Transient global amnesia

There is currently no consensus on an underlying cause of transient global amnesia (TGA). Possible mechanisms that have been proposed include:^[3][2]

• a vascular etiology, such as venous flow abnormalities
• hypoxia (deficiency of oxygen supply) and/or ischemia (deficiency of blood supply)
• a relation to migraine (some studies have shown that history of migraine is associated with TGA)
• epilepsy
• psychological factors

However, none of these theories clearly and consistently explain the features of TGA.^[3] Because no one theory appears to apply to all people with TGA, some speculate that TGA may have multiple different causes.^[3]

There is a distinct, benign form of TGA that may occur following excessive alcohol consumption; large sedative doses of barbiturates; the use of several illicit drugs; or sometimes, relatively small doses of benzodiazepines.^[2]

Events that reportedly may trigger an episode of TGA include:^[2][4]

• sudden immersion in cold or hot water
• physical exertion
• emotional distress or psychological stress
• pain
• medical procedures
• head trauma
• sexual intercourse
• a Valsalva maneuver

Transient global amnesia (TGA) is considered a sporadic disorder (not inherited, occurring in only one person in a family). However, familial cases of TGA have rarely been reported.^[5] Most familial reports have involved siblings, with only occasional or possible parental involvement. While details of these cases have been incomplete, several of the affected people in these families had a history of migraine.^[5]

Some clinicians believe that TGA can be a manifestation of a migraine aura, in which a familial predisposition to TGA may not be surprising. It is also possible that other genetically-influenced developmental factors might predispose only certain families. On the other hand, rare familial cases of TGA could possibly be coincidental.^[5]

The underlying cause of TGA is largely unknown, and additional published reports of familial cases are needed to investigate a possible genetic component of the disorder.

There is no specific treatment for transient global amnesia (TGA).^[6] Fortunately, this condition resolves on its own, typically within hours of onset.^[1] Most people with TGA do not experience repeat episodes.^[6][4]

People with repeat episodes of TGA should document the circumstances triggering the event. For some, it may be possible to prevent TGA by avoiding triggers. However, for many this is not possible. Possible triggers of TGA, include:^[7][4]

Sudden immersion in cold or hot water
Strenuous physical activity
Sexual intercourse
Medical procedures, such as angiography or endoscopy
Mild head trauma
Acute emotional distress (e.g., from bad news, conflict or being overworked)
Exposure to high altitudes

Much of what we know about treatment of recurrent TGA comes from single case reports. These reports emphasize the need to rule out all other possible causes of recurrent TGA type episodes, such as transient epileptic amnesia, vascular disease, heart conditions, and adverse drug events, as this will affect treatment.^{[8][9][10][11]}

The cause of transient global amnesia is not known, but migraines seem to be associated in many cases. We found a single report of metoprolol use for treatment of recurrent TGA in a man with a history of migraine.^[7] Further study is needed to assess the efficacy of this treatment.