Neuropsychological outcome following thalamic stroke in adolescence: an identical twin comparison

Objective: Medial thalamic stroke in adults commonly results in severe learning and memory impairments and executive dysfunction, particularly during the acute phase. However, there is limited research on the cognitive recovery from thalamic stroke in physically healthy adolescents. This study aimed to fill this gap in the literature by utilizing a monozygotic twin control to investigate the neuropsychological outcomes of bilateral thalamic stroke in adolescence. Method: We evaluated an otherwise healthy 17-year-old male with a history of premature birth, developmental delay, and learning disability 2 and 7 months after he sustained a bilateral medial/anterior thalamic stroke of unknown etiology. His identical twin brother served as a case control. Results: The patient presented with improvements in many cognitive skills between assessments, most notably processing speed. Despite some mild improvement, however, he presented with significant deficits in fine motor speed/coordination, spatial perception, and rapid naming. Additionally, he exhibited persistent, severe deficits in verbal learning and memory. Relative sparing of executive functions (i.e., planning and set-shifting) and attention on standardized measures in this case may be explained by good underlying health, limited extra-thalamic damage, and/or recovery of function. The effects of thalamic injury resulted in minimal adaptive dysfunction or deterrence from academic or athletic success for the presented case. Conclusions: These results suggest risk for deficits in encoding of new verbal information following bilateral thalamic stroke in adolescence, as well as risk for persistent cognitive deficits despite initial improvements. This is consistent with descriptions of anterograde memory impairments in adults with similar lesions.