Transcript Disorders of Memory

Secondary (Recent)
Memory
Secondary memory
Declarative
Episodic
Semantic
Procedural
Skills
Priming
Classical
Conditioning
Declarative Memory
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Knowing that
Explicit knowledge
Tulving: Two subdivisions
i) Semantic
ii) Episodic
Episodic Memory
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Memories that depend on temporal,
spatial or contextual cues in order the
retrieve the information (= explicit
memory)
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Consists of additional knowledge of
personal experience
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Involves remembering specific events
and episodes in the context in which
they occur
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***Typically disrupted in
amnestic conditions
Measures of Episodic Memory
Numerous
Examples:
WMS-IV/WMS-III: Paired
Associates, Logical Memory,
Visual Reproduction, Designs
Rey Complex Figure
RAVLT/CVLT/SRT
Selective Reminding
Test
A taxonomy of memory
disorders
AMNESIA
Neurological
Psychogenic
Transient
Permanent
Selective
Amnesia
Progressive
Transient
Global Amnesia
Stable
Post-Traumatic
Amnesia
Material
Specific
Post ECT or
Convulsion
Global
Frontal Amnesia
Amnesic Syndrome
Psychotic
Conditions
Cerebral hemispheres
Material Specific Memory
Disorder
Reflection of lesion laterality – Pathology of
the dominant V’s nondominant
hemipshere
1.
Temporal Lobe Epilepsy (TLE)
Milner (1958, 1962): Patients
undergoing unilateral temporal lobe
resection for relief of intractable
complex partial seizures
Temporal lobectomy: Anterior portion
(5cm) of temporal lobe removed
including the anterior portion of the
hippocampus
Memory Disorder: Material specific not
modality specific
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Left TL resection: Verbal
Memory Deficit
(logical memory, word
lists)
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Right TL resection:
Nonverbal Memory Deficit
(maze learning, design
recall, recall of faces)
Hippocampus thought to be the
important structure
TLE – Case Example
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Case: KE
Age: 19 years
Sex: Female
History:6 month history of
complex partial seizures
Eduction: HSC graduate,
Commenced first year of a
degree in PE teaching –
deferred due to memory
problems
Index
Index Score
Verbal Comprehension
Perceptual Reasoning
Working Memory
Processing Speed
Full Scale
General Ability
101
108
109
95
101
1`05
KA: Wechsler Memory
Scale-IV (WMS-IV)
Index Score
Auditory Memory
Visual Memory
Visual Working Memory
Immediate Memory
Delayed Memory
87
105
109
95
71
KA: Further Memory
Testing
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Selective Reminding Test
CLTR = 50 (Mean = 115, SD =
15.5)
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Recognition Memory Test
Scale Score
Words
5
Faces
11
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15-Item Visual Memory Test
Raw score = 15/15
15-Item Visual
Memory Test
A
B
C
I
II
III
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a
b
c
1
2
3
KA: Assessment of
adaptive abilities
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Controlled Oral Word
Association Test (COWAT)
Words = 39 (Mean = 41.5, SD
= 6.7)
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Wisconsin Card Sorting Test
Categories = 6
Perseverative Responses =
11
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Rey Complex Figure Test
Copy = 34, Recall = 22
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Booklet Category Test
Errors = 23
KA: Rey Figure Copy
KA: Rey Figure Recall
Material Specific
Disorders of Memory
(con’t)
2. Cerebrovascular Disorders
Disruption of brain function secondary to vascular
pathology (includes haemorrhage (rupture),
narrowing (stenosis) and occlusion due to
presence of an obstructing clot (thrombus or
embolus)
Branches of the posterior cerebral artery supply
the inferior and medial surfaces of the
temporal lobes and posterior sections of the
hippocampus. Thus, infarction (tissue death)
may result from occlusion and produce a
material specific memory disorder
Unilateral thalamic infarction (secondary to PCA
disturbance) may also produce a material
specific disorder of memory.
Specific Disorders of
Memory
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Topographical disorientation
Damage to the right temperoparietal areas (MCA)
Unable to find way around.
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Tactile Memory
Impairment reported in
patients with unilateral
temporal lobe lesion resulting
from CVA with loss
demonstrated in hand
contralateral to the lesion.
BS: Lateralised
(R.Hem) Dysfunction
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45 yo female
9 years education
DSS (clerical) for 17 years
3-4 months preceding ABI worked as a taxi
driver
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1/1/02 assaulted during the course of her
work
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PTA: several days duration (no recollection
of visitors while in hospital, son receiving
HSC results)
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CT (2006): Local area of
enlargement of the temporal
horn of the right lateral ventricle,
enlargement of the right Sylvian
fissure. Appearances consistent
with an area of local atrophy.
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Psych Tx for PTSD
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Psychiatrist noted that she
intermittently complained of
memory problems and
geographical disorientation
Case BD
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Assessment
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February 2007
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Attended unaccompanied
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Fully cooperative
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c/o - memory problems (eg.
Forgets where she is meant
to be driving to, gets lost even
when driving to familiar
places, misplaces her
personal belongings)
- irritability
WAIS-IV
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Verbal IQ = 116
PIQ = 110
Working Memory = 117
Processing Speed = 104
Full Scale IQ = 111
General Ability = 113
WMS-IV
INDEX
ACTUAL
PREDICTED
Auditory Mem
103
106
Visual Mem
75
106
Visual Working
Mem
108
107
Immediate Mem
_
107
Delayed Mem
_
106
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Base Rates (General
Ability)
AM - >25%
VM - <1%
BD: Additional
Memory Tests
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Selective Reminding Test
Consistent Long-Term
Retrieval – Average
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Rey Complex Figure Test
Copy = 25
Recall = 4.5 (<1st percentile)
BD: Adaptive Abilities
and Emotional Status
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Trail Making Test
Part A = 26 seconds, 0 errors
Part B = 50 seconds, 0 errors
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Controlled Oral Words Association Test
(COWAT)
Words = 45, Errors = 3
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Wisconsin Card Sorting Test
Categories = 6, Errors = 12
Perseverative Responses = 6 (Above
Average)
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Booklet Category Test
Errors = 107 (Impaired)
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Depression, Anxiety, Stress Scales
Depression = 40 (Ex.S.),
Anxiety = 36 (Ex.S.), Stress = 32 (Ex.S.)
BD: Opinion
The results of the assessment revealed
clear evidence of cognitive impairment.
Although generally able to achieve at an
average to high average level on
measures of verbal ability, her nonverbal
skills proved markedly disordered.
Specifically, she demonstrated difficulty
in acquiring, retaining and processing
visuospatial material. Although she is
clearly suffering significant levels of
emotional distress, reference to these
factors alone would not appear to be
sufficient to account for all of the deficits
seen on testing.
Neither depression nor anxiety would be
expected to produce a material-specific
disorder of memory and adaptive ability.
A disparity between performance on
measures of verbal and nonverbal ability,
when of the magnitude that was evident
in the present case, is strongly
suggestive of lateralised cerebral
pathology. The profile of performances
returned on testing would suggest that
there has been damage to the frontal
and temporal lobes of the nondominant
(right) hemisphere. The CT report
provides independent evidence of focal
damage to these areas.
BD: Opinion (con’t)
Given the results of the assessment it is not
surprising to learn that BD complains of
a tendency to get lost while driving and
occasion geographic disorientation. The
ability to remember routes and to
understand spatial relations is known to
be mediated by the right hemisphere.
Recalling the temporal detail of various
events is thought to represent one of the
functions that is subserved by the frontal
lobes. As stated above, the results
would suggest that these areas have
been damaged.
BD: Opinion (con’t)
On a day to day level BD’s deficits are most
likely to manifest as a difficulty in
recalling visual information (scenes,
routes, faces etc), a difficulty in planning
her approach to nonverbal tasks (eg.
when assembling an item or dealing with
procedures that involve a number of
steps) and an inability to reason and
problem-solve in the nonverbal modality.
She may experience difficulty in learning
the requirements of any new position,
particularly if the work involves nonverbal
displays or tasks. She should be
encouraged to verbalise information and
to make written note of new procedures.
Her ability to operate a computer may be
compromised in that she is likely to
find it difficult to remember the
meaning of various symbols and
the full range of responses that a
particular visual cue is designed
to elicit. Even when her mistakes
are drawn to her attention she is
likely to have difficulty in
generating some alternative
method of response. Modelling of
the correct procedure would be of
use. Flow-charts or other
nonverbal displays are unlikely to
be of assistance.
Frontal Amnesia
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A. Organisational Deficits
Simple registration and recall not affected by frontal
lesions
Memory problems may be secondary to an inability to
organise material for the purpose of committing it
to memory
i.e. failure to impose a meaningful structure on the
information, to generate appropriate learning
strategies
Frequent concomitant of traumatic brain injury
Manifest on tests such as Rey Complex Figure, Rey
Auditory Verbal Learning
Frontal Amnesia
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B. Retrieval Problems
Retrieval involves strategic problem-solving.
Often disturbed following frontal lesions
Patient with a retrieval deficit will demonstrate a
disturbance of free recall
Recognition memory should, however, be intact
eg. RAVLT: poor score on recall of list A (trials 16)
recognition 15/15
One advantage of WMS-III relative to WMS-R
Frontal Amnesia
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C. Temporal Discrimination
Increasing attention being devoted to this aspect of
memory
Patients with frontal lesions are markedly impaired in
making temporal discriminations. Great difficulty in
judging recency and temporal order and in
reconstructing sequences.
Note, deficits of temporal ordering may be seen in the
absence of fontal lobe pathology
Two processes involved:
a) Encoding of information needed for temporal
memory
b) Effective processing of retrieved information
regarding temporal order
In patients with lesions of the frontal lobes deficit lies in
b) ie. Is one of faulty processing (c.f. WKS patients
where the deficit lies in a)).
General Amnesic
Syndrome
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Definition
A permanent, stable and global
disorder of memory due to
organic brain dysfunction which
occurs in the absence of any
other extensive perceptual or
cognitive disturbance.
NB. Permanency
Stability
Pervasiveness
Specificity
Clinical Features of
the Amnesic
Syndrome
1.
2.
3.
4.
5.
Profound difficulty or total inability to
acquire new material (anterograde
amnesia)
Preservation of immediate memory
as measured by tasks such as digit
span
Preservation of semantic memory
Preservation of procedural learning
Some retrograde amnesia (variable
across patients)
Neuopathology
Brain structures implicated:
1.
Bilateral damage to the mesial temporal
lobes of both the right and left hemispheres
Within these areas the hippocampus has
been seen to represent the crucial structure
2. Structures within the diencephalon and
specifically:
Nuclei within the thalamus
Mamillary bodies
Mamillo-thalamic tract
Fornix
All above structures represent part of the limbic
system
Aetiology
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6.
GAS typically seen in
association with
Wernicke-Korsakoff Syndrome
Herpes Simplex Encephalitis
Hypoxia
Anterior Communicating Artery
Aneurysm
Thalamic Infarction
Temporal Lobe Resection
Other causes:
CVA
Tumour
Wernicke-Korsakoff
Syndrome
Typically the result of chronic alcoholism
Principle cause: Thiamine deficiency
Results in damage to the subcortical structures and in
particular the diencephalon
Minimal requirement: Lesion of the mamillary bodies
and dorsomedial nucleus of the thalamus
Typically additional lesions in the frontal lobes
(atrophy) due to alcohol neurotoxicity and often
the medial temporal structures including the
hippocampus
Treatment. Thiamine. Amnesia often persists
WKS: Characteristics
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6.
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Normal memory span
Severe anterograde amnesia
Normal rate of forgetting
Extensive, temporally graded
retrograde amnesia
Confabulation present
Cued recall better than
spontaneous recall
Recognition relatively intact
Poor at recency judgements
Frontal lobe dysfunction
typically present