Organic Amnesia Syndrome

What is Organic Amnesia Syndrome?

Among patients with neurosurgical departments, amnesia syndromes are observed in 15%. Since amnesia is a criterion for the severity of craniocerebral injuries, in all cases of such injuries, and they are 25-30%, amnesia is recorded in these patients. In neurovascular departments, short-term episodes of amnesia were also noted in 30% of patients.

Causes of Organic Amnesia Syndrome

The syndrome is caused by an organic process, in particular traumatic brain injury, tumor, infection, hematoma, hypoxia, for example, as a result of cardiac arrest, degenerative processes, epilepsy, after ECT sessions and insulin-comatose therapy, carbon monoxide poisoning. Short-term amnestic episodes can be both with fainting, and after strokes and transient disorders of cerebral circulation. The development of the syndrome is associated with the Papec circle, which includes the cortex, hypothalamus, hippocampus and thalamus, as well as the reticular formation, tonsils and septum.

Symptoms of Organic Amnesia Syndrome

In an amnestic syndrome as a result of traumatic brain injury, there is usually no fixation amnesia, but there are memory disorders for events preceding the injury (retrograde amnesia) or subsequent (anterograde amnesia). Loss of memory can be filled with false memories (confabulations) or memories from other periods of life (pseudoreminescence). In cases where fixation amnesia is still present, the syndrome begins to resemble Korsakovsky.

Retrospective assessment of the syndrome is always different from the current. Thus, in the acute period of a craniocerebral trauma or stroke, one can simultaneously observe stunning consciousness disorders, and amnesia syndrome, and after leaving this state, only amnesia syndrome.

In an amnesic disorder, after a session of ECT, a time regression syndrome is observed, in which the events of the recent, including the psychotic past, are remembered with difficulty, and the patient begins to behave and treat the events a few years ago. With short-term hypoxia as a result of ventricular extrasystoles, amnesia is possible for very short periods of time or the feeling that events occurred as in a dream.

In a chronic course, the boundaries of amnesia can be narrowed and expanded according to Ribot’s law, that is, from real events to past ones, while hypermnesia of past events is possible, in which events that have not been remembered before become relevant and even determine the patient’s behavior. Usually, the memory function is not intact to other mental functions. Emotional, behavioral, and cognitive impairments join the amnesic disorder.

Diagnosis of Organic Amnesia Syndrome

The diagnosis of amnestic syndrome is based, in fact, on the identification of amnesia and the organic background that could cause it.

However, in itself such a diagnosis is possible only as an additional and clarifying, or in cases where there is an organic basis, but it has not yet been specified. That is, the diagnosis can be considered in chronic course (more than 3 months) as an intermediate or retrospective. For example, in case of hypoxia as a result of incomplete suicide or cardiac arrest, after the first head injuries, the initial diagnosis of organic amnestic syndrome is usually justified, but in case of its chronic course of the same type as hypoxic encephalopathy or traumatic brain disease, one should usually think about an increase in the dementiating process. Previously suffered injuries with retro-anterograde amnesia may not affect the current mental state, but the transferred amnesia affects behavior and motivation on the principle of trace response. Person’s reaction to amnesia is often active, it can be accompanied by anxiety, anxiety, or confusion.

The main clinical criteria are:

  1. Fixation, anterograde and retrograde amnesia, memory loss according to Ribot’s law;
  2. Data indicating the presence of a stroke or a disease of the brain (especially involving bilateral-diencephalic and temporal structures);
  3. The absence of a defect in the direct playback (memory for current events is not changed);
  4. The absence of impaired attention and consciousness.

Additional symptoms: confabulations, emotional changes, etc.

Differential diagnostics

The amnestic organic syndrome should be differentiated with dementia, dissociative amnesia, amnesia as a result of the use of psychoactive substances, multiple personality disorders.

In the acute stage, the differential diagnosis is based only on a neurological examination, data from an objective study, as well as anamnesis. With dementia, the course of chronic amnesia is joined by impairments of other cognitive functions. When psychoactive substances are used, there is a disturbance in the reproduction of immediate events, that is, fixation disorders, which are rare in organic amnestic syndromes. Dissociative amnesia is the result of crowding out of a traumatic event and is directly connected with it, with no organic background detected. In disorders of the multiple personality amnesia preceded by the style of behavior, motivation and memory related to another person.

Treatment of Organic Amnesia Syndrome

Therapy for amnestic syndrome depends on the underlying disease. It is always necessary to persistently retrain and saturate the environment with symbols of the situation that should be remembered. Personality response to amnesia is stopped by anxiolytics and small doses of tricyclic antidepressants. Nootropics and large doses of vitamins are used to stimulate memory.