Authors: Lewis, Steven L.
Title: Field Guide to the Neurologic Examination, 1st Edition
Copyright ©2004 Lippincott Williams & Wilkins
> Table of Contents > Section 2
– Neurologic Examination > Mental Status Examination > Chapter 5
– Approach to the Mental Status Examination
– Neurologic Examination > Mental Status Examination > Chapter 5
– Approach to the Mental Status Examination
Chapter 5
Approach to the Mental Status Examination
PURPOSE
The purpose of the examination of mental status is to
look for evidence of disorders that can affect the level of
consciousness (alertness) or any aspect of cognitive function.
look for evidence of disorders that can affect the level of
consciousness (alertness) or any aspect of cognitive function.
WHEN TO PERFORM THE MENTAL STATUS EXAMINATION
Mental status should be informally assessed in all
patients simply by observing and listening to the patient while you are
taking the history. Formal evaluation of mental status should be
performed when there is a clinical suspicion or complaint of a
cognitive problem, or when there appears to be a decrease in the
patient’s level of consciousness.
patients simply by observing and listening to the patient while you are
taking the history. Formal evaluation of mental status should be
performed when there is a clinical suspicion or complaint of a
cognitive problem, or when there appears to be a decrease in the
patient’s level of consciousness.
NEUROANATOMY OF THE MENTAL STATUS
Level of Consciousness
To be awake and alert requires intactness of at least
one of the cerebral hemispheres, as well as the upper brainstem from
the middle of the pons and above (see Chapter 42, Examination of the Comatose Patient).
one of the cerebral hemispheres, as well as the upper brainstem from
the middle of the pons and above (see Chapter 42, Examination of the Comatose Patient).
Cognition
Cognition is a general term
referring to mental abilities, such as memory, language, orientation,
knowledge, and other aspects of intellectual functioning. Some
cognitive abilities have well-recognized neuroanatomic localization,
such as language to the dominant cerebral hemispheric cortex (see Chapter 6, Language Testing) or memory to the medial temporal lobes and thalami (see Chapter 7,
Memory Testing); most other cognitive functions, however, although
known to involve the cortex, are not clinically localizable to a
specific neuroanatomic area.
referring to mental abilities, such as memory, language, orientation,
knowledge, and other aspects of intellectual functioning. Some
cognitive abilities have well-recognized neuroanatomic localization,
such as language to the dominant cerebral hemispheric cortex (see Chapter 6, Language Testing) or memory to the medial temporal lobes and thalami (see Chapter 7,
Memory Testing); most other cognitive functions, however, although
known to involve the cortex, are not clinically localizable to a
specific neuroanatomic area.
EQUIPMENT NEEDED TO PERFORM THE MENTAL STATUS EXAMINATION
None (except paper and a pen or pencil).
HOW TO EXAMINE MENTAL STATUS
See Chapter 6, Language Testing; Chapter 7, Memory Testing; and Chapter 8, Testing Orientation, Concentration, Knowledge, and Constructional Ability for additional information.
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NORMAL FINDINGS
Normally, patients should be awake and alert, fully
oriented, have no impairment of language or memory, and have
intellectual functioning compatible with their level of education and
occupation.
oriented, have no impairment of language or memory, and have
intellectual functioning compatible with their level of education and
occupation.
ABNORMAL FINDINGS
Level of Consciousness
Changes in the level of consciousness from drowsiness to
coma can occur due to dysfunction of both cerebral hemispheres,
dysfunction of the upper brainstem (from the middle of the pons or
above), or the combination of hemispheric and upper brainstem
dysfunction (see Chapter 42, Examination of the Comatose Patient).
coma can occur due to dysfunction of both cerebral hemispheres,
dysfunction of the upper brainstem (from the middle of the pons or
above), or the combination of hemispheric and upper brainstem
dysfunction (see Chapter 42, Examination of the Comatose Patient).
Cognition
-
Changes in cognition can occur due to
dysfunction anywhere within the cerebral hemispheres. Cognitive changes
generally do not occur with lesions of the brainstem. -
Dysfunction of language (see Chapter 6, Language Testing) usually occurs due to a lesion within the dominant hemisphere.
-
Disorders of memory (see Chapter 7, Memory Testing) tend to occur due to dysfunction of the medial temporal lobes or the thalami.
-
Patients with the cognitive deficit of
neglect of the left side of space, such as ignoring the left side of a
figure when drawing (see Chapter 8, Testing
Orientation, Concentration, Knowledge, and Constructional Ability), or
ignoring the left side of their body, have dysfunction of their right
(usually nondominant) hemisphere. -
Other cognitive problems, such as confusion and problems with orientation and knowledge (see Chapter 8,
Testing Orientation, Concentration, Knowledge, and Constructional
Ability), may not be localizable to a specific anatomic lesion and are
likely due to multifocal or diffuse brain dysfunction. -
Impairment of processes such as judgment,
mood, or the perception of reality (e.g., psychosis) can occur due to
psychiatric disorders (in which the discrete neuroanatomic or
physiologic lesion causing such symptoms is generally unknown),
although similar symptoms can occur as a result of diffuse brain
dysfunction associated with dementing illnesses or acute
encephalopathies (delirium).
ADDITIONAL POINTS
-
Changes in cognition can and usually do
occur without necessarily affecting the level of consciousness. For
example, patients with chronic dementia usually have normal alertness
despite significant deterioration in cognitive functioning. -
Standardized batteries of mental status
testing are used by many clinicians to screen patients for cognitive
impairment, particularly in the setting of possible dementia. The most
commonly used of these is the Folstein Mini-Mental State Examination,
which uses a series of tasks to assess multiple areas of cognition.
This test can give a somewhat quantitative score of global cognitive
function, which can be followed serially to assess for worsening or
improvement in the patient’s symptoms. In the undiagnosed patient with
a disorder of mental status, however, it is the assessment of the
patient’s ability to perform the specific individual components of
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mental
status testing (whether part of a standardized battery or not) that is
of greatest diagnostic significance when attempting to localize and
diagnose a potentially focal neurologic disease process. -
Cognitive testing should always be
interpreted within the context of the patient’s baseline level of
intellectual functioning, as determined by the information obtained
from the history (through the patient and family) about factors such as
the patient’s educational status and occupation.