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 7 – Memory Testing
Chapter 7
Memory Testing
PURPOSE
The purpose of memory testing is to look for evidence of
difficulty remembering that can occur from illnesses that affect
cognition in general (such as dementing diseases) or from illnesses
that affect memory alone (amnesic disorders).
difficulty remembering that can occur from illnesses that affect
cognition in general (such as dementing diseases) or from illnesses
that affect memory alone (amnesic disorders).
WHEN TO TEST MEMORY
The ability of your patient to recall recent and distant
events is often evident during your conversation with the patient while
you are taking the history. You should formally test memory when there
is a complaint by the patient or the patient’s family of a problem with
memory or any other cognitive difficulty, or when you suspect a
disorder of memory or cognition from your conversation with the patient.
events is often evident during your conversation with the patient while
you are taking the history. You should formally test memory when there
is a complaint by the patient or the patient’s family of a problem with
memory or any other cognitive difficulty, or when you suspect a
disorder of memory or cognition from your conversation with the patient.
NEUROANATOMY OF MEMORY
Definitions of the various aspects of memory differ
depending on whether you are talking to a clinical neurologist or a
neuropsychologist. Most neurologists simply divide the kinds of memory
that we test (called episodic memory) into
immediate recall, short-term memory, and long-term memory, and the
following discussion defines these terms as they are commonly used and
understood by most clinical neurologists.
depending on whether you are talking to a clinical neurologist or a
neuropsychologist. Most neurologists simply divide the kinds of memory
that we test (called episodic memory) into
immediate recall, short-term memory, and long-term memory, and the
following discussion defines these terms as they are commonly used and
understood by most clinical neurologists.
Immediate recall (also called working memory)
refers to the kind of memory that we use to remember things for
seconds, and it should probably be thought of more within the realm of
concentration than memory. Examples of immediate recall include
remembering a telephone number for the few seconds before finding a
piece of paper on which to write it down or remembering the beginning
of a sentence before getting to the end of the sentence. The
neuroanatomic localization for immediate recall is not clear.
refers to the kind of memory that we use to remember things for
seconds, and it should probably be thought of more within the realm of
concentration than memory. Examples of immediate recall include
remembering a telephone number for the few seconds before finding a
piece of paper on which to write it down or remembering the beginning
of a sentence before getting to the end of the sentence. The
neuroanatomic localization for immediate recall is not clear.
Short-term (also called recent) memory
refers to memory for events that occurred minutes, days, weeks, or even
months ago. Examples of short-term memories include remembering what
you had for breakfast this morning or for dinner last Sunday, or where
you went on vacation last month. The brain structures that are involved
in the ability to recall short-term memories are the hippocampi (which
reside in the medial temporal lobes) and the thalami.
refers to memory for events that occurred minutes, days, weeks, or even
months ago. Examples of short-term memories include remembering what
you had for breakfast this morning or for dinner last Sunday, or where
you went on vacation last month. The brain structures that are involved
in the ability to recall short-term memories are the hippocampi (which
reside in the medial temporal lobes) and the thalami.
Long-term memory refers to
memory for distant events, such as events that occurred years ago.
Examples of long-term memories include remembering where you lived and
went to school when you were a child. Where these long-term memories
reside within the brain is not clear, but they probably are stored
somewhere within and possibly throughout the cerebral cortex.
memory for distant events, such as events that occurred years ago.
Examples of long-term memories include remembering where you lived and
went to school when you were a child. Where these long-term memories
reside within the brain is not clear, but they probably are stored
somewhere within and possibly throughout the cerebral cortex.
EQUIPMENT NEEDED TO TEST MEMORY
None.
HOW TO EXAMINE MEMORY
Immediate Recall (Working Memory)
-
Tell the patient you will be asking him or her to repeat a list of numbers back to you after you have recited the list.
-
Recite a list of approximately six or seven single-digit numbers to the patient, such as “3, 9, 6, 4, 8, 7.”
-
Listen to the patient’s ability to repeat
the numbers back to you and note any errors or omissions. Repeat the
test with a shorter list if the patient has difficulties. -
Another test of immediate recall—and
probably all that is usually necessary to test this—is imbedded in the
initial part of the short-term memory test: A patient’s ability to
immediately repeat three words back to you (that you give to test
short-term memory as described below) is a test of immediate recall.
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Short-Term (Recent) Memory
-
Tell the patient you will be asking him
or her to try to remember three words that you will recite. Explain to
the patient that you will ask him or her to repeat the words
immediately to you and that you also want the patient to remember the
words because you will ask him or her to recall the words again in a
few minutes. -
Tell the patient the three words. Choose
simple but unrelated words; a common choice is “apple, table, penny,”
but any three words will do. -
Ask the patient to repeat the words back
to you. If the patient is able to immediately recall all the words,
remind the patient that you will ask him or her to repeat the words
back to you in a few minutes. If the patient is unable to immediately
repeat all three words, restate the words until he or she is able to
immediately recall all of them. -
Wait approximately 2 minutes. During the
intervening minutes, bide the small amount of time (e.g., make notes in
your chart, talk with the patient, or perform another brief part of the
examination). -
Ask the patient what the three words were that you instructed him or her to remember. Make a note of any errors or omissions.
-
If the patient forgets one or some of the
words, it is helpful to give the patient a clue (such as “One of the
words was a kind of fruit”) and see if this prods the patient into
recalling the forgotten word.
Long-Term (Distant) Memory
-
Testing long-term memory is imbedded in
taking the patient’s history, such as when you ask about past medical
illnesses, family history, and the patient’s occupation. To
specifically test the patient’s recall of distant memories not already
included in the routine history, ask the patient a verifiable question,
such as where he or she grew up and where he or she went to high school
or college. -
Verify that the answer is correct by
asking a family member if one is present with the patient. In the
absence of such verification, accuracy of long-term memories may be
difficult to confirm.
NORMAL FINDINGS
Immediate Recall
Normally, patients should be able to correctly
immediately recall a list of approximately six numbers, and they should
also be able to immediately recall the three words that you give them
when you begin the test of short-term memory.
immediately recall a list of approximately six numbers, and they should
also be able to immediately recall the three words that you give them
when you begin the test of short-term memory.
Short-Term (Recent) Memory
Patients should normally be able to recall three words
after a delay of a few minutes. Note, though, that the ability to
successfully recall a word or words with clues does suggest some intact
memory for that word and can also be
after a delay of a few minutes. Note, though, that the ability to
successfully recall a word or words with clues does suggest some intact
memory for that word and can also be
P.25
consistent
with normal memory function (one way to report this finding on a memory
test would be, “The patient recalled two out of three words after 2
minutes, and did recall the third word after given a clue.”).
Long-Term (Distant) Memory
Normally, patients should be able to accurately recall significant personal events from the distant past.
ABNORMAL FINDINGS
Immediate Recall
-
Difficulty correctly recalling a list of
six numbers or difficulty immediately recalling the three words that
you give the patient when you begin the test of short-term memory is
consistent with difficulty in immediate recall. -
Because immediate recall is more of a
test of concentration than memory, errors of immediate recall suggest
difficulty with concentration and attention (see Chapter 8,
Testing Orientation, Concentration, Knowledge, and Constructional
Ability), as can be seen as a result of any cause of (diffuse or focal)
brain dysfunction.
Short-Term (Recent) Memory
-
Difficulty remembering any of three words, even with clues, after a few minutes suggests a problem with short-term memory.
-
Problems with short-term memory suggest
dysfunction of the hippocampal or medial thalamic memory structures.
Generally, to have significant impairment of short-term memory, there
needs to be bilateral dysfunction of these structures. For example, a
unilateral hippocampal or medial thalamic lesion usually does not
significantly affect short-term memory. Memory is usually severely
affected by bilateral hippocampal or bilateral medial thalamic lesions,
however. Such dysfunction of the hippocampal/ thalamic memory system
can be seen due to focal lesions affecting these areas alone (amnesic
disorders) or, for example, as part of the diffuse cortical dysfunction
that can be seen in dementing illnesses.
Long-Term (Distant) Memory
Problem with recall of significant distant personal
events is unusual and would mainly be seen in the context of diffuse
cortical dysfunction, such as can occur from severe dementing
illnesses. In most cases of dementia, however, recall of past events is
affected later and less severely than recent memories.
events is unusual and would mainly be seen in the context of diffuse
cortical dysfunction, such as can occur from severe dementing
illnesses. In most cases of dementia, however, recall of past events is
affected later and less severely than recent memories.
ADDITIONAL POINTS
-
It is rare for patients to lose memory
for self. Loss of personal identity suggests a nonneurologic cause of
the “memory” dysfunction, such as conversion disorders or malingering. -
The kind of memory assessed in clinical neurology, as described in this chapter, is called episodic memory.
Episodic memory refers to memory for events and experiences (including
memory for a list of words presented by the examiner); it is episodic
memory that we divide into time-related functions, such as immediate
recall and short-term and long-term memories. Other types of memory
function include procedural memory (memory for skills, such as how to
ride a bicycle) and semantic memory (memory for facts, concepts, and
the meaning of words). Unlike episodic memory, these types of memories
are not related to specific events or experiences, and they are not
what we’re testing at the bedside when we examine memory in clinical
neurology.