A Tc-99m SPECT study of regional cerebral blood flow in patients with transient global amnesia

Abstract

Objectives This study aimed to determine whether regional cerebral blood flow (rCBF) is abnormal in patients who have Transient Global Amnesia (TGA). Methods We obtained noninvasive rCBF measurements using Tc-99m-ethyl cysteinate diamer Single Photon Emission Computed Tomography (SPECT) in 7 patients diagnosed with TGA within 4 days of onset of the amnestic episode while the patients were still symptomatic and in 17 age-matched healthy control subjects. We assessed memory functioning using the Hopkins's Verbal Learning Test (HVLT) and Statistical Parametric Mapping to compare rCBF across diagnostic groups. Results The patients with TGA were significantly impaired in their performance on the 20-minute delayed recall of the HVLT. They also exhibited significantly decreased rCBF on their SPECT scans in the inferior and middle frontal gyrus bilaterally, with more prominent left-sided reductions in the superior temporal, precentral, and postcentral gyri, as well as increased rCBF primarily in the right hemisphere within the middle temporal, superior temporal, and inferior frontal gyri, cerebellum, and thalamus, compared with the normal control group. Conclusion These findings suggest that lateralized abnormalities in brain functioning are an important component of the pathophysiology of TGA. Lateralized abnormalities may disrupt functions that are relatively specific to the left hemisphere, including receptive language, symbolic representation, and the processing of local features in the environment, while preserving anterograde memory processes. Increased flow to the right hemisphere centered on regions that subserve the functions of expressive language and visuospatial processing, and may represent processes that compensate for flow reductions to the left hemisphere.

Cortical morphology in patients with transient global amnesia

“…These findings are compatible with our previous study using VBM, which also found volume reductions in the left hippocampus only. This left lateralization is consistent with other previous studies using EEG and SPECT (Chung et al., ; Jang et al., ; Kwon et al., ). Kim et al.…”

Left dominance of EEG abnormalities in patients with transient global amnesia

“…Yang suggested that lateralized abnormalities in brain functioning may be an important component of the pathophysiology of TGA, as evidenced by a significantly decreased regional cerebral blood flow on the SPECT scans in the superior temporal, precentral, and postcentral gyri with a relative left dominance. 26 Mark reported that patients with left hippocampal sclerosis differ from normal subjects in the distribution of memory-encoding activity between left and right hippocampus. 27 The lateralization of MRI and SPECT in the patients was not significant, unlike that of the EEG ( Table 3).…”

Functional Neuroimaging in Dementia and other Amnesic Disorders: A Radiological Review

“…However, most studies have also noted concomitant decreased or increased changes in cerebral blood flow in other anatomical structures, such as unilateral or bilateral thalamic, prefrontal, frontal, amygdaline, striatal, cerebellar, occipital, precentral and post central areas (Eustache et al, 2000;Nardone et al, 2004). In some studies, no mesiotemporal changes, no cerebral changes, or a global hypo perfusion were detected (Chung et al, 2009). In summary, the imaging data derived from PET and SPECT studies are difficult to compare and interpret.…”