Sudomotor dysfunction is frequent and correlates with disability in Friedreich ataxia

Objectives

To evaluate autonomic symptoms and function in Friedreich’s Ataxia (FRDA).

Methods

Twenty-eight FRDA patients and 24 controls underwent clinical/electrophysiological testing. We employed the Friedreich’s Ataxia Rating Scale (FARS) and the Scales for Outcomes in Parkinson’s Disease: Autonomic Questionnaire-SCOPA-AUT to estimate the intensity of ataxia and autonomic complaints, respectively. Cardiovagal tests and the quantitative sudomotor axonal reflex, Q-SART, were then assessed in both groups.

Results

In the patient group, there were 11 men with mean age of 31.5?±?11.1?years. Mean SCOPA-AUT score was 15.1?±?8.1. Minimum RR interval at rest was shorter in the FRDA group (Median 831.3?×?724.0?ms, p?p?>?0.05). Sweat responses were significantly reduced in patients for all sites tested (forearm 0.389?×?1.309?µL; proximal leg 0.406?×?1.107?µL; distal leg 0.491?×?1.232?µL; foot 0.265?×?0.708?µL; p value?

Conclusions

We found abnormal sudomotor but normal heart rate variability in FRDA. Small cholinergic post-ganglionic fibers are affected in the disease.

Significance

Quantification of sudomotor function might be a biomarker for FRDA.