Transient global amnesia
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Transient global amnesia (TGA) is a sudden an episode of confusion and memory loss in an otherwise alert individual. It is not caused by common neurological conditions like epilepsy or stroke.
During an episode of transient global amnesia, a person experiences difficulties in forming new memories (anterograde amnesia) and struggles to recall recent memories (retrograde amnesia). They may have trouble remembering their current location or how they arrived there. They may be unable to recollect ongoing events and repeatedly ask the same questions due to the inability to retain answers. Additionally, they may draw a blank when trying to remember events from the recent past, whether it be a day, a month, or even a year ago.
This condition primarily affects individuals in middle or older age. Despite the memory impairment, people with transient global amnesia typically retain their personal identity and can recognize familiar individuals. These episodes usually last for a few hours, rarely extending up to 24 hours. As the person recovers, their memory of events and circumstances gradually returns. Although transient global amnesia is not a severe condition, it can be distressing for those experiencing it.
Symptoms
Transient global amnesia is characterized by a sudden inability to create new memories. Additionally, individuals may experience difficulty in recollecting memories from recent hours, days, or even longer periods in the past. It is crucial to investigate and eliminate other potential causes of amnesia once this symptom is identified.
To be diagnosed with transient global amnesia, the following signs and symptoms should be present:
- A sudden onset of confusion accompanied by memory loss, which is observed by someone else.
- The individual remains awake, alert, and aware of their own identity, despite experiencing memory loss.
- Normal cognitive abilities, including the ability to recognize and name familiar objects and to understand and follow simple directions.
- No indications of specific brain damage, such as the inability to control movements or comprehend language.
- Repeatedly asking the same questions, particularly regarding the date, time, and location.
People experiencing transient global amnesia typically do not:
- Lose consciousness.
- Exhibit other neurological or cognitive symptoms, such as language impairment or motor difficulties.
- Experience transient global amnesia immediately upon waking up; it tends to occur later in the day.
Transient global amnesia is a condition characterized by certain symptoms and history that can help in diagnosing it. These include:
- Symptoms that last for a maximum of 24 hours and often shorter.
- Memory gradually returning over time.
- Absence of any recent head injury.
- No signs of seizures during the period of amnesia.
- No previous history of active epilepsy.
If someone suddenly becomes confused and forgets what just happened, it’s important to seek medical help right away. This could be a sign of a serious condition that requires immediate attention. If the person is too confused to call for help themselves, it’s crucial to call an ambulance for them. While transient global amnesia is not dangerous, it can be challenging to distinguish it from other life-threatening illnesses that can also cause sudden memory loss.
Causes
The exact cause of transient global amnesia is not known, and the factors contributing to the condition are not fully understood. There is a potential association between transient global amnesia and a history of migraines, although the underlying reasons for this link remain unclear. Another possible cause is related to issues with the flow of blood, such as the overfilling of veins due to blockages or other problems leading to venous congestion.
Although the occurrence of transient global amnesia following these events is very rare, some commonly reported triggers include:
- Sudden exposure to cold or hot water
- Physical exertion
- Emotional or psychological stress
- Pain
- Sexual intercourse
- Undergoing medical procedures like angiography or endoscopy
- Mild head injury
- Performing the Valsalva maneuver, which involves closing the mouth and pinching the nose while bearing down as if having a bowel movement, often done during certain medical tests or to slow down a rapid heart rate.
Risk factors
The primary risk factors associated with transient global amnesia include:
- Age: Individuals aged 50 and above are at a greater risk of experiencing transient global amnesia compared to younger individuals.
- History of migraines: If you have a history of migraines, your risk of developing transient global amnesia is significantly higher than someone without migraines.
Diagnosis
Before diagnosing transient global amnesia, healthcare providers need to eliminate more serious conditions such as stroke, seizure, or head injury. These conditions can present with similar memory loss symptoms.
- Physical exam: Includes a neurological assessment. During this examination, healthcare providers evaluate reflexes, muscle tone, muscle strength, sensory function, gait, posture, coordination, and balance. Additionally, doctors may administer cognitive tests and ask questions to assess thinking, judgment, and memory.
- Imaging: The diagnosis of transient global amnesia involves conducting brain and imaging tests to identify any abnormalities in the brain’s electrical activity and blood flow. Your healthcare provider may recommend one or more of the following tests:
- Computerized tomography (CT): This test uses specialized X-ray equipment to capture images of the brain and skull from different angles. These images are then combined to create cross-sectional views. CT scans can reveal structural abnormalities in the brain, such as narrowed, overstretched, or damaged blood vessels, as well as past strokes.
- Magnetic resonance imaging (MRI): MRI utilizes a magnetic field and radio waves to produce detailed cross-sectional images of the brain. These images can be combined to create 3D representations that can be viewed from various angles. If you have already undergone a CT scan that did not detect any brain abnormalities during the episode, an MRI may not be necessary.
- Electroencephalogram (EEG): An EEG records the electrical activity of the brain by placing electrodes on the scalp. People with epilepsy often exhibit changes in their brain wave patterns, even when they are not experiencing a seizure. Your doctor may order an EEG if you have had multiple episodes of transient global amnesia or if they suspect that you might be having seizures.
Treatment
Transient global amnesia does not have a specific treatment and typically resolves on its own within 24 hours, returning memory function to its normal state. To ensure that there are no underlying medical causes and to monitor for any additional symptoms, healthcare professionals usually advise patients to remain in the hospital until the amnesia subsides.
