Transient global amnesia is scary, usually not dangerous


Dear Doctor: My husband is 68 years old and recently had an episode of memory loss. He suddenly didn’t know where he was. It lasted for about two hours and was very scary. Our son, who is a nurse, says maybe it was transient global amnesia. Can you please tell us something about that?

Dear Reader: Transient global amnesia refers to a sudden episode of temporary memory loss that is sometimes accompanied by confusion. It occurs separately from a condition that could commonly trigger it, such as a head injury, tumor or stroke. The causes aren’t yet understood, but it’s sometimes compared to the brief and specific bouts of amnesia that can arise after drinking too much, or from drug use.

Someone who is experiencing transient global amnesia, or TGA, is suddenly unable to recall recent events. They can, however, remember who they are, remember the names of familiar objects and recognize family members and people who have a regular part in their lives.

Although an episode of TGA can last up to 24 hours, it is usually much shorter. The average episode lasts about six hours. During the course of an episode of TGA, the individual is unable to either make or store new memories. They often repeatedly ask the same questions, because they are unable to retain the information in the answers that were given. These episodes typically occur in middle-aged and older adults.

While the onset of an episode of TGA is sudden, the recovery is usually gradual. As time passes, the individual will have increasing recall of places and events, until they feel completely oriented again. Once it’s over, most people won’t be able to recall anything that occurred during the episode. The causes of the condition are not known. A link between migraine and TGA is suspected, but it has not yet been proven. Possible triggers of the condition include physical or emotional stress, physical exertion, pain, sudden immersion in cold or hot water and medical procedures.

Elizabeth Ko, MD and Eve Glazier, MD

Because other serious conditions can share some of the symptoms of an episode of TGA, it’s important to seek medical attention. Even though your husband has recovered from his bout of memory loss, it would be wise for him to be evaluated by his health care provider. They will take a medical history and ask for a detailed description of the event. Since this isn’t something your husband can provide, you or someone else who was present will be asked for the narrative. It is likely that a neurological exam will take place. This will check sensory function, reflexes, gait, balance and coordination. Tests to assess memory and recall also will be performed. Depending on the findings, additional scans, such as magnetic resonance imaging, electroencephalogram or computerized tomography -- an MRI, EEG or CT scan -- will be used to detect any abnormalities in the brain’s blood flow or electrical function. Although alarming, an episode of TGA is not considered to be dangerous. For most people, it’s a unique event and is not repeated.

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