NEUROPSYCHOLOGICAL EVALUATION
Structural vs. Functional Deficits in Neurological Conditions
When evaluating neurological conditions, neurologists and physicians use a
variety of techniques, including, physical examination, x-rays, EEGs, CT scans,
PET-scans, and MRI scans. Over the years, these evaluations have become more and
more sophisticated and accurate. Nevertheless, these assessments are still
limited, in that they frequently fail to identify brain dysfunction.
One reason why x-rays and brain scan may miss the presence of brain
dysfunction is that these assessments are designed primarily to identify
structural deficits in
the brain. They will identify structural abnormalities such as the presence of a
skull fracture, haematoma, contusions on the brain, asymmetry of the brain, and
so on. The findings from these assessments can be likened to photographs showing
the dents and broken structures of a car after an accident. In the absence of
observable structural defects, one cannot tell, just by looking at the
photograph of it, whether the car can move or not. Neuropsychological
evaluations are useful in that they help to identify
functional deficits of the
brain. They evaluate the brain in action.
For example, it is a common finding from
neuropsychological tests that although the CT scan could not find any structural
abnormalities. Neurologists also evaluate functional deficits, with techniques
such as EEGs and blood flow studies. Neuropsychological evaluations are an
important complement to these measures.
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Diagnostic role for neuropsychology
- Neuropsychological evaluation is used to discriminate between
neurological conditions and psychiatric conditions; and in differentiating
between different neurological conditions.
- Neuropsychological tests and interviews relying on neuropsychological
models are helpful in localizing sites of brain injury. For example,
depending on how one performs on cognitive tests, it may be possible to
determine whether the injury to the brain is in the right or the left
hemisphere of the brain.
Quantifying progress with neuropsychological tests
- Using neuropsychological tests, we can quantify the changes that take
place before and after surgical operations on the brain, or drug treatment.
- Neuropsychological tests come in handy when assessing the side-effects of
medication. One can objectively measure the effects of medication on motor
functions, attention and concentration, as well as on memory.
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What functions do neuropsychologists evaluate?
Neuropsychological evaluations cover the following areas:
1. Sensory and Motor functions
This covers assessment of perception in the visual, auditory, tactile,
and olfactory senses. Motor function involves assessment of grip strength,
and assessment of motor dexterity.
Above is a picture the hand dynamometer (by LEFAYETTE), one of the
devices used to assess motor functions in patients. The patient grips and
squeezes the lever as hard as he or she can. This moves the pointer,
indicating the extent of force used in kilograms, which is referred to as
grip strength. Assessment of grip strength is important in neurological
evaluations because it helps us to document whether or not there is a
weakness of the limbs.
2.
Verbal functions and Language Skills
The tests used here are for the evaluation of aphasia, verbal expression,
and verbal academic skills.
3.
Cognitive functions
- attention and concentration
- memory
- concept formation and reasoning
- general intellectual functioning (IQ)
4.
Evaluation of executive functions of the brain
By the term "executive functions" is meant the brain's ability to
formulate goals, to determine strategies for achieving the goal, to
implement the strategies, and to evaluate one's performance against the
original goals (Luria, 1973).
The executive functions depend on an intact frontal lobe. (see OVERVIEW OF BRAIN FUNCTIONS)
5.
Behavioural and personality evaluation
We interview patients and/ or their relatives or employers to document
whether or not there has been any significant changes in behaviour. Frontal
and temporal lobe damage are frequently associated with major changes in
behaviour, such as lack of motivation, disinhibition, and irritability.
Third Party Evaluations: Motor Vehicle Accidents
In cases of traumatic brain injury from motor vehicle accidents,
neuropsychologists are frequently asked to write medico-legal reports for
the courts. We receive referrals come either from lawyers, or directly from
the Road Accident Fund.
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Copyright © 2001, Dr. J.F.L.
Mureriwa. All rights reserved.
www.biofeedback.co.za