The spinal and cerebral profile of adult spinal-muscular atrophy: A multimodal imaging study

Abstract

Spinal muscular atrophy (SMA) type III and IV are autosomal recessive, slowly progressive lower motor neuron syndromes. Nevertheless, wider cerebral involvement has been consistently reported in mouse models. The objective of this study is the characterisation of spinal and cerebral pathology in adult forms of SMA using multimodal quantitative imaging.

Methods

Twenty-five type III and IV adult SMA patients and 25 age-matched healthy controls were enrolled in a spinal cord and brain imaging study. Structural measures of grey and white matter involvement and diffusion parameters of white matter integrity were evaluated at each cervical spinal level. Whole-brain and region-of-interest analyses were also conducted in the brain to explore cortical thickness, grey matter density and tract-based white matter alterations.

Results

In the spinal cord, considerable grey matter atrophy was detected between C2-C6 vertebral levels. In the brain, increased grey matter density was detected in motor and extra-motor regions of SMA patients. No white matter pathology was identified neither at brain and spinal level.

Conclusions

Adult forms of SMA are associated with selective grey matter degeneration in the spinal cord with preserved white matter integrity. The observed increased grey matter density in the motor cortex may represent adaptive reorganisation.

Highlights

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  (SMA) type 3 and 4 is a lower motor neuron syndrome. Nevertheless, wider involvement of the nervous system might be possible.

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  25 adults type 3 and 4 SMA patients were studied using brain and cervical spinal cord neuroimaging techniques.

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  Grey matter atrophy was observed in the spinal cord. No white matter degeneration was present at brain and spinal level.

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  Increased grey matter density was detected in cerebral motor regions and explained as compensatory mechanism.