Transient Retrograde Amnesia: a focal and selective (but temporary) loss of memory for autobiographical events.
Rosaleen A McCarthy George Pengas
Wessex Neurological Centre Southampton General Hospital
[email protected]
Introduction The sudden onset of severe amnesia occurs relatively frequently in the older population (5 7 per 100,000 cases in a General Hospital emergency room: Larner, 2006). In many instances recovery is complete within 24 hours (Hodges, 1991). The most widely documented presentation of is one of globally impaired anterograde and retrograde memory for events and episodes with preservation of other cognitive abilities including orientation in person (Hodges and Warlow, 1990) and recognition of friends and family (Hodges and Ward, 1989). After the event, patients typically “remember being unable to remember” but have no further recognition or recall.
Two main syndromes of Transient amnesia are recognized: Transient Global Amnesia (TGA: Fisher and Adams, 1964) and Transient Epileptic Amnesia (TEA: Kapur, 1990; Bultler and Zeman, 2008; Zeman et al1998) with a third, psychogenic form, being associated with a younger age of onset (e.g., Markowitsch, 2003; Kopelman, 2000: See Table 1). Other causes of transient memory loss include head injury, delirium, migraine, vascular ischemia and the effects of medication or alcohol.
Table 1: Near here
Transient memory disorders are not all global. Temporary disruption may affect procedural knowledge (Stracciari et al, 1997), semantic memory (Hodges, 1997); verbal learning and memory (Damasio et al, 1983; Nishiyama et al, 1993); autobiographical knowledge (Venneri and Caffarra, 1998); people (Kapur et al, 1994) and topographical orientation (Gil-Néciga et al, 2002; Stracciari et al, 1994). We have recently learned of a case of focal Transient
Retrograde Amnesia (TRAM) that appears to have spared the patient’s anterograde memory as well as retrograde familiarity for friends and family. To our knowledge, this is the first case of focal transient retrograde amnesia that cannot be explained by functional and psychiatric factors (e.g., Stracciari et al, 2008). The disorder could be “missed” or overlooked quite easily in clinical practice because of the subtlety of its presentation.
Case Report Frances A is a 62 year old, right handed retired professional woman who has been under investigation at the Wessex Neurological Unit following three episodes of transient global memory loss. In 2011 She had been investigated for paraesthesia and vertigo, undergoing an MRI scan. The first TGA (13/03/12) lasted for approximately four hours and occurred at a family funeral: Frances repeatedly greeted the same friends as if they had just arrived and repetitively asked whether certain people were going to attend. She made a full recovery. After the event, Frances listened to a CD recording of the funeral but did not experience any recognition. The second TGA (27/05/14) took place in the middle of the day. Frances was intending to entertain friends at her home but they found her in a confused state. She was asking where her husband was repetitively. Frances had largely recovered by the time she was seen in A&E (approximately 3 hours later) but, according to her husband, Frances seemed to be “daydreaming” for two or three days afterwards and was vague and forgetful for two weeks. The third TGA (24/08/14) occurred after an early afternoon nap. Frances began asking repetitive questions and was taken to A&E where her questioning continued. She reported tingling and pins and needles on her right foot and lower leg and had the same conversation
repeatedly with members of staff. The episode had resolved within four hours. Frances was admitted for observation and, when tested on the following day, scored 99 on the ACE-R.
The episode of Transient Retrograde Amnesia (TRAM) occurred at the reception following another family funeral (15/09/14).
Frances’s TRAM event differed very clearly from the previous three TGA occurrences due to sparing of Frances’s anterograde memory and new learning •
There was no repetitive questioning
•
Frances clearly remembered the immediate past and present
•
Older memories from the previous day and earlier were not retrieved
Frances’s husband recorded the details of the event and his notes are reproduced below (with minimal editing to preserve anonymity).
Frances was in conversation with a relative who asked her something like “What did the consultants say last week?” Frances said, “I don’t know” and smiled. Her husband asked “Do you really not know?” and Frances confirmed she could not remember.
“We sit down with M (a close friend) and go through some questions. Frances could remember everything that has happened that morning – (including a conversation and the name of one of the people who had sent flowers)”
“Frances knows where she is, why she is there and everyone in the room. Frances cannot remember her previous medical appointments, who is currently staying with us (Tom and
Jean had arrived the previous afternoon to stay and were planning to visit the Boat Show). Frances could not remember what we did Saturday afternoon/evening (visiting neighbours for a barbeque).”
“After 5 minutes Frances began to remember some details from the weekend - seeing Tina and Joe on Saturday and then Carol and Jeff and then the barbeque…. Remembers some details unprompted (“I made salads”). Remembers Tom and Jean arriving to stay. After 1015 minutes she was back to normal.”
Investigations MRI scanning in 2011 showed a small ischemic infarct in the right centrum semiovale; there was no change in 2014. EEG was normal.
Frances was seen in Neuropsychology on 17/09/2014: two days after her period of TRAM. Frances had clear recall of the TRAM episode and remembered that, at the time, she felt distressed at her difficulties (as well as being concerned at the time of the assessment in case another event occurred). On formal testing she scored within her expected average/good average range on measures of intellectual function (WAIS III) with scores at a superior level on Vocabulary, and average on Similarities and Digit Span. France’s NonVerbal subtest scores were all average.
Table 2 near here
On tests of anterograde memory most of Frances’s scores were mostly good (see Table 2). She made an increased number of false positives and missed a number of targets on the yes/no recognition phase of the California Verbal Learning Test (CVLT). Frances’s retrograde memory was tested by measures of Famous Face recognition and naming and by questioning about “public” events spanning the previous thirty-five years (e.g. why was there concern about Volcanic Ash in the UK?). Frances’s knowledge of personal events was evaluated across the same era using pictures and details of events provided by her husband (e.g., holidays, weddings and family get-togethers). Frances could give the same information as her husband in regard to these items. We were led to conclude that her retrograde memory had fully recovered to its good pre TRAM level.
Comment Frances experienced an episode of focal TRAM followed by full recovery of function. Her autobiographical memory was clearly affected but we cannot ascertain whether her retrograde amnesia extended to include public events as well. We are also unable to be sure of the duration of her TRAM as the amnesia only became apparent to others when Frances was directly asked to recall a specific event of the previous week. At a minimum the episode lasted for 20 minutes and at a maximum it may have lasted for around two hours. It is possible that Frances herself only became aware of her autobiographical amnesia following direct questioning: her preserved memory for events earlier in the day may have been due to her good anterograde memory. The characteristics of Frances’s amnesia differ from those reported in psychogenic memory loss (see Table 1) in terms of duration (very brief) and the apparent sparing of personal semantic knowledge including recognition of friends and family. The characteristics of Frances’s TRAM are very similar to
those observed in cases of chronic retrograde memory loss associated with amnesia in which autobiographical memory for events and episodes is compromised with relative sparing of personal semantic knowledge and familiarity for family members and places (e.g. McCarthy et al, 2005).
Frances’s overall presentation, with 3 recurrent TGAs and a TRAM is itself unusual, in that, although TGA can recur (Quinnette et al, 2006), and patients with a prior episode of TGA are at a higher risk of recurrence compared to the general population (5.8% annual recurrence rate), the sheer number of recurrences has raised questions of an alternative (i.e. ictal) diagnosis. However, we have found no evidence of temporal lobe seizure semiology, nor of features of TEA (such as confusional state in the mornings, persisting remote autobiographical episodic memory loss or lacunes, nor accelerated forgetting).
Frances’s case contributes to the debate as to whether a focal retrograde amnesia can be observed in the setting of spared anterograde memory. TGA (as well as classical amnesia) presents with variable durations of anterograde and retrograde memory impairment suggesting that differing processes and systems are involved in anterograde and retrograde retrieval. We would argue that Frances’s TRAM lies at one extreme of the range of possible presentations of TGA. Whereas classical TGA has its major impact on anterograde memory, Frances TRAM affects her retrograde memory and spares her anterograde memory.
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Table 1 Transient Amnesic Syndromes Incidence
Transient Global Amnesia 3-‐10 per 100,000
Age at onset Hypertension Frequently Associated symptoms Duration
Over 50 50% Migraine
Anterograde Retrograde
Defining symptom Variable: affects events No evidence of impairment
Personal Semantics Recognition family/friends Starting points Recurrence Recovery
Associated symptoms
Pathology
Treatment
2-‐12 hours
Physical or emotional Stressors 10-‐25% with average of 5% p.a. No persisting deficits
Transient Epileptic Amnesia Not known: under-‐ diagnosed? Over 50 Other epilepsy
Transient Psychogenic Amnesia Under 50 Migraine, Head injury, Low Mood,
Usually less than 1 hour: some last for days Defining symptom Variable: affects events No evidence of impairment
8 hours-‐6 months
On awakening
Variable – high prevalence of “organic” triggers Variable
Frequent (c. 3 per year) Residual deficits Accelerated long term forgetting; Poor retrograde autobiographical memory Occasional Other seizure types Dizziness, headache, (66%) Olfactory drowsiness, nausea hallucinations; oral and vomiting automatisms; occasional loss of responsiveness Medial temporal? EEG and MRI May be EEG and MRI normal: interictal: Vascular Migraine? temporal lobe sharp Venous? waves (33%); slow waves (33%) None Anti-‐epileptic drugs
Minimal Substantial Markedly Impaired Impaired
May be complete
Psychological
Frontal hypometabolism in some cases
Psychotherapy
Legend Table 1: Principal features of Transient Amnesic syndromes
Table 2: Frances’s scores on measures of anterograde and retrograde memory Anterograde Verbal BMIPB Story 1 Immediate BMIPB Story 1 Delay
Percentile 50 50-75
-CVLT:
Retrograde Famous Names Alive/Dead
Score 100%
Face Familiarity
75/75
Face Identification
73/75 65/75
◦
Trial 1-‐5
79
Face Naming
◦
List B
7
Public Events (N=33)
◦
Short-‐Delay Free
50
◦
1981-1985
1.75
◦
Short-‐Delay Cued
50
◦
1986-1990
1.71
◦
Long-‐Delay Free
16
◦
1991-1995
1.4
◦
Long-‐Delay Cued
31
◦
1996-2000
1.83
◦
Intrusions
31
◦
2005-2012
1.86
◦
Total Hits
2
-Autobiographical Events
Good
◦
False Positives
16
-Flashbulb: Diana’s death
Good
◦
Recognition d’
2
-Flashbulb: 911 attack
Good
75
Graded Naming Test
95th percentile
-Warrington RMT Words Anterograde Non-verbal
Mean (max 2)
Verbal Fluency
-Digit Symbol paired recall
>50
◦
FAS
91st percentile
-Digit Symbol free recall
>50
◦
Semantic
98th percentile
-Warrington RMT Faces
75
◦
Switch
84th percentile
Legend Table 2: Results of memory tests carried out on 17/09/2014 two days after Frances’s episode of TRAM. Anterograde memory test scores are converted to the nearest equivalent percentile rank (from Z and T values) in order to facilitate comparisons.
