Epidermal Nerve Fiber Density Normative Reference Range And Studies Of Skin Nerve Biopsy In The Diagnosis Of Peripheral Neuropathy

Objective1. To develop a normative reference values of epidermal nerve fiber density in healthy control subjects. To mark different fiber types using different peptides.2. To compare the concordance between clinical features, electrophysiology and the results of skin biopsy results in the patients with peripheral neuropathies.3. To investigate skin nerve changes in diabetic neuropathy. To evaluate correlation between IENFD and duration of diabetes, glucose, glycosylated hemoglobin.4. To investigate skin nerve changes in painful peripheral neuropathy. To discuss possible mechanism of pain.Methods1. 10 volunteers (age range, 21-43years )were examined. Each subject had 2 punch biopsies performed in the thigh and distal part of the leg. Immunocytochemistry for the general neuronal marker protein gene product 9. 5( PGP9. 5) and three neuropeptides (Calcitonin gene-related peptide CGRP, subsantce P SP, Vasoactive intestinal polypeptide VIP)were performed on 10 volunteers.2 .We studied 65 patients with peripheral neuropathies . Skin biopsies were obtained from distal leg and/or proximal leg and nerve identified using immunohistochemistry with antibody to protein gene product (PGP)9.5 and neuropeptides. Detailed physical examination were performed in each patient. 57/65 performed routine nerve conduction velocity and electromyography, 40/65 performed SSR, 18/65 performed sural nerve biopsy. The concordance of the consequences was compared. 3. Analyse changes of skin nerves in 26 cases of diabetic neuropathy. Discuss correlation between IENDF and duration of diabetes , as well as glucose and glycosylated hemoglobin.4. Analyse changes of skin nerves in 27 cases of painful peripheral neuropathy. Discuss correlation between symptoms and immunocytochemistry of PGP9. 5 and neuropeptides .Results1.The distribution of PGP9.5 immunoreactive nerve fibers were seen abundantly in the epidermis, dermis, around sweat glands, arrectores pilorum and hair follicles. We enumerated intra-epidermal nerve fibers per millimeter to derive a linear density (Intraepidermal nerve fiber density , IENFD). IENFD was 21. 44±2.73 IENF/mm (mean±SD) in thigh and 15.44±2. 20IENF/mm(mean±SD) in the distal part of the leg. VIP immunoreactive nerve was seen in autonomic nerve fibers around sweat glands and arrectores pilorum . CGRP immunoreactive nerve was found in a population of sensory nerve fibers and around sweat glands. SP immunoreactive nerve was seen in sensory nerve, which was spare compared to CGRP immunoreactive nerve.2. The intraepidermal nerve fiber density were significant lower in patients than in healthy controls both in proximal and distal legs. 50/65(76.9%) patients showed abnormalities in skin biopsy, in which 24 patients accompaniment with morphological changes of skin nerves, length-dependent neuropathy. In the whole cohort , 57 have performed route electrophysiology, in which 27(47.4%) were abnormal. 40 have performed SSR, in which 25(62. 5%) were abnormal. IENFD correlated with the densities of sural nerve total myelinated fibers(r=0.576 , P=0.020), small myelinated fibers(r=0.524, P=0.037), and large myelinated fibers(r=0.560, P=0.024)3. The intraepidermal nerve fiber density were significant lower in patients with diabetes. There were significant inverse correlations between IENFD and the duration of diabetes. There was no significant difference between IENFD and glucose, glycosylated hemoglobin.4. There was no significant difference of IENFD between patients with and without pain. SP- and CGRP- positive fibers were significant lower in patients with pain than those without pain.Conclusion1.Skin biopsy was safe and tolerated. It was useful to assess the distribution of small fibers in skin. Skin biopsy may have a role in the assessment of small fiber neuropathy.2. Skin biopsy can play an important role in the diagnosis of peripheral disorders. Besides reduced IENFD .morphological changes in skin nerve fibers might be an early sign of peripheral neuropathy. IENFD correlated with the densities of sural nerve total myelinated, small myelinated and large myelinated fibers. Distal leg IENFD may be more sensitive than sural nerve biopsy in small fiber sensory neuropathy.3. In patients with diabetic neuropathy , skin biopsy can reveal loss of small-diameters nerve fibres even there were no symptoms. The extent of epidermal denervation rises with the duration of diabetes.4. In patients with painful symptoms , skin biopsy can reveal loss of SP-and CGRP- positive fibers more severe than those who have no pain.