Amnestic disorders [2013]
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1) Amnestic disorders are characterized by memory impairment alone, most commonly caused by identifiable medical conditions that damage memory centers in the brain like the hippocampus. 2) Organic amnesic syndrome is memory loss due to brain injury or disease, with anterograde amnesia preventing new learning and retrograde amnesia involving inability to recall events prior to the onset of amnesia. 3) Common causes include alcoholism leading to Wernicke-Korsakoff syndrome, head trauma, viral infections, hypoxia, and strokes affecting memory areas like the medial temporal lobes.
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Amnestic disorders [2013]
- 1. AMNESTIC DISORDERS Dr Zahiruddin Othman JANUARY 2013
- 2. ICD-10: Organic Mental Disorder F00 Dementia in Alzheimer disease F01 Vascular dementia F02 Dementia in other diseases classified elsewhere F03 Unspecified dementia F04 Organic amnesic syndrome, not induced by alcohol and other psychoactive substances F05 Delirium, not induced by alcohol and other psychoactive substances F06 Other mental disorders due to brain damage and dysfunction and physical disease F07 Personality and behavioral disorders due to brain disease, damage and dysfunction F08 Unspecified organic or symptomatic disorder
- 3. DSM-IV Cognitive Disorders DELIRIUM Delirium due to a GMC DEMENTIA Dementia of Alzheimer ‘s Type Vascular dementia AMNESTIC DISORDER Amnestic disorder due to a GMC Amnestic disorder NOS OTHER COGNITIVE DISORDERS
- 4. Amnestic Disorders Are Disorders In MEMORY ALONE AMNESTIC DISORDER AMNESIA DEMENTIA Apraxia Agnosia Aphasia Executive dysfunction DELIRIUM Acute onset Fluctuating course Altered consciousness Major attention deficit Causes: General Medical Condition (organic)
- 5. MEMORY SENSORY MEMORY SHORT-TERM MEMORY LONG-TERM MEMORY DECLARATIVE MEMORY EPISODIC MEMORY (events) Specific personal experience from a particular time & Place SEMANTIC MEMORY (facts) Knowledge NON-DECLARATIVE MEMORY PROCEDURAL MEMORY Skills (motor & cognitive) CLASSICAL CONDITIONING Conditioned responses NONASSOCIATIVE LEARNING Habituation & sensitization Memory foam
- 7. HM’s lesion: bilateral medial temporal lobe removal
- 8. Time Memory Trauma Anterograde amnesiaTime-limited retrograde amnesia REMOTE MEMORY RECENT MEMORY Impaired temporal localization of past experience, as in Korsakoff, which leads to confabulation Autobiographic memory also intact, but amnesic for recent events before onset of amnesia Retrograde amnesia, an inability to retrieve information that was learned prior to the onset of amnesia if it was not purely semantic or implicit memory Anterograde amnesia, episodic memory: dramatic inability to learn something new after the onset of amnesia due to inability to build up new episodes.
- 9. CONFABULATION ‘‘False statements that are not made to deceive, are typically more coherent than thoughts produced during delirium” It ranges from small distortions on laboratory tasks to striking bizarre stories that patients tell in describing their personal histories Typically occurs in the context of executive deficits such as perseveration, poor self-monitoring, and difficulty with self- initiated processes
- 10. Amnestic Disorders Are Caused by IDENTIFIABLE PRECIPITANTS Amnestic Disorder Due to a GMC • Head Trauma • Hypoxia • Herpes Simplex Encephalitis • Transient Global Amnesia • Seizures Substance-Induced Persisting Amnestic Disorder • Alcohol • Sedatives • Hypnotics • Anxiolytics • Wernicke-Korsakoff Syndrome (WKS)
- 11. Syndromes of Transient Amnesia Transient Global Amnesia (TGA) • sudden onset often precipitated by exercise, immersion in water, emotional stress, etc • dense anterograde amnesia with repetitive questioning • lasts around 4 – 10 hours • rarely recurs • etiology unknown Transient Epileptic Amnesia (TEA) • recurrent, brief (usually < 1 hour) amnesic episodes • often occur upon waking • may be associated with olfactory hallucinations or automatisms • responds to anticonvulsant medication • persistent memory deficits
- 12. Amnesic syndrome with bilateral mesial temporal lobe involvement in Hashimoto’s encephalopathy Despite clinical and radiologic improvement after steroid and thyroid hormone replacement therapy, a severe amnesic syndrome with associated localized MRI abnormalities persists. Investigations showed biochemical hypothyroidism, raised thyroid microsomal antibodies, and weakly positive antineuronal antibodies. A T2-weighted MRI of the brain showed bilateral symmetric areas of increased signal in the mesial temporal lobes and hippocampi that had a low signal intensity on T1-weighted imaging. A 25-year-old woman presented with a subacute confusional state, headaches, unsteadiness, myoclonus, seizures, and an amnesic syndrome as a manifestation of Hashimoto’s encephalopathy.
- 13. BLACKOUTS • Blackouts are periods of amnesia for events that occur during heavy drinking. • Typically, a person awakens the morning after consumption and does not remember what happened the night before. • Blackouts are more a measure of the amount of alcohol consumed at any one time.
- 14. Chronic Amnestic Disorders Causes - Pathological Process • Damage to specific diencephalic and mediotemporal lobe structures (e.g., mamillary bodies, hippocampus, fornix) – head trauma – surgical intervention – infarction of the distribution of PCA – hypoxia – herpes simplex encephalitis
- 15. Substance-Induced Persisting Amnestic Disorder • “Persisting” means the memory disturbances persists long after the effects of substance intoxication or withdrawal have ended • CNS depressants – Alcohol, sedatives, hypnotics, anxiolytics, anticonvulsants • Toxin: lead, mercury, intratheceal methotrexate, organophosphate insecticides, and industrial solvents
- 16. WERNICKE-KORSAKOFF SYNDROME [WKS] CAUSES • Alcoholism • CO poisoning • Encephalitis WERNICKE ENCEPHALOPATHY • Delirium • Ophtalmoplegia • Ataxia • Peripheral neuropathy KORSAKOFF SYNDROME • Amnesia • Confabulation
- 17. TREATMENT • The primary goal in the amnestic disorders is to discover and treat the underlying cause. • Some of these causes of amnestic disorder are associated with dangerous self-damaging behavior – e.g., suicide attempts by hanging, carbon monoxide poisoning, deliberate motor vehicle accidents, self-inflicted gunshot wounds to the head and chronic alcohol abuse