Lecture 8 - Cerebral Disorders 1

Question 1

What are seizures?

Answer 1

• EEG synchronisation (hypersychronised) > more synchrony = less integrated activity
• sudden burst of excitation
• loss of cerebral differentiation
• glutaminergic neurotoxicity (flood of excitatory neurotransitters > glutamate release in surge > toxic! brain slowly being damaged)
• depletion of GABA (bad bc. inhibition provides balance to brain activity; excitation goes unchecked)
• SPECT: focal rise in blood flow

Question 2

Explain Dr Z’s condition

Answer 2

• talking to one patient, next thing he remembers is in a diff place talking to a diff patient
• also eg. of job interview: remember sitting in chair outside, next thing he remembers the interview is over (but he got the job!)
• eg. of how integrated a person can be while amnestic
• first case of TEA
• fully functioning but had no memory of what occurred > can continue to do things in coherent fashion while amnestic
• TINY lesion (‘softening of cortex’): perirhinal cortex (medial surface on temporal lobe) > probably caused by hemorrhagic stroke

Question 3

What is Transient Epileptic Amnesia (TEA)?

Answer 3

• onset middle-older age
• brief attacks (<30mins), recurrent, unusual feelings
• no consistent triggers (but preceded by unusual feelings)
• amnesia typically sole feature (sometime focal seizure semiology)
• very treatable: respond to anti-epileptic meds
• persistent forgetting over days/weeks and ‘patchy but dense’ loss of remote autobiographical memories

Question 4

What is deja vu?

Answer 4

• inappropriate feeling of intense familiarity
• not fleeting (up to mins)
• accompanied by odd feeling: “at one with the universe”; luminous; I know not what
• related to memory, inappropriate memory
• mediated by perirhinal cortex (surgical stimulation > deja vu)
• sense of knowing

Question 5

What does the hippocampus do?

Answer 5

• recollection of ‘thing’ memory (events, things, occurances)
• perirhinal cortex
• veridical, detailed recall

Question 6

Explain object and subject consciousness

Answer 6

• object: awareness of events/things

- subject: all knowing feeling, sense of familiarity, intense, voluminous feeling

Question 7

What is the difference between deja vu and jamais vu?

Answer 7

• deja vu: inappropriate attachment of familiarity to a situation (object intact, subject impaired)
• jamais vu: inappropriate attachment of unfamiliarity to a situation (object intact, subject impaired)
• eg. “I know he’s my husband but he doens’t feel like my husband”

Question 8

Explain the role of ictal memory in TEA

Answer 8

• brief, recurrent amnestic attacks in the 2nd half of life
• partial recall in 40% of cases > able to remember not being able to remember (incomplete anterograde amnesia)
• in some attacks, no anterograde amnesia is evident > memory gap may only become evidence in chance conversation “retrospective amnesia” > suggests pure consolidation failure
• retrograde amnesia most prominent ictal feature

Question 9

What are the prev rates of Transient Global Amnesia (TGA)?

Answer 9

• prev: 3-8/100,000
• rare in <40
• recurrance 6-10% annually

Question 10

What are the comorbidities and risk factors of TGA?

Answer 10

COMORBIDITIES

• increased emotional instability
• hx anxiety
• personality disorders

RISK FACTORS

• personality disorder
• panic attacks
• emotional inability

Question 11

What are the precipitating events in TGA?

Answer 11

• precipitants effects poorly identified
• women: emotional stressors
• men: physical stressors
• emotional stress 20-30%
• strenuous physical activity 10-20%
• temperature change (water contact)
• sexual intercourse
• neck hyperextension (whiplash)

EMOTIONAL PRECIPITANTS

• new of disease/illness in family
• witness serious road accident
• house fire
• attending funeral
• give evidence at medical tribunal

Question 12

Explain the lesions in TGA

Answer 12

• reversible
• T2 hyperintensities
• in CA1 of hippocampus (centre of memory clockwork)

Question 13

What is the hypothesised mechanism of TGA?

Answer 13

• trigger
• metabolic stress of CA1 neurons
• reversible T2 prolongation (MRI correlates; transient evolution of diffusion lesion)
• acute TGA/acute perturbation of CA1 neurons (behavioural correlates)
• rapid, often full, compensation (4-12hrs)

Question 14

What is the key hallmark of TGA?

Answer 14

repetitive questioning!

may look normal in all other respects imaginable but cannot remember what is being said to them

Question 15

What are the features of post-concussional syndrome?

Answer 15

COGNITIVE

• attention/concentration
• memory
• speed of processing

AFFECTIVE

• irritability
• depression
• anxiety

SOMATIC

• headache, dizziness
• fatigue
• sensitivity to noise/light
• insomnia
• cranial nerve symptomatology

Question 16

What are dissociative disorders?

Answer 16

• disruption of usually integrated features of consciousness, memory, identity and perception of the environment
• psychogenic amnesia disorder
• minor lesions > functional changes
• role of a model and period of mediation
• model-drive elaboration (FAS, “I have alexia without agraphia”)

Question 17

What are the effects of a concussion?

Answer 17

• concussion is serious!! loss of consciousness may be followed by post-traumatic amnesia (usually <24hrs)

PRIMARY

• tear bridging veins
• subdural haematoma
• associated intracerebral haematoma
• petechial bleeds

SECONDARY

• hypoxic-ischaemic
• swelling/oedema
• raised ICP

DIFFUSE AXONAL INJURY

• white matter shearing injury
• midline haemorrhages (acute)
• Wallerian degeneration (chronic)

Question 18

Explain the persistence of post-concussional syndrome

Answer 18

• 80-100% in immediate post-injury period
• 10-40% at 12mths (in uncomplicated MTBI)

PERPETUATING FACTORS

• medicolegal matters
• post-traumatic stress
• pre-traumatic psych vulnerability
• malingering
• education
• psychoeducational intervention

Question 19

What are transient elaborative disorders?

Answer 19

• pseudo-neurological conditions
• “transient” > eventually end
• minor lesions, functional changes
• role of model + period of meditation
• model-drive elaboration
• elaborative response to minor and transient symptoms

Question 20

What is psychogenic foreign accent syndrome?

Answer 20

• woman > driving > weakness in L arm > VERY awkward gait
• MRI: left hemiparesis (no connectivity with language structures, wrong side to explain arm weakness)
• switch b/w Aus and French accents
• entirely psychogenic bc flight of accents

Question 21

What are transient amnesias?

Answer 21

• amnesia = loss of PERSONAL memory function (NOT forgetting)
• sudden onset
• devastating to family/friends
• time-limited

Question 22

Explain the case example of TGA

Answer 22

• woman, 50s
• sudden onset of repetitive Q during sexual intercourse > no recall of events that day
• EEG no seizure; CT scan normal
• no recall of seeing health practitioners upon return to cubicle
• could have normal convo with her > wouldn’t know that anything was wrong
• alert, non-dysphasic, puzzled
• model-drive elaboration on things she’d heard outside the cubicle (hold on to de-contextualised fragments)
• 2 weeks later: entirely normal; no recall of being in hospital

Question 23

What are the 4 key transient amnesias we focussed on?

Answer 23

• post-traumatic amnesia
• transient epileptic amnesia
• transient global amnesia
• psychogenic amnesia