21 - Vestibular Disorders

21.1About vestibular disorders

The vestibular system - or balance system - is a sensory apparatus localized in the inner ears.  It provides information to the nervous system about a person’s movement and orientation in space. Vestibular input contributes to:

  • control of balance
  • gaze stabilization so that a person can see clearly while moving, and
  • spatial orientation so that a person knows their position with reference to gravity.

Vestibular disorders may result in:

  • vertigo
  • dizziness
  • disturbed vision such as involuntary eye movement, and
  • illusory movement of the visual world as a result of head movement.

A hallmark of vestibular disorders is vertigo, a term that refers to the sensation of spinning or whirling resulting from a disturbance in balance (equilibrium).  Most commonly an attack of vertigo generally lasts less than one minute (30 seconds is typical) but it may last up to 60 minutes. A small number of people may experience vertigo lasting as long as 24 hours and an even smaller number may experience vertigo lasting up to, or beyond, 30 days.

Disorders of the vestibular system are classified as either peripheral or central.

Peripheral vestibular disorders

Peripheral disorders are characterized by episodic fluctuating symptoms; the dominant symptom is ‘true spinning vertigo’, that is the sensation of motion when no motion is occurring relative to earth’s gravity.  Peripheral vestibular disorders typically occur as a single acute episode or as recurrent acute episodes.  However, complete bilateral hypofunction may result in severe and constant disequilibrium and motion sensitivity.

The most common peripheral vestibular disorders and the typical duration of an episodic event are shown in the following table.

Disorder Duration
benign paroxysmal positioning vertigo (BPPV) 20-30 seconds
vestibular neuronitis (labyrinthitis) Tends to be single attack lasting days to weeks
Meniere’s Disease 20 minutes – 24 hours

Less common peripheral vestibular disorders are described in the following table.

Disorder Description

Drop Attacks (Tumarkin’s Otolithic Crisis)

Sudden, spontaneous fall to the ground without prior warning
Complete bilateral vestibular hypofunction (absence of function) May result in severe and constant disequilibrium and motion sensitivity

Central vestibular disorders

Central vestibular disorders generally arise from underlying persistent medical conditions. Because of this, they are more likely to produce prolonged continuous non-specific dizziness.  They are characterized by difficulty in interpretation of vestibular, visual and proprioceptive (the unconscious perception of movement and spatial orientation arising from stimuli within the body itself) inputs.  Gaze stabilization and posture during locomotion may also be affected.

Common persistent medical conditions that can cause persistent central vestibular dysfunction are:

  • cerebrovascular disease
  • cervical vertigo
  • epilepsy
  • multiple sclerosis
  • normal pressure hydrocephalus
  • paraneoplastic syndromes (a response to the effects of a tumour in the body), and
  • traumatic brain injury.

Common episodic medical conditions that are not related to structural brain disease but that may cause central vestibular disorders, and typical episode duration, are shown in the following table.

Disorder Duration
migraines a few seconds to hours
Psychogenic vertigo/anxiety (hyperventilation syndrome) a few seconds to hours

21.2Prevalence

Peripheral vestibular disorders are more common than central vestibular disorders.

Age-related decrements in vestibular function are well documented and are likely due to degeneration at both the central and peripheral level.  BPPV is reported as a common underlying cause of impairments in balance with aging.

A 2005 study on the frequency of moderate or severe vertigo and dizziness reported that 36.2% of women and 22.4% of men had experienced vertigo or dizziness at some point in their life.

One study identified that 32.5% of people with Meniere’s disease developed drop attacks (Tumarkin’s otolithic crisis); the attacks typically occurred in a flurry during a period of 1 year or less. No patient in the study required treatment for the drop attacks. Most people with this have a spontaneous remission of the drop attacks.

21.3Vestibular disorders and adverse driving outcomes

The evidence linking vestibular disorders with adverse driving outcomes is weak because there has been little empirical research in this area. Nonetheless driving ability is dependent on the normal functioning of the vestibular mechanism to sense movement and position.

In subjective studies where drivers with vestibular disorders were asked about driving, driving difficulties were commonly reported and included a wide range of difficulties including driving in the rain, at night, pulling in and out of parking spaces, changing lanes, and freeway and rush hour driving.

In one study, 20-40% of drivers reported that they had had to pull off the road while driving due to vertigo.  In a different study, 43% indicated that they had felt dizzy while driving; only 27% indicated that they ‘always’ or ‘usually’ got a warning that a dizzy spell was about to occur, with more than 1/3 indicating that they ‘rarely’ or ‘never’ get warnings.  Of those who did get warnings, 56% indicated that there was less than a 5-second interval between the warning and the dizzy spell.

21.4Effect on functional ability to drive

Condition Type of driving impairment and assessment approach Primary functional ability affected Assessment tools

Vestibular disorders resulting in episodic impairment, including:

  • migraines
  • psychogenic vertigo/anxiety (hyperventilation syndrome)
  • benign paroxysmal positioning vertigo (BPPV)
  • Meniere’s Disease
  • vestibular neuronitis (labyrinthitis)
  • Drop Attacks (Tumarkin’s Otolithic Crisis)
Episodic impairment: Medical assessment – likelihood of impairment Sensorimotor Medical assessments
Persistent impairment: Functional assessment Cognitive

Medical assessments

Functional assessments

Vestibular disorders resulting in persistent impairment, including:

  • complete bilateral vestibular hypofunction (absence of function), or
  • vestibular disorder resulting from an underlying persistent medical condition
Persistent impairment: Functional assessment

Sensorimotor

Cognitive

Medical assessments

Functional assessments

The functional effects associated with vestibular disorders can occur suddenly and with sufficient severity to make safe driving of any type of vehicle impossible.

People with vestibular disorders become disoriented more easily by extraneous visual stimuli or visual noise. This means that drivers are more likely to have difficulty driving in reduced visual conditions such as driving at night or in the rain.

Rapid head movements are also likely to elicit vertigo in people with vestibular disorders. This means that tasks such as parking a car, manoeuvring in a parking space, lane maintenance and lane changes, and entering traffic may be risk factors for the onset of vertigo.

Research also indicates that damage to the vestibular system results in cognitive deficits in people with both peripheral and central vestibular disorders.  People with vestibular disorders exhibit a range of cognitive deficits including those that are spatial and non- spatial.  The cognitive deficits do not appear to be related to any particular episode of vertigo or dizziness and the deficits may occur even in those people who have no symptoms of dizziness or postural deficits.

Central vestibular disorders

The majority of central vestibular disorders have a persistent impact on driving because they arise from underlying persistent medical conditions. However, two common causes of central vestibular disorders - migraines and hyperventilation syndrome - are episodic in nature with short disease duration.

Peripheral vestibular disorders

Peripheral vestibular disorders are generally more episodic with, in general, shorter disease duration.  Drivers, however, with complete bilateral vestibular hypofunction (absence of function) may have severe and constant disequilibrium and motion sensitivity forever.  These drivers may have more difficulty driving, particularly during evening hours or on bumpy roads, and may not be safe to drive.

21.5Compensation

Drivers with vestibular disorders are not able to compensate for their functional impairment.

21.6Guideline for assessment

21.6.1 Recurrent episodes of vertigo that occur with warning symptoms

This may include drivers with:

  • benign paroxysmal positioning vertigo (BPPV)
  • Meniere’s disease
  • vestibular neuronitis (labyrinthitis)
  • migraines, or

psychogenic vertigo/anxiety (hyperventilation syndrome).

National Standard

All drivers eligible for a licence if

  • warning symptoms do not themselves impair ability to drive
  • warning symptoms are of a sufficient duration to allow a driver to safely pull off the road, and
  • the conditions for maintaining a licence are met
BC Guidelines

If further information is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report; or
  • additional information from the treating physician
Conditions for maintaining licence

RoadSafetyBC will impose the following condition on an individual who is found fit to drive

  • if you experience an episode of vestibular dysfunction, you must not resume driving until all symptoms associated with the episode have stopped
Reassessment No re-assessment, other than routine commercial or age-related assessment, is required
Information from health care providers
  • Description of warning symptoms and effect on functional ability
  • Whether the driver has insight into the impact their vestibular dysfunction may have on driving
  • History of compliance with prescribed treatment regime
  • If known, whether the driver is compliant with any current conditions of licence related to their vestibular dysfunction
Rationale The risk from an episodic vestibular dysfunction can be mitigated where the episode is consistently preceded by warning symptoms that are not incapacitating and which last long enough for a driver to safely stop their driving until the episode is over

21.6.2 Recurrent episodes of vestibular dysfunction that occur without warning symptoms – All drivers

This may include drivers with:

  • benign paroxysmal positioning vertigo (BPPV)
  • Meniere’s disease
  • vestibular neuronitis (labyrinthitis)
  • migraines, or
  • psychogenic vertigo/anxiety (hyperventilation syndrome).
National Standard

All  drivers eligible for a licence if

  • it has been at least 6 months since an episode of vestibular dysfunction
  • the treating physician or specialist indicates that their symptoms have been controlled or have abated, and
  • the conditions for maintaining a licence are met
BC  Guidelines

If further information regarding an individual’s medical condition is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report
  • additional information from the treating physician, or an assessment from a specialist
Conditions for maintaining licence

RoadSafetyBC will impose the following condition on an individual who is found fit to drive

  • you must immediately stop driving and report to RoadSafetyBC and your physician if you have an episode of vestibular dysfunction
Reassessment No re-assessment, other than routine commercial or age-related assessment, is required
Information from health care providers
  • Date of last episode of vestibular dysfunction
  • Treating physician’s opinion as to whether the symptoms have been controlled or have abated
  • Treating physician’s opinion as to whether the driver has insight into the impact their vestibular dysfunction may have on driving
  • History of compliance with prescribed treatment regime
  • If known or applicable, whether the driver is compliant with any current conditions of licence related to their vestibular dysfunction
Rationale Where episodes of vestibular dysfunction are not preceded by warning symptoms or the warning symptoms are not sufficient to allow the driver to safely stop driving, evidence that further episodes are unlikely to occur is required to mitigate the risk. Consensus medical opinion suggests that this evidence should include a minimum period of 6 months without an episode and opinion of the treating physician that this episode-free period reflects effective treatment or abatement of the episodes

21.6.3 Drop attacks  (Tumarkin’s otolithic crisis)

National Standard

All drivers eligible for a licence if

  • it has been at least 6 months since experiencing a drop attack, or
  • the treating physician indicates that the attacks have been successfully treated, and
  • the conditions for maintaining a licence are met
BC Guidelines

If further information regarding an individual’s medical condition is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or additional information from the treating physician
Conditions for maintaining licence

RoadSafetyBC will impose the following condition on an individual who is found fit to drive

  • you must immediately stop driving and report to RoadSafetyBC and your physician if you have a drop attack
Reassessment
  • If an attack occurred within the past 12 months, RoadSafetyBC will re-assess in one year.
  • If no new attacks are reported at that time, RoadSafetyBC will re-assess in 5 years, or in accordance with the schedule for routine commercial or age-related re-assessment.
  • If no new attacks are reported at that time, no further re-assessment is required, other than routine commercial or age-related re-assessment
Information from health care providers
  • Date of last drop attack or opinion of treating physician as to success of treatment
  • Treating physician’s opinion as to whether the driver has insight into the impact their condition may have on driving
  • History of compliance with prescribed treatment regime
  • If known or applicable, whether the driver is compliant with any current conditions of licence related to their vestibular disorder
Rationale

For drop attacks, which occur without warning, evidence that further attacks are unlikely to occur is required to mitigate the risk.

Consensus medical opinion suggests that this evidence should be an opinion from the treating physician that the driver has been successfully treated or that 6 months has passed without an attack

21.6.4 Single episode of vestibular dysfunction – transient impairment

National Standard All drivers eligible for a licence
BC Guidelines RoadSafetyBC will not generally request further information
Conditions for maintaining licence None
Reassessment No re-assessment, other than routine commercial or age-related re-assessment, is required
Information from health care providers None
Rationale A single episode of vestibular dysfunction is a transient impairment

21.6.5 Vestibular disorder resulting in a persistent impairment

National Standard

All drivers eligible for a licence if

  • functional assessments indicate ability required for driving safely
BC Guidelines
  • If further information regarding an individual’s medical condition is required, RoadSafetyBC will request
    • a Driver’s Medical Examination Report, or additional information from the treating physician
  • If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC will request
    • functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessmentv
Conditions for maintaining licence No conditions are required
Reassessment RoadSafetyBC will determine the appropriate re-assessment interval on an individual basis
Information from health care providers
  • Results of functional assessment
  • Treating physician’s opinion as to whether the driver has insight into the impact their vestibular disorder may have on driving
  • History of compliance with prescribed treatment regime
  • If known or applicable, whether the driver is compliant with any current conditions of licence related to their vestibular dysfunction
Rationale Persistent vestibular dysfunction may cause significant impairment of the functions needed for driving.  Decisions about driver fitness should be based on an individual functional assessment