Subcortical aphasia after striatocapsular infarction: quantitative analysis of brain perfusion SPECT using statistical parametric mapping and a statistical probabilistic anatomic map.

UNLABELLED

This study examined the relationship between the severity of aphasia and regional cerebral perfusion on brain SPECT using statistical parametric mapping (SPM) and a statistical probabilistic anatomic map (SPAM) in patients with a striatocapsular infarction (SCI) along with the other clinical and imaging findings.

METHODS

The subjects were 16 right-handed Korean-speaking patients with a left SCI who underwent 99mTc-ethylcyteinate dimer (99mTc-ECD) SPECT (8.1 +/- 4.8 d [mean +/- SD] after onset). MRI showed that no patient had any abnormality in the cerebral cortex (6.8 +/- 6.0 d after onset). The aphasia quotient (AQ), which is a measure of the severity of aphasia, was obtained by using the Korean version of the Western Aphasia Battery (5.3 +/- 3.9 d after onset). For quantitative evaluation of cerebral perfusion, the asymmetry indices (AIs) for subcortical and cortical areas were calculated using SPM and SPAM. The infarct size was measured using MRI.

RESULTS

Aphasia occurred in 15 (2 global, 7 transcortical, and 6 anomic aphasia) of the 16 patients. Left cerebral cortical hypoperfusion was observed in all 15 patients with subcortical aphasia. Aphasia was more severe in 6 patients with extensive cerebral cortical hypoperfusion than in the remaining 10 patients (AQ = 41.8 +/- 25.2 points vs. 84.2 +/- 7.7 points [mean +/- SD], P = 0.001). There was an association between the AQ and age (rho = -0.665), infarct size (rho = -0.594), AIs of the frontal cortex (rho = -0.653), temporal cortex (rho = -0.782), parietal cortex (rho = -0.694), whole cerebral cortex (rho = -0.768), and the cerebellar cortex (rho = 0.765). Voxel-based SPM analysis showed a significant positive correlation between the AQ and the perfusion of the left temporal cortex and the right cerebellum.

CONCLUSION

The severity of subcortical aphasia after a left SCI without cortical abnormalities on MRI is associated with the extent and severity of the left cerebral cortical hypoperfusion on brain perfusion SPECT performed during the subacute stage, particularly in the left temporal cortex. Quantitative brain perfusion SPECT using SPM and SPAM can help in evaluating subcortical aphasia in a SCI because it provides functional information that cannot be obtained by morphologic imaging.