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Amnestic Syndrome

Clinical features: -Memory impairment (esp recent memory) in absence of other significant cognitive impairment.

Types: - Important ones are
  1. Thiamine deficiency (Korsakoff syndrome) 
  2. Brain Condition Eg. Head Injury, Transient Global Amnesia, Ect Etc.
Comparison between Delirium & Dementia
  Features Delirium Dementia
  1. Onset Usually acute Usually insidious
  2. Course usually recover in 1 week Usually protracted
  may take upto 1 month Although may be reversible
  3. Clinical features
  i. Consciousness Clouded usually normal
  ii. Orientation grossly disturbed usually normal
  Distubred only in late stages
  iii. Memory Immediate retention and Immediate retention and
recall disturbed recall normal
recent memory disturbed Recent memory disturbed
  Remote memory disturbed
  only in late stages
  iv. Comprehension Impaired Impaired only in late stages
  v. Sleep wake cycle usually reversal of sleep Usually normal
wake cycle grossly disturbed
  vi. Attention and concentration grossly disturbed Usually normal
  vii. Diurnal variation Marked sundowning present Usually absent
  viii. Perception Visual illusion and Hallucinations
hallucinations very common may occur
  ix. Other features Asterixis, Multifocal catastrophic reaction
myoclonus perseveration
Def: - characterized by multiple cognitive deficits which include impairment in memory with out impairment in consciousness.In this memory loss is along with the loss of Intelligence , loss of Personality and loss of the learned activities. The Screening Instrument of Dementia is MMSE( Mini-Mental status examination ) , The Normal score is 30 and any score <24 , is dementia. The various causes of dementia are:

  1. Neurological Disorders:
  2. Alzheimer Dementia – most common type
  3. Parkinson’s disease, Pick’s disease, Huntington’s chorea, Progressive supranuclear
  4. Palsy( steel Richardson syndrome), Lewy body
  5. Vascular: multi-infarct
  6. Drugs: Alcohol, CO
  7. Vitamin deficiency: B1, B12, Niacin
  8. Metabolic: Uraemia, dialysis, wilson’s
  9. Endocrine: Hypthyroidism, cushing’s, Hypo-and hyperparathyroidism, Addison
  10. Infections: AIDS, Creutzfeldt Jacob disease, Herpes simplex
  11. Trauma: subdural haematoma
  12. Tumours
  13. Others: Normal Pressure hydrocephalous
Reversible Dementias: Hypothyroid (Most common cause in India), normal pressure hydrocephalus, vitamin deficiency, brain tumours, Toxin (Most common cause in developed countries)

Irreversible Dementias: The most common cause across globe is Alzheimer’s disease

Cortical and Subcortical Dementia 
Features Cortical Dementia        Subcortical Dementia
1. Site of lesion Cortex (Frontal and
temporo-parieto occipital
association areas, and
Subcortical grey matter
(Thalamus, basal ganglia,
and rostral brain stem)
2. Examples Aizheimer’s disease
Pick’s disease
Huntigton chorea, HIV – Related dementia
Parkinson’s disease,
palsy, Wilson’s disease
3. Severity Progressive supranuclear,
Mild to moderate
4. Motor system usually normal
posture, tremors, dystonia,
chorea, ataxia, rigidity
Dysarthria, lexed/extended
5. Other features Simple delusions:
Depression uncommon
Severe aphasia amnesia
agnosia, apraxia, acalculia;
slowed cognitive speed
Complex delusions;
Depression common;
Rarely mania
6. Memory deficit
(short term
Recall helped very little
by cues
Recall partially helped by
Cues and recongnition tasks

Clinical Differentiation of the Major Dementias
Disease Initial Symptom Mental Status Neuropsychiatry Neurology Imaging
AD Memory loss Episodic memory Initially normal Initially normal Entorhinal and
Vascular Often sudden; Frontal/executive Apathy, Usually motor Cortical and/or
variable initial cognitive delusions, slowing, subortical
symptoms; slowing/ can anxity spasticity/ can infarctions
apathy, falls, spare memory   be mormal confluent white
focal weakness       matter disease
FTD Apathy/ reduced Frontal/executive, Apathy, Vertical gaze Frontal and/or
judgment/ language; spares disinhibition, palsy, axial temporal
insight/speech/ drawing hyper orality, rigidity, atrophy; spares
language   euphoria, dystonia, alien posterior parietal
hyperorality   depression hand(due to lobe
DLB Visual Drawing and Visual Parkinsonism Posterior parietal;
hallucinations, frontal/ hallucinations, hippocampi
REM-sleep executive; depression, larger than in
disorder spares memory; sleep disorder, AD
dilirium, delirium prone delusions  
syndrom, parkinsonism      
Prion Dementia, mood Variable, frontal/ Depression, Myoclonus, Coricla ribboning
Changes, executive, focal anxiety rigidity, and basal ganglia
anxiety, cortical,   parkinsonism hyperintesities
movement memory     on diffusion/flare
disorder       MRI

AD = Alzheimer Dementia, FTD = Frontotemporal dementia, DLB = Dementia Lewy body

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