Acute Korsakoff Syndrome Following Mammillothalamic Tract Infarction
Yuichiro Yoneokaa,b,
Norio Takedaa,
Akira Inouea,
Yasuo Ibuchia,
Takashi Kumagaia,
Tsutomu Sugaia,
Ken-ichiro Takedaa and
Kaoru Uedaa
a Departments of Neurosurgery and Emergency Medicine, Yamagata Prefecture Central Hospital, Yamagata, Japan
b Department of Clinical Neurology and Neurosurgery, Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
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FIG 1. T2-weighted images examined 3 days after onset (A and B) show multiple ischemic lesions in the midpons, the head of the right caudate nucleus, and the left anterior thalamus. A DW image confirms the left anterior thalamic lesion as a new ischemic lesion (D). Medial temporal lobes appear intact both on T2-weighted and DW images (A and C).
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FIG 2. Area of detail on T2-weighted images examined 3 days after onset (A and B) demonstrate anatomic structures, such as the anterior nucleus (An), caudate nucleus (Cd), dorsomedial nucleus (DM), globus pallidus (GP), MTT, pulvinar (P), putamen (Pt), ventral anterior nucleus (VA), ventral lateral nucleus (VL), and ventral posterolateral nucleus (VPL). An infarction on the left MTT (C, upswept thick arrow) demonstrated on a DW image is identical to that on the T2-weighted image (B, upswept thick arrow) and on the fluid-attenuated inversion recovery image, which was seen on a follow-up CT scan 4 weeks after onset (D, upswept thick arrow), which was the same as on MR images at admission. Older ischemic lesions were also seen in the corpus callosum on the right (A, upper descending thick arrow), on the right MTT (A, lower descending thick arrow), and in the head of the right caudate nucleus (B and D, descending thick arrow). Thick arrows show ischemic lesions, and thin arrows, MTTs.
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FIG 3. T2-weighted images obtained 8 weeks after onset show ischemic lesions in the corpus callosum on the right and the right anterior thalamus (C and D). The infarction of the left MTT (D) is identical to that on MR images obtained at admission (Fig 1). DW imaging shows no acute ischemic lesions (E and F). The medial temporal lobes (A and B) are intact, which is the same finding as that on the MR images obtained at admission (Fig 1).
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FIG 4. Magnified T2-weighted images examined 8 weeks after onset demonstrate that both MTTs are affected (A and B), which are not visible on DW images (C). They are not acute ischemic lesions as shown on DW images (C) and on fluid attenuation inversion recovery images (D).
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FIG 5. Schematic figure of the limbic system and its connections. The hippocampus projects to the septal nuclei and the mammillary body via the fornix. The mammillary body projects to the anterior nucleus of the thalamus via the MTT. The anterior nucleus of the thalamus projects to the cingulated cortex via the internal capsule. The cingulated cortex projects back to the hippocampus via the cingulum bundle. Both MTT lesions can interrupt the input from the hippocampus, resulting in dysfunction of the neurocircuit in the limbic system.
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