Vestibular pathology/vestibular system part 2 Flashcards
vascular system of the vestibular system
- vertebral arteries
- basilar artery
- posterior inferior cerebellar arteries (PICA)
- anterior inferior cerebellar arteries (AICA)
balance and postural control
vestibulospinal reflexes
- generates reaction that compensate for displacements of the head
- postural responses evoke which stabilize the body to facilitate vertical alignment
- extesnor activity is induced on the side to which the head is inclined and flexor activity is induced on the opposite side
balance and postural control
vestibulo-collic reflex
- neck muscles activation to stabilize the head with respect to space
- compensates for displacements of the head that occur during gait
peripheral vestibular disorders types
- reduced vestibular function
- disorted vestibular function
- fluctuating vestibular function (tough to treat as PT)
reduced function disorders
what occurs
- decreased sensitivity of peripheral sensory apparatus to stimuli
- caused by damage to vestibular nerve, labyrinth, hair cells
- damage can be unilateral/bilateral or partial/complete
Reduced vestibular function (UVH/BVH)
etiology of damage
- labyrinthitis/neuritis
- age-related hair cell damage
- drug-induced hair cell toxicity
- brain trauma
- vascular occlusion
- acoustic neuroma/vestibular schwannoma
reduced function pathology
vestibular neuritis
- typically due to a virus in the vestibular nerve
- 50% of cases preceded by upper respiratory of GI infection
- spontaneous onset of vertigo (typically days in duration) - assoicated with nausea/vomiting and imbalance
- good candidate for vestibular compensation exercises
reduced function pathology
labyrinthitis
- infection (viral or bacteria) to labyrinth
- spontaneous onset of vertigo (typically days) within assoicated nausea/vomiting, imbalance and AUDITORY symptoms (hearing loss)
- appropriate for vestibular rehab
reduced function pathology
anterior vestibular artery ischemia
- spontaneous onset of vertigo (typically days)
- assoicated nausea/vomiting/imbalance
- no assoicated auditory symptoms
- approriate for vestibular rehab
reduced function pathology
acoustic neuroma/vestibular schwannoma
what is it, signs and symptoms, treatment
- benign tumor on CN VIII - progressive/slow onset
Signs and symptoms:
- progressive hearing loss
- tinnitus
- disequilibrium
treatment:
- surgical excision
- often sacrifice all/part of vestibular nerve
reduced function pathology
unilateral vestibular hypofunction
symptoms
- oculomotor distrubances
- vertigo
- asymmetrical CN VIII firing
- balance deficits
- spontaneous nystagmus
- skew deviation of eye
reduced function pathology
UVH: spontaneous nystagmus
- involuntary eye movement
- slow phase movement toward side of lesion
- disappears in light within few days
VOR disturbance in UVH
- head rotation normally causes increased firing in ips CN VIII
- ips lesions= head movement toward side of lesion = brain recieves decreased firing = inadequate eye movement
Nystagmus as a sign
- abnormal activation of VOR
- slow movement in one direction
- faster movement in opposite direction = toward the more neurally active side
- named by nature of direction and fast movement
- horizontal = right and left
- torsional = up/down
VOR disturbance in UVH
postural instability
- abormal gait
- ataxia
- even when compensated later, can be produced during gait with quick turn arounds/turning head to side
reduced function pathology
bilateral vestibular hypofunction causes
- ototoxicity: systemic antibiotics, neoplastic drugs
- often accompanied by hearing loss
- bilateral sequential loss
- traumatic
reduced function pathology
BVH: symptoms
- primary complaint = balance deficits
- oscillopsia: illusion that visual environment is moving making it difficult to see clearing while moving
- no nsytagmus
- severe dysnamic VOR disturbances: no VOR to stabilize gaze during head movement
reduced function pathology
postural instability in BVH
- severe dynamic balance disturbances
- unable to walk with eyes closed
- wide based ataxic gait
- unable to turn head or turn around without loss of balance
Distorted vestibular function pathologies
BPPV
Distorted vestibular function pathologies
BPPV
- benign positional paroxysmal vertigo
- one or more SCCs inappropriately excited
- brief episodes of vertigo disequilibrium when head moved into a particular position
- latency of 1 or more seconds after head moved into provokign position
- duration less than 60 seconds
Distorted vestibular function pathologies
BPPV: pathophysiology
- canalithiasis: debris floating within endolymph of SCC
- cupulolithiasis: Debris adhering to cupula of affected canal
Fluctuating vestibular function
- occasional disruptions in vestibular function
- periods of normal and abnormal function
- endolymphatic hydrops
- meniere’s disease, perilymphatic fistual
Fluctuating vestibular function
meniere’s disease
- low frequency hearing loss + episoding vertigo
- epsiodes last 1-2 hours
- etiology = increased endolymph
- treatment: prevent fluid buildup and low Na diet
Fluctuating vestibular function
perilymphatic fistual
tears or defects of the thin membranes between the middle and inner ear
