Effectiveness of Metanx Prescription Medical Food on Small Nerve Fibers and Monofilament Sensation in Patients with Diabetic Peripheral Polyneuropathy

Purpose: Diabetic peripheral neuropathy (DPN) is prevalent among the population with type 2 diabetes, and treatment approaches are limited. The combination of L-methylfolate-methylcobalamin-pyridoxal-5-phospate (LMF-MC-PP, Metanx?) is a prescription medical food that has demonstrated significant improvements in sensory perception and quality of life as well as reduced neuropathic pain in patients with DPN. The present study examined the effects of LMF-MC-PP on sensory perception and epidermal nerve fiber density (ENFD) among patients with confirmed DPN. Methods: Patients with type 2 diabetes and diagnosed with diabetic peripheral polyneuropathy, based on loss of vibratory perception, warm-cold discrimination or monofilament sensation, underwent bilateral lower extremity ENFD assessments via skin punch biopsy and were started on LMF-MC-PP. ENFD and monofilament testing were repeated at 6 months. Findings: Of 123 patients evaluated, all had monofilament testing at baseline and 6 months and 122 had assessments at both time points. A significant (p < 0.05) improvement in ENFD from baseline to 6 months was observed. A significant (p = 0.0001) improvement in monofilament testing also was observed. Overall, more patients had intact sensation after 6 months, with 60 (48.8%) of 123 patients having positive monofilament test at baseline as compared to 95 (77.2%) positive after 6 months. An analysis of the association between improvements in ENFD and monofilament testing found that the two tended to occur together, and this was significant (p < 0.05) for the right limb. Implications: Clinically important and statistically significant improvements in ENFD and monofilament sensation were associated with LMF-MC-PP in patients with DPN. When compared to the decrease in ENFD expected among DPN patients, the improvements are even more clinically significant. These findings should be validated in a larger, placebo-controlled study.

Clinical Characteristics, Electrophysiology, and Skin Biopsy of 38 Peripheral Neuropathy Cases with Small Fiber Involvement of Various Etiologies

Background：In small fiber neuropathy （SFN）,thinly myelinated Aδ and unmyelinated C fibers are primarily affected,resulting in sensory and/or autonomic symptoms.Various etiologies have been shown to be associated with SFN.This study was aimed to analyze a variety of features in peripheral neuropathy （PN） with small fiber involvement.and to compare disease severity among patients with idiopathic PN,PN associated with impaired glucose tolerance （IGT）,and metabolic syndrome （MS） PN.Methods：Thirty-eight PN patients with small fiber involvement were enrolled from December 20,2013 to May 31,2016.Patients were divided into idiopathic PN,IGT-related PN,and MS-related PN groups.Detailed medical history and small fiber neuropathy were investigated,and symptom inventory questionnaire was conducted,as well as the visual analog scale.Nerve conduction studies and skin biopsies were also performed.The differences among the groups were analyzed using analysis of variance and Kruskal-Wallis test.Results：Eight patients were diagnosed with pure SFN.lntraepidermal nerve fiber density （I ENFD） weakly correlated with motor conduction velocity （MCV） （r =0.372,P =0.025）,and proximal （r =0.383,P =0.021） and distal （r =0.358,P 0.032） compound muscle action potential （CMAP） of the tibial nerve.IENFD also weakly correlated with MCV of the peroneal nerve （r=0.399,P =0.016）.IENFD was shown to be significantly different among all groups （x2 =9.901,P-0.007）.IENFD was significantly decreased （x2 =23.000,P=0.003） in the MS-related PN group compared to the idiopathic PN group.The MCV of the tibial nerve was significantly different among all groups （x2 =8.172,P 〈 0.017）.The proximal （F =4.336,P =0.021） and distal （F =3.262,P =0.049） CMAP of the tibial nerve was also significantly different among all groups.Conclusions：IENFD of patients included in the present study weakly correlated with various electrophysiological parameters.Small and large fibers are more involved in patients with MS-related PN than in patients with idiopathic PN.