Assessment of Small Fiber Neuropathy in Rare Diseases Using Sudoscan

Not Applicable

Completed

Conditions: Small Fiber Neuropathy
Ehlers Danlos Syndrome
Fabry Disease
Mitochondrial Disease

Brief Summary: 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.

Detailed Description: 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.

Recruitment & Eligibility

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

Arm && Interventions

Group	Intervention	Description
Sudoscan Plus	Sudoscan	Patients in this arm will get Sudoscan testing as well as a skin biopsy and QSART testing.
Sudoscan Plus	Skin biopsy	Patients in this arm will get Sudoscan testing as well as a skin biopsy and QSART testing.
Sudoscan Plus	QSART	Patients in this arm will get Sudoscan testing as well as a skin biopsy and QSART testing.
Sudoscan only	Sudoscan	Patients in this arm will only undergoing testing with Sudoscan.

Primary Outcome Measures

Name	Time	Method
Number of Patients With Abnormal Electrochemical Skin Conductance in the Different Study Groups Who Have Clinical Symptoms Consistent With Small Fiber Polyneuropathy.	12 months	The internal software of the Sudoscan will allow analysis of skin conductance in all patients and quantification into normal or abnormal. Correlation of an abnormal conductance measurement with clinical symptoms and signs of small fiber neuropathy will be evaluated for accuracy of Sudoscan measurements

Secondary Outcome Measures

Name	Time	Method
Number of Patients in Whom a Specific Skin Conductance (ESC) Signature Pattern Was Detected in the Hands and/or Feet on Sudoscan Measurements.	48 months	Distribution of the electrochemical skin conductance (ESC) in both hands and feet was reviewed as an indirect measure of the subject's capacity to sweat. Normative scales of adult sweat function are preloaded in the device and compared to actual measurements to determine if a subject's sweat response is reduced, which is associated with neuropathy. A positive outcome is the identification of a lower ESC in either hands or feet that distinguishes Fabry disease from other disorders and would be a reflection of the presence of SFPN.