J Korean Med Sci.  2007 Dec;22(6):1094-1097. 10.3346/jkms.2007.22.6.1094.

Amnesic Syndrome in a Mammillothalamic Tract Infarction

• Park KC
• Yoon SS
• Chang DI
• Chung KC
• Ahn TB
• Ku BD
• Adair JC
• Na DL

• KMID: 1785778
• DOI: http://doi.org/10.3346/jkms.2007.22.6.1094

Abstract

It is controversial whether isolated lesions of mammillothalamic tract (MTT) produce significant amnesia. Since the MTT is small and adjacent to several important structures for memory, amnesia associated with isolated MTT infarction has been rarely reported. We report a patient who developed amnesia following an infarction of the left MTT that spared adjacent memory-related structures including the anterior thalamic nucleus. The patient s memory deficit was characterized by a severe anterograde encoding deficit and retrograde amnesia with a temporal gradient. In contrast, he did not show either frontal executive dysfunction or personality change that is frequently recognized in the anterior or medial thalamic lesion. We postulate that an amnesic syndrome can develop following discrete lesions of the MTT.

Keyword

Amnesia; Cerebral Infarction; Mammillothalamic Tract

MeSH Terms

Aged
Amnesia/*etiology
Cerebral Infarction/*complications
Humans
Male
Mamillary Bodies/*physiopathology
Neuropsychological Tests
Thalamus/*physiopathology

Figure

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  Fig. 1 Diffusion-weighted (A) and T2-weighted (B) images from the previous stroke (40 days prior to admission) show acute infarction of the right cerebellar hemisphere, an old infarct in the left lingual gyrus, and a slit-like suspicious old hemorrhage in the right anterior thalamus.

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  Fig. 2 Axial FLAIR (A), coronal (B), and sagittal (C) T2-weighted images from the current amnesic stroke show a new infarction in the left thalamic area (arrowhead) in addition to the old left lingual gyrus and right anterior thalamic (arrow) lesions. Axial diffusion- weighted images (D, E) confirmed acuteness of the infarction that is localized to the mammillothalamic tract according to an anatomic atlas (5) (F, G). ac, anterior commissure; cc, crus cerebri; fx, fornix; h, hypothalamus; mt, mammillothalamic tract; na, nucleus accumbens; pc, posterior commissure; pu, pulvinar; r, red nucleus; sc, superior colliculus; sn, substantia nigra; vpl, ventral posterolateral thalamic nucleus; 22, third ventricle.

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