Peripheral nerve morphology and intraneural blood flow in chronic kidney disease with and without diabetes

Analysis of the Factors of Wound Healing Problems After Transtibial Amputation in Diabetic Patients

Diabetes mellitus has a global impact, necessitating surgical intervention when conservative methods fail. Transtibial amputation (TTA) is commonly performed on diabetic patients, yet surgical site complications can lead to more procedures. This study aimed to identify factors linked to wound healing issues post-TTA in diabetics.A total of 181 patients who underwent TTA between 2004 and 2021 at a single hospital were included in the study. Exclusion criteria comprised trauma, non-diabetic mellitus, follow-up duration of less than 1 year, incomplete medical records, and surgeries performed by different surgeons. The comparison focused on underlying diseases other than diabetes between the group with wound problems and the group without. Additionally, factors impacting blood flow, such as presurgery hemoglobin levels, intraoperative blood transfusion, the use of antithrombotic or anticoagulant drugs, and the presence of procedures like percutaneous transluminal angioplasty (PTA) and bypass surgery, were analyzed.Among the 181 cases, 22.1% experienced problems at the surgical site while 77.9% did not. Statistical analysis revealed that age was a significant variable affecting wound healing problems after TTA in diabetic patients (p = .007). However, there were no significant differences in wound problems based on comorbidities other than diabetes (p = .209), gender (p = .677), preoperative anemia (p = .102), intraoperative blood transfusion (p = .633), the use of antithrombotic or anticoagulant medications (p = .556), and the performance of PTA or bypass surgery (p = .6).In conclusion, this study found that age was a significant variable affecting wound healing problems after TTA in diabetic patients. Although no association was observed between underlying diseases and wound healing problems, further investigation and cautious management of factors such as preoperative anemia, intraoperative blood transfusion, the use of antithrombotic or anticoagulant drugs, and the performance of PTA or bypass surgery are warranted to prevent complications and optimize wound healing outcomes in diabetic patients undergoing TTA.

The Role of Neuromuscular Ultrasound in the Diagnosis of Peripheral Neuropathy

The classification of peripheral neuropathies has traditionally been based on etiology, electrodiagnostic findings, or histopathologic features. With the advent of modern imaging, they now can also be characterized based on their varied distribution of imaging findings. We describe the major morphologic patterns of these changes, which include homogeneous enlargement; homogeneous thinning; focal, multifocal, and segmental enlargement; and focal thinning and beading (multifocal thinning). Representative disorders in each of these categories are discussed, along with examples of the more complex imaging manifestations of neuralgic amyotrophy, nerve transection, and hereditary amyloidosis. An appreciation of the diverse morphologic manifestations of neuropathy can help neuromuscular clinicians conduct appropriate imaging studies with ultrasound and, when needed, order suitable investigations with magnetic resonance neurography.

Nerve cross-sectional area in advanced uremic neuropathy: A nerve ultrasound pilot study

BACKGROUND AND PURPOSE

Uremic neuropathy (UN) is a disabling neuropathy in end-stage kidney disease (ESKD) affecting the majority of patients receiving long-term hemodialysis (HD). One previous nerve ultrasound study reported an increased cross-sectional area (CSA) of the median nerve in moderate UN, while another study found enlarged sural nerves in small-fiber polyneuropathy associated with ESKD. The present cohort study aims to analyze bilateral CSA of multiple nerves in UN.

METHODS

Ten nondiabetic ESKD patients with UN on HD for at least 2 years and 10 healthy age-matched controls underwent bilateral ultrasound examinations with CSA measurements in 13 arm and leg nerve sites. Nerve conduction studies (NCS) and the total neuropathy score (TNS) were recorded. Pearson's coefficient and the Mann-Whitney U-test were used to analyze correlations and compare groups.

RESULTS

ESKD patients presented advanced neuropathic symptoms (mean TNS 15.9). NCS showed significantly reduced motor and sensory amplitudes in the UN group compared to the control group, and a slightly reduced nerve CSA was observed in 5 of 13 nerve sites (p < .05); the other nerve sites were not enlarged. Sural nerve CSA (p < .05) and sensory amplitude (p < .01) were negatively correlated with the TNS.

CONCLUSIONS

Nerve enlargement was not observed in the present study in advanced UN. A reduced nerve CSA observed in the sural nerve suggests an axonal loss associated with long-term HD in ESKD. During clinical workup of an acute disease of the peripheral nervous system in ESKD patients, nerve enlargement might be attributable to other causes than chronic UN.

Electrochemical Skin Conductance by Sudoscan in Non-Dialysis Chronic Kidney Disease Patients

BACKGROUND

Peripheral neuropathy is prevalent among patients with chronic kidney disease (CKD). Sudoscan non-invasively detects polyneuropathy by measuring electrochemical skin conductance (ESC). We conducted a study on sudomotor function in CKD patients across various stages based on their estimated glomerular filtration rate (eGFR).

METHODS

In this cross-sectional study of 700 CKD patients, all underwent Sudoscan. Pathological ESC was defined as hands < 40 μS or feet < 50 μS. Clinical neuropathy scores including Michigan Neuropathy Screening Instrument (MNSI) and Douleur Neuropathique en 4 questionnaire (DN4) were obtained.

RESULTS

Among participants, 344 had diabetes and 356 did not. Hands and feet ESC decreased with CKD progression (median (IQR) in stage 1-2, 3, 4-5: 54.0 (39.0-68.0), 45.5 (30.0-63.0), 41.8 (26.5-60.5), p trend < 0.001; 64.5 (53.5-74.0), 60.5 (43.0-72.5), 55.0 (39.0-69.8), p trend < 0.001). Pathological hands and feet ESC increased in later CKD stages (stage 1-2, 3, 4-5: 26.6%, 40.9%, 45.7%, p trend < 0.001; 21.7%, 34.0%, 40.6%, p trend < 0.001). Positive hands and feet ESC-eGFR correlation existed irrespective of diabetes. Diabetic patients had lower hands and feet ESC than non-diabetics as CKD progressed. However, multivariate regression found no significant ESC-eGFR association. Sudoscan correlated with clinical neuropathy scores.

CONCLUSION

Pathological sudomotor function was common in non-dialysis CKD stages 4-5. Diabetic patients had worse function. Sudomotor dysfunction progressed with renal disease but eGFR was not an independent risk factor.

Assessing the Potential for Error in Investigating Intraneural Vascularity: A Need for a Standardized Imaging Protocol

Objective

This study examined the implementation of a Doppler sonography imaging protocol to assess intraneural blood flow, within the median nerve, in healthy individuals.

Materials and Methods

A total of 176 participants were examined, and this involved 717 retrospective observations of the images collected. The implemented imaging protocol was assessed, and the data that were collected were cleaned and checked for fidelity and validity.

Results

A large percentage of missing evidence (11%-35%) across proximal, mid, and distal carpal tunnel locations. Only a quarter of cases with evidence of intraneural blood flow had the strongest evidence of a power Doppler video clip, of which only three-quarters were valid. The study identified potential areas for improving the imaging protocol to reduce missing data and improve data quality.

Conclusion

This study demonstrates the significance of a standardized imaging protocol to guide the sonographic acquisition of Doppler images and provides important insights into potential issues with data quality. The recommendations have the potential to help future studies assess intraneural blood flow in healthy populations in a more rigorous and reliable way. Incorporating the study's recommendations into a standardized protocol, there is potential to enhance the diagnostic accuracy of carpal tunnel syndrome and improve diagnosis and treatment.

Normative Reference Values of the Tibial Nerve in Healthy Individuals Using Ultrasonography: A Systematic Review and Meta-Analysis

BACKGROUND

High-resolution ultrasound of the tibial nerve has been used for screening of several neurologic disorders, but normative reference values of tibial nerve cross-sectional areas (CSA) have not been well established. Thus, the present meta-analysis was performed to generate normative estimates of tibial nerve CSA at various sites of the lower limb based on ultrasonography.

METHODS

Google Scholar, Scopus and PubMed were searched for potential studies. Studies were required to report tibial nerve CSA in healthy individuals to be included. A random-effect meta-analysis was performed to calculate tibial nerve CSA values. Subgroup and statistical analyses were performed to study covariates.

RESULTS

Forty-eight eligible articles consisting of 2695 limbs were included. The average tibial nerve CSA was found to be 10.9 mm2 at the ankle (95% CI: 9.9-11.8) and should not exceed 11.8 mm2 in healthy adults. At the popliteal fossa, the overall CSA was 21.7 mm2 (95% CI: 17.5-25.8) in healthy adults. At both sites, the average tibial nerve CSA was significantly larger in adults than in children, and the differences by geographical region were not statistically significant. At the ankle, tibial nerve CSA increased with age and body mass index, while at the popliteal fossa it increased with age and weight.

CONCLUSIONS

our findings indicate that the tibial nerve varied not only along its course but also among sub-variables. Establishing normal references values of tibial nerve CSA is helpful to differentiate healthy from diseased tibial nerves such as in diabetic peripheral neuropathy or tarsal tunnel syndrome.

The Effects of Indoxyl Sulfate and Oxidative Stress on the Severity of Peripheral Nerve Dysfunction in Patients with Chronic Kidney Diseases

Pieces of evidence support the view that the accumulation of uremic toxins enhances oxidative stress and downstream regulation of signaling pathways, contributing to both endothelial microangiography and cell dysfunction. This study is to address the impact of protein-binding uremic toxins on the severity of peripheral nerve function in patients with chronic kidney disease (CKD). Fifty-four patients with CKD were included in the Toronto Clinical Neuropathy Score (TCNS), nerve conduction study (NCS), and laboratory studies including protein-binding uremic toxin (indoxyl sulfate [IS] and p-cresyl sulfate [PCS]), oxidative stress (Thiol and thiobarbituric acid reacting substances [TBARS]), and endothelial dysfunction (serum intercellular adhesion molecule 1 [sICAM-1] and serum vascular adhesion molecule 1 [sVCAM-1]) at enrollment. We used composite amplitude scores (CAS) to analyze the severity of nerve conductions on peripheral nerve function. TCNS and CAS were higher in the diabetic CKD group (p = 0.02 and 0.01, respectively). The NCS revealed the compound muscle action potential of ulnar and peroneal nerves and the sensory nerve action potential of ulnar and sural nerves (p = 0.004, p = 0.004, p = 0.004, and p = 0.001, respectively), which was found to be significantly low in the diabetic group. CAS was significantly correlated with age (r = 0.27, p = 0.04), urine albumin-creatinine ratio (UACR) (r = 0.29, p = 0.046), free-form IS (r = 0.39, p = 0.009), sICAM-1 (r = 0.31, p = 0.02), sVCAM-1 (r = 0.44, p < 0.0001), TBARS (r = 0.35, p = 0.002), and thiols (r = −0.28, p = 0.045). Linear regression revealed that only TBARS and free-form IS were strongly associated with CAS. The mediation analysis shows that the sVCAM-1 level serves as the mediator between higher IS and higher CAS. IS and oxidative stress contribute to the severity of peripheral nerve dysfunction in patients with CKD, and chronic glycemic impairment can worsen the conditions.