Neuropsychological Assessment in Neurorehabilitation

By: Jose Leon-Carrion, Ph.D.

"Assessment" refers to the purposeful gathering of information on an individual, including clinical interview material, psychometric data, formal observations, and past medical records. Generally speaking, the purpose of an assessment is to generate a diagnosis, to provide direction for treatment planning, to assist in patient care, and to advance research efforts (Leon-Carrion, Taffee & Barroso y Martin, 2006).

Neuropsychological assessment is a specific methodological procedure for measuring functional changes due to impairment of specific cognitive or behavioral domains. This assessment is done in order to determine rehabilitation needs based on the measured strengths and weaknesses of the individual in the functional domains assessed. Normally, neuropsychological assessment is carried out through the administration ofneuropsychological tests that have proven to be sensitive to the effects of brain injury.

A typical neuropsychological assessment consists of administering tests or tasks that examine a set of functional cognitive, behavioral, emotional and social domains that are controlled by known brain systems. According to the National Academy of Neuropsychology (NAN, 2006), neuropsychological assessment is a neurodiagnostic, consultative service, and not a mental health evaluation or treatment service.

Is it possible to assess only through tests and batteries?

There are two main models for neuropsychological assessment, the quantitative and the qualitative method. Whereas the quantitative neuropsychologist is mainly concerned with the mathematics and statistics of the functional impairment, the qualitative neuropsychologist endeavors to find the procedural breakdowns implicit in the loss of functional integrity.

The quantitative perspective is based on comparing the results obtained from a patient who undergoes a test battery with those of a normal person who undergoes the same tests and observing the deviation from the latter results. Comparisons can also be made between the results of the assessed patient and those of other patients with different cognitive impairment profiles in order to see if the patient fits a certain profile, given that damage to different regions of the brain may result in characteristic patterns of deficit. These patterns may explain the neurological processes involved in the cognitive, emotional, and functional impairment of the patient. Numbers are the product of quantitative assessment. Scores are viewed as having some intrinsic meaning upon which assumptions are made as to the existence of a lesion, its location, and associated deficits. The treatment plan emerging from the test results calls for a return to the pre-morbid level of functioning. Rehabilitation outcome has to also be measurable (Leon-Carrion et al, ibidem).

In contrast, the foundation of qualitative assessment, lies in classic clinical examinations, where the clinical and theoretical knowledge of the neuropsychologist are the most important tools, together with flexibility in choosing the instruments used in examining the patient. This examination is process-oriented rather than data-driven, producing behavioral and cognitive signs and symptoms thought to be meaningful only in a broad context. The patient’s relative strengths and weaknesses must be considered with respect to treatment efforts. Furthermore, the goal of rehabilitation is to assist the patient in achieving an optimal level of cognitive and behavioral coherence and independence, not necessarily a return to normalcy (Leon-Carrion et al. ibidem).

Over the years, American neuropsychologists have seemed most comfortable with tests that have strong psychometric properties and might be categorized as being quantitative in nature (e.g., Halstead-Reitan´s procedures). European neuropsychologists, on the other hand, have appeared to be most comfortable with qualitative clinical examinations (e.g., Luria´s procedures). Currently, the requirement of most scientific journals, quantitative methodology, seems to be the most extended and used method of assessment. Nonetheless, there is some merging of quantitative and qualitative methods, perhaps in an effort to be more universally appealing and comprehensive.

What are the goals of the Neuropsychological Assessment?

There are four main goals of neuropsychological assessment. Firstly, and most importantly, is to understand the nature of cognitive and behavioral problems produced by any brain injury and how this affects an individual’s functional activities. Only a complete neuropsychological assessment can comprehensively explain the changes and impairments produced in behavior, emotion, mood, attention, thinking, language, memory, reasoning, executive functioning, calculation, social relationships, etc. The data obtained from a sound neuropsychological assessment are the best guarantee for designing a sound rehabilitation program. There is no other way to understand and explain functional individual changes than through neuropsychological assessment. Secondly, neuropsychological assessment it is the main contributor to a diagnosis that determines the functional nature of an underlying neurological problem. Thirdly, assessments may be undertaken to control and monitor functional changes over time as a consequence of neuropsychological rehabilitation or treatments using drugs (Leon-Carrion, 1998). And lastly, neuropsychological assessment is the most powerful method to explain changes in an individual’s voluntary activities in a medico-legal case (Leon-Carrion & Leon-Jimenez, 2001), providing important evidence in personal injury litigation or in any other type of court action in which a person with brain damage is seeking compensation.

Can other methodologies be used in place of neuropsychological assessment?

A comprehensive neuropsychological assessment is the only way to obtain a comprehensive understanding of the functional deficits of neurological patients, including those suffering from stroke, traumatic brain injury, dementia, epilepsy, and brain tumors, among others (McKhann et al., 1984; Roman et al., 1993; Leon-Carrion, ibidem; Martelli et al., 2006) Of course, neuropsychologists work in a multidisciplinary setting with primary or consulting physicians such as neurosurgeons, neuroradiologists, and neurorehabilitators. The Social Security Administration has stated that a comprehensive neuropsychological examination, performed by a qualified and specialized neuropsychologist, may be used to establish the existence and extent of compromise of brain function (SSA, 2002). The American Academy of Neurology has rated neuropsychological testing as “Established” with Class II evidence and a Type A recommendation and having ICD diagnoses (National Academy of Neuropsychology, 1996).

Who can perform a neuropsychological assessment?

According to the official position of the Division of Clinical Neuropsychology of the American Psychological Association (APA, 2006), Division 40,the selection of tests, interpretation of those tests, clinical interviewing of patients or family members, and communication of test results and their implications is the sole and exclusive responsibility of the licensed neuropsychologist. Some neuropsychologists elect to use technicians that have a very narrowly defined and highly specific role in the overall process. These technicians are responsible only for the administration and scoring of neuropsychological tests under the supervision of a neuropsychologist who must be a licensed psychologist in that state or province. The ultimate responsibility for testing procedures and training remains with the licensed supervising neuropsychologist. The professional relationship in clinical neuropsychology is between the patient and the licensed neuropsychologist. Fees for service and accountability for the quality of professional work are exclusively the purview of the licensed neuropsychologist.

Is Neuropsychological Assessment reliable and valid?

Most published neuropsychological tests meet the requirements for reliability and validity. Test reliability is defined as the degree to which a test is consistent in measuring a cognitive function, a type of behavior, an emotional characteristic or a mood. A test with optimal reliability is one that gives the same values each time it is administered to a patient (Leon-Carrion, 1995).

In neuropsychological assessment, the most important types of reliability are those of interexaminer and test-retest. Neuropsychological tests require very high reliability. The interexaminer reliability coefficient should be over 0.90, and that of the test-retest should be no lower than 0.85 over a one week period (Rourke & Adams, 1984). Test validity refers to what a test measures and how this is done. Test validity aims to determine if a test actually measures what it claims to measure and if it does so with precision. A test may be valid for measuring a cognitive function such as emotion, for example, but not for measuring reasoning.

The two most important types of validity in neuropsychological assessment are criteria validity and content validity. The validity coefficients should always be over 0.60, and preferably over 0.70. Tests which do not meet this criterion, which must be described in their manuals, should not be applied in neuropsychological assessment. Some neuropsychological tests are very sensitivity and may reveal cognitive or behavioral abnormality in the absence of positive findings in MRI and CT scans. If the tests being used in these cases are considered valid and reliable, then these results should be accepted, for they may indicate the need for further testing using functional neuroimaging, which would explore the cerebral regions associated with the functional deficits found in the neuropsychological assessment. A comprehensive neuropsychological assessment can identify patterns of impairment that are normally not possible to determine through other procedures, thereby indicating the most appropriate treatment recommendations.

Paper-and-pencil neuropsychological-test batteries versus computerized neuropsychological-test batteries

Traditional paper-and-pencil neuropsychological batteries used to explore cognitive deficits in people with acquired brain injury have demonstrated some weaknesses. Traditional tests lack timing precision, making it difficult to accurately measure cognitive and psychomotor slowing in patients. Furthermore, traditional test batteries depend, in large part, on the motor and sensory skills of the examiner, who must take down all the details of the neuropsychological test with precision, particularly that of reaction times or complex and multitask responses. Finally, these traditional batteries may become lengthy and expensive.

Computerized neuropsychological-test batteries improve precision and accuracy, require less administration time, measure response time more precisely, are ideal for rapid screening/triage and most of the people feel comfortable, given that they are accustomed to using their personal computer. The new computerized batteries have been developed with normative data and with the reliability and validity of computerized measures. Both traditional and computerized test batteries identify patients with or without neurocognitive impairment, although computerized batteries seem to increase the accuracy of neuropsychological assessment as well as the accessibility of patients to this kind of testing.

Fig 1. Computerized Assessmen

Fig 1. Computerized Assessment: Assessment of decision making capacity through tower of Hanoi-Sevilla. The goal of this task is to build a pyramid on the 3rd bar by moving the discs one at a time, thus discovering the rules that govern the task (Leon-Carrion, 2007a).

Adapting or translating?

Qualitative methodology in patient assessment may be performed in the same manner in any hospital in the world, whereas quantitative methodology has specific requirements. Neuropsychological tests must be properly adapted. When the tests to be used were originally developed in a different language, a simple translation is insufficient and totally inadequate. Furthermore, any translation must provide an adaptation of certain patient characteristics, such as age, gender, and socio-economical/cultural status, to where the test or battery is going to be used (see Ponton and Leon-Carrion, 2001).

It is possible to exaggerate symptoms or malinger?

In the context of brain injury litigation, magnification of symptoms or non-optimal effort on neuropsychological tests is frequent. This must be taken into careful consideration during the administration of tests and during the process of scoring and interpretation. Some people exaggerate symptoms and others directly malinger. We should suspect malingering when we observe exaggeration in definitive negative response bias, discrepancy between test and known patterns of brain functioning, discrepancy between test data and observed behavior, discrepancy between test data and reliable collateral reports and discrepancy between test data and documented background history (Slick, Sherman, & Iverson, 1999). We normally solve this problem of symptom validity, especially in legal cases, by using what we call “neuroimaging neuropsychological assessment”. This involves the application of functional neuroimaging or neurophysiological techniques together with neuropsychological testing. An example of this would be the clinical implementation of event-related brain potentials (ERPs) as an on-line index of cognitive processing.

Fig 2. Neuroimaging in Neuropsychological Assessment

Fig 2. Neuroimaging in Neuropsychological Assessment: Different DLPFC Oxy-Hb concentrations and temporal courses for different reaction time (RT) groups in a computerized version of the classic Stroop task. Mean Oxy-Hb correlated negatively with reaction time in even (superior) channels (Leon-Carrion et al, submitted). (Full size)

Fig 3. Detecting malingered functional dependence through neuroimaging

Fig 3. Detecting malingered functional dependence through neuroimaging: QEEG pattern of the absolute amplitude measure for the complete dependence group minus the independence group (t values). The EEG scores of complete dependence patients showed greater slow wave activity (delta and theta), and less fast wave activity (alpha and beta). Bands that displayed significant differences were delta, with greater activity in the right hemisphere and posterior regions; alpha, with a generalized decrease; and high-beta, with greater activity in frontal regions (Leon-Carrion, 2007b.) (Full Size)

 

Jose Leon-Carrion, Ph.D.

 

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