Hippocampal infarction: Identification of three new types

Area of Science:

• Neurology
• Neuroradiology
• Vascular Neurology

Background:

• Hippocampal infarction (HI) is a common yet understudied neurological condition.
• Understanding HI patterns is crucial for diagnosing and managing stroke.
• Previous research has not comprehensively detailed diverse HI presentations.

Purpose of the Study:

• To identify and classify novel patterns of hippocampal infarction (HI).
• To investigate associated ischemic lesions outside the hippocampus.
• To infer underlying vessel occlusions based on HI patterns and lesion distribution.

Main Methods:

• Diffusion-weighted imaging analysis of 222 patients with HI.
• Classification of HI into established types (1-4) and novel types (5-7).
• Assessment of concurrent ischemic lesions in cerebral artery territories, brainstem, and cerebellum.

Main Results:

• Three novel HI patterns (types 5, 6, and 7) were identified.
• Types 5 and 6 HI were significantly associated with acute ischemic lesions in the anterior choroidal artery (AChA) territory (60% vs. 5.5%, P<0.001).
• Posterior cerebral artery territory involvement was most common (89.6%), followed by cerebellum (20.3%) and middle cerebral artery territory (14.9%).

Conclusions:

• Three novel hippocampal infarction (HI) types were identified.
• Types 5 and 6 HI are likely attributable to anterior choroidal artery (AChA) occlusion.
• These novel HI types are rare, possibly due to enhanced collateralization during AChA occlusion.