Vestibular Rehabilitation (VR)

1. Definition and Rationale

2. Neurophysiological Basis

a) Static Compensation

• Occurs within 24-72 hours of an acute vestibular insult, regardless of movement
• Mediated by tonic rebalancing of resting activity in the vestibular nuclei
• Minimizes side-to-side discrepancies in tonic firing rates of second-order neurons
• Provides relief from intense vertigo and vomiting but does not address dynamic (movement-related) symptoms
• Results in continued motion-provoked vertigo until dynamic compensation is achieved

b) Adaptation

• The process of VOR improvement through exposure to retinal slip
• The vestibulo-ocular reflex (VOR) maintains fixation during head movement by producing compensatory eye movements equal and opposite to head velocity (VOR gain = eye velocity/head velocity = 1.0)
• In peripheral vestibular disorders, VOR gain is reduced, causing retinal image slip and visual blurring during head rotations
• Retinal image slip acts as an error signal that drives VOR improvement
• Recent evidence shows that compensatory saccades also contribute to VOR gain improvement, particularly in more severe hypofunction
• Adaptation exercises incorporate gaze fixation with head movement to simulate retinal slip

c) Habituation

• A decrease in the magnitude of response to repetitive sensory stimuli
• The classical Cawthorne-Cooksey exercises (1940s-50s) were based on this principle
• Involves repeating the provoking movement at regular intervals until symptoms cease
• Modern evidence supports customized VR programmes focusing on individual deficits rather than generic habituation alone

d) Sensory Reweighting / Substitution

• The CNS's ability to adapt its relative reliance on specific sensory modalities depending on environmental conditions and task demands
• When a sensory input is reduced or absent, other sensory inputs are centrally upregulated
• A patient with unilateral/bilateral vestibular failure develops increased postural responses to visual motion stimulation
• VR exercises in environments with altered sensory information promote sensory reweighting
• Sensory substitution exercises (gaze shifting, remembered targets) are used for patients with poor/absent vestibular function (e.g. bilateral vestibular hyporeactivity)

3. Patient Selection Criteria (Primary, Adjunctive, and Therapeutic Trial)

Vestibular Rehabilitation as a Primary Treatment

• BPPV - Particle repositioning maneuvers (Epley, Semont, etc.) with identification of the affected canal; effective in >90% of cases. Recurrence in up to 30%.
• Unilateral vestibular hypofunction (e.g. vestibular neuritis, labyrinthitis, post-surgical ablation)
• Bilateral vestibular hypofunction
• Concussion/mild TBI with persistent vestibular symptoms (Level 2-3 evidence)
• Multiple sclerosis - pilot data shows promise with gaze and postural stability exercises

Vestibular Rehabilitation as an Adjunctive Modality

• Endolymphatic hydrops / Meniere's disease (combined with medical/surgical management)
• Acoustic neuroma post-resection
• Post-ablative procedures (gentamicin labyrinthectomy, vestibular nerve section)

Vestibular Rehabilitation as a Therapeutic Trial

• In cases of diagnostic uncertainty (e.g. mixed central and peripheral pathology after head injury), a supervised 4-6 week course of VR has diagnostic value:
  • Outstanding progress suggests poor compensation for a stable lesion
  • Failure to improve or worsening makes an unstable lesion considerably more likely (raises suspicion of perilymph fistula, posttraumatic endolymphatic hydrops)
• Cummings Otolaryngology, p. 3254

4. Clinical Assessment Before VR

• Spontaneous, gaze-evoked and positional nystagmus
• Dynamic visual acuity (DVA)
• Head thrust test (video or clinical)
• Vestibular/Ocular Motor Screening (VOMS) - 5 domains: smooth pursuit, horizontal and vertical saccades, near point of convergence, horizontal VOR, visual motion sensitivity

• Improve functional balance, gait, and daily activities
• Decrease falls risk
• Decrease symptom severity
• Improve VOR function
• Improve sensory integration and reweighting
• Patient education

5. Vestibular Rehabilitation: Common Techniques

a) Gaze Stability Exercises (Adaptation Exercises)

• Principal goal: improvement in functional VOR performance and gaze stability for those with a VOR deficit
• ×1 viewing exercise (VOR ×1): Patient fixes gaze on a stationary target while moving the head side-to-side or up-and-down. Speed is gradually increased.
• ×2 viewing exercise (VOR ×2): Target moves in the direction opposite to head movement. Promotes greater retinal slip and more aggressive VOR adaptation.
• Gaze transfer exercises: patient practices the normal head-and-eye movement for transferring gaze between two objects

Gaze transfer and adaptation exercises - Scott-Brown's Vol. 2

b) Habituation Exercises

• Designed for motion-provoked symptoms
• Patient repeats the symptom-provoking head movement or position change at regular intervals
• Symptoms should initially be provoked (mild-moderate) and gradually habituate
• Classical Cawthorne-Cooksey protocol based on this mechanism

c) Sensory Substitution Exercises

• Used for patients with poor to absent vestibular function (bilateral vestibular hyporeactivity)
• Gaze shifting and remembered target exercises: Patient maintains clear visual image on a fixed target (e.g. letter X), turns head toward it, then shifts fixation to another target (letter Z) and turns head toward Z. Can be progressed to eyes-closed (remembered target) head turns

Sensory substitution exercises - Cummings Otolaryngology

d) Postural and Balance Exercises (Vestibulospinal Reflex Training)

• Aimed at improving postural stability and gait
• Static balance exercises: narrowing the base of support, tandem standing, single-leg stance
• Exercises progressively vary:
  • Surface: firm → foam → tilt boards → moving platforms
  • Vision: eyes open → eyes closed → visual conflict domes
  • Head position: head still → head moving during balance tasks
• Dynamic balance: weight shifting, stepping responses, multidirectional stepping
• Fall prevention strategies in elderly patients

e) Sensory Strategy Retraining

• Addresses disruption in appropriate sensory selection for postural stability
• Somatosensory over-reliance: exercises on foam, tilt boards, or compliant surfaces to reduce dependence on proprioception
• Visual dependency (visual vertigo): exercises with conflicting or absent visual input to learn reliance on proprioceptive and vestibular cues
• Optokinetic stimulation using rotating drums, computers, or YouTube videos promotes desensitization to visual motion; shown to improve postural stability, visually-induced dizziness, and psychological state (depression, anxiety)

f) Gait Exercises

• Walking with deliberate horizontal/vertical head turns
• Walking on varying surfaces and in complex visual environments
• Functional Gait Assessment tasks

g) Dual-Task Training

• Vestibular patients show decreased attentional resources during simultaneous cognitive and postural tasks, with deviation from linear gait path
• Progressive balance exercises (tandem standing, walking) combined with secondary cognitive tasks (counting backwards by 3s, recounting daily activities)
• Attention can be directed at one or both tasks

h) Particle Repositioning Maneuvers (for BPPV)

• Epley maneuver (canalith repositioning) for posterior SCC canalithiasis
• Semont maneuver
• Barbecue roll for horizontal SCC canalithiasis
• Use of infrared goggles to block fixation and improve canal identification via nystagmus patterns

6. Novel and Supplementary Techniques

Virtual Reality (VR) Systems

• Full-field immersive VR (grocery store models), head-mounted devices, Nintendo Wii Fit Plus have all been studied
• Two RCTs found no significant between-group differences comparing customized VR vs. VR-based rehabilitation for gait speed, posturography, or symptoms
• This is attributed to the fact that both small- and large-field optokinetic stimulation shows similar visual-vestibular interactions - sensory reweighting occurs independently of visual field size, frequency, velocity, and texture

Balance exercise using Nintendo Wii Fit Plus - Scott-Brown's Vol. 2

Vestibular Balance Rehabilitation Therapy (VBRT)

• A specific programme combining habituation and behavioural modification (analogous to graded exercise therapy in fibromyalgia/chronic fatigue syndrome)
• Encourages "avoidance of avoidance"
• Effective against hypersensitivity to motion, improves confidence, reduces avoidance behaviour
• Early trials combining VBRT with CBT show positive effects on disability but not on core symptoms of vertigo, anxiety, or depression
• Patients must experience symptoms during exposure for compensation to occur

Optokinetic Stimulation

• Induces adaptation of VOR reflex gain
• Clinical optokinetic drums, computer screens, accessible YouTube visual stimulation
• Particularly beneficial for visual vertigo - desensitizes patients to visual motion
• Exposure should be gradual and progressive

7. General Principles and Programme Characteristics

1. Specificity - exercises target documented deficits
2. Repetition - consistent practice (typically 2-3 times per day at home)
3. Progression - exercises are made progressively more difficult
4. Patient education - explain that symptoms may initially worsen before improving; improvement is uneven

• Neck pain
• Loss of consciousness or vision
• Numbness, weakness or tingling in face/limbs
• Increased migraine frequency

8. Role of Medication

• Vestibular suppressant medications (e.g. antihistamines, benzodiazepines) and other centrally acting agents have been shown to delay the time course of recovery during vestibular rehabilitation
• Whenever possible, these should be tapered or discontinued
• However, if essential for complicating medical conditions or symptom relief during the programme, their continued use does not appear to dramatically reduce the chances of a satisfactory ultimate outcome
• Cummings Otolaryngology, p. 3265

9. Expected Results and Evidence

• Severe bilateral peripheral lesions
• Combined central and peripheral vestibular deficits
• Headache syndromes after head injury
• Established long-term disability
• Elderly patients with multisensory dysfunction (vision, hearing, proprioception impairment)

Summary Table: VR Mechanisms and Corresponding Exercises