Assessment of Small Fiber Neuropathy in Rare Diseases Using Sudoscan

Assessment of Small Fiber Neuropathy in Rare Diseases Using Sudoscan

Sudoscan™ (Impeto Medical, Paris France) uses electrochemical skin conductance as a novel noninvasive method to detect sudomotor dysfunction. Several small studies have recently shown that Sudoscan use in the assessment of small fiber polyneuropathy (in diabetes mellitus) can be performed non-invasively, quickly and effectively. The investigators aim to study the use of Sudoscan in rare disease condition associated with small fiber polyneuropathy.

Small fiber polyneuropathy (SFPN) is diagnosed through a combination of symptoms, signs and confirmatory diagnostic testing. Nerve conduction studies are not sensitive enough in most of the cases leaving the ankle skin biopsy with measurement of intraepidermal nerve fiber density (IENFD) as the main diagnostic tool. Despite its utility and reproducibility, skin biopsy is invasive, expensive and requires a central laboratory for processing and interpretation. Quantitative sudomotor axon reflex testing (QSART) is also routinely used for evaluation of small fiber neuropathy as sudomotor axons can also be involved. This test however remains technically challenging and requires testing conditions in specialized labs that are not always suitable for all patients' population. By comparing findings on skin biopsy and/or QSRT, accepted gold standard for diagnosing SFPN, the investigators seek to find faster, less-invasive ways to diagnose and monitor small-fiber polyneuropathy in rare diseases using Sudoscan measurement.

Inclusion Criteria:

• Males and females with confirmed disease: Fabry (by GLA enzymes and/or DNA testing) naïve and on ERT, Mitochondrial diseases (electron transport chain and/or DNA testing) or connective tissue diseases (clinical criteria and/or DNA testing when available)
• Consenting adults (18 years and older) who agrees and consents to skin biopsy and QSART procedure

Exclusion Criteria:

• Subjects with cognitive, psychiatric, or other problems that preclude informed consent.
• Patients with history of glucose intolerance or diabetes.
• Patient on chemotherapy
• People with any open or bleeding wounds at any sensor plate contact surface location
• People with any type of implantable device
• People with missing hand(s) and/or leg(s)
• Pregnant women or women who are uncertain about a possible pregnancy
• Patients sensitive to chemicals used to induce sweating
• Patients with heat intolerance
• Patients with bleeding disorders
• Patients on current anticoagulant therapy
• Patients with keloids on the intended biopsy site
• People with hypersensitivity to local amide-type anesthetics