Pilot Study to Evaluate Changes in Intra-Epidermal Nerve Fiber Density (IENFD) in Patients With Small-Fiber Neuropathy (SAL SFN PILOT)

This prospective observational pilot study will evaluate structural, functional, and patient-reported outcomes in adults with small fiber neuropathy who receive Saluda Evoke ECAP-controlled spinal cord stimulation as part of routine clinical care. The study does not assign, direct, or modify spinal cord stimulation therapy. All decisions regarding patient selection, trial stimulation, permanent implantation, and device programming are made independently by the treating physician according to standard clinical practice.

The primary objective is to assess change in intra-epidermal nerve fiber density from baseline to 12 months. Secondary objectives include evaluation of quantitative sensory testing, pain intensity, patient-reported outcomes, and correlations between changes in nerve fiber density, sensory function, and neuropathic pain outcomes.

The study will enroll up to 10 adult participants with clinically diagnosed small fiber neuropathy and chronic neuropathic pain. Research assessments include patient-reported outcome measures, quantitative sensory testing, review of available clinical records, and a 12-month follow-up skin biopsy for intra-epidermal nerve fiber density.

This aligns with the approved protocol: observational, 10 adults, 12-month participant follow-up, primary IENFD endpoint, and secondary QST/pain/correlation endpoints.

Study Overview

• Status: Enrolling by invitation
• Conditions: Small Fiber Neuropathy
• Intervention / Treatment: Device: Evoke SCS system

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Nebraska
    • Grand Island, Nebraska, United States, 68803
      • Grand Island Pain Relief Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 19 years or older.
• Clinically diagnosed small fiber neuropathy based on abnormal intra-epidermal nerve fiber density (IENFD) skin biopsy.
• Chronic neuropathic pain with Numeric Pain Rating Scale score of at least 6.
• Candidate for ECAP-controlled spinal cord stimulation therapy based on the - - - Principal Investigator's medical judgment.
• Able and willing to undergo baseline and 12-month skin biopsies.
• Able to comply with 12-month quantitative sensory testing.
• Able to provide informed consent.

Exclusion Criteria:

• Confounding factors that may independently contribute to small fiber damage or alter nerve fiber density, including uncontrolled diabetes defined as HbA1c greater than 8.5% within the last 3 months, autoimmune disorders such as lupus, or history of alcohol abuse.
• Contraindications to spinal cord stimulation therapy, including active infection, coagulation disorders, allergy to medical device components, or other relevant surgical/device contraindications.
• Uncontrolled medical or psychiatric conditions.
• Pregnancy or planning to become pregnant during the study period.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Other: Saluda Evoke ECAP-Controlled Spinal Cord Stimulation System; Participants with clinically diagnosed small fiber neuropathy and chronic neuropathic pain who receive Saluda Evoke ECAP-controlled spinal cord stimulation as part of routine clinical care will be followed for 12 months. The study does not assign, direct, or modify spinal cord stimulation therapy. All treatment decisions, including trial stimulation, permanent implantation, and device programming, are made independently by the treating physician according to standard clinical practice. Outcomes include intra-epidermal nerve fiber density, quantitative sensory testing, pain intensity, and patient-reported measures.

Device: Evoke SCS system; Spinal cord stimulation using the Saluda Evoke system, an ECAP-controlled closed-loop SCS device that monitors neural response and adjusts stimulation in real time. Participants receive SCS therapy as part of routine clinical care. The study observes structural, sensory, pain, and patient-reported outcomes over 12 months and does not assign, direct, or modify device use, implantation, or programming. This matches the protocol's device description and keeps the intervention generic enough for ClinicalTrials.gov while still identifying the Saluda Evoke system.; Other Names: ECAP-Controlled Spinal Cord Stimulation; Closed-Loop Spinal Cord Stimulation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Intra-Epidermal Nerve Fiber Density From Baseline to 12 Months	Change in intra-epidermal nerve fiber density measured by skin biopsy from baseline to 12 months in participants with small fiber neuropathy receiving ECAP-controlled spinal cord stimulation as part of routine clinical care.	Baseline to 12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Thermal Detection Thresholds From Baseline to 12 Months	Change in heat and cold detection thresholds measured by quantitative sensory testing as a functional measure of small fiber integrity.	Baseline to 12 months
Change in Numeric Pain Rating Scale Score Over 12 Months	Change in pain intensity measured using the Numeric Pain Rating Scale. The Numeric Pain Rating Scale is an 11-point scale from 0 to 10, where 0 indicates no pain and 10 indicates the worst pain imaginable. Higher scores indicate worse pain.	Baseline, 1 week, 3 months, 6 months, and 12 months
Patient Global Impression of Change Score Over 12 Months	Participant-reported overall impression of change measured using the Patient Global Impression of Change scale. The scale ranges from 1 to 7, where 1 indicates no change or worsening and 7 indicates a great deal better and a considerable improvement that has made all the difference. Higher scores indicate greater improvement.	1-week, 3 months, 6 months, and 12 months
Correlation Between Change in IENFD and Change in Quantitative Sensory Testing Thresholds	Correlation between change in intra-epidermal nerve fiber density measured by skin biopsy and change in heat and cold detection thresholds measured by quantitative sensory testing from baseline to 12 months..	Baseline to 12 months
Correlation Between Change in IENFD and Change in Pain Intensity	Correlation between change in intra-epidermal nerve fiber density measured by skin biopsy and change in pain intensity measured using the Numeric Pain Rating Scale from baseline to 12 months. The Numeric Pain Rating Scale is an 11-point scale from 0 to 10, where 0 indicates no pain and 10 indicates the worst pain imaginable. Higher scores indicate worse pain.	Baseline to 12 months

Collaborators and Investigators

• Sponsor: TriCity Research Center
• Collaborators: Saluda Medical Americas, Inc.
• Investigators: Principal Investigator: Pravardhan Birthi, M.D., TriCity Research Center, LLC; Study Director: Mahesh Pattabiraman, Ph.D., TriCity Research Center

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2026
• Primary Completion (Estimated): September 30, 2027
• Study Completion (Estimated): October 30, 2027

Study Registration Dates

• First Submitted: July 7, 2026
• First Submitted That Met QC Criteria: July 14, 2026
• First Posted (Actual): July 15, 2026

Study Record Updates

• Last Update Posted (Actual): July 15, 2026
• Last Update Submitted That Met QC Criteria: July 14, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Spinal Cord Stimulation; Quantitative Sensory Testing; Neuropathic Pain; QST; IENFD; SCS; Small Fiber Neuropathy; Intra-Epidermal Nerve Fiber Density; ECAP-Controlled Stimulation; Closed-Loop Stimulation; Saluda Evoke; Mixed Neuropathy; EMG/NCS
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Neuromuscular Diseases; Peripheral Nervous System Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Small Fiber Neuropathy; Neuralgia
• Other Study ID Numbers: SAL 002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared. The study involves a small pilot cohort and includes clinical, device-related, biopsy, sensory testing, and patient-reported data that may increase the risk of participant re-identification. De-identified aggregate results may be reported in publications or presentations, subject to applicable IRB, privacy, sponsor, and regulatory requirements.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No