Filed under: Amazing Mind
Transient global amnesia is a sudden, temporary episode of memory loss that can't be attributed to a more common neurological condition, such as epilepsy or stroke.
During an episode of transient global amnesia, your recall of recent events simply vanishes, so you can't remember where you are or how you got there. You may also draw a blank when asked to remember things that happened a day, a month or even a year ago. With transient global amnesia, you do remember who you are, and recognize the people you know well, but that doesn't make your memory loss less disturbing.
Fortunately, transient global amnesia is rare, seemingly harmless and unlikely to happen again. Episodes are usually short-lived, and afterward your memory is fine.
Transient global amnesia is identified by its main symptom, which is the inability to form new memories and to recall the recent past. Once that symptom is confirmed, ruling out other possible causes of amnesia is important.
Necessary symptoms for diagnosis
Doctors base a diagnosis of transient global amnesia on the following signs and symptoms:
Along with these signs and symptoms, a common feature of transient global amnesia includes repetitive questioning, usually of the same question — for example, "What am I doing here?" or "How did we get here?"
When to see a doctor
Seek immediate medical attention for anyone who quickly goes from normal awareness of present reality to confusion about what just happened. If the person experiencing memory loss is too disoriented to call an ambulance, call one yourself.
Although transient global amnesia isn't harmful, there's no easy way to distinguish the condition from the life-threatening illnesses that can also cause sudden memory loss. In fact, sudden amnesia is much more likely to be caused by a stroke or a seizure than by transient global amnesia. A medical evaluation is the only way to determine the cause of sudden memory loss.
The underlying cause of transient global amnesia is unknown. There appears to be a link between transient global amnesia and a history of migraines, though the underlying factors that contribute to both conditions aren't fully understood.
Some commonly reported events that may trigger transient global amnesia include:
Interestingly, high blood pressure and high cholesterol — which are closely linked to strokes — are not risk factors for transient global amnesia. Your sex doesn't seem to affect your risk, either.
The clearest risk factors are:
Transient global amnesia has no direct complications, but it can cause emotional distress. If you have an episode, the gap in your memory can be unsettling, and you're likely to worry about a recurrence. Also, a symptom as dramatic as memory loss often heralds a serious underlying disease. Transient global amnesia is an exception, but it can be hard to let go of the fear that you have a tumor or had a stroke.
If you need reassurance, ask your doctor to go over the results of your neurological exam and diagnostic tests with you. A counselor or psychotherapist can help you deal with persistent anxiety. Importantly, transient global amnesia is not a risk factor for stroke.
Anyone who experiences sudden loss of memory for all events leading up to the present needs emergency medical care. Call 911 or your local emergency number immediately. If a friend or family member develops these symptoms in your presence, go with him or her to the hospital. Because he or she doesn't remember recent events, you'll need to provide critical information to the doctor.
What you can do
Prepare a list of questions to ask the doctor on your loved one's behalf. Although people experiencing transient global amnesia can think and speak, it's likely that they will be feeling severe distress. For transient global amnesia, some basic questions include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time.
What to expect from your doctor
The doctor is likely to ask both of you a number of questions about your loved one's symptoms and about the period leading up to the memory loss.
The doctor may ask your loved one:
To determine the extent of memory loss, the doctor may check your loved one's knowledge of general information — such as the name of the current president — and assess his or her ability to recall a random list of words.
The doctor may ask you:
Diagnosis of transient global amnesia rests on excluding more-serious conditions — stroke, seizure or head injury, for example — that can cause the same type of memory loss.
The process begins with a neurological exam, checking reflexes, muscle tone, muscle strength, sensory function, gait, posture, coordination and balance. The doctor may also ask questions to test thinking, judgment and memory.
Brain and imaging tests
The next step is to conduct tests that detect abnormalities in the brain's electrical activity and circulation. The most common of these tests are painless and take less than two hours each:
Because the cause of transient global amnesia is unknown and the rate of recurrence is low, no standard approaches for preventing the condition exist. If your episode of transient global amnesia followed a particular activity, such as a strenuous workout or a vigorous swim in a chilly lake, talk with your doctor about what's safe going forward. He or she may recommend that you limit or avoid the activity that seemed to trigger your memory loss.