BPPV Flashcards
(17 cards)
What does normal vestibulo-occular reflex (VOR) do
maintains stable vision during head motion
primary mechanism for gaze stability during head movement
when head moves, eyes move in equal but opposite direction and velocity to keep image on the fovea
VOR gain =
what should it equal
eye velocity / head velocity
should equal 1
What if VOR gain ratio is <1
retinal slip = decreased visual acuity and blurring
Eyes move with head instead of staying still
What are the 3 vestibular reflexes
Vestibulo-occular reflex (VOR)
Vestibular collic reflex
Vestibular spinal reflex
What is vestibular nystagmus
involuntary, rapid eye movement caused by asymmetry in vestibular input
Linked to the VOR mechanism
2 phases of vestibular nystagmus
Slow phase: driven by the vestibulo occular reflex (VOR) - eyes move opposite to perceived head movement
Fast phase: a quick rest - eyes snap back to midline to fixate again
E.g. Head turns right, VOR moves eyes left (slow phase). Eyes then quickly flick right to reset (fast phase)
BPPV Pathophysiology
- calcium carbonate crystals (otoconia) dislodge from utricle and float into one of the canals (mostly posterior)
- otoconia are heavy so when person lies down or moves head, gravity causes particle to fall to lowest point of canal
- as otoconia moves through canal, they displace endolymph fluid. This creates a pressure gradient which causes stronger deflection of the cupula (where hair cells are) than normal
- bending of hair cells causes exaggerated neural signal sent to brain via vestibular nerve. This is interpreted as rapid spinning or movement
- opposite ear doesn’t send same signal, so brain receives asymmetric input from the two vestibular systems, creating a mismatch
- to compensate for perceived movement, vestibulo occular reflex (VOR) is triggered, resulting in nystagmus - specific pattern of invountary eye movement that corresponds to the canal being stimulated
BPPV pathophysiology simplified
Dislodged otoconia
gravity and particle movement
endolymph movement and pressure gradient
strong neural signal
asymmetry and sensory conflict
VOR activation –> nystagmus
Which canal generally in BPPV
Posterior
then Horizontal
Then anterior (very rare)
BPPV (benign paroxysmal positional vertigo) overview
Benign paroxysmal positional vertigo
- illusion of movement (world or self)
- episodic tempo, rapid onset, short duration
- <60s
- triggers: head movement, rolling, lying flat, getting out of bed
Signs: normal upright oculomotor exam, positive Dix Hallpike or Roll test for BPPV
Types of BPPV
Canalithiasis (common)
on testing short latency prior to nystagmus
- nystagmus lasts <60s then stops
Cupulolithiasis (advanced)
- on testing nystagmus starts immediately
- nystagmus only stops when patient moved out of provoking position
BPPV ICF Framework
Impairments
- vertigo: brief, intense spinning sensation triggered by head movement
- nystagmus: involuntary eye movements
- postural imbalance: difficulty maintaining steady posture, especially during head movement
- gaze instability: inability to maintain stable vision during head movement due to abnormal VOR
- Nausea and/or vomiting
Activity limitations
- sleep and sleeping positions
- transfers in and out of bed
- self care e.g. washing hair
- bending over e.g. emptying dishwasher
- stairs
- driving
Participation restrictions
- sport
- work
- domestic chores
- hobbies e.g. yoga/pilates
Vertigo subjective
Type of dizziness
Tempo of symptoms: all the time vs time to time
Timing of dizziness: how long does it last for. BPPV <60s
Trigger: positional vs spontaneous
Other
- Is this first episode, severity of symptoms
- associated symptoms: ear, visual symptoms, neuro - headache and 5Ds and 3Ns, Autonomic, migraine
- medical history: recent infection, migraine Hx, head trauma, medication, alcohol
Vertigo objective
VBI screening
HR/BP - screen for CV causes
Neuro: Strength, sensation, coordination, speech
Balance/gait Ax
Oculomotor examination - VOR issues and nystagmus. Generally neg in BPPV as provoked by positional change
Head impulse Test: assess VOR function - see if patient can maintain gaze on assessors nose following head movement
HINTS+: differentiates between peripheral vestibular issue from a stroke
Positional tests: Dix Hallpike, Roll test
Prognosis of BPPV
symptoms may subside without treatment (20% at 1 month, 50% at 3 months)
Recurs - 1/3 have recurrent episode within 1st year post treatment
PT intervention for BPPV
Want to reduce positional vertigo, reduce imbalance and reduce falls risk
Epley manoeuvre for posterior canal
avoid long term use of vestibular suppressants
Education - recurrence, provoking head positions, management post acute event, falls prevention
specific balance exercises, falls prevention
Differentials for BPPV and how they are different
Vestibular neuritis - no positional trigger, associated with previous infection
Meniere’s disease - longer episodes, hearing loss/tinnitus
Vestibular migraine - headache, photophobia, phonophobia and no consistent positional trigger
PICU stroke - neuro symptoms (weakness/sensation loss), HINTS+ positive for peripheral symptoms
