Sudomotor Testing: Early Detection of Small Fiber Neuropathy

The Challenge of Small Fiber Neuropathy

Small fiber neuropathy (SFN) is notoriously difficult to diagnose. Standard nerve conduction studies (NCS) measure large fiber function — they miss small fiber damage entirely. Yet small fibers are often the first to be affected in diabetes, metabolic syndrome, and autoimmune conditions.

Sudomotor dysfunction — impairment of the sweat response — is one of the earliest objective markers of small fiber nerve damage.

How SudoCheck Works

The SudoCheck module in the VitalScan ANS+ System measures sudomotor function by assessing the electrochemical sweat response at the hands and feet. It evaluates:

• Sweat gland nerve fiber density (indirectly)
• Postganglionic sympathetic function
• Small nerve fiber regeneration capacity

The test takes approximately 2–3 minutes and is completely non-invasive.

Clinical Applications

SudoCheck is particularly valuable for:

• Diabetic neuropathy screening: Detect sudomotor dysfunction years before clinical symptoms of peripheral neuropathy appear
• Podiatry: Identify patients at risk for foot complications before they develop ulcers or deformities
• Pain medicine: Confirm nerve-level drivers of chronic pain with objective data
• Cardiology: Assess autonomic imbalance in cardiovascular patients

Why Early Detection Matters

In diabetic patients, sudomotor dysfunction can be detected years before clinical signs of peripheral neuropathy. This early window allows for:

• Glycemic optimization before irreversible nerve damage occurs
• Lifestyle interventions (diet, exercise, smoking cessation)
• Medication adjustments (alpha-lipoic acid, aldose reductase inhibitors)
• Patient education on foot care and complication prevention

Billing

Sudomotor testing is included in CPT code 95923 (sudomotor function testing). Typical reimbursement is $100–$180 per test.

Key Takeaway

SudoCheck provides objective, reproducible data on small fiber nerve function — something standard nerve conduction studies cannot do. For practices serving diabetic, neurological, or pain populations, sudomotor testing fills a critical diagnostic gap.