右言語、失行、視覚性注意のすべてが良好な左半球大血管閉塞症：症例報告

To describe a rare case of large left hemisphere (LH) middle cerebral artery (MCA) stroke with intact language, praxis, visuospatial cognition, and attention, suggesting lateralization of all these functions to the intact right hemisphere (RH).

A 53-year-old right-handed woman who had a stroke at age 42 was enrolled in a study of long-term stroke outcomes. She underwent standardized behavioral assessments and functional MRI (fMRI) with a visual field test and an adaptive semantic matching task.

Despite a 432 cm³ area of encephalomalacia, encompassing both MCA and posterior anterior cerebral artery territories of the LH, she exhibited intact language both acutely and chronically (Western Aphasia Battery Aphasia Quotient = 99.2) and normal praxis. fMRI demonstrated right-hemisphere dominance for language. Visuospatial cognition and attention were preserved (WASI II-Block Design; Behavioral Inattention Test-conventional subtests) despite right hemianopia.

This case suggests that language, praxis, and visuospatial functions can simultaneously lateralize to the RH. Although previous cases report reciprocal hemispheric reorganization, such as in crossed aphasia, this case of "crossed non-aphasia" supports the view that lateralization of functions can occur independently. Clinically, this rare pattern of atypical lateralization should be considered when expected poststroke deficits are absent.