METHODS OF NEUROLOGICAL ASSESSMENT:Level Of Performance, Pattern Analysis

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Clinical Psychology (PSY401)

Lecture 42

METHODS OF NEUROLOGICAL ASSESSMENT

WHAT IS A NEUROLOGICAL ASSESSMENT?

Neurological assessment was traditionally carried out to assess the extent of impairment to a particular skill

and to attempt to locate an area of the brain which may have been damaged after brain injury or

neurological illness. With the advent of brain imaging techniques, location of brain damage can now be

accurately determined so the focus has now moved onto the measurement of cognition and behavior,

including examining the effects of any brain injury or neuropsychological process that a person may have

experienced. A core part of neurological assessment is the administration of neurological tests for the

formal assessment of cognitive functioning. Aspects of cognitive functioning that are assessed typically

include orientation, new-learning/memory, intelligence, language, visuoperception, and executive-

control/self-awareness. However, clinical neurological assessment is more than this and encompasses a

focus also on a person's psychological, personal, interpersonal and wider contextual circumstances.

Assessment may be carried for a variety of reasons, such as: Clinical evaluation, to understand the pattern

of cognitive strengths as well as any difficulties a person may have, and to aid decision making for use in a

medical or rehabilitation environment.

Miller outlined three broad goals of neurological assessment.

Firstly, diagnosis, to determine the nature of the underlying problem.

Secondly, to understand the nature of any brain injury or resulting cognitive problem and its impact

on the individual,

And lastly, assessments may be undertaken to measure change in functioning over time.

DEFINITION:

"Neuropsychology is the study of brain-behavior relationships".

Clinical Neuropsychology combines the knowledge base developed through classical, localizationalist

neurology with the modern methods of American psychometric psychology.

The objectives of neuropsychological assessment in clinical practice are to assess and diagnose disturbances

of mentation and behavior and to relate these findings to their neurological implications and to the issues of

clinical treatment and prognosis. (By Gregory P. Lee, PhD)

The clinical neuropsychologist offers a variety of services, including the assessment of the psychological-

behavioral effects of real or suspected brain lesions, the diagnosis of organic brain conditions, and the

planning and implementation of rehabilitation programs for brain injured patients.

At a time when clinical psychologists' interest in traditional psychological assessment techniques

(Rorschach, Thematic Apperception Test, Bender Gestalt, and so on) has decreased, interest in clinical

neuropsychological evaluation procedures has risen markedly.

Historically, the field of neuropsychology evolved from a lesion localization model (e.g., trauma to a

particular part of the brain leads to a particular kind of deficit) and from studies of the effects of

neurological disease, primarily in adults, on cognitive functioning. At present, behaviors are further defined

and linked to brain processes through the use of new technologies (e.g., neuroimaging or brain scans). The

neuropsychologist endeavors to assess different domains of functioning (e.g., attention, memory, problem

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solving) in order to generate a profile of strengths and weaknesses that can inform treatment planning and

adaptation in daily life.

A neuropsychological assessment typically evaluates multiple areas of functioning. It is not restricted to

measures of intelligence (e.g., IQ) and achievement but examines other areas of functioning that also have

an impact on performance in the classroom, with peers, at home, or on the job. The following represents a

set of cognitive functions that is likely to be assessed:

Sensory perceptual and motor functions

Attention

Memory

Auditory and visual processing

Language

Concept formation and problem solving

Planning and organization

Speed of Processing

Intelligence

Academic skills

Behavior, emotions, and personality

WHAT INFORMATION DOES NEUROPSYCHOLOGICAL ASSESSMENT PROVIDE?

A comprehensive assessment can yield information to assist in distinguishing one disorder from another as

well as better clarifying its nature. The diagnostic referral question may also involve discriminating between

neurological and psychiatric disorders. In addition, based on knowledge of brain-behavior relationships,

evidence for dysfunction in one region of the brain may tell us something about other difficulties that might

be present.

In this regard, knowing more about the individual's strengths and weaknesses can assist in interpreting their

behaviors and guiding program/treatment planning. For example, a parent or teacher may observe: `It feels

like I have to teach Sara everything, every time.' Underlying this behavior may be deficits in identifying the

rules for more abstract concepts, identifying or discovering the common (or "unwritten") principle,

discriminating relevant versus irrelevant information, or memory.

Finally, a written report should be provided following completion of the assessment that can be shared with

those involved in the individual's care. Reasons for referral, Background information (history and current

concerns), Tests administered, Behavioral observations, Test results and interpretation, Summary of

impressions, Recommendations and need for referrals to other specialists

APPROACHES TO NEUROLOGICAL EVALUATION:

Neuropsychologist make inferences regarding an individual's neurological functioning based on measures

of behavior (neuropsychological test performance). In the neuropsychological exam, an attempt is made to

elicit the individual's best performance in order to measure his or her maximum capability or potential. This

information is helpful from the standpoint of both assessment and rehabilitation.

Another very important conceptual issue in the neuropsychological examination has to do with the

premorbid level of functioning. Inferences regarding an individual's present neurological condition are

based on an assumed change in neurological status. To assess the degree of change, it is necessary to obtain

an estimate of premorbid level of ability against which to compare the current level of functioning. Such an

estimate can be reconstructed from a variety of sources, including academic and employment history,

reports from the family, and previous standardized test scores, where such data are available.

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Lezak (1976) discusses 2 methods. The first is based on the assumption that certain well established

abilities, such as vocabulary skills and fund of general information, are frequently preserved in individuals

with brain injury, while other skills are impaired. A clinician using this method examines the level of

performance on tasks like the vocabulary and information subtests of the WAIS and compares this

performance with other neuropsychological test scores. However, the clinician must be careful, since

certain localized injuries (mainly of the left hemisphere) often produce deficits in language usage that may

severely compromise the individual's verbal skills.

The second method assumes that the individual's best current performance provides the closest

approximation to his original ability level;" hence the clinician simply looks for the highest scores or set of

scores.

Again, caution is warranted, since some patients are so severely impaired that all test scores are depressed.

Lezak warns that a single high test score on a memory task may not be a good estimate of premorbid level

of functioning, since memory is the least reliable indicator of general intellectual ability of all intellectual

functions.

There are several other methodological approaches that neuropsychologist use in evaluating and

interpreting a given patient's performance. No single approach is itself satisfactory, but when they are used

in concert each approach supplements the other.

The more common approaches are level of performance, pattern analysis, pathognomonic signs, and right-

left differences. Each is described more fully below.

1. Level Of Performance:

In the level of performance approach, the patient is administered tests that are sensitive to cerebral

impairment. The patient's scores on such tests are compared to normative levels that have an established

degree of accuracy in differentiating brain-damaged from non-brain damaged persons. Thus if a given

patient scores higher than the cutoff score on this test, this performance is considered typical of organically

impaired individuals and there is some probability that he does have brain dysfunction. This approach,

when used alone, has many problems associated with it. Some non-brain damaged patient's score in the

brain damaged range for reasons having nothing to do with the intactness of their cerebral cortices.

In the past, many psychologists used the Bender Gestalt as a single measure of organicity. This is an

inappropriate use of this test; although the Bender may be of help in the diagnosis. It is by no means

sufficient, because it provides just one bit of data about the patient.

Another problem with the level of performance approach particularly when a single test is used is that a

patient may do well on this test despite having significant deficits in other areas of higher cortical

functioning. For example, right handed patient with lesions in the left temporal lobe may perform well on a

measure of visual constructive abilities such as the Bender Gestalt, but do very poorly on measures of

language functioning. Brain damage is not a unitary concept: its effects may vary widely and can be

pervasive or highly circumscribed.

2. Pattern Analysis:

Pattern analysis means that the patient is given a battery of tests with known association to higher cortical

functioning; and the neuropsychologist then looks at the pattern of test performance--on which tests did the

patient perform relatively poorly, and on which tests did the patient perform well? The classic example of

the pattern approach is examination of verbal performance discrepancies on the WAIS. In pattern analysis,

the examiner looks for common areas of deficit, noting those areas in which test performance tends to be

lower in brain-damaged individuals with specific brain lesions. The problem with pattern analysis approach

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is that a person could have a low score on a given test for numerous reasons, and the simple presence of the

low score does not necessarily mean a localized problem.

3. Pathognomonic Signs:

A pathognomonic sign is a problem that a patient manifests that is an absolute indication of organic brain

disorder. A pathognomonic sign is present the patient is, by definition, suffering from an organic

neurological disorder. Examples of pathognomonic signs are visual field deficits, spatial inattention or

neglect, aprexia and alexia. There are also a large number of signs that are not pathognomonic, but whose

presence strongly implies an organic problem. These specific behavioral deficits include profound difficulty

in perceiving numbers written on the tops of the patient's fingers, difficulty in naming certain fingers that

are touched while the patient is blind folded, and consistent deficits in the perception of stimuli under

condition of bilateral simultaneous stimulation.

The major advantage of the pathognomonic sign approach is that if the sign is present, the patient definitely

has organic impairment. The major disadvantage, however, is that absolute pathognomonic signs are seen

rather infrequently on neuropsychological evaluation.

4. Right-Left Differences:

To use the right-left difference approach, the clinician examines the test scores of patient on the tasks that

require performance or participation of both sides of the body. A number of tests on the Halstead Battery

involve having the patient perform a given task with his or her dominant hand and then perform the same

task with the non-dominant hand. For example, to give another example on the Tactual Performance Test, a

right handed patient who takes a significantly longer time for block placement with the left hand than for

the right might suggest a lesion in the parietal area of the right hemisphere. One problem with this approach

is that measuring right-left differences typically means measuring motor and sensory-motor deficit, so the

number of tests in this category is limited.

The level of performance, pattern analysis, right-left differences, and pathognomonic sign approaches to

neuropsychological evaluation are the methods most frequently used in clinical practice. Several other

approaches have been developed but are not in wide spread use. Brief description of 2 of these approaches

follow.

USES OF CLINICAL NEURO-PSYCHOLOGICAL ASSESSMENT:

1. Diagnostic Clarification:

In confusing or complex cases, neuropsychological assessment can be useful for teasing out the relative

contributions of neurological conditions (e.g., cellular degeneration, neurochemical disruption), emotional

states (e.g., anxiety, depression), and psychiatric illnesses (e.g., personality disorder, psychoses). Neuro-

psychological assessment can be used to help localize brain damage.

2. Measuring Change:

Repeat assessment can be valuable in charting progress (e.g., recovery from cerebrovascular accident or

closed head injury) as well as for recognizing a decline in mental status (e.g., following the course of

various dementias, identifying unexpected declines in patients undergoing various treatments or during the

process of recovery).

3. Evaluating Cognitive And Functional Status:

Neuropsychological testing is able to delineate an individual's pattern of cognitive strengths and weaknesses

relative to his or her own ability as well as compared to normative samples of age-matched peers (Ideally,

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norms should be matched for age, education, gender, and race if each variable has been shown to affect test

performance).

APPLICATIONS OF NEURO-PSYCHOLOGICAL ASSESSMENT:

1. Vocational Interventions:

With the input of the neuropsychologist, a patient's ability to rejoin the work force can be evaluated and

efforts toward re-entry can be facilitated (e.g., develop specific routines that are tailored to the patient's

existing strengths and that anticipate the impact of his or her limitations). Aspects of neuropsychological

testing can be integrated with organizational psychology in order to enhance the quality of vocational

assessment.

2. Academic Interventions:

As with vocational interventions, results of a neuropsychological assessment may be used to plan a special

educational program to better meet the needs of an individual. This may be useful with developmental

disorders as well as with patients recovering from illness or injury.

3. Family Interventions:

Accurate knowledge about a patient's functional status may assist him or her to adjust their role within a

family system. Neuropsychological information may enable family members to recognize the need for

changes and accommodations within their relationships, highlight the need for environmental changes to

accommodate patient deficits, and provide an opportunity for emotional processing and eventual acceptance

of the patient's limitations.

4. Competency Issues:

Neuropsychological status plays an important role in determining a patient's overall competency. Questions

typically involve one's ability to exercise rational judgment, make competent decisions, and live in an

independent fashion. In addition to cognitive status, assessment of the patient's awareness of their

limitations is also important in establishing ability for independent functioning.

METHODS OF NEURO-PSYCHOLOGICAL ASSESSMENT:

1. Medical History:-All relevant medical records, especially results of neurological examination, imaging

studies, and electrophysiological (EEG) results.

2. Clinical Interview:-Includes review of cognitive, sensorimotor, and neurovegetative complaints as well

as medical, psychiatric, and substance abuse history. Family members may be interviewed when necessary.

3. Behavioral Observations:-Qualitative assessment of mentation, motor function, speech, motivation for

optimal test performance, emotion, manner of relating, and humor.

4. Psychometric Tests:-These may be "paper and pencil" tasks or measures requiring performance of a

relevant skill (e.g., assembly of blocks or puzzles, reaction time tasks). Major cognitive domains typically

assessed include: Attention, Memory, Intelligence, Visual-Spatial-Perceptual functions, Psychosensory and

Motor abilities, "Executive" or "Frontal Lobe" functions, and Personality or Emotional Functioning.

INTERPRETATION OF RESULTS:

Deficit patterns occurring across neuropsychological tests can be suggestive of various sites of cerebral

dysfunction and neurological processes underlying the deficit pattern. An effort is made by the

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neuropsychologist to integrate test data, history, clinical interview, behavioral observations, and available

laboratory and radiological evidence into one cohesive summary report that arrives at a neurobehavioral

diagnosis, discusses the neurological implications (e.g., localization, course, prognosis), and can be used in

the process of treatment planning.

There are a number of ways in which neuropsychologists interpret test data. First, a patient's level of

performance may be interpreted in the context of normative data. For example, does a patient's score fall

significantly below the mean score for the appropriate reference group, suggesting some impairment in this

area of functioning?

Second, some calculate difference scores between two tests for a patient; certain level of difference suggests

impairment.

Third, Pathognomonic analysis of scores on tests has been reliably associated with specific neurological

injuries or impairments.

Finally, a number of statistical formulas that weight test scores differently may be available for certain

diagnostic decisions.

A final point with the interpretation has to do with the desirability of making qualitative evaluations of

patient's responses. Many neuropsychologists probably combine the two approaches which need not to be

mutually exclusive.

NEURO-DIAGNOSTIC PROCEDURES

The medical field has a variety of neurodiagnostic procedures. they include the tradition neurological

examination performed by the neurologist, spinal taps, X rays, electroencephalograms (EEGs),

computerized axial tomography (CAT) scans, positron emission tomography (PET) scans, and the more

recent nuclear magnetic resonance imaging (NMR or MRI) technique. These are indeed valuable means for

locating the presence of damage and disease. But not all of these procedures work equally well in

diagnosing impairment.

Finally, some of these procedures pose risks for the patient. Spinal taps can be painful and sometime

harmful; we all know about the dangers of too many x rays. In addition to these standard forms of

procedures, several other imaging methods are available that provide a better sense of "working" brain.

(Lowry, 1997).

Single photon emission computed tomography (SPECT) imaging is based on cerebral blood flow and this

provides a "picture" of how the brain is working. As another example, functional MR imaging (MRI) also

assesses blood flow changes in the brain. Both of these newer alternative neurodiagnostic procedures hold

some promise in clinical neuropsychology because perhaps they are more likely to provide information on

how different areas of the brain are working.

Many of these neurodiagnostic procedures are quite expensive, and some are invasive. Therefore, it may be

helpful to use neuropsychological tests as screening measures, the results of which may indicate whether

more expensive neurodiagnostic tests are indicated.

TESTING AREAS OF COGNITIVE FUNCTIONING:

A. Intellectual Functioning:

A number of techniques have been used over to assess levels of intellectual functioning. To estimate level

of intellectual ability, many neuropsychologists use the WAIS -3 and subtests from a modified version of

the WAIS-R called the WAIS-R-NI (Kaplan, 1991). The modifications include, for example, changes in

administration (such as allowing the patient to continue on a subtest despite consecutive incorrect answers)

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and additional subtest items. Because of these modifications, it is believed that the WAIS-R-NI provides

more information regarding the patient's cognitive strategies (R.M. Anderson, 1994).

It is not possible to administer the entire WAIS-3, certain individual subtests may be used--most commonly,

the Information subtest, Comprehensive subtest, and Vocabulary subtest. These subtests are believed to be

least affected by the brain trauma or injury and thus it also provides estimates of premorbid intelligence.

This is important because often no preinjury test data are available to serve as a baseline against which to

compare present functioning.

B. Abstract Reasoning:

For many years, clinicians observed that patients diagnosed with schizophrenia or those deemed cognitively

impaired seemed to find it difficult to think in an abstract or conceptual fashion. Such patients seemed to

approach tasks in a highly concrete manner. Some of the more commonly used tests to assess abstract

reasoning abilities include the Similarities subtest of the WAIS-3 and the Wisconsin Card Sorting Test, or

WCST (Heaton, 1981). The Similarities subtest requires the patient to produce a description of how 2

objects are alike. The WCST consists of decks of cards that differ according to the shapes imprinted, the

colors of the shapes, and the number of shapes on each card. The patient is asked to place each card under

the appropriate stimulus card according to a principle (same color, same shapes, same number of shapes)

deduced from the examiner's feedback ('that's right' and 'that's wrong'). At various points during the test, the

examiner changes principles; this can only be detected from the examiner's feedback regarding the

correctness of the scoring of the next card.

C. Memory:

Brain injury is often marked by memory loss. To test for such loss, Wechsler (1945) developed the

Wechsler Memory Scale, or WMS. The Wechsler Memory Scale-3 is the most recent revision of the WMS.

The WMS-3 was developed in conjunction with the WAIS-3 (Wechsler, 1997), because clinicians often

measure intellectual ability and memory concurrently. WMS-3 subtest scores are combined into 8 primary

indexes that assess a range of memory functioning: Auditory Immediate, Visual Immediate, Immediate

Memory, Auditory Delayed, Visual Delayed, Auditory Recognition Delayed, General Memory and

Working Memory. Four supplementary Auditory Process Composites can also be calculated. These are

used to assess memory processes when stimuli are presented auditorily.

D. Visual-Perceptual Processing:

Visual-spatial skills are necessary for a broad range of activities, including reading a map, parallel parking a

car, a throwing a baseball from the outfield to a base. In addition to the Rey-Osterrieth Complex Figure

Test, many neuropsychologists seeking to assess visual-spatial skills examine performance on certain

WAIS-3 subtests, such as the Block Design subtest. Several specialized tests of these skills are also

available. For example, the judgment of Line Orientation Test requires examinees to indicate the pair of

lines on a response card that 'match' the 2 lines on the stimulus card.

E. Language Functioning:

Various forms of brain injury or trauma can affect either the production or comprehension of language.

Tests that require patients to repeat words, phrases, and sentences can assess articulation difficulties and

paraphasias (word substitutions); naming tests can help diagnose anomias (impaired naming). Language

comprehension can be assessed using the Receptive Speech Scale of the Luria-Nebraska. This subtest

requires patients to respond to verbal commands. Speech and language pathologists do an excellent job of

comprehensively assessing language dysfunction, and the neuropsychologist may choose to refer patients to

these health professionals if a screening test indicates suspected problems in language production or

comprehension.

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CONCLUSION:

The neuropsychological assessment is a method of examining the brain by studying its behavioral product.

As with other psychological assessments, neuropsychological evaluations include the comprehensive study

of behavior by means of standardized tests that are sensitive to brain-behavior relationships. In effect, the

neuropsychological assessment offers an understanding of the relationship between the structure and

function of the nervous system.

Thus the goal of the clinical neuropsychological assessment is to be able to evaluate the full range of basic

abilities represented in the brain.

In practice, the neuropsychological assessment is multidimensional (concerned with evaluating different

parts aspects of neurofuntioning from basic to complex), reliable and valid.

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