Measuring peripheral nerve involvement in Friedreich's ataxia

Area of Science:

• Neurology
• Biomarker Discovery
• Dermatology

Background:

• Friedreich's Ataxia (FRDA) is a rare genetic disorder impacting the nervous system.
• Developing effective experimental therapies for FRDA necessitates validated biomarkers.
• Non-invasive in-vivo reflectance confocal microscopy (RCM) of skin shows promise for quantifying Meissner's corpuscle (MC) density, a potential marker for sensory polyneuropathies.

Purpose of the Study:

• To evaluate RCM of MCs as a candidate peripheral nerve marker in FRDA.
• To compare RCM findings with conventional peripheral nerve measures, including skin biopsies for epidermal nerve fiber density (ENFD), nerve conduction studies (NCS), and quantitative sensory testing (QST).

Main Methods:

• A prospective, cross-sectional study involving 16 individuals with FRDA and 16 age/gender-matched controls.
• Participants underwent RCM of MC density and morphology, skin biopsies for ENFD, NCS, and QST (touch, vibration, cooling thresholds).

Main Results:

• MC densities were significantly lower in individuals with FRDA compared to controls at multiple skin sites.
• Conventional NCS demonstrated floor effects and were poorly obtainable in FRDA patients.
• QST showed elevated thresholds for touch, vibration, and cooling in FRDA patients; reduced ENFDs were observed in more severely affected individuals.

Conclusions:

• MC density, ENFD, and QST thresholds serve as valuable structural and physiological markers of sensory involvement in FRDA.
• These markers correlate with clinical disease severity and duration.
• Further longitudinal studies are required to assess their utility in tracking disease progression and treatment response.