Post-traumatic amnesia: symptoms, causes and characteristics

Post-traumatic amnesia or post-traumatic amnesic syndrome it occurs frequently in people with head trauma and can persist for years, severely affecting memory of events. Let’s see what are its characteristics.

    Post-traumatic amnesia: definition

    The term post-traumatic amnesia was first coined by the English neurologist Charles P. Symonds to designate general impairment of brain function after recovery of consciousness. Current research defines post-traumatic amnesia as a persistent, stable and comprehensive memory impairment due to an organic brain disorder, in the absence of other cognitive deficits.

    In post-traumatic amnesia, it is difficult to evoke and acquire new information; the subject is unable to keep a continuous record of daily activities. This syndrome is common in moderate to severe head trauma (TBI), as well as in permanent mnemonic deficits.

    These memory deficits are mainly due to focal lesions of the hippocampus (Structure closely related to memory and a particular location) and contiguous structures, as well as other diffuse brain damage.

      Characteristics of this syndrome

      Post-traumatic amnesia is the result of the sum of several factors such as loss of consciousness caused by the injury, retrograde amnesia ranging from minutes to years before the accident and anterograde amnesia ranging from “ a few hours in the months following the healing of consciousness.

      This mnemonic syndrome is made up of several factors such as loss of consciousness following an injury or trauma, retrograde amnesia (inability to remember events that occurred before the injury) and sometimes anterograde amnesia. Parkin and Leng defined the following characteristics of post-traumatic amnesia:

      • There is no short-term memory deficit (assessed by tasks such as number range).
      • Semantic memory, which is responsible for encoding, storing, and retrieving the information learned, is not affected.
      • Permanent inability to store new information after injury (assessed by evocation and recognition tests).
      • In some patients, inability to retrieve information stored in long-term memory prior to injury.
      • Procedural memory (responsible for recording motor and executive skills) is not affected.
      • Motor skills are preserved and the subject is able to form new memories in procedural memory.

      What can cause this memory impairment?

      Blows to the head and skull are the most well-known causes when we talk about post-traumatic amnesia. However, there are a number of other factors – some preventable – to consider when it comes to what can cause such a syndrome.

      1. Stroke

      A stroke occurs when blood flow to the brain stops and it cannot continue to receive oxygen and nutrients. Neurons can die, causing permanent functional and structural damage.

      2. Encephalitis

      Encephalitis or inflammation of the brain can result from a viral infection (for example, the herpes simplex virus) or from an autoimmune reaction to cancer.

      3. Hypoxia or anoxia

      Hypoxia, in case of lack of oxygen, and anoxia, in case of total absence, May be a causative factor in post-traumatic amnesia. This lack of oxygen can be due to a heart attack, difficulty breathing, or carbon monoxide poisoning, for example.

      4. Alcohol abuse

      Long-term alcohol abuse can lead to thiamine (vitamin B1) deficiency. Severe deficiency of this vitamin can lead to brain damage and the appearance of Wernicke-Korsakoff syndrome, Brain disease that causes damage to the thalamus and hypothalamus, resulting in irreversible damage to cognitive functions such as memory.

      5. Degenerative diseases, tumors and other pathologies

      Degenerative brain diseases, tumors and other conditions such as cancer can cause mnemonic syndromes depending on the areas of the brain affected.


      Post-traumatic amnesia is usually accompanied by severe temporal and spatial disorientation, attention deficits (mainly in sustained and focused attention), retrograde and anterograde amnesia, conspiracy, restlessness and uninhibited behavior.

      During the syndrome, patients feel confused, disoriented and have great difficulty processing information from the environment. Depending on the intensity of the injury, patients will have more or less difficulty remembering events around the accident or a few minutes before.

      In terms of language, subjects with post-traumatic amnesia often exhibit inconsistent speech and their perception of the environment and new stimuli is distorted, leading to exacerbation of confusion and fear.

      It is also common for patients to be aggressive (physically or verbally) and restless. In addition, people with post-traumatic amnesic syndrome they may have hallucinations.

      Other memory deficits

      In addition to post-traumatic amnesia, there are other types of mnemonic syndromes in which different types of memory are affected in various areas of the brain. The following are the most common:

      1. Temporary amnesic syndrome

      In amnesias in which the medial temporal lobe is affectedThe patient usually presents with episodic and anterograde semantic amnesia (affects both general and personal and autobiographical information) and retrograde amnesia. However, short-term and procedural memory is preserved.

        2. Amnesic syndrome of diencephalon

        In encephalic amnesia, patients present with retrograde amnesia and anterograde amnesia (both semantic and episodic) which are not always explained by an inability to store information but may be related, in part, to a disorder of memory, an element that distinguishes them from temporary amnesias.

        On the other hand, in this syndrome there is also a deficit in metamemory (Ability to assess own memory capacity)

        3. Frontal amnesic syndrome

        Amnesia due to damage to the frontal cortex they do not produce overall memory lossAs this area of ​​the brain is responsible for the strategic processes of retrieving, monitoring and verifying information. On the other hand, patients see their ability to search and select information relevant to each situation and context diminished.

        4. Semantic dementia

        This type of amnesic syndrome race with significant impact on declarative retrograde memory (Responsible for storing memories and events in our lives that can be expressed explicitly). However, non-declarative memory, language grammar, and other cognitive functions are preserved.

        Bibliographical references:

        • Fernández-Ballesteros, R. (2005). Introduction to psychological assessment I and II. Ed. Pyramid. Madrid.
        • Kolb, B. and Wishaw, IQ (2006) Human Neuropsychology (5th ed.). Pan-American Medical Editorial: Buenos Aires.

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