People with diabetic peripheral neuropathy display a decreased stepping accuracy during walking: potential implications for risk of tripping

Peripheral neuropathy, an independent risk factor for falls in the elderly, impairs stepping as a postural control mechanism: A case-cohort study

BACKGROUND/AIMS

Peripheral neuropathies perturbate the sensorimotor system, causing difficulties in walking-related motor tasks and, eventually, falls. Falls result in functional dependency and reliance on healthcare, especially in older persons. We investigated if peripheral neuropathy is a genuine risk factor for falls in the elderly and if quantification of postural control via posturography is helpful in identifying subjects at risk of falls.

METHODS

Seventeen older persons with a clinical polyneuropathic syndrome of the lower limbs and converging electrophysiology were compared with 14 older persons without polyneuropathy. All participants were characterized via quantitative motor and sensory testing, neuropsychological assessment, and self-questionnaires. Video-nystagmography and caloric test excluded vestibulocochlear dysfunction. For further analysis, all subjects were stratified into fallers and non-fallers. Overall, 28 patients underwent computerized dynamic posturography for individual fall risk assessment. Regression analyses were performed to identify risk factors and predictive posturography parameters.

RESULTS

Neuropathy is an independent risk factor for falls in the elderly, while no differences were observed for age, gender, weight, frailty, DemTect test, timed "Up & Go" test, and dizziness-related handicap score. In computerized dynamic posturography, fallers stepped more often to regain postural control in challenging conditions, while the Rhythmic Weight Shift test showed a lack of anterior-posterior bidirectional voluntary control.

INTERPRETATION

Our study confirms peripheral neuropathy as a risk factor for older persons' falls. Fallers frequently used stepping to regain postural control. The voluntary control of this coping movement was impaired. Further investigations into these parameters' value in predicting the risk of falls in the elderly are warranted.

Orthopedic footwear has a positive influence on gait adaptability in individuals with hereditary motor and sensory neuropathy

BACKGROUND

Individuals with Hereditary Motor and Sensory Neuropathy (HMSN) are commonly provided with orthopedic footwear to improve gait. Although orthopedic footwear has shown to improve walking speed and spatiotemporal parameters, its effect on gait adaptability has not been established.

RESEARCH QUESTION

What is the effect of orthopedic footwear on gait adaptability in individuals with HMSN?

METHODS

Fifteen individuals with HMSN performed a precision stepping task on an instrumented treadmill projecting visual targets, while wearing either custom-made orthopedic or standardized footwear (i.e. minimally supportive, flexible sneakers). Primary measure of gait adaptability was the absolute Euclidean distance [mm] between the target center and the middle of the foot (absolute error). Secondary outcomes included the relative and variable error [mm] in both anterior-posterior (AP) and medial-lateral (ML) directions. Dynamic balance was assessed by the prediction of ML foot placement based on the ML center of mass position and velocity, using linear regression. Dynamic balance was primarily determined by foot placement deviation in terms of root mean square error. Another aspect of dynamic balance was foot placement adherence in terms of the coefficient of determination (R2). Differences between the footwear conditions were analyzed with a paired t-test or Wilcoxon signed-rank test (α = 0.05).

RESULTS

The absolute error, relative error (AP) and variable error (AP and ML) decreased with orthopedic footwear, whereas the relative error in ML-direction slightly increased. As for dynamic balance, no effect on foot placement deviation or adherence was found.

SIGNIFICANCE

Gait adaptability improved with orthopedic compared to standardized footwear in people with HMSN, as indicated by improved precision stepping. Dynamic balance, as a possible underlying mechanism, was not affected by orthopedic footwear.

Sensory-Motor Mechanisms Increasing Falls Risk in Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is associated with peripheral sensory and motor nerve damage that affects up to half of diabetes patients and is an independent risk factor for falls. Clinical implications of DPN-related falls include injury, psychological distress and physical activity curtailment. This review describes how the sensory and motor deficits associated with DPN underpin biomechanical alterations to the pattern of walking (gait), which contribute to balance impairments underpinning falls. Changes to gait with diabetes occur even before the onset of measurable DPN, but changes become much more marked with DPN. Gait impairments with diabetes and DPN include alterations to walking speed, step length, step width and joint ranges of motion. These alterations also impact the rotational forces around joints known as joint moments, which are reduced as part of a natural strategy to lower the muscular demands of gait to compensate for lower strength capacities due to diabetes and DPN. Muscle weakness and atrophy are most striking in patients with DPN, but also present in non-neuropathic diabetes patients, affecting not only distal muscles of the foot and ankle, but also proximal thigh muscles. Insensate feet with DPN cause a delayed neuromuscular response immediately following foot–ground contact during gait and this is a major factor contributing to increased falls risk. Pronounced balance impairments measured in the gait laboratory are only seen in DPN patients and not non-neuropathic diabetes patients. Self-perception of unsteadiness matches gait laboratory measures and can distinguish between patients with and without DPN. Diabetic foot ulcers and their associated risk factors including insensate feet with DPN and offloading devices further increase falls risk. Falls prevention strategies based on sensory and motor mechanisms should target those most at risk of falls with DPN, with further research needed to optimise interventions.

Quantitative gait and postural analyses in patients with diabetic polyneuropathy

BACKGROUND

Although gait disturbances are relatively common symptoms in diabetic polyneuropathy (DPN), few studies have quantitatively analyzed gait and posture in DPN patients. This study aimed to analyze gait and posture quantitatively in DPN patients and to determine the association between clinical and electrophysiological parameters and gait and posture parameters.

METHODS

Sixty-four DPN patients were enrolled in this study. DPN was clinically assessed using the Toronto clinical neuropathy score (TCNS). All participants underwent nerve conduction study (NCS), three-dimensional motion analysis, and static posturography. We evaluate the correlation of gait and posture parameters with electrophysiological and clinical parameters.

RESULTS

Foot height, step length, and stride length among gait parameters were inversely correlated with the TCNS. Anteroposterior range during eyes-closed and mediolateral distance and range during eyes-open and eyes-closed were inversely correlated with the sensory nerve action potential amplitude in the sural nerve. Mediolateral distance during eyes-open and eyes-closed was correlated with the compound muscle action potential amplitude in the peroneal nerve.

CONCLUSIONS

Gait parameters are associated with clinical parameters, and postural parameters are associated with electrophysiological parameters, particularly sensory NCS. Gait and postural analysis can be a useful tool for assessing the neurological status in DPN patients.

The 2017 Banting Memorial Lecture The diabetic lower limb - a forty year journey: from clinical observation to clinical science

A series of clinical research projects conducted over the past 40 years, all of which were informed by clinical observation or discussions with people with diabetes and staff colleagues are described in this review. A study of necrobiosis lipoidica diabeticorum confirmed that this rare skin complication occurs predominantly in young women with Type 1 diabetes and other microvascular complications. Biopsies of necrobiotic lesions showed destruction of superficial nerve fibres by inflammatory tissue, which likely causes the sensory loss in lesions that is pathognomonic of the condition. The development of corneal confocal microscopy as a new non-invasive surrogate marker of peripheral neuropathy in diabetes is described next and several small studies of the use of this new technique in clinical research are reported. The influence of blood glucose instability on the genesis of neuropathic pain is then explained, with results suggesting that the stability of glycaemic control may be more important than the level of control achieved. Lastly, in neuropathy, studies of gustatory sweating are discussed, including the observation that sweating in the head and neck region is more common in people with end-stage diabetic nephropathy than in those with neuropathy. The disappearance of gustatory sweating after renal transplantation suggests a metabolic cause and for those with troublesome sweating, use of the anticholinergic, anti-muscarinic, topical cream glycopyrrolate is confirmed in a randomized control trial. In the area of diabetic foot research, distended dorsal foot veins were observed to be a clinical sign of sympathetic autonomic neuropathy: raised venous Po₂ and Doppler abnormalities of blood flow are highly suggestive of arteriovenous shunting. A series of studies of the abnormalities of pressures and loads under the neuropathic diabetic foot are described: high dynamic plantar pressures are highly predictive of subsequent ulceration in the neuropathic foot. Lastly, a number of recent studies on unsteadiness and gait abnormalities when climbing and descending stairs are described. It is hoped that the art of clinical observation survives in the highly technological 21st century.

Combined exercise and visual gaze training improves stepping accuracy in people with diabetic peripheral neuropathy

INTRODUCTION

Patients with diabetes and diabetic peripheral neuropathy (DPN) place their feet with less accuracy whilst walking, which may contribute to the increased falls-risk. This study examines the effects of a multi-faceted intervention on stepping accuracy, in patients with diabetes and DPN.

METHODS

Forty participants began the study, of which 29 completed both the pre and post-intervention tests, 8 patients with DPN, 11 patients with diabetes but no neuropathy (D) and 10 healthy controls (C). Accuracy of stepping was measured pre- and post-intervention as participants walked along an irregularly arranged stepping walkway. Participants attended a one-hour session, once a week, for sixteen weeks, involving high-load resistance exercise and visual-motor training.

RESULTS

Patients who took part in the intervention improved stepping accuracy (DPN: +45%; D: +36%) (p < 0.05). The diabetic non-intervention (D-NI) group did not display any significant differences in stepping accuracy pre- to post- the intervention period (-7%).

DISCUSSION

The improved stepping accuracy observed in patients with diabetes and DPN as a result of this novel intervention, may contribute towards reducing falls-risk. This multi-faceted intervention presents promise for improving the general mobility and safety of patients during walking and could be considered for inclusion as part of clinical treatment programmes.

Altered Achilles tendon function during walking in people with diabetic neuropathy: implications for metabolic energy saving

The Achilles tendon (AT) has the capacity to store and release elastic energy during walking, contributing to metabolic energy savings. In diabetes patients, it is hypothesized that a stiffer Achilles tendon may reduce the capacity for energy saving through this mechanism, thereby contributing to an increased metabolic cost of walking (CoW). The aim of this study was to investigate the effects of diabetes and diabetic peripheral neuropathy (DPN) on the Achilles tendon and plantarflexor muscle-tendon unit behavior during walking. Twenty-three nondiabetic controls (Ctrl); 20 diabetic patients without peripheral neuropathy (DM), and 13 patients with moderate/severe DPN underwent gait analysis using a motion analysis system, force plates, and ultrasound measurements of the gastrocnemius muscle, using a muscle model to determine Achilles tendon and muscle-tendon length changes. During walking, the DM and particularly the DPN group displayed significantly less Achilles tendon elongation (Ctrl: 1.81; DM: 1.66; and DPN: 1.54 cm), higher tendon stiffness (Ctrl: 210; DM: 231; and DPN: 240 N/mm), and higher tendon hysteresis (Ctrl: 18; DM: 21; and DPN: 24%) compared with controls. The muscle fascicles of the gastrocnemius underwent very small length changes in all groups during walking (~0.43 cm), with the smallest length changes in the DPN group. Achilles tendon forces were significantly lower in the diabetes groups compared with controls (Ctrl: 2666; DM: 2609; and DPN: 2150 N). The results strongly point toward the reduced energy saving capacity of the Achilles tendon during walking in diabetes patients as an important factor contributing to the increased metabolic CoW in these patients. NEW & NOTEWORTHY From measurements taken during walking we observed that the Achilles tendon in people with diabetes and particularly people with diabetic peripheral neuropathy was stiffer, was less elongated, and was subject to lower forces compared with controls without diabetes. These altered properties of the Achilles tendon in people with diabetes reduce the tendon's energy saving capacity and contribute toward the higher metabolic energy cost of walking in these patients.