eye movement of the same speed, but opposite direction to head movements
central vs peripheral nystagmus fatigability
central - persistant
peipheral - disappears on repitition
what does an abnormal VOR indicate
vestibular lesion
what types of drugs can cause vertigo
antidepressants, anticonvulsants, anxiolytics, anti-hypertensives, muscle relaxants
what tumours commonly arise at the cerebello-pontine angle and what syptom do pts usually resent w
vestibular schwanomma - present w unilaterla hearing loss as the tumour grows on the vestibular nerve and exerts pressure onto the adjeacted auditory nerve -> tumour grows slowly and brain can recieve vestibular info from the other ear and so vertigo is not usually a presentaiton
how does vestibular rehabilitation work
due to central compensation and CNS neuroplasticity rehabilitation exercises (e.g. cawthorn-cooksey) can allow for recalibration og vestibular reflexes
why does nystagmus occur in BPPV
when the cupula is artificiall displaced by the crystals of otoconia it stimulates the VOR which triggers the slow phase of nystagmus, as the eyes respond to canalith-induced deflection of the cupula. This is then followed by a saccade in the opposite direction (the fast phase of nystagmus) via a corrective response by the brain
