Objective: Impairment of speech repetition following injury to the dorsal language stream is a feature of conduction aphasia, a well-described "disconnection syndrome" in adults. The impact of similar lesions sustained in infancy has not been established.
Methods: We compared language outcomes in term-born individuals with confirmed neonatal stroke (n = 30, age = 7-18 years, left-sided lesions in 21 cases) to matched controls (n = 40). Injury to the dorsal and/or ventral language streams was assessed using T1 - and T2 -weighted magnetic resonance imaging (MRI) and diffusion tractography. Language lateralization was determined using functional MRI.
Results: At the group level, left dorsal language stream injury was associated with selective speech repetition impairment for nonwords (p = 0.021) and sentences (p < 0.0001). The majority of children with significant repetition impairment had retained left hemisphere language representation, but right hemisphere dominance was correlated with minimal or absent repetition deficits. Post hoc analysis of the repetition-impaired group revealed additional language-associated deficits, but these were more subtle and variable.
Interpretation: We conclude that (1) despite the considerable plasticity of the infant brain, early dorsal language stream injury can result in specific and long-lasting problems with speech repetition that are similar to the syndrome of conduction aphasia seen in adults; and (2) language reorganization to the contralateral hemisphere has a protective effect. Ann Neurol 2018;83:664-675 Ann Neurol 2018;83:664-675.
© 2018 American Neurological Association.