Forgetting the Unforgettable

A 71-year-old male presented to the ER with a history of confusion and amnesia around 05:30 pm. At the time of the episode, he had just finished his shower and was found standing in his room with excessive sweating and confusion while repeating the same question: “What happened?”. He was not able to recognize his family members. Prior to the shower, he was normal.

There was no past medical history of stroke, seizures, dementia, traumatic brain injury, psychiatric illnesses or similar episodes. Currently on beta-blockers, anti-platelets and statins for hypertension and coronary artery disease. He denied any tobacco, alcohol, or recreational drug use.

The initial ER evaluation did not demonstrate any facial asymmetry or signs of unilateral neurological deficits. Vitals: pulse – 92 bpm, blood pressure – 140/100 mmHg, respiratory rate – 18 breaths per minute, T – 98.4°F, SpO2 – 99% on room air, and CBG of 106 mg/dL. When assessing the patient’s alertness and orientation level, the patient provided incorrect answers to the current prime minister, current calendar year and address / location of his residence. He was able to perform deducting serial 7s and counting backwards from 20.

Although the patient demonstrated impaired short-term memory, his long term memory appeared reasonably intact. There were no  hallucinations or delusions. He had no aphasia or dysarthria. The Cranial nerve exam was normal. His motor and sensory examination was normal, including normal gait.

Laboratory workup (consisting of a complete blood analysis, liver function test, and renal function test, thyroid function test) was normal.B12 and folic acid were also normal.

The brain MRI, including MR Angiogram, was normal. EEG did not show any abnormal cerebral activity.

Upon evaluation, 24 hours since the incident, the patient was alert and orientated to person, place, and time  had returned to baseline. However, he was not able to recall the events that occurred during this 24-hour period.

A diagnosis of Transient Global Amnesia was made based on clinical findings and rapid recovery of memory within 24 hours. A follow-up visit was planned for one week later.

DISCUSSION:

Transient global amnesia (TGA) is a temporary, anterograde amnesia with an acute onset that typically occurs in middle to older-aged individuals.  Patients have striking loss of memory from recent events with inability to retain new information with anxiety and mild agitation. They may repeatedly ask questions about the recent events. Often, language function, attention, visual-spatial, and social skills are preserved. Amnesia will usually resolve within 24 hours, but they may have a distinct lapse of memory for events during the attack.

TGA is often initiated by high-stress situations, migraines, and particularly by strenuous activity, especially associated with prolonged breath-holding spells, e.g. repeated crying, lifting heavy objects, diving underwater etc. Current studies have not established conclusive risk factors for the development of this condition, however, few in the field have suggested that hyperlipidemia, migraine, and a history of previous heart disease pose increased risk.

The precise pathophysiology is not clear, but findings have reported transiently disturbed blood flow to specific areas of the brain, thalamus, mesial temporal lobe, especially amygdala and hippocampus based on PET, SPECT, and MRS studies. Patients with TGA have a significant risk of developing TIA or mini-stroke in the future and would typically undergo risk factor screening and treatment for cerebrovascular events.

Pranav R. Chandramohan
Clinical Observer (Bachelor’s in Neuroscience Student from Texas A&M University)

Dr. Yashica Priya R.,MD
Internal Medicine
Kauvery Hospital, Chennai

Dr. Sivarajan Thandeswaran, MBBS, MRCP (UK)
Senior Consultant
Kauvery Hospital, Chennai