PTY3051 Week 6: Introduction to the vestibular system & BPPV

Anatomy of vestibular system

Peripheral sensory apparatus: sense head movements via movements of otolit0hs and hair cells within otolithic membrane

Central processor: CNS

Motor output

Peripheral sensory apparatus of the vestibular system

- Utricle (horizontal movements)

- Saccule (vertical movements)

- Anterior, posterior & horizontal semicircular canals (rotational movements)

Motor output of the vestibular system

- Vestibular ocular reflex: eye movements to allow for clear vision during head movements

- Vestibulospinal reflex: head righting reflex & postural responses

Symptoms of vestibular dysfunction

- Dizziness

- Postural instability (dysequilibrium)

- Unsteady gait

Secondary complaints:

- Deconditioning

- Falls

- Physical &/ mental fatigue

- Restrictions / alterations to ADLs

- Cervical / shoulder pain & stiffness

Mechanisms of different types of dizziness

- Lightheadedness: ↓ cerebral blood flow

- Floating, rocking: psychologically induced

- Vertigo (spinning): imbalance of tonic activities to central vestibular structures

- Dysequilibrium & gait ataxia: loss of vestibular, proprioceptive or visual inputs / ↓ motor control

Common lesions to the vestibular system

- Viral infection (labyrinthitis, neuronitis)

- Meniere's disease

- Degenerative (age-associated)

- Benign Paroxysmal Positional vertigo (BPPV)

- Acoustic neuroma

Signs & symptoms of vestibular labyrinthitis / neuronitis

- Sudden onset of vertigo, nystagmus &/ nausea

- Tendency to fall to side of lesion

- Dizziness present at rest and exacerbated by position changes

- Spontaneous / horizontal nystagmus

- No other neurological symptoms

- Auditory symptoms (for labyrinthitis)

Vestibular degeneration

- Insidious onset

- Likely age-related decline

Signs & symptoms of Meniere's disease

- Aural fullness

- Tinnitus

- Fluctuating hearing loss

- Presents as "longer attacks" with relatively normal function between attacks

- At later stages: residual vestibular dysfunction (similar to MS)

Pathology of Meniere's

- Altered fluid pressures within the cochlea and semicircular canals

- Links to autoimmune system

Causes of BPPV

Crystals either freely floating or adhering within the posterior semicircular canal

Signs & symptoms of BPPV

- Bouts of vertigo (< 60 sec)

- Onset of dizziness with head turns (eases with stopping of movements)

Pharmacological management of dizziness

Vestibular suppressors e.g. Stemetil

- Relieves symptoms (nausea) but not acute vertigo

- Can be prescribed in very acute stage where symptoms limit ability to perform exercises / movements

- Should aim to reduce ASAP

When is vestibular rehabilitation appropriate?

- Motion induced symptoms (not purely spontaneous)

- Continuous symptoms with motion exacerbation

- Functional balance / gait dysfunction

- Stable lesion (not rapidly progressive)

Principles of vestibular rehabilitation

- Capitalising on the innate plasticity of the cerebellum and brainstem

- Vestibular system adaptations to head movements

Assessment of vestibular function

- Spontaneous & gaze-evoked nystagmus

- Smooth pursuit & saccadic movements

- Head thrust & gaze stabilisation testing (peripheral causes)

- VOR cancellation (central causes)

- Positional changes (e.g. head turns, rolling, lie to sit)

- Balance & gait

Outcome measures in the assessment of a dizzy patient

Balance: CTSIB

Dizziness:

- Self-rating of dizziness /10

- Dizziness Handicap inventory

Treatment options for BPPV

- Epley's manoeuvre

- Liberatory (Semont's) manoeuvre if Epley's contraindicated

- Brandt-Daroff exercises

Specific assessments for BPPV

Roll test (horizontal canal)

- Positive test: horizontal nystagmus

Hallpike-Dix manoeuvre (posterior canal)

- Positive test: upbeat, torsional nystagmus that starts after latency period, and resolves within 60 secs

Treatment options in vestibular rehabilitation

- Habituation training

- Gaze stability exercises

- Balance & gait retraining

- Cervical ROM exercises

- Education

- Referrals to MDT (e.g. psychology & OT)

Habituation training

- Performing provocative positional changes (at appropriate speeds)

- Provoking 3-4/10 dizziness that subsides within 30 secs.

- 3x3reps daily

Gaze stability exercises

- Turning head left and right at a speed such that the words start to slip off a card

- Induce "error signals"

- Aiming to build up to 12 mins (acute) or 20 mins (chronic)

Negative prognostic indicators for dizziness

- Longer delay for rehab start from onset

- Long term use of vestibular suppressants

- Migraine

- Peripheral neuropathy

- Anxiety & depression

- Catastrophising & hyper-vigilance