Transient global amnesia

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Are you having a friend or a dear one suffering from mental confusion and an inability to recall all major happenings in the recent past? The problem may be a condition known as Transient global amnesia. Read and know all about the disease, including its main causes, symptoms, diagnosis and treatment options.

Transient global amnesia Definition

Transient global amnesia (TGA) refers to an abrupt, temporary loss of memory that cannot be associated to more common neurological disorders such as stroke or epilepsy.

Transient global amnesia ICD9 Code

The ICD9 Code for this disorder is 437.7.

Transient global amnesia Incidence

The annual incidence of TGA has been estimated to vary between 23 and 32 cases in every 100,000 individuals in the United States. The disorder is most common in individuals aged between 56 and 75 years. The average age of onset of the disease has been reported to be around 62.

Transient global amnesia Symptoms

Movies and soaps often feature characters, even protagonists, suffering from temporary loss of memory. TGA is mainly characterized by a similar inability to remember the recent past and form new memories on a temporary basis. Once that problem is confirmed, doctors should rule out other possible causes of amnesia.

At the time of an episode of TGA, the ability of a person to recall recent happenings simply goes away. Sufferers cannot remember their surroundings and how they got there. They may also be unable to answer when asked to recall things happening within a day, month or even a year.

While individuals suffering from TGA tend to remember who they are and recognize the people around them, the loss of memory about recent events can be quite disturbing for them.

During the episode of memory loss, patients may also exhibit other physical symptoms although they can be variable in nature. The most common physical symptoms include:

  • Panics
  • Sweats
  • Racing heartbeat
  • Stomach upset
  • Headache

If the physical problems are not reported at the time of memory loss, patients are not likely to report them again as they are unlikely to remember them at a later time.

Transient global amnesia Causes

The underlying cause of TGA is not known as yet. According to medical researchers, there is apparently a link between the disorder and a history of migraines. However, the underlying factors that can cause both conditions have not been completely understood.

Some events that are commonly reported and suspected to be the trigger factors for TGA include:

  • Sexual intercourse
  • Strenuous physical activity
  • Mild head trauma
  • Sudden immersion in hot or cold water
  • Medical techniques, such as endoscopy or angiography
  • Severe emotional distress, as might occur due to overwork, conflict or bad news

This condition is supposed to arise as a consequence of some types of trauma, physical activities like sexual activity or physical horseplay or medical techniques like catheterization. Extremely bad and traumatic news can also cause severe mental trauma and lead to TGA.

Transient global amnesia Risk Factors

The most apparent risk factors for this disorder are:

Age

Those aged 50 and above are more susceptible to TGA than younger individuals.

History of migraines

In people having migraines, the risk of TGA is much more than those without migraines. Those suffering from migraine headaches seem to be predisposed to this disease.

It is interesting to note that high cholesterol and high blood pressure are not risk factors for TGA, despite being associated closely to strokes. Being male or female does not seem to make any difference and there is probably no sexual predilection for the disease.

According to certain theories, pressure on the large veins located in the back portion of the head might lead to an emergence of this condition.

Transient global amnesia Diagnosis

Physicians base the diagnosis of TGA on the following symptoms:

  • Abrupt onset of memory loss, confirmed by a familiar person
  • Ability to remember personal identity, despite memory loss
  • Episode of memory loss lasting for not more than 24 hours
  • Normal cognition, such as the ability to follow simple directions and make out and name familiar things
  • No sign of seizures at the time of amnesia
  • Gradual coming back of memory
  • No history of recent head injury or active epilepsy
  • No signs that indicate damage to the nerves of a particular brain area, such as defective word recognition, involuntary movement or paralysis of a particular limb

Patients also commonly tend to ask same type of questions repetitively, such as “How did I get here?” or “What am I doing here?”

Although TGA is not a harmful condition, physicians are unable to easily differentiate the disease from life-threatening disorders that may also lead to abrupt loss of memory. Sudden amnesia is in fact, much more likely to result from a seizure or stroke than due to TGA. The exact cause of abrupt loss of memory can only be determined by a medical assessment.

Transient global amnesia – Testing and Diagnostic Tests

The diagnosis of the condition is based on the exclusion of more severe disorders, such as head injury, seizure or stroke that can lead to some form of memory loss.

The diagnostic tests for this disorder include:

Physical examination

The process starts with a neurological test and checking the following:

  • Balance
  • Coordination
  • Gait
  • Posture
  • Reflexes
  • Sensory function
  • Muscle tone
  • Muscle strength

Doctors may also ask questions to test memory, judgment and thinking capacity of affected individuals.

Brain and imaging tests

These include detecting abnormalities in the circulation and electrical activity of the brain. The most common tests out of these are painless and take less than 2 hours to be performed.

These tests include the following:

Magnetic resonance imaging (MRI)

The process involves radio waves and a magnetic field to construct cross-sectional, detailed images of the brain. These images can be combined by an MRI machine to render 3-D pictures that can be viewed from a variety of different angles.

Electroencephalogram (EEG)

This technique records the electrical activity of the brain’s through electrodes that are firmly attached to the scalp. Epileptic individuals often suffer from changes in their brain waves even when they do not suffer from seizures.

Computerized tomography (CT)

The process makes use of special X-ray equipment known as CT machines that obtain and combine images from various angles to get cross-sectional images of the skull and brain. CT scans can show abnormalities in brain structure, which include broken, narrowed or overstretched blood vessels and signs of strokes in the past.

Transient global amnesia Differential Diagnosis

The differential diagnosis for TGA includes isolating its symptoms from those of other disorders than can give rise to similar problems. These include:

  • Head injury
  • Nonconvulsive epilepsy
  • Hysterical amnesia
  • Korsakoff psychosis
  • Cardioembolic Stroke
  • Basilar Artery Thrombosis
  • Lacunar Syndromes
  • Complex Partial Seizures
  • Migraine Variants
  • Frontal Lobe Epilepsy
  • Posterior Cerebral Artery Stroke
  • Syncope and Related Paroxysmal Spells
  • Temporal Lobe Epilepsy
  • Various causes of acute confusional states like dementia, drug or alcohol intoxication and hypoglycemia

Physical examination as well as assessment of clinical history of sufferers is usually helpful in confirming the disorder.

TGA can generally be distinguished from Complex partial seizures on clinical grounds, as they are related with affected ability to perform complicated tasks and altered consciousness.

Transient global amnesia Treatment

The condition does not require any medical treatment. It tends to disappear on its own and is confirmed to result in no after effects. Once the condition is detected, cure only involves providing reassurance to sufferers and scheduling for them at least one follow-up visit with a neurologist.

Patients with this disease do not need any dietary restrictions. However, they should avoid all activities that can lead to an increase in intrathoracic pressure.

Transient global amnesia Prognosis

Luckily, TGA is a rare and apparently harmless condition. Episodes of this disorder are generally temporary and unlikely to occur again. The memory is usually fine after an episode of TGA.

Transient global amnesia Complications

Although the condition is not known to directly give rise to any complications, it can result in mental distress in sufferers. The loss of memory can be disturbing in patients and they are likely to worry about a recurrence of the disorder. Symptoms like abrupt memory loss can often indicate a more acute underlying disorder. Although TGA does not indicate any severe underlying disorder as a cause, it can difficult to get rid of the fear of a possible severe cause like a stroke or a tumor. Patients can be reassured by going through a neurological exam and getting good test results. Persistent anxiety can be reduced through counseling or psychotherapy. TGA is not a risk factor for stroke.

Transient global amnesia Prevention

No standard preventive approaches for TGA tend to exist as the cause of the disease is unknown and its rate of recurrence is low. In case an episode of TGA occurs after a specific activity like swimming in very cold waters or working out severely, it is better to consult a doctor about what can be done. Physicians may recommend limitation or avoidance of activities that seem to trigger loss of memory in sufferers.

 

If you have a friend or a family member who enters a state of confusion about recent events from normal awareness, it is important that you seek medical attention on an immediate basis. Call an ambulance if the person is too disoriented or suffering from some other problems apart from mental confusion.

References:

http://en.wikipedia.org/wiki/Transient_global_amnesia

http://www.mayoclinic.com/health/transient-global-amnesia/DS01022

http://emedicine.medscape.com/article/1160964-overview

http://edition.cnn.com/HEALTH/library/transient-global-amnesia/DS01022.html

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