Transient global amnesia

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 17, 2016
StartDiseasesTransient global amnesia

Transient global amnesia (TGA) is a specific type of amnesia where an individual experiences a temporary loss of memory. Those who experience an episode of TGA typically have anterograde amnesia, which is the inability to create new memories, and they may also experience retrograde amnesia, which is the inability to remember events in the past. After an attack, their memory gradually returns to normal.

Contents

Definition & Facts

Five in every 100,000 people experience an episode of transient global amnesia each year. This neurological disorder affects people between the ages of 40 and 80 and affects both men and women. The average age of people who experience this form of amnesia is 61 years of age.

Those experiencing an episode of transient global amnesia will still have basic knowledge of the world around them as well as information about themselves, such as who they are and their age. They will also have the ability to name general objects, recognize words, and follow simple directions or instructions.

Symptoms & Complaints

An attack is usually characterized by the individual asking questions such as: What's happening? Where am I? How did I get here? What day is it? What time is it? During a TGA attack, the patient will not be able to establish memories of the attack. For example, two hours into the attack, they won't remember what happened at the beginning of the attack.

Throughout the duration of the attack, the person afflicted by TGA may appear normal to an outside observer. For instance, someone could have an attack while driving, swimming or bathing, and the only immediately noticeable change to an observer is that the patient may appear nervous or agitated. After an attack, the patient will not be able to remember having the attack, but all other memories and awareness will return. Memories immediately prior to the attack will return last.

Episodes last no more than 24 hours, but will usually last around 8 hours. It is not always possible to tell whether an attack is caused by something more dangerous, such as a heart attack. It is best to call an emergency medical hotline. If the patient can't call by himself or herself, then an observer should make the call.

Causes

A variety of mechanisms and factors may be at play and research is inconclusive as to a definitive cause. A possible risk factor may include a history of migraine headaches. Other theories posit that certain personality disorders may be associated with TGA. Situations that commonly precede attacks include:

  • Diving or Swimming
  • Sexual intercourse
  • Struggling to exhale when air passages are completely blocked
  • Sudden immersion in hot or cold water
  • Intense pain
  • Psychological stress. Some research indicates that this may precipitate TGA among women more frequently than among men.
  • An angiography, endoscopy, or related medical procedure
  • Coughing
  • Strenuous activities, such as any type of lifting of heavy objects, straining, chopping, sawing, etc.

Diagnosis & Tests

The patient's doctor will first rule out any serious health conditions that need immediate attention; these include a head injury, stroke, or seizure. Any injuries that may have occurred prior to or at the onset of the attack will also be addressed. The doctor will ask the patient what the last thing he or she remembers. This will help the doctor determine when the attack started.

The doctor will do a neurological exam. He or she will carry out brain and imaging tests, such as magnetic resonance imaging (MRI), electroencephalogram (EEG), and a computerized tomography scan (CT scan).

In order to diagnose TGA, the episode must have been witnessed. There must not be a recent history of seizures or head injury, and there must not be any loss of personal identity or cognitive impairment.

Treatment & Therapy

It is important for individuals to seek medical attention if they are in a state of confusion about what just happened, where they are, what day it is and so forth. At this point, it may not be known whether the individual is having a classic case of TGA or if they are having a stroke or seizure - both of which cause a different type of amnesia.

After an attack, when someone informs the patient of what had just happened or the patient realizes many hours have elapsed, then it is common to feel uneasy, worried or distressed. To put one's fears completely to rest and to be sure of the diagnosis, the patient should ask his or her doctor to go over the test results and neurological exam.

Once a person knows he or she is prone to a condition, he or she can keep items on hand to help out in certain situations. Some items that may come in handy are a clock or watch, a calendar, a telephone, friends and family and a notepad listing anything urgent that must be taken care of in the next 24 hours.

If the patient is still left worrying about this occurrence and fearing another attack, then seeing a counselor or psychotherapist can help the patient put his or her fears to rest and possibly be better prepared for a future attack. The patient may also be able to get in touch with others who have had episodes of TGA in order to get support and trade stories and ideas for how to cope and remain out of harm's way.

Prevention & Prophylaxis

Methods to treat and prevent transient global amnesia are difficult to establish because it is a temporary phenomenon. There is a 4% chance that there will be a reoccurrence each year. Besides trying to avoid some of the activities that may trigger an episode, such as submersion in extremely warm or cold water, or forcefully trying to exhale while blocking air ways, there are limited options for preventing or decreasing the frequency of episodes.