Clinical Geriatrics

Case Presentation

Mrs. W, a 72-year-old female, was admitted to a senior behavioral health inpatient unit following two episodes of transient amnesia. The first episode occurred following a near motor vehicle accident in a parking lot while she had been driving alone in her car. Immediately afterwards, she moved to the passenger’s seat where she was found by security guards, to whom she reported that she could not remember how to operate her car. Mrs. W was disoriented to situation and place but was able to provide her daughter’s name and phone number. She was taken to a community hospital emergency department (ED) and underwent an evaluation. Laboratory tests including a complete blood count, cardiac markers, a basic metabolic panel, and liver function tests were normal with the exception of an elevated total serum protein of 8.9 g/dL. Her electrocardiogram was normal. Chest radiograph and head computed tomography (CT) scan were performed.

The patient was diagnosed with “acute anxiety” and discharged with a prescription for alprazolam. The radiological studies were not reviewed by the ED doctor or discussed with the patient or her family prior to discharge. Mrs. W and her family were not contacted regarding these studies after discharge.

One week later, the patient had a second amnesic episode while driving. She recalled leaving her house, and the next thing she remembered was driving in Mexico and being lost. After several hours, Mrs. W found her way back across the border and telephoned her daughter, who picked her up and brought her directly to the senior behavioral health inpatient unit, where she was admitted.

Discussion

Transient global amnesia (TGA) is a syndrome characterized by acute onset of anterograde amnesia accompanied by variable retrograde amnesia. Episodes last less than 24 hours and most often occur in older adults. During the amnesic period, patients recall their identities and recognize familiar people, but they cannot remember recent events and are unable to acquire new information. The memory loss is accompanied by disorientation and repetitive questions. Patients appear bewildered and confused but have insight into their memory problem. Patients are usually free from neurological deficits, but difficulty copying complex constructions has been observed in the midst of an episode.1

The cause of TGA continues to be a matter of debate. A vascular mechanism is most commonly described.2 Vascular causes of TGA include basilar artery thrombosis, transient ischemic attack (TIA), posterior circulation arterial stroke, migraine, and venous congestion. The venous congestion hypothesis is supported by the association between TGA and circumstances that result in reduced venous return and retrograde venous blood flow, such as the Valsalva maneuver, stress, pain, sexual activity, or excessive exertion. On positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWMRI) scans, transient disruption of blood flow to specific brain areas including the thalamus and mesial temporal structures may be seen.3,4

Although TGA is considered a benign disorder and is rarely associated with intracranial lesions, other causes of transient amnesia include brain tumors, seizures, and psychiatric disorders including dissociative disorders.1 Transient amnesia associated with tumors is believed to occur when there is bilateral involvement of the temporal lobes or unilateral involvement with associated bilateral ischemia.5-7 In addition to transient ischemia, other suggested explanations of the etiology of transient amnesia in patients with brain tumors include hemorrhage within the tumor and complex partial seizures.