Impairment of Consciousness, Memory or Cognition Flashcards
Consciousness definition
Being aware of both the environment and of oneself as a subjective being
- global cognitive function
Cognition definition, 5 main domains and their defects/responsible lobes
Mental activities that allow us to perceive, integrate and conceptualise the world
- global functions of consciousness, orientation, attention
- specific domains of memory, executive function, praxis
Language - dysphasia/aphasia –> receptive dysphasia (understanding; temporal lobe) and expressive dysphasia (speaking; frontal lobe)
Praxis - dyspraxia/apraxia –> loss of ability to carry out skilled motor functions despite intact motor function (frontal lobe)
Perception - dysgnosia/agnosia –> loss of ability to interpret sensory information despite intact sensory function (parietal lobe)
Memory - amnesia –> loss of ability to learn or recall new information (temporal lobe; hippocampus)
Executive function - disinhibition, perseveration, apathy, dysexecutive syndrome –> loss of ability to plan and sequence activities or to use abstract information (frontal lobe; limbic for emotions)
Memory - most common type disrupted, types of memory
One of the most common cognitive domains to be impaired
Explicit/Declarative memory = stored memory which individual is “aware” of, can declare - most commonly disrupted
- -> semantic: facts
- -> episodic: autobiographical events
Types of explicit memory
- short term/working: 15-30 seconds, frontal cortex (digit span, 3 items registration)
- long term recent: mins-months, hippocampus and mamillary bodies (anterograde delayed recall, retrograde recent events)
- long term remote: lifetime, frontal and temporal cortex (past important events)
Implicit/Procedural memory = stored without conscious awareness e.g. speaking a language, riding bicycle
Amnesia - definition, types and related areas of damage
Loss of ability to store new memories or retrieve old memories
Anterograde: unable to store new memories from event onwards
- damage to medial temporal lobes esp hippocampal formation
Retrograde: unable to retrieve memories stored before the event
- damage to frontal or temporal cortex
Key points in Hx taking
Onset (r/o delirium if acute)
Initial problem/most prominent (AD vs non-AD)
Severity – functioning, orientation, frequency, coping mech
Risk assessment - suicide, others, self-neglect (food, fire, abuse, meds, self-care)
BPSD - mood, psychosis, motor dysfunction
Caregiver stress
Examinations of patients
MSE
Cognitive tests
Physical
Functional
Standardised cognitive examinations - purpose, adv and disadv
For SCREENING, NOT DIAGNOSIS!
MMSE
- covers most cognitive domains but NOT TESTING EXECUTIVE functions
- not sensitive to mild cases
- influenced by premorbid IQ, language, culture
- > 25/30 = normal, 21-24 mild dementia, 10-20 mod
Abbreviated mental test
- fast
- not sensitive to mild/moderate cases
- <6/10 = delirium
Clock drawing test
- praxis and executive function
- not sensitive to mild
- very influenced by poor motor control/visual impairment
Addenbrooke’s cognitive examination
- test all domains and sensitive to mild
- lengthy, influenced by premorbid culture/IQ/language
HKMoCA
- tests memory and executive function
- age and education corrected data
HKBC
Physical examination
Neurological exam
Look for:
- reversible causes of impairment e.g. hypothyroid, SOL
- risk factors e.g. hypertension, AF
- Ddx e.g. hemiparesis or visual field defect suggestive of CVA
- self-neglect, falls
Investigations for cognitive impairment
Delirium - acute illness
- ECG, septic screen
Chronic impairment
- VitB12, folate
- TFT for hypothyroid
- Ca for hyperCa
- Glucose, U&E for Cushing’s, Addison’s
- CT/MRI for subdural haematoma, tumour
Differential diagnosis for cognitive impairment
Delirium Dementia Mild cognitive impairment Subjective cognitive impairment Stable cognitive impairment Depression (pseudo dementia) Psychotic disorders Mood disorders Intellectual disability
(Specific syndrome a/w organic brain disease e.g. amnesic syndrome, organic mood/delusional state/personality disorder)
Delirium 譫妄 (zim mong) - general definition, diagnostic criteria
Syndrome of acute generalised cerebral dysfunction characterised by
- ALTERED CONSCIOUSNESS, DISORIENTATION, attention, perception, thinking, memory, emotion, sleep-wake cycle, psychomotor behaviour
- Disturbance in attention and awareness
- Disturbance develops OVER SHORT PERIOD OF TIME and tends to FLUCTUATE in severity during the day
- An additional disturbance in cognition e.g. memory deficit, language, perception, disorientation
- Disturbances are not better explained by another neurocognitive disorder and do not occur in the context of severely reduced level of arousal e.g. coma
- There is evidence that disturbance is direct physiological consequence of another medical condition, substance intoxication or withdrawal or multiple aetiologies
Salient features of delirium
ABRUPT onset
SHORT duration
FLUCTUATION of consciousness during the day, worsening at night
- hypoactive type with drowsiness/coma
- hyperactive type with agitation and hypervigilance
COGNITIVE DYSFUNCTION
- short term and recent memory
- DISORIENTATION TO TIME, and often place
- language abnormalities (rambling, incoherent)
PERCEPTION AND THOUGHT disturbance - often present but not essential
- misinterpretations, illusions, hallucinations (esp visual)
- fleeting persecutory or referential delusions
MOOD disturbance
- labile
- range from depression, irritable, euphoric, anxious, angry, fearful, apathy
Sleep-wake cycle disturbance
- reversal of normal cycle e.g. daytime drowsiness, night time hyperactivity
(diffuse slowing on EEG)
Delirium - epidemiology and risk factors
Common, affecting 15% inpatients and 40-60% in the ICU
All age grps can be affected, more common in children and elderly
Risk factors:
- “at risk brain” e.g. pre-existing dementia (50% cases of delirium) or cognitive impairment, previous serious head injury
- serious physical illness
- polypharmacy
- visual impairment (decreased sensory input)
- isolation, stress
Aetiology of delirium
Primary cause often outside brain and multiple aetiologies
Systemic illness
- sepsis and infections e.g. URTI, UTI
- anoxia e.g. CHF, MI, resp failure (COAD, asthma)
- metabolic and endocrine e.g. electrolyte disturbances, hepatic encephalopathy, hypoBG, hyper or hypo-thyroid/PTH/adrenocortical
- nutritional e.g. VitB12, folate deficiency, thiamine
Intracranial causes
- meningitis, encephalitis
- head injury
- SOL, cerebrovascular e.g. TIA
- epilepsy
Drugs (intoxication and withdrawal)
- anticholinergics (worsen dementia brain which already has Ach deficits), BZD, opiates, anti-parki drugs, steroids
- alcohol (delirium tremens), opiates, cannabis, ICE
- poisons (heavy metals, CO)
Management of delirium
Marker of severity of illness (compromised coping) –> MEDICAL EMERGENCY, high mortality
- *Find and treat underlying disorder
- pre-existing RFs, current picture
- CBC, LRFT, TFT, BG, clotting, Ca, P, CRP, Trop-T, ABG
- CXR
- blood and urine cultures
- Urinalysis, urine toxicology
- CT/MRI, LP, EEG if needed
Maintain adequate hydration and diet, maintain physical condition
Consistent routine to meals, care
Environment – quiet/isolated room with no dangerous objects or triggers, light in day and dark at night, safety, maximise visual acuity and auditory input
Improve orientation by clocks
Encourage visit by relatives (give patient reassurance, reduce anxiety)
Meds:
- avoid any unnecessary medication
- sedation if severe sleep disturbance – not BZD since will worsen confusion UNLESS ALCOHOL WITHDRAWAL; zoplicone, haloperidol
- antipsychotics if high risk, aggression – haloperidol
Monitor improvement using abbreviated mental test score – <6/10 = delirium
Ddx of delirium
- *Dementia
- gradual onset, long duration, normal consciousness, intact attention, impaired orientation at late stages, normal sleep-wake cycle, normal mood, paranoid/fixed delusions/perceptual disturbance in later stages, not reversible, progressive course
Depression
- gradual onset, normal consciousness, inconsistent memory, low mood, mood congruent delusions, diurnal variation
Non-organic psychoses
- variable onset, normal consciousness, intact memory, incongruent mood, complex systematised delusions, sometimes reversible, chronic/relapsing course
