20 - Traumatic Brain Injury

20.1About traumatic brain injury

Traumatic brain injury (TBI) is a nondegenerative, noncongenital insult to the brain from an external mechanical force, possibly leading to permanent or temporary impairment of cognitive, physical and psychosocial functions, with an associated diminished or altered state of consciousness. The leading causes of TBI are falls and motor vehicle crashes.

Descriptions of the severity of a TBI reflect the length of time a person is unconscious or lacks awareness of their environment.  Mild TBI indicates only a brief change in mental status or consciousness, while severe TBI describes an extended period of unconsciousness or amnesia after the injury.

TBI can result in a wide range of impairments, which will vary depending on the severity and location of the injury, and the age and general health of the injured person. Possible sensory impairments include:

  • visual field deficits
  • visual neglect
  • diplopia, and
  • loss of sensation or hearing.

Possible motor impairments include paralysis, paresis (partial loss of movement or impaired movement) and slowed reaction times.  Possible cognitive impairments include deficits in:

  • attention
  • memory
  • executive functioning
  • processing speed, and
  • visuo-spatial abilities, including visual memory.

Behavioural impairments are common, including disorders affecting mood and impulse control.  Sleep disturbances, sleep apnea and fatigue are also commonly reported. TBI is also associated with epilepsy.

Anosognosia (unawareness of impairment) is common in individuals with TBI, particularly in those with moderate to severe TBI, and is of particular concern for driving. Research suggests that anosognosia is more frequently associated with cognitive and behavioural impairments than with physical deficits.

20.2Prevalence

Rates of incidence and prevalence of TBI are difficult to determine due to a lack of uniformity in definitions and reporting methods.  Canadian data suggest that the overall prevalence of TBI is 62.3 per 100,000 adults. Rates were highest in the 45 to 64 year old age range, three times the rate of those in the 15 to 24 year old range.

20.3Traumatic brain injury and adverse driving outcomes

Numerous studies have examined the relationship between TBI and driving outcomes. Although few studies have examined crash rates, the existing research indicates higher rates of crashes and traffic violations for those who have experienced a TBI.  Notably, studies indicate that approximately 50% of those experiencing a TBI will not resume driving after the TBI.  Research examining road test results indicates that approximately 30% of individuals who have experienced a TBI will fail a subsequent road test.

20.4Effect on functional ability to drive

Condition Type of driving impairment and assessment approach Primary functional ability affected Assessment tools
Traumatic brain injury Persistent impairment: Functional assessment Variable – cognitive, motor or sensory

Medical assessments

Functional assessment

Episodic impairment: Medical assessment – likelihood of impairment Variable – sudden impairment (epilepsy) Medical assessments

Traumatic brain injury may result in a persistent cognitive, motor or sensory impairment, or an episodic impairment (epilepsy), or both.

20.5Compensation

Drivers who have experienced a persistent impairment of motor or sensory function may be able to compensate.  An occupational therapist, driver rehabilitation specialist, driver examiner or other medical professional may recommend specific compensatory vehicle modifications or restrictions based on an individual functional assessment.

Some examples of compensatory mechanisms are shown in the following table.

Motor impairment Sensory (vision) impairment
  • Steering wheel spinner knob
  • Restriction to automatic transmission or power-assisted brakes
  • Scanning horizon more frequently
  • Turning head 90◦ to maximize area scanned
  • Large left and right side mirrors

20.6Guidelines for assessment

20.6.1 Traumatic brain injury

If a driver has epilepsy as a result of a TBI, also see the standards in Chapter 17.

National Standard

All drivers eligible for a licence if

  • movement and strength are sufficient to perform the functions necessary for driving
  • cognitive and visual functions necessary for driving are not impaired
  • any pain associated with the condition, and any treatment for the condition, do not impair the functional abilities necessary for driving
  • where required, a functional assessment indicates that the driver is able to compensate for any loss of functional ability necessary for driving, 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
  • If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may 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 assessment
Conditions for maintaining licence No conditions are required
Restrictions

RoadSafetyBC will restrict an individual’s licence so that they only drive with any permitted vehicle modifications and devices required to compensate for their functional impairment. This may include one or more of the following restrictions

  • 26        Specified vehicle modifications required
  • 28        Restricted to automatic transmission
  • 51        [specify type of restriction]
Reassessment No re-assessment is required, other than routine commercial or age-related re-assessment
Information from health care providers
  • Whether the driver suffers from epilepsy as a result of the TBI. See the standards under Chapter 17 if epilepsy is present
  • Opinion of treating physician on whether the driver has a loss of movement or strength that may affect functional ability to drive
  • Opinion of treating physician on whether pain or treatment may adversely affect functional ability to drive
  • Opinion of treating physician on whether the driver suffers from diplopia and/or a visual field deficit that may affect functional ability to drive.  See the standards under Chapter 22 if the treating physician indicates that either of these conditions may be present.
  • Where required, the results of a functional assessment
Rationale The potential functional impairments associated with traumatic brain injury are variable