Transient global amneisa Diagnostic Imaging
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Role of Imaging
- Brain imaging is commonly performed to exclude infarction or other structural lesions, especially in the emergency setting.
- Initial imaging studies are usually normal early in the course of the episode.[1]
Diagnostic Imaging
Diffusion-Weighted MRI (DWI) – Key Modality
- Most patients have one or more punctate lesions in the hippocampus or adjacent structures on diffusion-weighted MRI[2].
- In a series of 390 patients, such lesions were seen in about 70% of cases[2].
Timing of MRI Findings
- They are most often detected 12 to 48 hours after the episode[2].
- The lesions are usually fleeting, but may persist for several days[2].
Typical Lesion Characteristics
- Left-sided lesions have been reported more often than right-sided or bilateral ones[2].
Atypical / Expanded Patterns
- Unusual anatomical or temporal patterns of diffusion restriction have been described in some patients who did not have the typical clinical syndrome[3].
- Similar hippocampal lesions may occasionally be found incidentally in patients with cognitive or emotional symptoms without amnesia, leading some authors to broaden the imaging-based definition[3].
Other Imaging modalities
Functional / Perfusion Imaging
- Functional studies have shown bitemporal hypoperfusion during episodes[4].
- Network analyses demonstrate reduced connectivity of the hippocampi, parahippocampal gyri, amygdala, and parts of the lateral temporal lobe during the attack[5].
References
- ↑ 1.0 1.1 1.2 Ropper AH (February 2023). "Transient Global Amnesia". N Engl J Med. 388 (7): 635–640. doi:10.1056/NEJMra2213867. PMID 36791163 Check
|pmid=value (help). - ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Szabo K, Hoyer C, Caplan LR, Grassl R, Griebe M, Ebert A, Platten M, Gass A (July 2020). "Diffusion-weighted MRI in transient global amnesia and its diagnostic implications". Neurology. 95 (2): e206–e212. doi:10.1212/WNL.0000000000009783. PMID 32532848 Check
|pmid=value (help). - ↑ 3.0 3.1 Piffer S, Nannoni S, Maulucci F, Beaud V, Rouaud O, Förster A, Cereda CW, Maeder P, Michel P (October 2022). "Transient global amnesia with unexpected clinical and radiological findings: A case series and systematic review". J Neurol Sci. 441: 120349. doi:10.1016/j.jns.2022.120349. PMID 35944401 Check
|pmid=value (help). - ↑ Stillhard G, Landis T, Schiess R, Regard M, Sialer G (April 1990). "Bitemporal hypoperfusion in transient global amnesia: 99m-Tc-HM-PAO SPECT and neuropsychological findings during and after an attack". J Neurol Neurosurg Psychiatry. 53 (4): 339–42. doi:10.1136/jnnp.53.4.339. PMC 1014174. PMID 2341849.
- ↑ Peer M, Nitzan M, Goldberg I, Katz J, Gomori JM, Ben-Hur T, Arzy S (May 2014). "Reversible functional connectivity disturbances during transient global amnesia". Ann Neurol. 75 (5): 634–43. doi:10.1002/ana.24137. PMID 24623317.