Right-Hemisphere Language Dominance Unmasked by Acute Ischemic Stroke: A Case Report.

Language functions are typically lateralized to the left cerebral hemisphere in most right-handed individuals; however, a minority exhibit atypical language dominance, including right-hemisphere representation. In these cases, right-hemispheric lesions may result in aphasia, a rare entity known as crossed aphasia in dextrals (CAD). We report a 63-year-old strongly right-handed individual with no familial history of left-handedness who developed severe motor aphasia following an acute right-hemispheric ischemic stroke. The patient presented with a sudden-onset language disturbance and left-sided weakness. Neurological examination revealed severe non-fluent aphasia with impaired speech production and repetition, preserved comprehension, and left hemiparesis, with a National Institutes of Health Stroke Scale (NIHSS) score of 14. Initial CT scan demonstrated an acute infarction in the right middle cerebral artery territory without left-hemispheric involvement. Etiologic evaluation identified critical aortic stenosis, suggesting a probable cardioembolic mechanism. Neuropsychological assessment confirmed severe motor aphasia secondary to a right-hemispheric lesion. Motor deficits improved during hospitalization; however, expressive aphasia persisted and required intensive speech therapy. This case highlights the variability of cerebral language organization and the limitations of inferring language dominance solely from handedness. It supports network-based models of language that emphasize the contribution of the right-hemisphere and subcortical structures to expressive language function. Clinically, systematic language assessment in right-hemispheric stroke and early targeted rehabilitation are essential to optimize outcomes in patients with atypical language lateralization.