There are several major cognitive domains that should be assessed in a comprehensive neuropsychological exami-nation for TBI. These include attention, memory, execu-tive functioning, speech and language, visuospatial and visuoconstructional skills, intelligence, and psychomotor speed, strength, and coordination (Vanderploeg 1994b).
Measures of psychological functioning are also frequently administered and are an important aspect of the evalua-tion given that mild, moderate, and severe TBI are asso-ciated with increased risk of onset of psychiatric illness after injury (Fann et al. 2004). There are numerous neu-ropsychological tests that purport to measure specific aspects of neurocognitive functioning, and some of the more popular test instruments are listed in Table 8–1.
This table provides a list of the major cognitive domains and examples of neuropsychological tests that are used to assess those domains.
Alertness and Orientation
Impairment in alertness and orientation is common in patients with TBI, particularly in the immediate hours and days after their injury. A neuropsychological evalua-tion during this period would be difficult and most likely invalid. Traumatically brain-injured patients have a high probability of developing a disorder of alertness in the presence of certain etiological factors that further com-promise brain function (brainstem reticular activating system damage, supratentorial and subtentorial lesions, reduction in brain metabolism, organ failure, increased or decreased body temperature, seizure) as well as from sedating medications and lack of sleep (Stringer 1996).
Patients with psychiatric disorders such as depression, schizophrenia, factitious disorder, and conversion disor-der can appear sleepy, apathetic, or unresponsive, and psychiatric disorders should be ruled out when determin-ing if the patient has impaired alertness. However, misat-tributing a patient’s impaired alertness to psychiatric causes can have life-threatening consequences for the patient if the cause is actually physiological.
The Galveston Orientation and Amnesia Test (GOAT; Levin et al. 1979) is a brief test that is often administered at bedside to assess the patient’s current level of orientation and recall of events that occurred before and after the accident (Figure 8–1). The GOAT is particularly useful for determining posttraumatic amnesia within the acute hospital setting. During post-traumatic amnesia, the patient is disoriented and con-fused, and his or her ability to learn and remember new information is disrupted. Posttraumatic amnesia is acute and time-limited, and its duration can be an im-portant prognostic indicator of recovery from brain in-jury, with a longer period of posttraumatic amnesia (> 1 or 2 weeks) predictive of poor recovery (Lovell and Franzen 1994).
Attentional Processes
Disorders of attention are a common consequence of TBI and frequently occur with rapid deceleration injuries such as in traffic accidents. Attentional impairments can inter-fere with rehabilitation, especially if the deficit is severe.
Patients with severe attentional impairments may be too distractible and unable to focus their attention long enough to learn compensatory strategies or to benefit from retraining (Lezak 1995).
Assessment of attention is necessary because it is a prerequisite for successful performance in other cognitive domains. Additionally, deficits in attention can mimic other cognitive deficits. For example, a patient who is un-able to fully attend to the stimuli on a memory test will not adequately encode the information. This patient’s test scores may indicate memory impairment when in fact the deficit is in attention, rather than in memory. Patients T A B L E 8 – 1 . Cognitive domains and
representative neuropsychological tests Attention and concentration
Digit Span (WAIS-III, WMS-III; Wechsler 1997a, 1997b) Spatial Span (WMS-III; Wechsler 1997b)
Digit Symbol (WAIS-III; Wechsler 1997a) Continuous Performance Test (Rosvold et al. 1956) Paced Auditory Serial Addition Task (Gronwall 1977) Stroop Color and Word Test (Golden 1978)
Consonant Trigrams (Peterson and Peterson 1959) Memory and learning
Wechsler Memory Scale––III (WMS; Wechsler1997b) California Verbal Learning Test (Delis et al. 1987, 2001) Rey-Osterrieth Complex Figure Test (Osterrieth 1944) Hopkins Verbal Learning Test (Brandt 1991)
Rey Auditory-Verbal Learning Test (Rey 1964) Benton Visual Retention Test (Benton et al. 1983) Brief Visuospatial Memory Test––Revised (Benedict 1997) Executive functioning, concept formation, and planning Booklet Category Test (DeFilippis and McCampbell 1997) Wisconsin Card Sorting Test (Heaton 1981)
Design Fluency (Jones-Gotman and Milner 1977) Controlled Oral Word Association Test (Benton and
Hamsher 1978)
Trail Making Test—Part B (Reitan 1958) Matrix Reasoning (WAIS-III; Wechsler 1997a) Language
Boston Diagnostic Aphasia Examination (Goodglass and Kaplan 1972)
Multilingual Aphasia Examination (Benton and Hamsher 1978)
Western Aphasia Battery (Kertesz 1979) Aphasia Examination (Russel et al. 1970) Boston Naming Test (Kaplan et al. 1983) Visuospatial and visuoconstructional skills
Visual Form Discrimination Test (Benton et al. 1983) Judgment of Line Orientation Test (Benton et al. 1983) Hooper Visual Organization Test (Hooper 1958) Rey-Osterrieth Complex Figure (Copy Condition)
(Osterrieth 1944)
Block Design (WAIS-III; Wechsler 1997a) Intelligence
Wechsler Adult Intelligence Scale (WAIS-III; Wechsler 1997a)
Motor processes
Finger Tapping Test (Reitan and Wolfson 1993) Grooved Pegboard Test (Matthew and Klove 1964)
Note. WAIS=Wechsler Adult Intelligence Scale; WMS=Wechsler Memory Scale.
T A B L E 8 – 1 . Cognitive domains and
representative neuropsychological tests (continued)
with attentional deficits can also appear to have problem-solving deficits even though these cognitive processes are intact (Fisher and Beckly 1999). For example, a patient with an attentional deficit may respond impulsively or have difficulty maintaining his or her attention on the task long enough to correctly solve it. Behaviorally, a patient with an attentional impairment may start many new tasks or projects but is unable to complete them. Socially, his or her conversation may shift from topic to topic without
any issue being dealt with thoroughly (Stern and Pro-haska 1996).
There are multiple components of attention, and spe-cific tests are used to evaluate the different aspects of at-tention. An individual’s attention to the task at hand requires him or her to focus on some aspect of the environment (focused and/or selective attention), to sustain that focus for as long as necessary (sustained attention and/or vigi-lance), and to shift the focus when required (cognitive F I G U R E 8 – 1 . The Galveston Orientation and Amnesia Test (GOAT).
Source. Reprinted from Levin HS, O’Donnell VM, Grossman RG: “The Galveston Orientation and Amnesia Test: A Practical Scale to Assess Cognition After Head Injury.” Journal of Nervous and Mental Disease 167:675–684, 1979. Copyright © Williams & Wilkins, 1979. Used with permission.
flexibility and/or divided attention) (Anderson 1994;
Campbell 1996).
When assessing attention, it is first important to assess general level of arousal. Next, the attention span, or den-sity of information the person can hold in attention at one time, is assessed. Tests such as Digit Span and Spatial Span (WMS-III; Wechsler 1997b) are often used to assess auditory and visual attention span. Divided attention (e.g., being able to maintain a conversation while ignor-ing environmental distractions) is often assessed with the Stroop Color and Word Test (Golden 1978) or the Paced Auditory Serial Addition Task (PASAT; Gronwall 1977).
The Stroop test is commonly used because it addresses multiple aspects of attention such as focused and divided attention as well as executive functioning abilities. The Interference score on the Stroop test has been particu-larly useful in looking at the ability to inhibit an over-learned response and cognitive flexibility (Groth-Marnat 2000). The PASAT, a challenging test of sustained and di-vided attention, is particularly useful as a measure of re-covery from mild brain injury and is sensitive to the subtle but meaningful deficits that may occur after multiple head injuries. The PASAT is also useful for assessing informa-tion processing deficits in patients with brain injury (Gronwall 1977).
The third component of attention that should be as-sessed is sustained attention, or vigilance. This area is fre-quently referred to as distractibility and is the ability to sustain concentration on a set of stimuli that falls within the person’s span of concentration while ignoring extra-neous stimuli (Stringer 1996). Thus, vigilance is the abil-ity to maintain attention over time. The Continuous Per-formance Test (Rosvold et al. 1956) is commonly used to measure vigilance, as are the Digit Symbol Test from the WAIS-III (Wechsler 1997a) and letter and number can-cellation tests.
Memory
Memory impairment is one of the most common com-plaints after TBI. Memory represents a multifaceted process that can generally be described as the ability, process, or act of remembering or recalling, and the ability to reproduce what has been learned or experi-enced (Campbell 1996). Memory deficits can be tempo-rary, as occurs with posttraumatic amnesia, or more per-manent. In general, memory impairment can be classified as either retrograde amnesia or anterograde amnesia. Retrograde amnesia involves memory loss for events in a time period before the injury. Anterograde amnesia involves memory loss for events after the injury.
Similar to attentional processes, memory is a
multidi-mensional cognitive process that involves multiple underlying brain structures. In neuropsychological assessment, memory for verbal and visual information is formally measured. Memory for material immediately after the material has been presented is referred to as immediate memory. Memory for information after a delay of minutes to hours is referred to as delayed recall or recent memory (Anderson 1994). Additionally, the patient’s acquisition, retention, and retrieval of newly learned information should be assessed.
Although patients with mild brain injury frequently complain of memory problems, their perceived problems may often be the result of impairment in the ability to at-tend to or acquire the material rather than to a memory disorder per se. Patients with more focal damage, as can occur in penetrating injuries, are likely to demonstrate material-specific deficits in learning and remembering as a result of selective damage to the language-dominant (usually left) or nondominant hemisphere (usually right).
Specifically, patients with dominant hemisphere damage are more likely to have impaired recall of verbal material but preserved recall of nonverbal material, although this is not always the case. The California Verbal Learning Test (CVLT; Delis et al. 1987), Hopkins Verbal Learning Test (Brandt 1991), and Rey Auditory-Verbal Learning Test (Rey 1964) are commonly used to assess verbal memory.
Visual memory is typically assessed through tests that require the patient to learn and reproduce spatial designs. The Rey-Osterrieth Complex Figure (Osterri-eth 1944) assesses visual memory by having the patient reproduce a drawing of a geometric design at different time intervals after the initial presentation (which in-volves copying the figure) (Lovell and Franzen 1994).
The Benton Visual Retention Test (Benton et al. 1983) is another commonly used test of visual memory that re-quires the patient to draw a series of simple designs. The WMS-III (Wechsler 1997b) is a battery of tests specifi-cally designed to measure various aspects of memory functioning. Clinicians often supplement their evalua-tions with one or more of the subtests (e.g., Logical Memory and Visual Reproduction) from the Weschler Memory Scale batteries. More recently, the Brief Visu-ospatial Memory Test—Revised (Benedict 1997) has be-come a popular visual memory assessment tool. The pa-tient is asked to draw a series of six designs over three 10-second exposures to the test stimuli. Delayed mem-ory is evaluated by having the patient draw the designs after a 25-minute delay.
One aspect of memory that is frequently compro-mised after TBI is working memory. Working memory is a form of short-term memory that encompasses the
abil-ity to hold or retain information in a temporary storage system while simultaneously concentrating on another task (Stringer 1996). The Auditory Consonant Trigrams (ACT) test, also known as the Brown-Peterson test of mem-ory (Peterson and Peterson 1959), assesses short-term (working) memory, divided attention, and information-processing capacity. It is a 10-minute test that was origi-nally designed for adults but currently has versions appro-priate for children ages 9–15 years. The ACT is useful for a variety of populations but is particularly sensitive to mild head injury (Spreen and Strauss 1998). The ACT re-quires the patient to hold information in mind (three let-ters) while simultaneously performing another task (counting backward by threes).
Executive Functioning
Executive functioning encompasses the abilities necessary for an individual to perform a problem-solving task from beginning to end. The major areas of executive functioning include judgment, reasoning, concept formation, and abstraction; initiation and fluency; planning and organiz-ing; set maintenance and mental flexibility; and disinhibi-tion and impulse control. These skills enable a person to engage with others effectively, plan activities, solve prob-lems, and interact with the environment to have his or her needs met (Sbordone 2000). A deficit of executive func-tioning can be the most crippling impairment that afflicts the TBI patient and can intensify deficits seen in other cog-nitive processes such as memory (Lezak 1995). Research suggests that executive functioning is often impaired when a frontal-subcortical circuit or loop is damaged (Cum-mings and Trimble 1995). This damage can occur from lesions in the frontal-subcortical circuits or from alter-ations in metabolic activity of the neural structures that form the circuit. Cummings and Trimble (1995) described five frontal-subcortical circuits. Three of these circuits (dorsolateral prefrontal, lateral orbitofrontal, and medial frontal/anterior cingulate) play an important role in execu-tive function, and damage in these areas produces a neu-robehavioral syndrome with executive functioning impair-ments. Thus, instead of one global “frontal lobe syndrome” there are three distinct “frontal syndromes”
that display executive impairments. Damage to the dorso-lateral prefrontal area results in a syndrome characterized by an inability to maintain set, disassociation between ver-bal and motor behavior, deficits in motor programming and concrete thinking, poor mental control, and stimulus-bound behavior (Sbordone 2000). Orbitofrontal lesions produce a syndrome characterized by tactlessness, disinhi-bition, emotional lability, insensitivity to the needs and welfare of others, and antisocial acts. Damage to the medial
frontal/anterior cingulate area produces a syndrome char-acterized by apathy, diminished motivation and interest, psychomotor retardation, diminished social involvement, and reduced communication (Cummings and Trimble 1995). The cluster of executive deficits that accompany the previously mentioned neurobehavioral syndromes can be misinterpreted as emotional problems or personality aber-rations (Lezak 1997). For example, the apathy, diminished initiative, reduced motor and verbal output, and impaired motivation that are typical of medial frontal/anterior cin-gulate injuries mimic depression.
Executive functioning deficits can severely impact a patient’s adaptive functioning. Problems with planning, impulsivity, and disinhibition can adversely affect every-day skills such as preparing a meal, handling finances, and social appropriateness (Sbordone 2000). Additionally, im-paired executive functioning has been found to be one of four of the most reliable correlates of unemployment (Crepeau and Scherzer 1993). The Wisconsin Card Sort-ing Test (WCST; Heaton 1981) and the Category Test (Reitan and Wolfson 1993) are two measures typically used to assess different aspects of executive functioning.
The Category Test and its more portable and efficient format the Booklet Category Test (DeFilippis and Mc-Campbell 1997) are considered tests of abstract concept formation, reasoning, and logical analysis abilities. Suc-cessful performance requires mental flexibility, attention and concentration, learning and memory, and visuospatial skills (Mitrushina et al. 1999). The WCST (Heaton 1981) is an abstract problem-solving test that is particularly use-ful because there has been substantial research on its abil-ity to measure perseveration (Flashman et al. 1991). In general, the WCST provides information across multiple behavioral domains, including ability to form concepts, problem-solving ability, ability to learn from experience, and capacity to shift conceptual sets.
Speech and Language
Language processes are often disrupted after TBI and vary greatly depending on the nature, localization, and severity of brain injury. TBI patients who do sustain dam-age to the langudam-age centers tend to have minimal to no deficits on verbal tests of overlearned material, culturally common information, and reading, writing, and speech.
However, they may demonstrate difficulties with verbal retrieval of names of objects, places, and persons. TBI patients’ dysnomias, or word-finding problems, tend to present as slow recall of the word, paraphasias, and semantically related misnamings (Lezak 1995).
Injuries that are focal or penetrating and involve the language-dominant hemisphere are more likely to cause
language impairments. Aphasia is a disorder of oral lan-guage and can include compromised verbal expression and comprehension. In addition, written communication (alexia and agraphia) is also frequently impaired in pa-tients with aphasia. There are specific lesion locations that are likely to produce certain types of aphasia. For ex-ample, Broca’s aphasia often results from lesions in the frontal operculum that extend to subjacent white matter, the anterior parietal lobe, the insula, and both banks of the rolandic fissure. Conduction aphasia often results from lesions in the arcuate fasciculus (Stringer 1996). The major types of aphasia are differentiated by assessing three language domains: fluency, comprehension, and repetition. Although other aspects of language may be compromised, these three areas are typically considered the “cardinal” symptoms. For example, a patient with Broca’s aphasia will have deficits in fluency and repetition, but relatively adequate comprehension. Those with Wer-nicke’s aphasia are fluent (although their verbalizations may be incomprehensible) but have poor repetition and comprehension.
Evaluation of speech and language usually involves as-sessing spontaneous speech; repetition of words, phrases, and sentences; speech comprehension; naming; reading;
and writing (Lezak 1995). During the evaluation, it is im-portant to attend to fluency, prosody, articulatory errors, grammar and syntax, and the presence of paraphasias (Goodglass 1986). The Aphasia Examination (Russel et al. 1970) is a useful screening instrument for uncovering language deficits that may need further assessment. The Boston Diagnostic Aphasia Examination (Goodglass and Kaplan 1972) is a comprehensive and sensitive battery that is excellent for the description of aphasic disorders and for treatment planning (Lezak 1995). Rather than us-ing the entire battery, many clinicians selectively use por-tions of the battery in combination with other neuropsy-chological tests.
Assessment of Motivation and Malingering
Although the majority of traumatically brain-injured patients have bona fide deficits, the issue of secondary gain should always be considered. In addition to assess-ing the major cognitive domains detailed above, the neuropsychologist should also include formal tests of motivation and malingering within the evaluation. This is particularly true in cases in which litigation may be pursued to assign blame and/or financial responsibility for the resulting disability. In these cases, a patient may attempt to fake or exaggerate a brain injury. Similarly, some patients who have legitimate deficits after their TBI may not put forth their full effort in an attempt to
receive needed treatments (rehabilitation), services (home care), and compensation (disability benefits) (Lovell and Franzen 1994). This can create difficulty in determining the patient’s actual strengths and weak-nesses and hinders the evaluation process. Addressing the issues of effort and motivation early in the evaluation can help prevent unnecessary testing and an invalid eval-uation. Tests that are commonly used to assess for moti-vation and malingering are
• Test of Memory Malingering (Tombaugh 1996)
• 21-Item Test (Iverson et al. 1991)
• Rey 15-Item Memory Test (Rey 1964)
• Portland Digit Recognition Test (Binder 1990)
• Victoria Symptom Validity Test (Slick et al. 1997) The 21-Item Test (Iverson et al. 1991) can be used to initially screen for exaggerated deficits in verbal memory.
The Rey 15-Item Memory Test (Rey 1964) was specifi-cally designed to detect attempts at faking memory defi-cits. The patient is told the difficulty of remembering the 15 items before their presentation. However, the stimuli are overlearned sequences and redundant, which makes the items relatively simple to remember (Stringer 1996).
Symptom validity testing is a method in which 100 trials of forced-choice stimuli that are relevant to the patient’s presenting complaint are presented. Malingering is sug-gested if the patient performs below 50% correct (sug-gesting a performance that is worse than chance) (Cros-son 1994). Although some measures are specifically constructed for malingering and motivation, other tests of cognitive functioning (e.g., memory) attempt to in-clude subtests that are useful for assessing motivation.
The most common method is the use of a forced-choice format. Many instruments, such as the WMS-III (Wech-sler 1997b) and CVLT-II (Delis et al. 2001), include these subtests in their measures. The premise of forced-choice tests is that the patient has a 50% chance of answering ap-proximately one-half of the items correctly without even trying. Thus, a patient who incorrectly answers 90% of the items is likely demonstrating poor effort. Recent re-search (Bender and Rogers 2004) has focused on the use of multiple measures and strategies to detect feigning.
These researchers found Magnitude of Error to be a use-ful detection strategy: "The Magnitude of Error assumes that feigners will not be especially concerned about which incorrect responses they select" (p. 50). In other words, the malingerer may focus on what item to fail rather than how the item should be failed (e.g., the plausibility of the error).
In addition to administering tests designed to assess for malingering and biased responding, the clinician
should compare the patient’s performance on neuropsy-chological measures to his or her ability to function in ev-eryday activities. For example, a patient who performs in the severely impaired range on neuropsychological test-ing yet continues to perform well in graduate-level coursework is demonstrating an inconsistency between his test performance and academic functioning. Obvi-ously, this disparity suggests suboptimal effort on testing.
Last, when assessing for malingering it is important to keep in mind that some patients may appear to be malin-gering but are not. A variety of factors can influence neu-ropsychological test performance (e.g., psychiatric disor-ders such as depression, poor rapport with the evaluator, uncooperativeness, and the context in which the evalua-tion is conducted) (Franzen and Iverson 1997). Franzen and Iverson (1997) stated that when assessing for malin-gering “It is important to remember that these test instru-ments evaluate the likelihood of nonoptimal perfor-mance, not malingering itself. As such, the specific assessment instruments provide information about biased responding, that is, information about the probability that variables other than skill level have adversely affected the level of effort” (p. 396).
Neuropsychological Screening Instruments
Time constraints, patient fatigue or noncompliance, and lack of health insurance and financial restrictions may necessitate the administration of a screening battery rather than a full neuropsychological evaluation. How-ever, although the advantages of neuropsychological screening are cost-effectiveness and short administration time, this approach has limited value in making differen-tial diagnoses. For example, the Mini-Mental State Examination (MMSE) is useful in determining the pres-ence or abspres-ence of dementia, but it is not useful for dif-ferentiating Alzheimer’s disease from other types of dementia. Additionally, screening devices are limited in their ability to discriminate mild head injury, and they do not provide specific information about rehabilitation needs (e.g., memory retraining) and individual strengths and weaknesses (e.g., impaired auditory memory but intact visual memory). Some examples of screening instruments are
• Mini-Mental State Examination (Folstein et al. 1975)
• Repeatable Battery for the Assessment of Neuropsy-chological Status (Randolph 1998)
• Neurobehavioral Cognitive Status Examination (Kier-nan et al. 2001)
• Shipley Institute of Living Scale (Revised Manual) (Zachary 1986)
• BNI Screen for Higher Cerebral Functions (Priga-tano 1991)
The MMSE is a well-known screening instrument that is brief and easy to administer. The MMSE is most useful for moderate to severe impairment in dementia pa-tients. However, its sensitivity and specificity decline with other patient populations, particularly those with mild cognitive impairment, focal neurological deficits, and psychiatric disorders (Spreen and Strauss 1998).
The Repeatable Battery for the Assessment of Neu-ropsychological Status (Randolph 1998) is a relatively new cognitive screening instrument that takes less than 30 minutes to administer and provides a total scale score and five specific cognitive ability index scores. It was de-signed for the dual purpose of identifying and character-izing abnormal cognitive decline in the older adult and as a neuropsychological screening battery for younger pa-tients (Randolph et al. 1998). It has also been found to be particularly useful in evaluating neuropsychological change in patients with schizophrenia (Wilk et al. 2002).