Section 16

Traumatic brain injury

In cases of traumatic brain injury (TBI), the apparent severity of the original event may not correlate with the degree of persisting cognitive dysfunction. There is also often great variability in recovery: people with severe injury may have minor persisting deficits, whereas those with apparently mild brain injury or concussion may have significant persisting deficits. Although it may be possible to confirm the presence of diffuse axonal injury with specialized magnetic resonance imaging (MRI), it is important to realize that full functional recovery may occur even after clearly abnormal findings on computed tomography (CT) or MRI. Conversely, persistent cognitive dysfunction is seen in some individuals after apparently normal neuroimaging.

A moderate to severe TBI is defined as a brain injury where the patient has a Glasgow Coma Scale score below 13, post-traumatic amnesia (confusion) lasting longer than 24 hours, and/or evidence of intracranial injury on CT or MRI of the brain, as well as a requirement for admission to hospital for treatment of the injury. Concussion is defined as a mild brain injury with no evidence of intracranial injury on imaging and an expectation of complete symptom resolution with 2 weeks (1 month for adolescents) for most individuals. Brain injury of either type may result in physical impairments such as motor dysfunction, as well as cognitive impairments often associated with frontal lobe injuries; the latter manifest as challenges with insight, problem solving, and decision-making. Such injuries can also result in behavioural impairments, including poor impulse control and aggression. The same is true for acquired brain injury resulting from anoxia, encephalitis, the effects of tumours, or other cerebral insults.

Even with the increasing number of published articles on mild TBI and concussion, there is very little evidence- based material on which to base recommendations concerning fitness to drive. A comprehensive effort to improve this situation included 71 specific recommendations for the assessment and treatment of patients with persisting symptoms after a brain injury (Marshall et al., 2012). However, a recent study (Sarmiento et al., 2021) revealed that many health care providers do not consistently screen or educate patients who have experienced mild TBI about driving after their injury. There is a need for clearer return-to-driving guidelines for this patient population and more education for physicians.

Internationally, efforts are under way to develop a better understanding of and methods of caring for patients with “[our] most complex disease, in [our] most complex organ” (Tenovuo et al., 2021) while recognizing the limitations of randomized controlled trials in contributing to this research.

In a systematic review, Chee et al. (2019) concluded that there was no evidence to support major changes to existing clinical guidelines for driving with TBI. Further research was recommended, particularly to examine the risk of motor vehicle crashes with respect to TBI severity and time after injury, with carefully defined injury severity and objective measures of crash risk.

For patients experiencing post-traumatic seizures, see Section 11.5.1.

Any patient who has sustained a moderate to severe TBI should not return to driving until a comprehensive medical assessment, including cognitive and physical examinations, has been completed. A detailed history about the effects of the TBI on the particular patient, including information from the family or other reliable informants and additional cognitive screening by an occupational therapist with experience as a driver rehabilitation specialist, will help the physician make the best decisions about the patient’s fitness to drive. If cognitive or significant physical deficits are found, the physician should consider referral for rehabilitation assessment.

To drive safely, TBI survivors require insight into their disability, as well as the following characteristics:

• adequate cognitive abilities, including information processing speed, visuospatial ability, and attention
• adequate upper- and lower-extremity motor coordination and power
• acceptable visual fields and acuity, with diplopia ruled out
• behavioural ability to comply reliably with the rules of the road and to drive within any conditions set by licensing authorities.

For patients with continuing cognitive, physical, or behavioural impairments that could affect the ability to drive, referral for a comprehensive on-road driving evaluation is recommended. For patients who are not medically fit to return to driving because of impairments after a TBI, consideration should be given to reporting the patient to the licensing authority as appropriate, at least until they have completed recovery or undergone successful driving rehabilitation.

If screening for post-traumatic amnesia is positive (according to the Abbreviated Westmead Post Traumatic Amnesia Scale incorporating the Glasgow Coma Scale; https://aci.moodlesite.pukunui.net/course/view.php?id=48), it is essential to notify a family member or trusted friend of the patient, as any opinion and instructions given directly to the patient will not be remembered, including advice not to drive. Palubiski and Crizzle (2016) found that the duration of post-traumatic amnesia was a probable predictor of on-road driving performance.

Patients with TBI are more likely to engage in serious driver aggression (Ilie et al., 2015, 2017).

Concussion is defined by the American Association of Neurological Surgeons (2021) as “an injury to the brain that results in temporary loss of normal brain function. Medically, it is defined as a clinical syndrome characterized by immediate and transient alteration in brain function, including alteration of mental status or level of consciousness, that results from mechanical force or trauma.” Unlike persons who have sustained a moderate to severe TBI, those who have sustained a concussion may have ongoing symptoms, which typically (in about 80% of cases) resolve completely within 1 to 3 months after the injury. Although symptoms may persist, a person who has sustained a concussion will typically have good insight and awareness, as well as being able to recognize the potential effect of the injury on their driving abilities. When symptoms are more prominent (e.g., severe migraine headache), the patient may not be able to drive; however, when symptoms have improved or are more tolerable, driving ability may not be affected. The physician should highlight for the patient that they are responsible for recognizing their own ability to operate a vehicle safely and competently. Patients may resume driving after concussion when their symptoms allow them to do so.

Most people with less severe injuries, such as concussion, recover spontaneously. They should, however, be monitored for symptoms, and a substantial proportion (10%–15%) may require further assessment. Implications for driving should be considered routinely. The importance of adequate physical and cognitive rest (i.e., complete rest for 1 or 2 days) to promote recovery after concussion cannot be overemphasized. After that, any return of symptoms during exercise-induced elevation in heart rate (e.g., while exercising on a stationary bicycle) or during cognitively demanding tasks indicates that more rest and evaluation are needed.

Post-concussion symptoms may peak in the 48 hours after the injury or later, the latter being more likely among those with inadequate rest after concussion. According to Iverson (2012), moderate or higher scores on more than one of four specific symptoms — headache, dizziness, noise sensitivity, and memory problems — with the Sport Concussion Assessment Tool, version 2 (SCAT2; https://bjsm.bmj.com/content/bjsports/43/Suppl_1/i85.full.pdf) may predict slower recovery. The current version of this tool (since 2017) is the SCAT5 (Concussion in Sport Group, 2017; https://cattonline.com/scat/). A YouTube video (27 minutes long) is available demonstrating application of the SCAT5 (https://www.youtube.com/watch?v=gNoadxx37_E).

Medical assessment alone is often insufficient to determine a patient’s fitness to drive, and further evaluation by medical specialists, neuropsychological testing, or formal comprehensive driving assessment may be needed for a more accurate evaluation and to help in developing a better understanding of specific driving problems. In a recent systematic review that considered neuropsychological testing after moderate and severe TBI, executive functions had the largest effect size with respect to driving ability, followed by verbal memory, processing speed/attention, and visual memory (Egeto et al., 2019).

Individuals with TBI are slower to anticipate traffic hazards than uninjured age-matched controls.

The recommendations of the Acquired Brain Injury Knowledge Uptake Strategy (ABIKUS Guideline Development Group, 2007) for driving after moderate to severe acquired brain injury are as follows (see Part III, Section 12.2 of the ABIKUS guideline):

• For all patients with moderate to severe acquired brain injury who wish to drive, including adolescents, a physician with experience in assessing brain injury should perform screening, in accordance with legislation and preferably in liaison with the multidisciplinary team.
• If members of the interdisciplinary rehabilitation team, during assessment or treatment, determine that the person’s ability to operate a motor vehicle safely may be affected, then they should take the following steps:
  • Advise the patient and/or their advocate that they are obliged by law (if applicable) to inform the motor vehicle licensing authority (driver fitness unit) that the individual has experienced a neurologic or other impairment and to provide the relevant information on its effects.
  • Provide information about the law and driving after brain injury.
  • Provide clear guidance for the physician, other treating health care professionals, and family/ caregivers, as well as the patient, about any concerns related to driving, and reinforce the need for disclosure and assessment if return to driving is sought after a substantial post-injury delay.
  • If the patient’s fitness to drive is unclear, a comprehensive assessment of capacity to drive should be undertaken at an approved driving assessment centre.

Support and counselling should be offered to patients who are unsafe to drive or who resist giving up driving or being tested. Finding alternative transportation may be challenging and time-consuming. TBI is often complicated by comorbid depression, and the loss of driving privileges may contribute to the risk of depression. The physician should advise patients that they may place themselves, their family, and others at risk of injury by driving. These discussions should be documented in the medical record.

It is routinely expected that people with mild TBI or concussion will be able to return to driving, and driving after moderate to severe brain injury may also be possible. Evaluation of the patient must consider any residual physical, cognitive, or perceptual impairment to safe driving, as well as the person’s emotional state. Reporting requirements will vary according to the jurisdiction where the physician practises.

In general, if there is uncertainty about a patient’s ability to drive, a formal driving evaluation, including an on-road assessment by a professional experienced in driving rehabilitation, should be performed.