Axial Amnesia

Introduction Axonal amnesia is a forgetfulness caused by damage to the ascending reticular system. The up-regulated reticular system that regulates alertness plays a major role in the memory mechanism. No matter what causes coma, the ascending reticular system stops functioning during coma, depriving all memory activities, and patients cannot retain this period. Any memories. Such memory disorders include: amnesia during a systemic episode of epilepsy and a period of time after the onset; amnesia caused by electroshock; amnesia caused by anesthesia.

Cause

Axonal amnesia caused by disease of the limbic system: brain lesions disrupting certain structures at the base of the brain located on the inner side of the cerebral hemisphere in a bilateral manner, leading to this very special syndrome, characterized by patients with isolated memory impairment Other advanced features and neurological examinations are normal.

an examination

Related inspection

EEG examination of brain CT

A. Clinical manifestations:

a. Very serious gradual forgetting, that is, antegrade forgetting, leading to major obstacles to memory. Learning new materials is almost completely powerless.

b. Poor memories of past events, that is, a certain degree of retrograde forgetting. Recurrences often occur in the amnestic amnesia syndrome.

c. Patients are well adapted to real life compared to severe gradual forgetting and recollection difficulties.

B. The axial amnesia syndrome caused by different causes has different characteristics:

a. Malnutrition encephalopathy: Chronic alcoholism is the most common cause of axial amnesia. Chronic alcoholism causes an indirect cause of B vitamin deficiency, especially the lack of B1. At this time, memory impairment is accompanied by confusion, increased muscle tension, eye movement paralysis and cerebellar syndrome.

b. Forgetful encephalitis: refers to the observation of universal amnesia syndrome with severe and rapid gradual forgetting and recall difficulties during some encephalitis. At this time, the characteristics of memory impairment are: serious information preservation obstacles in all fields; impossible recall; serious obstacles in the time of new events; tend to use rigid statements, lack of reasoning; fictional rare and poor content. The etiology of this type of encephalitis is not unique. These amnesia syndromes are seen in typhoid fever, mumps encephalitis, herpes zoster encephalitis, and even after cocciic meningitis or tuberculous meningoencephalitis. Most common in herpetic necrotizing encephalitis, necrotic lesions are located in the temporal cortex, subcortical white matter, hippocampal formation and amygdala.

c. Tumors at the base of the brain: Some tumors at the base of the brain, especially the tumors in and around the third ventricle, are common and severe.

d. Cerebrovascular disease: bilateral infarction of the hippocampus: caused by occlusion of the posterior small arteries of the posterior communicating artery, choroidal artery and posterior cerebral artery. At this time, memory impairment is often submerged in the symptoms of dementia, which is completely unavailable. New things. Bilateral thalamic infarction: At this time, the patient is lifeless, active activity is reduced, exercise initiation is reduced, and attention is noted. The latter is accompanied by mental sensory impairment.

e. Craniocerebral trauma: Craniocerebral trauma leads to memory impairment, caused by loss of consciousness. The amnesia syndrome is extremely diverse, and its characteristics and types depend on the extent of brain lesions. Fictional syndrome is a common symptom in traumatic sequelae, and is particularly common in imaginative subjects involving the environment in the event of an accident.

Differential diagnosis

Differential diagnosis of axial amnesia:

1. Cortical amnesia: This type of amnesia is characterized by recall, application, and learning of certain forms of cognitive difficulties. Can be classified as: A. Focal amnesia caused by dominant hemisphere prefrontal lesions: This type of speech disorder is a focal lexical amnesia caused by the destruction of word storage, the main feature is the difficulty of finding words Can be attributed to the aphasia forgotten project. In such focal amnesia caused by lesions in the speech area, immediate memory ability is often lower than normal.

B. Focal amnesia caused by non-dominant hemisphere frontal lesions: Non-dominant hemispheric lesions, whether extensive or localized, cause focal amnesia as acquired cognitive impairment.

C. Frontal amnesia: The patient's understanding of the situation is poor, and the barriers of the joint strategy lead to incomplete or inappropriate cognitive and recall functions. Patients with frontal lobe lesions have poor learning ability.

2. Complete amnesia: The diffuse lesions of the brain cause intelligent defects and loss of memory in different degrees, so that the accumulation of cognitive ability of the patient not only stops increasing, but also gradually shrinks and deteriorates. Such diffuse lesions are found in the sequelae of infectious, nutritionally deficient and traumatic encephalopathy, as well as in arteriosclerosis, degenerative, premature and senile dementia. This type of dementia causes complete forgetting; memory disorders actually involve various periods of life and involve all of the acquired activities of the patient, including speech, gestures, and all intellectual skills.

3. Transient organic amnesia: transient amnesia is common in metabolic encephalopathy, acute poisoning, and cerebral hypoxia. It is also seen in two cases: forgetting during generalized seizures and forgetting after seizures; a series of forgettings observed after electroshock; a series of oblivions observed after electroshock. A. Forgotten episodes: A forgotten episode, or transient complete forgetting, occurs suddenly in patients without any particular prior medical history.

In the course of an acute episode, which usually lasts for several hours, the patient's forgetting surprises the surrounding people. The patient seems to live in a constant reality, and quickly forgets what he has just done and said. This antegrade forgotten manifestation is a problem that patients often ask in a rigid manner. Retrograde amnesia is manifested in patients who have forgotten events that occurred several hours or even days before the attack. Transient vascular occlusion, epilepsy, migraine, hypoglycemia, etc. in the terminal distribution of the posterior cerebral artery can be the cause of amnestic seizures. Different causes of transient damage to the limbic system, especially the hippocampal formation, can lead to forgetting. attack. B. Traumatic amnesia: Most craniocerebral trauma with coma leads to memory impairment. Difficulties in memory involve not only the memory difficulties experienced during a period of trauma (antegrade amnesia), but also the recall difficulties (retrograde forgetting) experienced during the period before the trauma of the patient is completely normal. The two constitute all traumatic Forgotten blanks.

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