Medicine Review Course Approach to Transient Amnesia

Transcription

1 Medicine Review Course Approach to Transient Amnesia 9 Sept 2012 Dr See Siew Ju Neurology NNI@SGH

2 A Few Questions.. What did you have for breakfast on Friday? How many red lights did you stop at on your way here today? What did you do on your birthday last year?

3 Memory Acquisition of new memories. Consolidation of recently acquired memories. Retrieval of established memories.

4 Transient Amnesia? Temporarily unable to lay down new memories (anterograde amnesia), to retrieve established memories (retrograde amnesia) or both, while other cognitive function remain intact.

5 Transient Ammesia Transient global amnesia Seizures Complex partial seizures/ dyscognitive seizure Transient epileptic amnesia Closed head injury/ post traumatic amnesia Delirium Pyschogenic amnesia

6 Transient Ammesia Transient global amnesia Seizures Complex partial seizures/ dyscognitive seizure Transient epileptic amnesia Closed head injury/ post traumatic amnesia Delirium Pyschogenic amnesia

7 Case Mdm A Mdm A, 60+ year old, PMH hypertension. Came to your clinic 2 days after some memory problem: Mdm A failed to meet spouse at 4 pm as planned after their regular activities at a recreational club. Found by husband sitting by the swimming pool, still in her swim gear. Pt, Where am I? Why am I here? Spouse, Where are your things/ bags? Pt, What things? I don t know.

8 Case Mdm A History from patient and her spouse On that weekend, Mdm A woke up well, drove to her sister s home to deliver some food items, talked with her sister, later met spouse at the recreational club. Spouse went for his usual golf practice, Mdm A swimming, their usual practice. (Mdm A uses the same locker at the club when she visits). After that, she failed to meet her husband as they had originally planned.

9 Case Mdm A History from patient and her spouse Spouse found her, looked for her belongings, walked her to the car & they went home. She was able to speak, understand & reason, but was unable to explain what happened earlier. Unable to recall that she had been to her sister s home, gone to the recreational club, swimming & where she placed her belongings. Recognized her spouse, children, home. Behavior was described by family as being otherwise her normal self. The next day, she was alert, able to carry out her usual activities, no more puzzlement over where she was/ why she was where she was. Over days, she gradually recalled having being to her sister s home, seeing her, going to the club, but not events after till end of that day.

10 Case Mdm A Day 1 Events Drove to sister s home Passed her food items Drove to club Placed belongings in locker Swam Found by spouse: Where am I? Why am I here Went home Life goes on Retrograde amnesia TGA episode started Anterograde amnesia A few hours later... Memory of events returns Persistent gap Anterograde memory gradually returns

11 Transient Global Amnesia Who gets it? Rare. Three 8 per people per year 75% of attacks occur in persons years old. Any triggering event? Lancet Neurology 2010

12 Transient Global Amnesia Clinical syndrome with Reversible prominent anterograde amnesia Variable retrograde amnesia Retention of self awareness. Other cognitive functions and ability to perform complex tasks such as driving or cooking are retained. Accompanied by anxiety & agitation, repeated questions. Duration = 6 hours As spell resolves, retrograde amnesia usually resolves, leaving an anterograde amnesic gap for the main episode.

13 Transient Global Amnesia Neuroanatomy Hippocampus (CA-1) implicated. Unilateral or bilateral

14 Transient Global Amnesia Etiology or Etiologies Remains uncertain, hypotheses include Arterial insufficiency, i.e. TIA Venous congestion from jugular valvular insufficiency + valsava maneuver. Migrainous neuronal and glial depolarisation

15 Transient Global Amnesia No diagnostic test. Most valuable = Detailed witness s account Need to Exclude other conditions Seizure/ Epilepsy Hypoglycaemia No treatment Excellent prognosis Recurrences are rare Does not predict future cognitive decline.

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17 Epileptic Seizures Patients will be amnesic of events that occurred during a generalised or complex partial seizure where consciousness was affected. Component of retrograde & anterograde amnesia. Witness account = CRUCIAL

18 Epileptic Seizures Complex partial seizures These are often accompanied by other outward ictal manifestations. Automatism: lip smacking, stereotypic movements Posturing of limbs +/ - Dysphasia Duration 1-2 min May or may not be preceded by epileptic aura (and patient may not be able to recall having one). Fear, rising sensation in epigastrium, déjà vu etc

19 Complex Partial Seizure

20 Case 2

21 Transient Epileptic Amnesia Epileptic seizures where Patient is temporarily unable to form new memories (anterograde amnesia) or to retrieve established memories (retrograde amnesia), or both. Other cognitive functions remain intact. Zeman et al, JNNP 1998 Bulter et al, Ann Neurol 2007

22 Transient Epileptic Amnesia Other features of TEA attack Retrograde amnesia more prominent. Anterograde amnesia may not be complete Patient may have partial recall of event Absence of repetitive questioning (50%). Duration < 1 hour (typically < 30 min) Attacks often occur on awakening from sleep.

23 Transient Epileptic Amnesia Patients with TEA Onset: Age years old. 70% has other features suggestive of epileptic etiology: Other seizure types Amnesic attacks preceded by olfactory hallucinations, loss of responsiveness, automatism. Controlled with low dose AED (Automatism: stereotypic movements that occur during the patient s seizures e.g. Lip smacking, swallowing, hand fidgeting)

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25 Transient Epileptic Amnesia Epileptiform changes on EEG Other features of epilepsy sometimes present N = 50 patients Clear cut response to AEDs

26 Transient Epileptic Amnesia Pathophysiology Epileptic activity starting in or spreading to the mesial temporal lobes. Ictal electrical activity disrupts Acquisition of new memories. Retrieval of established memories. Consolidation of recently acquired memories. Amnesia can occur in aftermath of a seizure i.e. post ictal phenomenon.

27 TGA vs TEA Transient Global Amnesia Transient Epileptic Amnesia Duration of attack 1 24 H < 1 H Recurrence Rare Frequent Pattern of amnesia Repetitive questioning during attack Other ictal symptoms (accompanying amnesic attack or occurring independently) Prominent anterograde amnesia Prominent retrograde amnesia Typical Absent in approx 50% No Interitcal EEG Normal 30% has epileptic discharges Yes

28 Post Traumatic Amnesia Following a blow to the head (with or without LOC), patient may have a period of amnesia. Anterograde amnesia then to be more brief than Retrograde amnesia Both improve over hours or less. No loss of autobiographical information (name, DOB etc). Ropper & Gorson, NEJM 2007 McCrea et al, Neurosurgery 2002

29 Summary Transient amnesia = Temporarily unable to lay down new memories (anterograde amnesia), to retrieve established memories (retrograde amnesia) or both, while other cognitive function remain intact. Transient Global Amnesia & Transient Epileptic Amnesia shares several similar features but are distinct and clinically distinguishable conditions. Carefully obtained detailed history from patient and reliable witnesses is of outmost importance.

30 Minds are like parachutes, they only function when they re open Thomas Robert (Tommy) Dewar [ ] Thank you

31 Case Mdm A Day 1 Events Drove to sister s home Passed her food items Drove to club Placed belongings in locker Swam Found by spouse: Where am I? Why am I here Went home Life goes on Hours to days later Recovery of some of the memory gap Amnesic / Memory gap Able to form and retain new memories