Information about Results & Small Fiber Neuropathy Images

Delivery Methods

Test results are reported to the referring physician according to the instructions provided at the time of account setup. If no instructions are given, Therapath will send 1 copy via US mail and send 1 copy to the online portal.

Reports can be sent via fax, e-mail, and/or US mail. All reports are in color except those sent via fax.

Online Report Access (Portal)

Subscribers to Therapath’s online report access program can view and download their patients' reports and microscopic images, electronically, from their office or other locations that have internet access.

Instructions for the portal, along with a username and password, are mailed to the physician's office after the first case is received. For Portal access click here.

Interpretation of Results

The epidermal nerve fiber density (ENFD) of each sample is determined by using the published counting rules (Lauria G et al. Eur J Neurol 2005; 12:1-12 and Kennedy WR et al. in Dyck PJ, Thomas PK (eds) Peripheral Neuropathy. 4th ed. Philadelphia: WB Sanders, 2004. pp 869-95. The analysis is performed by counting the number of epidermal fibers that cross the basement membrane, counting 5 separate tissue sections. The total number of fibers is divided by the length of the epidermis in the five sections, giving the ENFD (fibers per millimeter length of epidermis).

The ENFD is compared to the values in specimens from normal control subjects determined by Therapath. The lower limit of normal (95% confidence interval) for ENFD is 6.8 at the thigh, 5.4 at the calf, and 3.1 at the foot. Lower ENFD values are considered to be significantly decreased and consistent with the diagnosis of small fiber neuropathy.

Values that are in the low normal range (90% confidence interval), may be suspicious for early or mild neuropathy. These range between 6.8 to 8 at the thigh, 5.4 to 5.7 at the calf, and 3.1 to 4.5 at the foot.

On occasion, the ENFD can be normal, but morphological examination reveals structural abnormalities such as axonal swelling or excessive branching. These are considered to be pre-degenerative changes that are also associated with small fiber neuropathy (Lauria et al, J Neurol Sci 1999; 164: 172-8; Lauria et al, Neurology 2003; 61: 631-6).

In length dependent neuropathies, the ENFD is more severely reduced at the level of the calf or foot than at the thigh, consistent with the distal accentuation. A greater reduction of the ENFD at the thigh than the calf may indicate the presence of a multifocal sensory neuropathy or sensory neuronopathy (Chai et al, Neurology 2005; 65: 925-7).

The presence of normal ENFD does not by itself rule out a diagnosis of small fiber neuropathy. A reduced ENFD also does not indicate a particular cause for the neuropathy or predict a response to therapy. The diagnosis and treatment of any medical condition depends on the patient's clinical presentation and results of all laboratory investigations as interpreted by the physician.

This test was developed and its performance characteristics determined by Therapath LLC. Therapath is licensed under the Clinical Laboratory Improvement Amendments of 1998 (CLIA) to perform epidermal nerve fiber density testing. Therapath LLC. has performed assay validation studies and has developed its laboratory protocols and operating procedures in accordance with the standards of the National Committee on Clinical Laboratory Standards (NCCLS).

Sample Test Results

Results cannot be given directly to patients

As specified in 10 NYCRR Subpart 58-1.8, laboratory results may only be given to a physician, his or her agent, or other person authorized by law to use the results in the conduct of his or her practice or the fulfillment of official duties.