A case with bilateral thalamic infarction manifesting mutism – Cerebral blood flow and neural fibers evaluation

Background: Acute bilateral thalamic infarction is rare, and occlusion of the artery of percheron (AOP) may be one of its reasons. AOP occlusion results in an acute disturbance of consciousness, but mutism due to AOP occlusion is rare. We described a mutism patient with bilateral thalamic infarction presumably due to AOP occlusion. We also performed cerebral blood flow (CBF) evaluation by N-isopropyl-p-[123I]-iodoamphetamine single-photon emission computed tomography (123I-IMP-SPECT) as well as neural fiber evaluation by diffusion tensor tractography, discussing the mechanism of mutism. Case Description: A 92-year-old woman presented a gradual deterioration of consciousness. Diffusion-weighted images revealed high-intensity areas at the bilateral thalami, and we diagnosed AOP occlusion. We administered a recombinant tissue plasminogen activator. On day 14, her Glasgow Coma Scale score was 11 (E4V1M6), and she did not present any apparent paresis. She was mute but cognitively alert, although she could communicate by nodding or facial expression. 123I-IMP-SPECT showed CBF increase in the bilateral cerebellum and CBF decrease in the infarcted bilateral thalami and frontal lobes. Diffusion tensor tractography revealed the bilateral dentatothalamo-cortical tracts (DTCs). However, the tracts terminated at the parieto-occipital cortex, but not at the frontal cortex. She still had mutism on day 30. Conclusion: We reported the bilateral thalamic infarction patient presumably due to AOP occlusion, who presented mutism. The discontinuity of the bilateral DTCs resulted in her mutism, and our results supported the hypothesis that the cerebellum plays a significant role in uttering, associated with the bilateral DTCs.