Cerebral changes in post-polio syndrome: A quantitative MRI study

Abstract Background Post-polio syndrome (PPS) has been traditionally considered a slowly progressive condition that affects polio survivors decades after their initial infection. Cerebral changes in PPS are poorly characterised and the few existing studies are strikingly conflicting. Objective The overarching aim of this study is the comprehensive characterisation of cerebral grey and white matter alterations in post-polio syndrome with reference to healthy- and disease-controls using quantitative imaging metrics. Methods Thirty-six patients with PPS, 88 patients with ALS and 117 healthy individuals were recruited in a prospective, single-centre neuroimaging study using uniform MRI acquisition parameters. All participants underwent standardised clinical assessments, T1-weighted imaging and diffusion tensor imaging. Whole-brain imaging and region-of-interest analyses were undertaken to evaluate patterns of grey matter changes. Tract-based spatial statistics were utilised to assess changes in diffusivity metrics in a study-specific whiter matter skeleton. Results In contrast to healthy controls, PPS patients exhibited increased grey matter density in the brainstem, cerebellum and occipital lobe, accompanied by increased FA in the corticospinal tracts, cerebellum, bilateral mesial temporal lobes and inferior frontal tracts. PPS patients exhibited increased integrity metrics in the same anatomical regions where ALS patients showed degenerative changes. Conclusions Our findings suggests that PPS is associated with considerable cortical and white matter reorganisation which may be interpreted as compensatory, adaptive change in response to severe lower motor neuron injury in infancy.