Characteristics of lower extremity pressure sensation impairment in developing diabetic sensory polyneuropathy

Vascular factors and neuropathy in lower limb of diabetic patients

Asymmetric clinical presentation in some patients with diabetic polyneuropathy may result from the different vascular environments in both lower limbs. The aim of the study is to determine the association of neuropathy with vascular factors in each lower limb of diabetic patients. A total of 102 patients (204 lower limbs) given a diagnosis of diabetic polyneuropathy were enrolled. The primary end points are sensory nerve action potential (SNAP) amplitude and conduction velocity (CV) of the sural nerve and independent variables are vascular and nonvascular factors. Vascular factors include mean arterial pressure and pulse pressure at the ankle, ankle-brachial index, and arterial stiffness assessed by pulse wave velocity. Nonvascular factors include age, gender, height, body weight, body mass index, total cholesterol, and hemoglobin A₁C. Age, hemoglobin A₁C, and ankle pulse pressure were inversely correlated with SNAP amplitude of the sural nerve, while no factors were correlated with CV of the sural nerve. Increased arterial stiffness was significant in the limbs group with abnormal SNAP amplitude of the sural nerve, while increased height was significant in the limbs group with abnormal CV of the sural nerve. Vascular factors were more significantly associated with decreased SNAP amplitude rather than decreased CV of the sural nerve in the nerve conduction study of diabetic patients.

Analysis of oxidative DNA damage and its repair in Polish patients with diabetes mellitus type 2: Role in pathogenesis of diabetic neuropathy

PURPOSE

Distal symmetric polyneuropathy (DSPN) is common complication of type 2 diabetes (T2DM). In this work we investigated the role of oxidative damage in connection with particular polymorphisms of DNA repair genes and their repair capacity.

MATERIAL/METHODS

Materials constitute the peripheral blood of patients with T2DM with and without DSPN and control subjects without disturbance of the carbohydrate fraction. The study of gene polymorphisms which products take part in base excision repair (BER) pathway: 726 Val/Ala adenosine diphosphate ribosyl transferase (ADPRT), 324 His/Glu MutYhomolog (MUTYH) and 148 Asp/Glu human apurinic/apyrimidinic endonuclease (APE) was carried out using restriction fragment length polymorphism polymerase chain reaction (PCR-RFLP) method. The study of DNA damage induced by hydrogen peroxide and the efficiency of their repair was carried out using comet assay.

RESULTS

None of the 3 polymorphisms were associated with the risk of DSPN. However, in group of patients together with T2DM and T2DM/DSPN 726 Ala ADPRT allele was significantly susceptible to increased risk of T2DM (OR=1.59; 95% CI: 1.08-2.36). Investigation of DNA damage and repair revealed that T2DM patients have decreased ability to DNA repair. This capacity even drops down in the group of T2DM/DSPN patients compared to subjects with diabetes alone. ADPRT and APE polymorphisms were significantly associated with higher DNA damages (P<0.05) in heterozygous and mutant homozygous in correlation to homozygous wild type, but for MUTYH polymorphism relation was not confirmed.

CONCLUSIONS

Pathogenesis of T2DM and development of DSPN may be related to oxidative stress connected with BER gene polymorphisms.

Reconsidering nerve decompression: an overlooked opportunity to limit diabetic foot ulcer recurrence and amputation

Nerve decompression for relief of subjective diabetic sensorimotor polyneuropathy pain and numbness has been labeled of "unknown" benefit. Objective outcomes in treatment and prevention of diabetic foot complications are reviewed. There is growing evidence that plantar foot ulceration and recurrence in high-risk feet are minimized with this operation. Avoiding neuropathic and neuroischemic ulcer wounds should theoretically reduce amputations and perhaps mortality risk. Protective effects are hypothesized to act via relief of neuro-vascular entrapment, thereby improving neurally modulated tissue homeostasis factors. Nerve decompression deserves considerable research attention to understand its role in limiting foot complications. Its apparent benefits challenge the paradigm that diabetic neuropathy is a purely length-dependent axonopathy and may necessitate appreciation of superimposed nerve entrapment as an significant operant factor.

Evaluation of oxidative stress markers in pathogenesis of diabetic neuropathy

Experimental evidences suggest that hyperglycaemia-induced overproduction of reactive oxygen species and subsequent damage to proteins, lipids and DNA may play a key role in the development of distal symmetric polyneuropathy (DSPN)—the most common complication of diabetes mellitus. The study population consisted of 51 individuals aged 52–82 years classified into 3 groups: 16 patients diagnosed with type 2 diabetes mellitus (T2DM) with DSPN, 16 T2DM patients without DSPN and 19 control subjects without diabetes and neuropathy. The study was conducted to determine the activity of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and total antioxidant status (TAS) in the examined groups. An alkaline comet assay was used to determine the extent of DNA damage of oxidized purines as glicosylo-formamidoglicosylase (Fpg) sites, and oxidized pyrimidines as endonuclease III (Nth) sites. A significant decrease of SOD (P < 0.05), GPX (P < 0.05) and nonsignificant decrease of CAT (P > 0.05), and TAS status (P > 0.05) were seen in T2DM patients with neuropathy compared to T2DM patients as well as controls. T2DM patients with or without neuropathy revealed significantly lower (P < 0.05) plasma concentration of nitrous oxide compared to the control subjects. Endogenous level of oxidative DNA damage in T2DM patients with DSPN was significantly higher compared both to the controls and T2DM patients without DSPN (P < 0.001). Moreover, lymphocytes isolated from T2DM patients with DSPN were more susceptible to oxidative DNA lesions induced by hydrogen peroxide than from T2DM patients without DSPN (P < 0.001). Our results confirm hypothesis that oxidative stress may play a substantial role in the development and progression of diabetic distal symmetric polyneuropathy.

Symmetry of sensory loss in developing diabetic sensory polyneuropathy

The medical literature presents diabetic sensory polyneuropathy (DSPN) as an axonal length-dependent symmetric pathology producing a stocking-like pattern of anesthesia in the lower extremities. This has been based on anecdotal reports. Objective research has shown that damage may not occur in a purely length-dependent manner. A stocking distribution of sensory loss is atypical, and plantar sensory loss predominates. A single-blinded, age-matched, control/experimental study was performed of the symmetry of nerve damage in developing DSPN. Control (n = 46) and experimental (n = 83) subjects were examined. The patterns of sensory loss and the severity of axonal damage were evaluated. The right/left symmetry of pathology was recorded for each individual. Although there was not a stocking pattern of anesthesia found in developing DSPN, the pattern and severity of anesthesia were found to be generally symmetric. The severity of sensory impairment was symmetric at the dorsal foot (93%), lateral foot (95%), and plantar foot (69%). The most predominant site of sensory impairment was also symmetric (81%). This argues against a purely metabolic etiology for axonal damage. An anatomic component is implied. Further research will need to include examination of the unique physical characteristics of predominantly affected nerves.