SMA is traditionally defined by almost exclusive involvement of the second motor neuron. Canadian clinicians compiled and analysed the literature on brain imaging in this disease with the aim of assessing possible additional involvement of the central nervous system.
- Twelve articles were retrieved from the PubMed and EMBASE databases.
- All the studies involved 39 patients with SMA with a wide range of ages at examination (from 11 days to 41 years),
- five had type 0, four had type 1, two had type 2, twenty-two had type 3 and six had type 4,
- structural abnormalities of the brain or cerebellum were noted in all the patients studied, with a distinct distribution and importance according to the age of onset of SMA.
This study, although burdened by an obvious recruitment bias, is consistent with the much more multi-systemic nature of SMA, which is not limited to the second motor neuron.