Cerebellar remodelling decades after spinal cord insult: neuroplasticity in poliomyelitis survivors

Abstract

Background:The cerebellum integrates a multitude of motor and cognitive processes through ample spinal and supratentorial projections. Despite emerging evidence of adaptive neuroplasticity, cerebellar reorganisation in response to severe spinal insult early in life is poorly characterised. The objective of this study is the systematic characterisation of cerebellar integrity metrics in a cohort of adult poliomyelitis survivors as a template condition for longstanding lower motor neuron injury. Methods: A total of 143 participants, comprising 43 adult poliomyelitis survivors and 100 age-and sex-matched healthy controls were recruited in a prospective, single-centre neuroimaging study with a uniform structural and diffusion imaging protocol. First, standard voxelwise grey and white matter analyses were performed. Then, the cerebellum was anatomically segmented into lobules, and cortical thickness and grey matter volumes were evaluated in each lobule. The integrity of cerebellar peduncles was also assessed based on their diffusivity profiles. Results: Compared to healthy controls, poliomyelitis survivors exhibited greater cortical thickness in lobules I, II, and III in the right hemisphere and in lobules VIIIA and VIIIB bilaterally. A trend of higher cortical thickness was also detected lobules I, II and III in the left hemisphere. Enhanced cerebellar peduncle organisation was detected, particularly within the middle cerebellar peduncles. Conclusions: Increased cerebellar integrity measures in poliomyelitis survivors are primarily identified in lobules associated with sensorimotor functions. The identified pattern of cerebellar reorganisation may represent compensatory changes in response to severe lower motor neuron injury in childhood and ensuing motor disability.

Promises and pitfalls of imaging-based biomarkers in motor neuron diseases

“…Hereditary spastic paraparesis (HSP) has overlapping clinical features with PLS and the marked corticospinal, corpus callosum and, depending on genotype, cerebellar degeneration is also reminiscent of some of the radiological alterations observed in ALS [11,12,13 && ,14]. Low-incidence ALS mimics, such as postpolio syndrome, was traditionally associated with widespread cerebral disease, but recent imaging studies have highlighted the lack of atrophy both in supra-tentorial and infra-tentorial regions [15,16]. Kennedy's disease or spinal and bulbar muscular atrophy (SBMA) has also been increasingly evaluated by computation imaging studies and some degree of cerebral involvement has been consistently captured [17].…”

The Potential of Applied Brain Imaging in Research and Clinical Settings

“…Two studies in this special issue highlight the potential of applied brain imaging for characterizing the pattern of compensatory processes in neurological disorders. Li Hi Shing et al [13] present an elegant, multimodal neuroimaging study on cerebellar GM and WM in poliomyelitis survivors. The authors report considerable cerebellar reorganization decades after the poliomyelitis infection, which may be interpreted as compensation for anterior horn insult in infancy.…”