Increased incidence of transient global amnesia during the Covid-19 crisis?

Transient cerebral vasospasm and global amnesia following post-CT contrast

We present a unique case of transient global amnesia following intravenous administration of a non-ionic iodinated contrast agent for abdominal CT examination. Follow up MR imaging and MR angiography studies revealed hippocampal microinfarction and transient cerebral vasospasm. To our knowledge, this is the first reported case capturing arterial vasospasm following intravenous use of iodinated contrast. Medical professionals handling contrast agents should note the potential for these rare but serious adverse effects.

Hippocampal alterations after SARS-CoV-2 infection: A systematic review

SARS-CoV-2 infection produces a wide range of symptoms. Some of the structural changes caused by the virus in the nervous system are found in the medial temporal lobe, and several neuropsychological sequelae of COVID-19 are related to the function of the hippocampus. The main objective of the systematic review is to update and further analyze the existing evidence of hippocampal and related cortices' structural and functional alterations due to SARS-CoV-2 infection. Both clinical and preclinical studies that used different methodologies to explore the effects of this disease at different stages and grades of severity were considered, besides exploring related cognitive and emotional symptomatology. A total of 24 studies were identified by searching in SCOPUS, Web Of Science (WOS), PubMed, and PsycInfo databases up to October 3rd, 2022. Thirteen studies were performed in clinical human samples, 9 included preclinical animal models, 3 were performed post-mortem, and 1 included both post-mortem and preclinical samples. Alterations in the hippocampus were detected in the acute stage and after several months of infection. Clinical studies revealed alterations in hippocampal connectivity and metabolism. Memory alterations correlated with altered metabolic profiles or changes in grey matter volumes. Hippocampal human postmortem and animal studies observed alterations in neurogenesis, dendrites, and immune response, besides high apoptosis and neuroinflammation. Preclinical studies reported the viral load in the hippocampus. Olfactory dysfunction was associated with alterations in brain functionality. Several clinical studies revealed cognitive complaints, neuropsychological alterations, and depressive and anxious symptomatology.

Transient global amnesia after COVID-19: A systematic scoping review of case reports

Background: Transient global amnesia (TGA) is a sudden-onset transient memory impairment along with intact neurologic examinations. Even though it is a benign neurologic condition with many differential diagnoses, the incidence rate of TGA is reported to have increased since the onset of the pandemic. Therefore, this systematic scoping review aims to investigate TGA in that context. Methods: MEDLINE, Scopus, and Google Scholar databases were systematically searched for relevant articles with a string of specified keywords. Results: The primary search yielded 90 studies. After all the necessary screening rounds were carried out, we were left with six included studies. One study was also identified through a search in other relatively relevant databases. Finally, seven case reports were accepted including three TGA patients with positive and one with negative test for coronavirus disease-2019 (COVID-19), respectively. COVID-19 status was unclear in the others. Conclusion: The reported COVID-19 positive cases had presentations similar to those with TGA before the pandemic. Therefore, we think that TGA might occur concomitantly with the COVID-19 infection or due to the psychological impact of the pandemic. In the confirmed cases of TGA and COVID-19, the abnormal findings may be due to COVID-19 infection. However, the reports were not as complete as desired. Therefore, providing the readers with more detailed reports in future cases is recommended.

COVID-19 Vaccine-Associated Transient Global Amnesia: A Disproportionality Analysis of the WHO Safety Database

Coronavirus disease 2019 (COVID-19) spread rapidly, resulting in a global pandemic for which vaccines were quickly developed. As their safety continues to be monitored, cases of transient global amnesia (TGA) following mRNA vaccination with elasomeran have been reported. TGA is characterized by sudden onset of anterograde amnesia with preservation of other cognitive functions and resolution within 24 h. We aimed to investigate the potential link of TGA with COVID-19 vaccines. We queried the World Health Organization VigiBase® for all reports of "Transient global amnesia", up to 6 December 2021. Disproportionality analysis relied on the Reporting Odds Ratio (ROR) with its 95% Confidence Interval (CI) and the Information Component (IC). A positive lower end of the 95% CI of the IC (IC025) is used to statistically detect a signal. Of all TGA cases, 289 were associated with a COVID-19 vaccine, representing the most frequent association. Tozinameran was mostly represented (147, 50.8%), followed by AZD1222 (69, 23,8%), elasomeran (60, 20.8%), and JNJ-78436735 (12, 4.2%). With an IC025 > 0, COVID-19 vaccines showed a significant ROR (5.1; 95%CI 4.4-6.0). Tozinameran reached the strongest ROR (4.6; 95%CI 3.9-5.0), followed by elasomeran (4.4; 95%CI 3.4-6.0), AZD1222 (3.8; 95%CI 3.0-5.0), and JNJ-78436735 (3.7; 95%CI 2.1-6.0). Our analysis of COVID-19 vaccines-related TGA reports shows significant disproportionality. Cerebrovascular, inflammatory, or migrainous mechanisms may underlie this association. Yet, numerous confounding factors cannot be tackled with this approach, and causality cannot be ascertained. The identification of this trigger of TGA may help the clinician in his etiological research.

New-Onset Transient Global Amnesia: A Clinical Challenge in an Air Medical Transportation Pilot With a History of Coronavirus Disease 2019

A 43-year-old male Bell 214C helicopter pilot presented to the emergency ward with flu-like syndrome. His nasopharyngeal severe acute respiratory syndrome coronavirus 2 real-time polymerase chain reaction test was positive, and a chest computed tomographic scan confirmed coronavirus disease 2019 pneumonia. He was admitted, received treatment, was discharged, and returned to flying. During the mission debrief, copilots who had flown with him reported that he experienced episodes of in-flight dizziness and blacked out. They occurred briefly during the cruise and hovering flight, perhaps for a few seconds of disorientation and unconsciousness. Rapid identification of the copilot and control of the helicopter prevented any incident or accident. Afterward, he explained the sudden onset and unexpected brief periods of loss of consciousness after a headache. The flight safety office referred him to the aviation medical center for further investigations. The cardiovascular, neurologic, laboratory, and toxicologic assessments were inconclusive with the approach to sudden-onset transient loss of consciousness. The only abnormal finding was hippocampus lesions on brain magnetic resonance imaging (MRI). Because of the possible diagnosis of transient global amnesia, the aviation medical examiner suspended him from flight duties until complete recovery and the absence of any probable complications.

A Case of Transient Global Amnesia: A Rare Diagnosis

Transient global amnesia (TGA) is a syndrome characterized by a loss of anterograde memory with a less prominent loss in retrograde episodic memory that resolves within 24 hours or less. In this report, we present a rare case of a 62-year-old male who presented to the emergency department with sudden onset confusion and memory loss. Prior to this, the patient had no significant medical or psychiatric history. Magnetic resonance imaging (MRI) and computerized tomography (CT) showed a normal presentation, and a neurology consultation ruled out any organic brain abnormalities. After ruling out all other potential causes, diagnosis of transient global amnesia was made. We present this case highlighting the importance of ruling out other acutely morbid conditions when addressing TGA, guidance on timing of imaging, as well as offering insight on other etiologies of this condition.