Driving after brain injury.

Driving an automobile is a deeply cherished part of American culture and acquiring a driver s license is a rite of passage into adulthood that signifies the onset of privileges and independence. However the capacity of survivors of brain injury to drive, with all its implications for independent function and self-esteem, must be carefully and thoughtfully balanced against concerns for each survivor's safety and the right of the public to be protected from unreasonable danger (van Zomeren, Brouwer, & Minderhoud, 1987).

It has been estimated that one to two million individuals sustain a brain injury each year in the United States and 70,000 to 90,000 of these individuals require rehabilitation and follow-up services that may last 5-10 years (Sells, 1993). The costs associated with the long-term care of an individual who sustains a severe TBI range from $4.1 to $9 million. Because of the increased survival rate for individuals with severe TBI, estimated to be four-fold between 1968 and 1988 (Hickey, 1993; McMahon & Growick, 1988), it is logical to assume that more individuals with some degree of cognitive impairment are both currently operating motor vehicles (Hopewell, 1988) and being assessed in various rehabilitation facilities for their capacity to drive safely. Great strides have been made in adapting vehicles for drivers with physical limitations (e.g., amputation, paralysis), so that those who have the motivation and the funds to equip their vehicles with necessary adaptive aids can be trained to drive safely. However different obstacles to safe driving arise for individuals whose disabilities cause seizures or affect their cognitive functions (e.g., slowed thinking, poor judgement, lack of insight, impulsivity, outbursts of anger, inability to sustain concentration, difficulty with divided attention, and inability to self-monitor) (Michon, 1979). This article provides an overview of models, research, and issues related to driving to assist rehabilitation professionals in evaluating the components of driving evaluation and training programs.

Predictors of Fitness to Drive

The complexity of issues involved with driving after brain injury has led to the development of two theoretical frameworks related to driving. Most research on driving after brain injury has been based on Michon's (1979) model, which posits a three-level hierarchy of task performance in car driving. The highest level of Michon's model involves strategical decisions such as time of day, planned route, and whether to drive or use alternative transportation. Decisions at this level affect all other driving-related behaviors. The second level is tactical, which involves decisions made while operating the vehicle (e.g., adapting speed to road and traffic conditions, deciding to pass or not). Appearing to have some overlap with the tactical, the third level is operational and includes the physical manipulation of the controls, use of visual-motor skills, and overall coordination.

In contrast to Michon's model, Galski, Bruno, and Ehle (1992) suggested a "Cybernetic Model of Driving," based on a computer analogy. This model was developed to identify and test elements of driving ability and to diagnose the cause of driving problems through neuropsychological tests, behavioral observations, simulator evaluations, and behind-the-wheel testing. The authors consider the complex of driving behaviors "an expert system" that requires the use of existing learning and permits integration of new learning on a continuous basis. The model includes two programs: (a) a general driving program "that initiates and directs all driving-related activities" (Galski, et al., 1992, p. 326) and (b) a specific driving program for each "trip" behind the wheel.

Most of the literature on driving after brain injury focuses on studies of various neuropsychological and performance tests as predictors of a survivor's capacity to pass the state driving examination and to drive safely (e.g., reaction time, severity of injury [generally judged by length of post-traumatic amnesia], performance in driving simulators, performance on a range of psychologic tests, and behind-the-wheel evaluations by a driving instructor or rehabilitation professional) (van Zomeren et al., 1987). In addition, most of the studies include some elements of pre-driving psychological tests, some type of visual screening, and a graduated system of behind-the-wheel experiences, starting in an environment that presents minimal distraction find stress (usually a parking lot) and gradually increasing to whatever level of on-the-road driving the evaluator and/or the treatment team of the facility judged reasonably safe.

Despite the nearly universal use of Michon's (1979) model, however, it is difficult to compare these studies. There are some common factors, especially standardized neuropsychological tests, but in many cases, there is a diversity in terminology, especially in terms of ocular functions, scanning, attention, and the various frontal lobe functions most often grouped under the umbrella "executive functions" (Mayer & Schwartz, 1993). Even the designation of the disability is confusing, because some studies refer to people with "brain damage," and do not distinguish between those with cerebro-vascular accidents (CVA), traumatic injuries, and other neurologic disorders. Also some studies refer to "head injury" rather than "brain injury." Despite the lack of a common linguistic framework, the results of the major studies conducted between 1986 and 1993 are as follows:

1. People with TBI are much slower than individuals without TBI, but reaction time is not predictive of on-the-road driving performance (Stokx & Gaillard, 1986).

2. Positive correlations exist between inability to return to driving and persistent visual problems, certain motor difficulties, an estimated post-injury IQ of 80 or less, failure on a driver simulation test, and post-traumatic amnesia of 11 weeks or longer (Hopewell, 1988). Hopewell suggested that a driver who sustained traumatic brain injury may present a "quadruple risk" in terms of impaired executive functions, overestimation of ability and denial of disability, generally slowed overall reaction time, and in some cases, the inherent higher level of risk represented by young males who historically have high accident rates.

3. Although individuals with and without TBI committed the same number of errors in the standardized on-the-road driving test, the errors of individuals with TBI are considered more serious. There was no particular pattern of deficits identified that was predictive of ability to drive, nor was the neuropsychological test battery predictive. A significant but non-conclusive correlation was found between driving experience and success in the on-the-road driving test (van Zomeren, Brouwer, & Rothengatter (1988). When the compensatory techniques and strategies used by aging drivers (undefined in this study; see Footnote 1) and drivers with brain injuries were compared, both groups were found to compensate for their shortcomings at the operational level by making better decisions at the tactical and strategic levels. The young men with brain injuries selected for this study had, with varying degrees of success, already returned to driving at the time of the study. Not all individuals with brain injuries are capable of the level of insight and self-awareness, which would enable them to evoke the hierarchical decision-making process regarding driving (van Zomeran, Brouwer, & Rothengatter, 1988).

4. Psychometric tests (particularly the Oral Symbol Digit Test), performance tasks (i.e., Driver Performance Test [Weaver, 1989], and operation of a "Small Scale Vehicle" in an adapted parking lot) were found to be valid predictors of driving. Although these findings were not externally validated with an on-the-road test, this study was an attempt to create a simple test battery to (a) screen out drivers who might present a significant danger to themselves and the behind-the-wheel evaluator, (b) identify deficits that might be ameliorated through remediation or compensation, and (c) control the costs of driving evaluations (Gouvier et al., 1989).

5. The lack of significant differences (a) between an experimental group of individuals who had successfully completed driving assessments and returned to driving and a matched control group in the types and incidences of driving mishaps and (b) results of the neuropsychological test battery given to members of the experimental group who had and had not had driving difficulties suggests that an initial comprehensive driving assessment (i.e., neuropsychological testing, extensive visual screening, ability to meet certain physical standards, and simulator and on-the-road evaluation) sets a reasonable standard for decision making about return to driving (Katz et al., 1990).

6. Sixty-four percent of in-traffic performance was predicted by the scores on seven neuropsychological tests, which measured visual perception, scanning and attention (especially sustained attention), and several executive functions. Predictive success was highest when parking lot performance, including behavioral observations, was added to pre-driving evaluations. The simulator evaluations showed slightly higher correlation with actual driving performance than the other pre-driving evaluation measures, however, the researchers (Galski et al., 1992) stated that more testing of Cybernetic Model of Driving was needed before definitive conclusions could be drawn.

7. Although significant relationships exist between performance on the Tactual Performance Test, the Trail Making Tests, and the driving evaluator's rating (pass/fail) of the subjects in the behind-the-wheel evaluation, no correlation was found to be sufficiently strong to be a precise predictor of driving performance (Brooke, Questad, Patterson, & Valois, 1992) for individuals evaluated within three to six months of injury. (This time period was selected, because the investigators' experience showed this to be the period in which survivors of closed head injury who do not show "blatant cognitive impairments" are most likely to seek to return to driving.)

8. The high rates of traffic violations for survivors of TBI who have been evaluated at rehabilitation hospitals indicate a need for better screening and training methods for survivors of TBI who wish to return to driving (Boake, Strowmatt, & Lehmkuhl, 1993).

In summary, the research on predictors of on-the-road driving performance for individuals with TBI is inconclusive. Reaction time, driving errors and patterns of errors, vision, motor control, post-injury IQ, driver simulations, length of post-traumatic amnesia, driving experience, psychometric and neuropsychological tests, and driver evaluator ratings have all been investigated. The research suggests that a combination of neuropsychological testing, visual screening, physical functioning, and actual driving (simulations and on-the-road evaluations) is necessary to predict driving performance.

The Cognitive Behavioral Driver's Inventory

The predictive system that appears to have been most widely tested is the Cognitive Behavioral Driver's Inventory (CBDI), first described by Engum, Pendergrass, Cron, and Lambert (1988). Because ability to drive was not accurately predicted by diagnosis, pathology, loss of brain mass, or by neuropsychological tests alone, they developed and investigated the CBDI, which consists of (a) a battery of computerized and paper-and-pencil neuropsychological tests (many related to visual processing); (b) visual screening using the Keystone Driver Vision Telebinocular, which is the machine used in many state drivers' licensing offices; (c) a reaction time test focused on braking ability; and (d) an examination of visual fields. Composite cut-off scores were established for ratings of pass or fail. Initially, cutoff scores on the pre-driving battery determined whether the individual would be permitted to proceed to an on-the-road test of graduated difficulty. Failing test results were used in making referrals for additional driving training. In later follow-up studies, Lambert and Engum (1992) recommended that the Driver Performance Test be administered to subjects in addition to the existing battery. It was further recommended (Engum, Pendergrass, Cron, Lambert, & Hulse, 1988) that all individuals be allowed to attempt some portion of the on-the-road test under controlled circumstances, as in a situational assessment, even if they had failed the pre-driving battery, to help them comprehend the effects of their disability on driving safety. Of the 44 patients initially determined by a psychologist to have passed the CBDI, 42 (95.5%) passed an independent on-the-road driving test. All of the later studies by these researchers strongly recommend that the pre-driving component of the CBDI not be used exclusively to determine driving fitness. Because measurement of activities at the tactical and strategic levels was considered more subjective, an on-the-road evaluation by a qualified evaluator/instructor was deemed necessary before final recommendations were made.

Although the correlations between the scores above and below the cut-off pass/fail composite scores and the ability to drive were clearly demonstrated, making driving recommendations based on the borderline scores was a major focus of later articles in this series (Engum et al. 1988; Lambert et al. 1990; Lambert & Engum, 1992). It was suggested that evaluators consider external evaluations and the driving history of each patient being tested.

In summary, the research with the CBDI supports the use of actual performance tests with other assessments (e.g., vision, reaction time). In addition to providing more accurate assessments, performance tests can also provide valuable feedback to individuals with TBI, when serious deficiencies in driving are not comprehended.

Driving Simulator Studies

Driving simulators have been used in a number of studies to determine their value as predictors of on-the-road performance and as training aids in helping people overcome challenges resulting from TBI. Kewman, Siegerman, Kintner, and Chu (1985) investigated whether specific cognitive remediation efforts (i.e., training tasks simulating different aspects of driving) would generalize to actual driving of an automobile for survivors of TBI who were more than six months post-injury. Results indicated that individuals who received training with an Amigo electric vehicle showed greater improvement in their on-the-road performances than did people with brain injuries who did not receive specific training. Although the Amigo training did not improve the experimental group's skills to the level of the able-bodied control group, the researchers concluded that the simulation training did generalize to on-the-road performance. They were unable to follow the experimental group to see how many went on to receive driver's licenses, and if they were able to drive in a safe manner.

Bowen, Hershler, Laszlo, and Miller (1989) investigated the use of the Computerized Driver Assessment Module to assess driving potential of people with brain injuries. Performance on the simulator appeared to predict passing or failing an on-the-road exam for the experimental group. Finally, Galski et al. (1992), as previously noted, incorporated a driving simulator (the Doron L225 Driving System) in the battery of diagnostic assessments, and found that the use of the simulator enhanced the predictive results of the other pre-driving tests by 6%, while assessment of driving skills performed in a parking lot enhanced predictive ability by 23%. Therefore, the use of driving simulators can help in (a) predicting the ability of individuals with TBI to pass driving exams, and (b) improving driving skills.

Assessments of Visual Processes

Most of the previously cited studies included some assessment of vision in their research protocols. There was divergence about which aspects of vision and visual processing were examined and the importance given to the various aspects. The studies of visual processing suggest that (a) standard optometric examinations are not sufficient and rehabilitation optometric examinations should be made a standard part of diagnosis and treatment for survivors of brain injury (Gianutos, Ramsey, & Perlin, 1988; Warren, 1992), and (b) driver rehabilitation specialists must be prepared to assess possible visual deficits associated with various disabilities (including brain injury), which might not be evident in standard optometric screenings (Strano, 1993).

There can be no question that vision is a vital component of driving ability (Johnson & Keltner, 1983), nor that problems with visual information processing are a frequent consequence of TBI. Cohen and Rein (1992) pointed out that most occupational therapy and cognitive rehabilitation services, including driving assessment and training, depend on visual information and processing. Defining visual perceptual processing as "...the entire process by which we receive visual information, integrate it, perform an action and adjust behavior accordingly," (p. 531), Cohen and Rein (1992) separated the physical and cognitive elements of visual processing, noting that the integrity of the optical system affects input to the brain, and that cognitive perception is a process that includes form constancy, visual closure, figure ground analysis, visual sequencing, spatial relationships, visual memory, visual auditory integration and visual motor integration.

In a general study of 10,000 individuals, Johnson and Keltner (1983) found that (a) individuals over the age of 65 had a 13% visual field loss, compared to a three to three and a half percent visual field loss for individuals ranging in age from 16 to 60; (b) half of the individuals were unaware of their visual field loss; and (c) individuals with binocular field loss had twice the accident and conviction rate for moving violations as people with normal visual fields. Similarly, Gianutos, Ramsey, and Perlin (1988) found that many individuals with TBI were unaware of neurologically based partial losses of vision, and therefore might not report nor be able to compensate for such losses. They also found that more than half of the 55 individuals studied had visual field problems that might not be detected in a standard optometric examination.

Proposing a hierarchical model of visual perceptual skills that has implications for both diagnosis and treatment of visual problems associated with TBI, including driving evaluation and remediation, Warren (1992) concurred with Gianutos et al. that conventional visual acuity tests are inadequate and that specialized optometric screenings should be part of any evaluation of a person with a brain injury. Warren theorized that higher level visual skills (i.e., visual memory, visual cognition) depend on mid-level skills (i.e., visual attention, scanning, pattern recognition), which further depend on basic skills (i.e., oculomotor control, acuity, visual field). Disruption of lower level skills disrupts skills at the next level and, conversely, remediation of lower level skills may improve functioning at the higher levels. In people with TBI, the predominant visual loss is in the superior horizontal visual fields, which Warren directly associated with driving ability.

In summary, the research related to visual processes supports the need for specialized rehabilitation optometric examinations. These specialized examinations are particularly important, because many individuals with TBI are unaware that they have lost some of their vision.

Issues of Liability

Noting the emerging trend to hold rehabilitation professionals liable for injuries to third parties caused by patients with cognitive impairments, Antrim and Engum (1989) insisted that physicians must go beyond simply warning a survivor of brain injury who has difficulty with judgment and reasoning of the risks of driving. To be protected, physicians must base decisions about driving on validated tests such as the CBDI, rather than on their experience or intuition. In a survey of 50 states, Pidikiti and Novack (1988) found that in only 15 were physicians authorized to report driving impairment secondary to a disabling injury, and in only seven states were they required to report such impairment. They found that state licensing offices were frequently uninformed about the potential effects of disability (in general) on driving performance and about reporting requirements. They also surveyed 100 rehabilitation centers, of which only 36 provided on-site training for drivers with all types of disabilities. Pidikiti and Novack recommended the establishment of consistent guidelines across states for reporting, evaluating, and re-evaluating drivers with disabilities, especially brain injury, and protecting physicians who must breach patient confidentiality to make such reports.

Liability issues are not limited to physicians. In addressing the legal issues of a driver rehabilitation program, Pierce (1993) outlined the responsibilities of the facility, the physician, and the driving rehabilitation professional and cited cases in which all of these individuals and organizations have been found liable, when traffic accidents resulted from driving by individuals with disabilities.

Clearly the presence of seizure disorders following brain injury must influence driving decisions made by both the physician/rehabilitation team and by the survivor and his/her family. Although higher accident rates exist for individuals with seizures (Gastaut & Zifkin, 1987; Hansotia & Broste, 1991; Spudis, Penry, & Gibson, 1986), there is not unanimity among groups/researchers in establishing rules that restrict driving following the onset of seizures. Finding significantly higher accident rates for individuals who have seizures, Gastaut and Zifkin (1987) suggested that individuals should be seizure free for one year before driving. They suggested that these decisions be individualized and that there may be instances in which some type of temporary or limited driving permit would be appropriate.

In contrast, Hansotia and Broste (1991) found only slightly higher rates of accidents in 30,240 individuals with epilepsy or diabetes mellitus and did not recommend automatic restrictions. Spudis et al. (1986) also recommended flexible guidelines rather than rigid, arbitrary codes (e.g., a certain number of months seizure free). Model driving legislation proposed by the Epilepsy Foundation (1991) suggested that each case should be considered on an individual basis, with a recommended period of three seizure-free months before return to driving. They further recommended that (a) each state have a medical advisory board to formulate guidelines for the department of motor vehicles or other licensing body, (b) the established criteria should appear as regulations and guidelines rather than statutes, and (c) restricted licenses should be considered on a case-by-case basis.

Cognitive Loss and Aging

A number of parallels have been noted between individuals with cognitive losses and individuals who are aging (e.g., Stokx & Galliard, 1986; Strano, 1993; Summers, 1986). Aging driver, however, have been defined differently by various researchers. The National Safety Council found that accident rates begin to increase at age 60 and are much higher after age 75 (Summers, 1986), whereas the National Highway Traffic Safety Administration (1994) considers drivers age 70 and older to be aging drivers.

Hypothesizing that "... severe concussions of the brain and normal aging have some underlying processes in common," Stokx and Gaillard (1986, p. 435) found that older individuals were better able to compensate for slowed reaction time in on-the-road testing than were people with TBI. Van Zomeren et al. (1988), however, found that both aged drivers and those with brain damage were able to compensate for their limitations at the operational level by making better decisions at the tactical and strategic levels (e.g., reducing the pressure for fast response by changing the time or route used when driving). Comparing reaction time tasks affected by diffuse and focal brain damage in people with brain damage and older persons whose mean age was 66, Korteling (1990) found that both groups reacted too slowly in laboratory tests, but that patients with brain damage made more errors than older patients. Lambert and Engum (1992), who used the term elders to describe individuals over age 63, documented the negative relationship between age and cognitive function and suggested that some medical personnel make erroneous driving recommendations because they conclude that certain impairments are due to recent brain injury rather than the normal process of aging. They supported the earlier conclusions that some older patients may have skills at the practical and strategic levels that might allow them to compensate for the operational shortcomings measured by the CBDI.

Discussion

Despite numerous studies of the effects of brain injury on driving, there is still little consensus on exactly how medical/rehabilitation teams can make accurate decisions that will allow the individual with brain injury maximum access to the many benefits of driving and still protect the safety of the individual and the general public. There are a number of programs that appear to have good predictive capacity for grossly judging how a survivor of brain injury will perform behind the wheel. No one, of course, can control or control for the behavior of individuals beyond the testing situation in which most people make maximum efforts to give the best possible performance. Areas of general consensus are as follows:

1. Drivers must be evaluated as individuals and no single type of test will provide data with predictive value equal to a battery of tests and screenings. It appears that the most important components of a driving evaluation specifically targeted to people with brain injuries include:

(a) assessment of the spectrum of factors that are required for visual processing;

(b) behavioral observations that address the capacity for self-evaluation, decision making skills and deficits in executive functions;

(c) a battery of neuropsychological tests that primarily measure visual function and attention; and

(d) some type of on-the-road test with a trained evaluator.

Simulators may also be of use in conjunction with these other measures. The on-the-road tests should be of gradually increasing complexity, starting in a controlled area such as a parking lot and moving to residential and then high-traffic areas and highways, if appropriate.

2. Visual screening must include more than testing acuity and a simple test of visual fields. Both the physical and cognitive components of visual processing must be evaluated by personnel trained to assess these abilities.

Information gathered from the full range of assessments can help some individuals with brain injury succeed in therapeutic driver training programs through remediation, compensation, or rehabilitation technology. Aging drivers who experience cognitive losses and slowed reaction time appear to make compensatory decisions at the strategic and tactical levels that allow them to drive safely despite limitations in operational skills. Some drivers with brain injury can be trained to make the same types of decisions.

Liability of physicians and other rehabilitation personnel varies widely from state to state. Ideally, attempts should be made by national bodies concerned with this issue to establish appropriate guidelines. Physicians who do not specialize in evaluating and treating neurologic and cognitive dysfunction, but who nonetheless are asked to determine patients' fitness to drive, as well as state licensing personnel would benefit from further training on these subjects. Our governmental institutions have taken responsibility for determining who should and should not drive by the establishment of licensing procedures that exist in every state. Some degree of uniformity is needed for making decisions about people with disabilities and/or special needs, including those with brain injuries. It is likely that these governmental bodies will be forced to address this issue in the near future as the provisions of the Americans with Disabilities Act require equal treatment of all citizens, regardless of disability.

Considerations for Future Investigation

There are many questions still to be answered and issues to be addressed regarding driving after brain injury. A few of the researchers (e.g., Brooke et al. 1992; Engum et al., 1988; Gouvier et al., 1989; Summers, 1986) mention the importance of controlling costs, but in most cases, these were costs to the facilities and institutions offering driving evaluation and remediation programs. Costs to the consumer are a separate issue that has not been addressed. In many states, Medicaid and Medicare will not pay for driving evaluations, and some insurance companies will similarly not reimburse practitioners. Given that the Commission for Accreditation of Rehabilitation Facilities (CARF) requires a rehabilitation center to provide driving rehabilitation services either directly or through referral (Pierce, 1993), this issue becomes critical. Better statistical data on the driving performance of people with brain injuries approved by facilities to drive will be vital in addressing fiscal issues. Insurance rates for drivers who have had their licenses medically restricted may present an additional complication.

A related issue is accessibility of facilities and/or professionals who can provide assessment and training services. In many areas, people with brain injury who require evaluation or would benefit from an opportunity to return to driving have no options available, unless they are able to travel to larger urban centers where such facilities are located. Even if these individuals can locate and afford such an evaluation, being tested in unfamiliar areas may not accurately predict their capacity to drive safely in well-known territory.

Provisions for issuing restricted licenses were mentioned by only a few of the researchers (i.e., Gastaut & Zifkin, 1987; Hopewell, 1988; Shreve, 1993; Spudis, Penry, & Gibson, 1986; Summers, 1986; Utah State Driver License Medical Advisory Board, 1981). For some individuals this may represent a solution that meets everybody's needs: the needs of the individual to maintain as much independence as possible and the needs of society to protect citizens from potential danger at the hands of drivers trying to perform beyond their capacities. The option of restricted licensure raises additional questions about assessment, enforcement, and liability.

Variations in language also complicate research efforts. It would be helpful if one (or more) national organization of professionals dealing with the treatment and rehabilitation of individuals with brain injury could attempt to reach consensus on language applied to the testing and treatment of the target population.

Another issue that requires further study and discussion at a national level is the qualifications of those who evaluate and teach people with brain injuries to drive or return to driving. Should these individuals be driving instructors (who may or may not have any expertise in working with people with disabilities), occupational therapists (who may or may not have any training in driving skills), or some combination of the two? What standards should be set for evaluators and trainers, and who should set them? Many school districts have dropped driver training from their curricula in the last five years. When students with brain injuries now in the school system reach driving age, who will provide the specialized training they may require to become safe drivers?

Finally, we have established that more people are surviving brain injury than in the past and that a percentage of those people are driving. We have also seen that cognitive capacities diminish with age in people who do not have disabilities. Research is needed on the aging survivor of brain injury. What types of assessments should be made of such individuals, at what intervals in time, and by whom? If we are able to establish guidelines for these individuals, what will the mechanisms of enforcement be and how can they be made uniform across the states?

Rehabilitation professionals, both practitioners and researchers, face numerous challenges in addressing these issues that are critical from both personal and vocational perspectives for individuals who have sustained traumatic brain injuries.

Author Note

Preparation of this article was supported in part by the Rehabilitation Services Administration Grant #H128A00006, which established the Rocky Mountain Regional Brain Injury Center.

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Barbara S. Handler, Rocky Mountain Regional Brain Injury Center, 220 Dunwoody Dr., Athens, Georgia 30605.