In patients with suspected neuropathy, skin samples are obtained by skin punch biopsy. Standard sites in the lower extremity include the foot, distal leg (calf), and proximal thigh.
For patients with symptoms in the upper extremity, standard sites include the proximal and distal arm. For patients 18 years and older, Therapath has established normal values by gender and age for both ENFD and SGNFD at all five sites. These values allow Therapath to provide a result that is both quantitative and diagnostic for small fiber neuropathy.
If focal neuropathy is suspected, a biopsy sample in the distribution of the affected nerve can be compared to the corresponding site on the non-affected side of the body.
The same biopsy sample can be used for both Epidermal Nerve Fiber Density and Sweat Gland Nerve Fiber Density.