Article

Targeted speech therapy can lead to substantial naming
improvement in some subjects with anomia following dominant-hemisphere stroke. We
investigated whether treatment-induced improvement in naming is associated with
poststroke preservation of structural neural network architecture. METHODS:
Twenty-four patients with poststroke chronic aphasia underwent 30 hours of speech
therapy over a 2-week period and were assessed at baseline and after therapy.
Whole brain maps of neural architecture were constructed from pretreatment
diffusion tensor magnetic resonance imaging to derive measures of global brain
network architecture (network small-worldness) and regional network influence
(nodal betweenness centrality). Their relationship with naming recovery was
evaluated with multiple linear regressions. RESULTS: Treatment-induced
improvement in correct naming was associated with poststroke preservation of
global network small worldness and of betweenness centrality in temporal lobe
cortical regions. Together with baseline aphasia severity, these measures
explained 78% of the variability in treatment response. CONCLUSIONS: Preservation
of global and left temporal structural connectivity broadly explains the
variability in treatment-related naming improvement in aphasia. These findings
corroborate and expand on previous classical lesion-symptom mapping studies by
elucidating some of the mechanisms by which brain damage may relate to treated
aphasia recovery. Favorable naming outcomes may result from the intact
connections between spared cortical areas that are functionally responsive to treatment.
CI - (c) The Author(s) 2015.