Diabetic neuropathy is a generalized phenomenon with impact on hand functional performance and quality of life

Patient Outcomes After Peripheral Nerve Injury Depend on Bimanual Dexterity and Preserved Use of the Affected Hand

BACKGROUND

Little is known about how peripheral nerve injury affects human performance, behavior, and life. Hand use choices are important for rehabilitation after unilateral impairment, but rarely measured, and are not changed by the normal course of rehabilitation and daily life.

OBJECTIVE

To identify the relationship between hand use (L/R choices), motor performance, and patient-centered outcomes.

METHODS

Participants (n = 48) with unilateral peripheral nerve injury were assessed for hand use via Block Building Task, Motor Activity Log, and Edinburgh Handedness Inventory; dexterity (separately for each hand) via Nine-Hole Peg Test, Jebsen Taylor Hand Function Test, and a precision drawing task; patient-centered outcomes via surveys of disability, activity participation, and health-related quality of life; and injury-related factors including injury cause and affected nerve. Factor Analysis of Mixed Data was used to explore relationships between these variables. The data were analyzed under 2 approaches: comparing dominant hand (DH) versus non-dominant hand (NH), or affected versus unaffected hand.

RESULTS

The data were best explained by 5 dimensions. Good patient outcomes were associated with NH performance, DH performance (separately and secondarily to NH performance), and preserved function and use of the affected hand; whereas poor patient outcomes were associated with preserved but unused function of the affected hand.

CONCLUSION

After unilateral peripheral nerve injury, hand function, hand usage, and patient life arise from a complex interaction of many factors. To optimize rehabilitation after unilateral impairment, new rehabilitation methods are needed to promote performance and use with the NH, as well as the injured hand.

An examination of relationships between vitamin B12 status and functional measures of peripheral neuropathy in young adult vegetarians

Introduction

Prevalence rates for vitamin B12 deficiency in U.S. adult vegetarians may exceed 30%, which is concerning given the role for this vitamin in numerous nervous system functions, including the synthesis of myelin sheaths. Defective myelin synthesis and repair are directly linked to peripheral neuropathy; yet, few investigations have examined how physical indicators of peripheral neuropathy (e.g., hand dexterity, vibration sensitivity and balance) are impacted in individuals adhering to vegetarian diets. This feasibility research explored the relationships between peripheral neuropathy and vitamin B12 status using a cross-sectional study design. In addition, a small pilot trial was conducted for limited-efficacy testing of vitamin B12 supplementation for reducing peripheral neuropathy.

Methods

Healthy, able-bodied adults (n = 38; 19-40 years of age) reported exclusive adherence to a vegetarian or vegan diet for 3 years. Peripheral neuropathy was measured using a force plate for assessing balance, and a vibration sensitivity tester and pegboard tests to assess hand dexterity. Serum vitamin B12 and folate were measured using standard radioimmunoassay techniques.

Results

Twenty-six percent of the sample displayed deficient or marginal vitamin B12 status (serum vitamin B12 <221 pmol/L). Participants with adequate vitamin B12 status scored 10% higher on the Purdue pegboard assembly test and 20% higher on the left hand adjusted functional dexterity test in comparison to participants with marginal-to-deficient vitamin B12 status (p < 0.05).

Discussion

These data provide preliminary evidence that peripheral neuropathy can be detected in individuals with marginal-to-deficient vitamin B12 status.

Dysmetabolism-related Early Sensory Deficits and Their Relationship With Peripheral Neuropathy Development

AIM

To investigate the association of early peripheral sensory dysfunction (EPSD) identified through quantitative sensory testing (QST) with factors related to a dysmetabolic status in individuals with and without type 2 diabetes (T2DM) without peripheral neuropathy (PN), and the impact of those factors on PN development.

METHODS

A total of 225 individuals (117 and 108 without and with T2DM, respectively) without PN based on clinical and electrophysiological criteria were analyzed. Comparative analysis was conducted between those identified as "healthy" and those with EPSD based on a standardized QST protocol. A total of 196 were followed-up over a mean of 2.64 years for PN occurrence.

RESULTS

Among those without T2DM, apart from male sex, height, and higher fat and lower lean mass, only higher insulin resistance (IR; homeostatic model assessment for IR: odds ratio [OR], 1.70; P = .009; McAuley index OR, 0.62, P = .008), was independently associated with EPSD. In T2DM, metabolic syndrome (OR, 18.32; P < .001) and skin advanced glycation end-products (AGEs; OR, 5.66; P = .003) were independent predictors of EPSD. In longitudinal analysis, T2DM (hazard ratio [HR], 3.32 vs no diabetes mellitus; P < .001), EPSD (adjusted HR, 1.88 vs healthy; P = .049 adjusted for diabetes mellitus and sex), higher IR and AGEs predicted PN development. Among the 3 EPSD-associated sensory phenotypes, "sensory loss" was most strongly associated with PN development (adjusted HR, 4.35; P = .011).

CONCLUSION

We demonstrate for the first time the utility of a standardized QST-based approach in identifying early sensory deficits in individuals with and without T2DM. These are associated with a dysmetabolic status signified by IR markers, metabolic syndrome, and higher AGEs, which in turn are shown to influence PN development.

"PNP slows down" - linearly-reduced whole body joint velocities and altered gait patterns in polyneuropathy

Introduction

Gait disturbances are a common consequence of polyneuropathy (PNP) and a major factor in patients' reduced quality of life. Less is known about the underlying mechanisms of PNP-related altered motor behavior and its distribution across the body. We aimed to capture whole body movements in PNP during a clinically relevant mobility test, i.e., the Timed Up and Go (TUG). We hypothesize that joint velocity profiles across the entire body would enable a deeper understanding of PNP-related movement alterations. This may yield insights into motor control mechanisms responsible for altered gait in PNP.

Methods

20 PNP patients (61 ± 14 years) and a matched healthy control group (CG, 60 ± 15 years) performed TUG at (i) preferred and (ii) fast movement speed, and (iii) while counting backward (dual-task). We recorded TUG duration (s) and extracted gait-related parameters [step time (s), step length (cm), and width (cm)] during the walking sequences of TUG and calculated center of mass (COM) velocity [represents gait speed (cm/s)] and joint velocities (cm/s) (ankles, knees, hips, shoulders, elbows, wrists) with respect to body coordinates during walking; we then derived mean joint velocities and ratios between groups.

Results

Across all TUG conditions, PNP patients moved significantly slower (TUG time, gait speed) with prolonged step time and shorter steps compared to CG. Velocity profiles depend significantly on group designation, TUG condition, and joint. Correlation analysis revealed that joint velocities and gait speed are closely interrelated in individual subjects, with a 0.87 mean velocity ratio between groups.

Discussion

We confirmed a PNP-related slowed gait pattern. Interestingly, joint velocities in the rest of the body measured in body coordinates were in a linear relationship to each other and to COM velocity in space coordinates, despite PNP. Across the whole body, PNP patients reduce, on average, their joint velocities with a factor of 0.87 compared to CG and thus maintain movement patterns in terms of velocity distributions across joints similarly to healthy individuals. This down-scaling of mean absolute joint velocities may be the main source for the altered motor behavior of PNP patients during gait and is due to the poorer quality of their somatosensory information.

Clinical Trial Registration

https://drks.de/search/de, identifier DRKS00016999.

Sciatic nerve fractional anisotropy and neurofilament light chain protein are related to sensorimotor deficit of the upper and lower limbs in patients with type 2 diabetes

BACKGROUND

Diabetic sensorimotor polyneuropathy (DSPN) is one of the most prevalent and poorly understood diabetic microvascular complications. Recent studies have found that fractional anisotropy (FA), a marker for microstructural nerve integrity, is a sensitive parameter for the structural and functional nerve damage in DSPN. The aim of this study was to investigate the significance of proximal sciatic nerve's FA on different distal nerve fiber deficits of the upper and lower limbs and its correlation with the neuroaxonal biomarker, neurofilament light chain protein (NfL).

MATERIALS AND METHODS

Sixty-nine patients with type 2 diabetes (T2DM) and 30 healthy controls underwent detailed clinical and electrophysiological assessments, complete quantitative sensory testing (QST), and diffusion-weighted magnetic resonance neurography of the sciatic nerve. NfL was measured in the serum of healthy controls and patients with T2DM. Multivariate models were used to adjust for confounders of microvascular damage.

RESULTS

Patients with DSPN showed a 17% lower sciatic microstructural integrity compared to healthy controls (p<0.001). FA correlated with tibial and peroneal motor nerve conduction velocity (NCV) (r=0.6; p<0.001 and r=0.6; p<0.001) and sural sensory NCV (r=0.50; p<0.001). Participants with reduced sciatic nerve´s FA showed a loss of function of mechanical and thermal sensation of upper (r=0.3; p<0.01 and r=0.3; p<0.01) and lower (r=0.5; p<0.001 and r=0.3; p=<0.01) limbs and reduced functional performance of upper limbs (Purdue Pegboard Test for dominant hand; r=0.4; p<0.001). Increased levels of NfL and urinary albumin-creatinine ratio (ACR) were associated with loss of sciatic nerve´s FA (r=-0.5; p<0.001 and r= -0.3, p= 0.001). Of note, there was no correlation between sciatic FA and neuropathic symptoms or pain.

CONCLUSION

This is the first study showing that microstructural nerve integrity is associated with damage of different nerve fiber types and a neuroaxonal biomarker in DSPN. Furthermore, these findings show that proximal nerve damage is related to distal nerve function even before clinical symptoms occur. The microstructure of the proximal sciatic nerve and is also associated with functional nerve fiber deficits of the upper and lower limbs, suggesting that diabetic neuropathy involves structural changes of peripheral nerves of upper limbs too.