[Clinical, electrophysiological and skin biopsy studies of peripheral neuropathy with small fibers involvement: a report of 34 cases].

OBJECTIVE: To explore the relationship between clinical features, electrophysiology and intraepidermal nerve fiber density (IENFD) in peripheral neuropathy with small fibers involvement and determine the diagnostic value of 13-item small-fiber neuropathy and symptoms inventory questionnaire (SFN-SIQ) and neuropathy symptom score [lower limb] (NSS [LL]) in small fiber neuropathy (SFN).

METHODS: A total of 34 consecutive patients with peripheral neuropathy with symptoms of small fibers were enrolled and divided into two groups of small fiber injury and small and large fiber injury.SFN-SIQ, NSS [LL] and neuropathy disability score [lower limb] (NDS [LL]) were administered.Nerve conduction studies and skin biopsy were conducted in unilateral lower limb. The relationship between IENFD and these scales was assessed by partial correlation.Receiver operating characteristic analysis was applied for evaluating the diagnostic value of SFN-SIQ and NSS [LL] in small fiber injury. Independent sample t test was used to compare various parameters of two groups. And similar statistical method was used for IENFD abnormal and normal groups to detect the clinicoelectrophysiological differences.

RESULTS: According to the international normative reference of IENFD, 13 patients could be diagnosed with peripheral neuropathy with small fibers involvement. IENFD was moderately correlated with SFN-SIQ (r = 0.437, P = 0.012) and marginally correlated with NSS [LL] (r = 0.334, P = 0.062). The diagnostic value of SFN-SIQ and NSS [LL] was moderate for small fiber injury (Az = 0.753, P = 0.012 for SFN-SIQ, Az = 0.712, P = 0.040 for NSS [LL]) and the best diagnostic indicator of each scale was 6. The value of NDS [LL] was apparently elevated in small and large fiber injury group versus small fiber injury group (t = -5.605, P < 0.001). The IENFD abnormal group had a higher NSS [LL] value than that of the IENFD normal group (t = -2.047, P = 0.049). No differences of electrophysiological parameters existed between IENFD abnormal and normal groups.

CONCLUSION: Chinese normative reference of IENFD should be formulated for the diagnosis of small fiber neuropathy. SFN-SIQ and NSS [LL] may screen for small fiber neuropathy and both are convenient during patient follow-ups.Large sample studies are warranted to further evaluate the clinical values of SFN-SIQ and NSS [LL].