Questions and Answers
Complete recovery from transient global amnesia is rare, and recurrence is common.
False
Patients with transient global amnesia retain procedural memory during their episodes.
True
Panic attacks and hyperventilation are classified under organic causes of neuropsychiatric symptoms.
False
The neurological examination is entirely normal in patients experiencing transient amnesia.
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Dissociative fugue is characterized by a loss of personal identity.
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Transient ischaemic attacks are classified under functional causes of transient amnesia.
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Amnesic disorders are characterized by a significant decline from prior levels of functioning and can include both anterograde and retrograde amnesia.
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Korsakov syndrome is synonymous with amnesic disorder and is not a specific form of it.
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The digit span is typically impaired in cases of amnesia, reflecting a deficit in short-term memory.
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Emotional blunting and inertia are common observations in individuals suffering from amnesic disorders.
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Alzheimer's disease is classified as an amnesic disorder in both ICD-10 and DSM-5.
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Loss of autobiographical information can extend back many years for individuals suffering from amnesia.
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Transient global amnesia is a persistent condition that results from a general medical condition significantly impacting memory.
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New learning is usually intact in patients with amnesic disorders, while retrograde memory tends to be grossly defective.
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Confabulation is characterized by filling gaps in memory with true accounts.
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Lesions in the medial thalamus can lead to amnesia.
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The commonest cause of amnesic disorder is Wernicke's encephalopathy.
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Korsakov syndrome can occasionally result from severe malnutrition.
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In the acute stage of Wernicke-Korsakov syndrome, the mortality rate is 84%.
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Thiamine should be administered after glucose-containing solutions in patients with amnesic syndrome.
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Amnesic syndrome typically indicates a reversible condition.
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Most patients with Wernicke-Korsakov syndrome demonstrate an improvement in their condition.
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The prognosis for amnesic syndrome caused by viral encephalitis is often positive.
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Progressive amnesia suggests a slowly expanding structural lesion such as a midbrain tumor.
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Study Notes
Amnesia and Amnesic Disorders
- Amnesia denotes memory loss, specifically affecting episodic memory, leading to a decline in functioning levels.
- Diagnosed as amnesic disorders under ICD-10, distinct from dementia and delirium, while DSM-5 includes them under major neurocognitive disorder.
- Two primary types of amnesia:
- Anterograde Amnesia: Inability to learn new information.
- Retrograde Amnesia: Inability to recall past events.
- Significant impairment in social or occupational functioning is a diagnostic criterion, alongside medical conditions related to memory impairment.
Clinical Features
- Profound deficit in episodic memory is the cardinal symptom.
- Patients may experience disorientation, memory loss, and inability to retain new information.
- Events may be remembered briefly only to be forgotten shortly afterward.
- Short-term memory (e.g., digit span) usually remains intact.
- Some emotional blunting and inertia may be noted, while other cognitive functions can be preserved.
Causes of Amnesia
Transient Causes
- Transient global amnesia
- Transient epileptic amnesia
- Head injuries
- Alcohol-related blackouts
- Post-traumatic stress disorder
- Psychogenic fugue and amnesia linked to criminal offenses
Persistent Causes (Amnestic Syndrome)
- Korsakoff syndrome (often associated with alcohol use)
- Herpes encephalitis
- Strokes affecting the posterior cerebral artery and thalamus
Differential Diagnosis
- Organic Causes: Syncope, transient ischemic attacks, migraines, seizures, hypoglycemia.
- Functional Causes: Panic attacks, dissociative disorders, schizophrenia, aggressive outbursts in personality disorders.
Characteristics of Transient Global Amnesia
- Patients often appear bewildered and require frequent reorientation.
- Alertness remains intact; personal identity is preserved.
- Procedural memory is unaffected, allowing competent actions like driving.
- Neurological examination typically shows normal results.
- Episodes usually resolve fully, with low recurrence rates. Investigation is crucial to exclude other causes.
Korsakoff Syndrome
- First described by neuropsychiatrist Sergei Korsakoff in 1889; often follows Wernicke's encephalopathy.
- Commonly caused by thiamine deficiency due to alcohol abuse; can also stem from severe malnutrition or medical conditions.
- Neuropathology shows neuronal loss, gliosis, and microhemorrhages in key brain regions.
Investigation and Management
- Quick recognition of amnesic syndrome is vital; it can be reversible.
- Investigations may reveal reduced transketolase levels and changes in MRI scans.
- Immediate thiamine administration is crucial, alongside rehydration and nutritional support.
- Coordination with physicians and neurologists is important for effective management.
Course and Prognosis
- High mortality (17%) during the acute stage of Wernicke-Korsakoff syndrome.
- Recovery rates:
- 50% show no improvement,
- 25% achieve complete recovery,
- Remaining have partial recovery.
- Favorable prognosis associated with shorter history and prompt thiamine treatment; poor prognosis in cases from viral encephalitis and other irreversible brain damage.
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Description
Test your knowledge on amnesia and amnesic disorders, including their definition and classification. This quiz will cover the criteria used to distinguish these disorders from others like dementia and delirium. Explore the nuances of memory loss and its impact on functioning.
