Can novel non-invasive autonomic tests help discriminate between pure autonomic failure and multiple system atrophy?

Pure autonomic failure (PAF) and multiple system atrophy (MSA) are rare disorders causing severe autonomic failure. Their initially similar clinical presentation may lead to years of diagnostic difficulties. Improving the differentiation would have an important impact on patients and families in view of better prediction of disease progression.

To investigate whether several new non-invasive autonomic tests are beneficial in discriminating between PAF and MSA.

Patients and controls underwent two tests examining the autonomic innervation of the skin (Sudoscan and water-induced skin wrinkling) and one test measuring retinal nerve fiber layer thickness in the eye.

The skin vasomotor tests yielded differences between the disease and control groups, but did not discriminate between PAF and MSA. No differences in retinal nerve fiber layer thickness were found between the groups.

The tests applied in this study may help to confirm autonomic failure but did not support the differential diagnosis between PAF and MSA.