What is Transient Global Amnesia?
Transient global amnesia is a condition that causes sudden memory loss, affecting mainly adults between the ages of 50 and 70. This episode of memory loss can last from 1 to 24 hours. It’s quite a common condition, especially seen in emergencies.
This condition is considered benign, meaning it’s not harmful in the long run, and has typical symptoms. It doesn’t require advanced imaging or treatment. A person with transient global amnesia will experience two types of memory loss – retrograde (losing past memories) and anterograde (difficulty forming new memories). During an episode, a repeated behavior might be asking the same question over and over. The patient might be unsure about other people and places, but they do not lose awareness of who they are.
It’s rare for the symptoms of transient global amnesia to happen again once they’ve subsided. When a person recovers from an episode, their memory returns gradually, usually starting with distant memories before recent ones come back. The events that happened during the episode, however, are often permanently forgotten. No other brain-related issues come with this condition.
The main way to diagnose transient global amnesia is through noting the patient’s symptoms. People who experience transient global amnesia don’t usually have serious brain-related complications like strokes, epilepsy, or neurodegenerative disorders. If the patient shows any uncharacteristic symptoms, further tests may be needed to rule out other conditions.
What Causes Transient Global Amnesia?
The cause of a condition called transient global amnesia, where people temporarily lose their memory, isn’t fully understood. Many theories have been suggested, but none have been proven beyond doubt. The most widely accepted theory is that it might be linked to migraines. This is mainly because 12% to 30% of people with transient global amnesia have a history of migraines. Some researchers believe the condition might be due to a process that causes a type of migraine.
Other possible causes suggested are related to blood vessels, epilepsy, or psychological reasons. Some studies have found a connection to arterial ischemia, which is lack of blood flow to the artery, whereas other studies have not found such a link. An idea that’s currently leading is vascular congestion – an abnormal accumulation of blood – but questions remain regarding this theory’s relation to certain age groups and why it doesn’t occur in venous thrombosis, a condition in which a blood clot forms in a vein.
It’s rare for someone to experience transient global amnesia more than a few times in their lifetime. In the end, no single theory fully accounts for all the symptoms seen in people with transient global amnesia.
Risk Factors and Frequency for Transient Global Amnesia
Transient global amnesia, a temporary loss of memory, affects 3.4 to 10.4 out of every 100,000 people each year. However, this rate goes up in folks who are 50 and older, with the majority of cases happening in those between 50 and 80 years old. Both men and women are equally likely to experience it.
Despite no obvious risk factors, it’s often seen in those who have ischemic heart disease (when the heart doesn’t get enough blood) and high cholesterol levels, but not in someone who’s had a previous stroke, or suffer from diabetes, or hypertension (high blood pressure). A person with migraines is more likely to experience transient global amnesia, with a risk ratio of 2.48.
It’s not very common for transient global amnesia to occur more than once, but it’s also not rare. The rates range from 2.9% to 26.3%. It’s interesting to note that episodes of transient global amnesia are more likely to happen in the morning between 10 and 11 AM and late afternoon between 5 and 6 PM.
Signs and Symptoms of Transient Global Amnesia
Transient global amnesia is a medical condition that is primarily diagnosed through a thorough review of a patient’s symptoms and a complete neurological check-up. In most cases, additional tests like advanced brain imaging, spinal fluid analysis, or an EEG aren’t necessary unless the symptoms don’t clearly point towards this diagnosis.
Patients with transient global amnesia often suddenly can’t remember things for several hours. This may include their memories before and during the event. They may frequently repeat questions because they can’t remember recent happenings. There are instances where people around them might note that they were under physical strain or severe stress recently, but there was no fainting. These patients remember who they are and don’t show any other signs of neurological or cognitive problems. They continue to be cooperative, can name objects correctly, and don’t have a history of physical trauma or epilepsy. These symptoms typically last anywhere between 1 and 24 hours, and are more likely to occur later in the day rather than after waking up.
However, some things can make transient global amnesia seem less likely. These include signs of toxicity or metabolism troubles, history of physical trauma or epilepsy, and reduced alertness or consciousness. Additionally, if a patient can clearly recall what happened during an episode or if they experience more than 3 episodes a year, it’s essential to question whether the diagnosis of transient global amnesia is right.
Testing for Transient Global Amnesia
If you go to the emergency room with symptoms that look like temporary global memory loss, more testing generally isn’t needed. Your doctor will likely run some basic lab tests, including checking your blood for drugs or alcohol and making sure your blood sugar and electrolytes levels are okay. If your memory issues clear up within a few hours, you’ll most likely be allowed to go home.
But, if your symptoms or the basic lab results make your doctor uncertain about the diagnosis, you might need to stay in the hospital for monitoring and further tests. The most important test in this situation is an MRI, a type of scan that uses strong magnetic fields to produce detailed images of the inside of your body. This scan of your brain should look normal during the acute (or severe) phase of temporary global memory loss. However, specific signs in the MRI images that are characteristic of this condition typically appear between 24 and 72 hours after the memory loss episode. These signs look like tiny spots of increased intensity in parts of the brain involved in memory, specifically one or both hippocampi, predominantly in an area called CA1.
An EEG, a test that records electrical activity in the brain, can also be helpful in distinguishing temporary global memory loss from memory issues caused by epileptic seizures. The EEG results are usually normal for patients with temporary global memory loss, although occasionally there might be nonspecific theta and delta waves – these are types of brain waves that are slower than those typically observed in people who are awake and alert.
Testing the cerebrospinal fluid, which is the fluid that surrounds your brain and spinal cord, generally isn’t necessary unless your doctor thinks you might have an infection or inflammation in your brain.
Treatment Options for Transient Global Amnesia
If you’re dealing with a condition called transient global amnesia, this means you’re experiencing a short-term memory loss that’s not caused by a serious underlying condition like stroke or epilepsy. Treatment for this condition is mainly focused on offering comfort and reassurance since there is no specific therapy or medication developed for it.
To ensure there’s no other more serious cause for your memory loss, doctors will conduct a thorough examination. They’ll check for any signs of damage to your nervous system or head injuries that could indicate the diagnosis should actually be something else.
In certain cases, you might need to stay in the hospital for observation until your memory returns to normal. In the meantime, you may receive an intravenous treatment with a vitamin called thiamine. Even though it’s quite rare, keep in mind that these temporary memory loss episodes can happen more than once.
Conversely, the good news is that once your memory returns to normal, you usually don’t have to limit your daily activities such as driving. So, even though it can be scary, transient global amnesia is in most cases not something to worry about in the long run.
What else can Transient Global Amnesia be?
In layman’s terms, if a person’s memory loss episode has unusual features, or they show certain signs of brain impairment, it’s vital to rule out the possibility of a stroke affecting the memory-centric part of the brain (the hippocampus) using a brain scan (MRI).
Doctors also need to consider the likelihood of a type of memory loss related to epilepsy, which is often seen in patients with a history of specific types of seizures. These episodes usually last less than an hour and can happen frequently (more than three times per year). This type of memory loss is unique in that there’s usually seizure-like activity leading up to the memory loss, and the memory loss is almost entirely of past events. This is in contrast to a condition called transient global amnesia, which primarily causes difficulty creating new memories and only affects recall of events happening around the onset. A particular type of brain scan called interictal EEG is the main tool used to distinguish between these two conditions.
Other conditions that need to be considered when diagnosing memory loss include:
- Thrombosis (blood clot) in the basilar artery
- Stroke caused by a blood clot originating from the heart
- Complex partial seizures
- Lacunar syndrome, a type of stroke affecting small blood vessels
- Variant forms of migraine
- Stroke affecting the posterior cerebral artery
- Syncope (fainting)
- Temporal lobe epilepsy
- Low blood sugar (hypoglycemia)
- Wernicke encephalopathy, a brain disorder caused by lack of vitamin B1
- Transient ischemic attack (warning stroke)
- Harmful effects on the brain from exposure to toxins
- Lack of oxygen supply to the brain (hypoxia)
- Head injury
- Effects of intoxication from substances
Often, these conditions need to be explored when the patient’s symptoms involve overall confusion rather than the specific memory loss and symptoms generally seen in transient global amnesia.
What to expect with Transient Global Amnesia
Transient global amnesia, a temporary loss of memory, generally happens as isolated events with good outcomes and very negligible harmful effects or death reported. Even though there’s a possibility of these memory loss events happening again, they occur between 2.9% to 26.3% of the time over different periods of observation. A study that went on for 10 years showed that there’s a 6.3% chance of recurrence.
A recent study from Korea indicated that there could be a slightly increased risk of epilepsy, a neurological disorder leading to frequent seizures, after an episode of transient global amnesia. This risk is estimated to be 46% higher compared to those without the condition. However, this finding also emphasizes how critical it is to accurately confirm the initial diagnosis of transient global amnesia.
Possible Complications When Diagnosed with Transient Global Amnesia
Transient global amnesia (TGA) usually doesn’t cause complications due to its temporary and non-harmful nature. However, it’s episodic nature can cause substantial worry and stress for patients and their loved ones during an episode. While unusual, it’s possible for TGA to happen more than once, adversely impacting the patient’s quality of life and requiring regular medical check-ups. In a small number of cases, according to some studies, TGA may increase the chances of developing epilepsy. This underscores the need for comprehensive diagnosis and follow-up care to keep an eye on any new neurological conditions or delayed effects. Despite these factors, the majority of people with TGA see their symptoms fully resolve without long-term issues or functional limitations.
- Infrequent complications with TGA due to its temporary nature
- Significant stress and worry can occur during episodes
- Re-occurrence can impact quality of life and require medical follow-ups
- In rare cases, it could increase the risk of developing epilepsy
- Importance of thorough diagnosis and follow-up care
- Most people with TGA experience full recovery without long-term complications.
Preventing Transient Global Amnesia
Prevention and teaching patients about their conditions are key factors in handling transient global amnesia, a temporary loss of memory that’s not serious. It’s important to let patients know that this condition usually happens only once and generally has a good outcome without any long-term effects. Patients must be told to get checked out by a healthcare professional during a memory loss episode to confirm the condition and make sure there are no other causes for the memory loss.
Encouraging patients to make changes to their lifestyle can also play a large part in managing this condition. For example, using stress reduction techniques and properly handling conditions that could affect their blood vessels, like high blood pressure or high cholesterol, could possibly lower the chances of experiencing more episodes of memory loss.
In addition, patients should be educated about the warning signs or symptoms that require immediate medical attention. This includes things like certain signs of nerve damage or longer periods of confusion. This knowledge will help patients to take the correct action and seek medical help promptly if needed. Equipping patients with this information promotes proactive management and ensures the best possible outcomes for those with transient global amnesia.
