Transient Global Amnesia by A.J. Larner

Author:A.J. Larner
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

4.2.2 Functional Neuroimaging

4.2.2.1 Single Photon Emission Computed Tomography (SPECT)

Of the various functional imaging modalities, single photon emission computed tomography using 99m-technetium hexamethylpropylene amine oxime (99mTc-HMPAO-SPECT) has been the most widely available to assess cerebral perfusion and hence the most likely to be deployed in cases of TGA. The low spatial resolution of SPECT imaging compares unfavourably to MR imaging.

Such studies have generally shown decreased perfusion, in temporal lobe(s), frontal regions, and parietotemporal regions, during attacks of TGA, with recovered perfusion seen in delayed imaging (e.g. Stillhard et al. 1990; Tanabe et al. 1991; Laloux et al. 1992; Evans et al. 1993; Sakashita et al. 1993; Schmidtke et al. 1998; Jovin et al. 2000; Warren et al. 2000; Bucuk et al. 2004; Lampl et al. 2004). However, reports have also appeared of thalamic hypoperfusion (Goldenberg et al. 1991; Sakashita et al. 1993; Goldenberg 1995; Schmidtke et al. 1998; Nardone et al. 2004) and global cerebral hypoperfusion (Yamane et al. 2008). Other reports have presented findings of hyperperfusion, of medial temporal lobe (Matsuda et al. 1993) and right parahippocampal gyrus (Asada et al. 2000, case 1).

Lampl et al. (2004) found that SPECT remained abnormal at 3 and 12 months in three patients with recurrent TGA, whereas perfusion abnormalities resolved in patients with a first episode of TGA, observations which may be relevant to the prognosis of TGA (Sect. 5.​2.​1).

SPECT with 99mTc-ethyl cysteinate dimer (ECD) has also shown significant hypoperfusion acutely in left hippocampus, left thalamus, and bilateral cerebellum, with restoration of hypoperfusion in follow-up scans (Kim et al. 2016).

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