Accuracy of Clinical Techniques for Evaluating Lower Limb Sensorimotor Functions Associated With Increased Fall Risk

Identification of Optimal Foot Tactile Sensation Threshold for Detecting Fall Risk Among Community-Dwelling Older Adults

OBJECTIVE

Foot tactile sensitivity loss, commonly assessed by monofilaments, is a fall risk factor among older adults. The broadly used threshold of the monofilament for fall risk assessment in older adults is 5.07. However, this threshold originates from assessing foot ulceration risk in people with peripheral neuropathy. The primary purpose of this study was to identify the optimal filament size and its cutoff number of sensitive sites that can be used to best identify a high risk of falls in terms of the foot tactile sensitivity for community-dwelling older adults.

METHODS

In this cross-sectional study, the foot tactile sensitivity was assessed by a 6-piece Semmes-Weinstein monofilament kit at 9 sites per foot among 94 older adults, including 38 fallers and 56 nonfallers. The number of sensitive sites was determined for each monofilament size as the cutoff. Logistical regression analyses were used to determine the monofilament size and number of sensitive sites best able to differentiate fallers from nonfallers.

RESULTS

Fallers showed overall worse foot tactile sensory measurements than nonfallers. Logistical regression analyses identified 4.31 as the best monofilament size and 7 as the number of sensitive sites to differentiate fallers from nonfallers with an accuracy of 71.3%.

CONCLUSION

The 4.31 monofilament could be the best filament to detect the risk of falls among older adults in terms of tactile sensory loss. Inability to feel the pressure from the 4.31 filament at more than 7 sites could indicate a high risk of falls.

IMPACT

These findings could help physical therapists and other rehabilitation professionals improve decision making in detecting older adults with a high risk of falls, thus facilitating the effort of fall prevention in older adults.

Extensor digitorum brevis bulk and associations with fibular motor nerve conduction amplitude

INTRODUCTION

Prior work demonstrates that fibular compound motor action potential (CMAP) amplitude <4.0 mV predicts impairment of ankle proprioceptive precision and increased fall risk. Extensor digitorum brevis (EDB) inspection may present a simple clinical surrogate for CMAP amplitude.

OBJECTIVE

(1) To estimate the inter-rater reliability of assessment of EDB bulk. (2) To determine whether inspection of EDB bulk is associated with fibular CMAP amplitude.

DESIGN

Prospective inter-raterreliability study.

SETTING

Academic center outpatient Physical Medicine & Rehabilitation electromyography (EMG) clinics.

PARTICIPANTS

Fifty-two adult participants (102 feet).

MAIN OUTCOME MEASURES

(1) Inter-rater reliability of assessment of EDB bulk. (2) Mean fibular CMAP amplitude. (3) A binary measure of fibular CMAP amplitude at/above or below a 4.0 mV threshold.

RESULTS

Inter-rater reliability of EDB bulk grading was moderate (kappa: 0.65 [95% confidence interval (CI) 0.48-0.82]). The mean CMAP value was 5.9 ± 2.2 mV when bulk was normal, 3.4 ± 2.1 mV when diminished, and 0.6 ± 0.9 mV when atrophied. A multivariable analysis demonstrated that EDB bulk, distal symmetric polyneuropathy (DSP), and lumbar radiculopathy were all associated with CMAP amplitude. The sensitivity and specificity of grading muscle bulk as normal versus abnormal in detecting CMAP amplitude above or below 4.0 mV were 0.86 (95% CI 0.78-0.94) and 0.71 (95% CI 0.54-0.88), respectively. An atrophied EDB was a highly specific indicator that CMAP amplitude was abnormal (<4.0 mV) in 100% of cases (8/8).

CONCLUSIONS

EDB bulk was associated with fibular CMAP amplitude. Atrophy was a highly specific indicator for CMAP amplitude below 4.0 mV. Evaluation of EDB bulk may represent a quick and easy clinical surrogate marker for CMAP amplitude and distal neuromuscular impairment.

Neurocognitive and Muscular Capacities Are Associated with Frailty in Adults with Cirrhosis

BACKGROUND

Frailty is common in cirrhosis and associated with mortality, hospitalization, and reduced quality of life. Interventions aimed at forestalling frailty are limited by a lack of understanding of underlying physiologic deficits.

AIMS

This study's aim was to examine contributions of discrete sensorimotor and neurocognitive capacities to conventional frailty measures of unipedal stance time, chair stands, and grip strength.

METHODS

This cross-sectional study enrolled 119 outpatients with cirrhosis (50% female, aged 62.9 ± 7.3 years). Capacities included sensory (lower limb sensation and visual contrast), neurocognitive (Number Connection Tests A and B, simple and recognition reaction time), and muscular (hip/core strength determined by lateral plank time (LPT)). Bivariate analyses and linear regression models were performed to identify significant contributors to each frailty measure.

RESULTS

The average performance was 9.8 ± 3.9 chair stands, 12.7 s ±9.9 unipedal stance time, and 60.3 ± 25.6 lb grip strength. In multivariate models, factors explained 40% of variance in unipedal stance and 43% of variance in chair stands. The LPT was most strongly associated with unipedal stance and chair stands. Grip strength was associated with LPT, but did not have physiologic predictors.

CONCLUSIONS

Clinically useful measures of frailty in adults with cirrhosis can be explained by disease severity but also deficits in strength and neurocognitive function. Recognition reaction time, a novel measure in cirrhosis, had a significant contribution to frailty. These findings have implications for frailty assessment and suggest that the optimal rehabilitation approach to frailty targets neurocognitive function in addition to strengthening.

Why Do Individuals with Cirrhosis Fall? A Mechanistic Model for Fall Assessment, Treatment, and Research

Falls are prevalent for people with cirrhosis and commonly lead to loss of independence, reduced quality of life, and mortality. Despite a critical need for fall prevention in this population, cirrhosis-specific fall-related mechanisms are not well understood. We posit that most falls in this patient population are due to a coalescence of discrete subclinical impairments that are not typically detected at the point of care. The combined effect of these subtle age- and disease-related neurocognitive and muscular impairments leads to the inability to respond successfully to a postural perturbation within the available 300 to 400 ms. This article provides a conceptual model of physiological resilience to avoid a fall that focuses on attributes that underlie the ability to withstand a postural perturbation and their clinical evaluation. Evidence supporting this model in cirrhosis and other high fall risk conditions will be synthesized and suggestions for fall assessment and treatment will be discussed.

Value-Added Electrodiagnostics: Targeting Interventions for Fall Risk Reduction

Walking confers numerous health benefits, particularly for middle-aged and older patients with diabetes and metabolic syndrome. Nevertheless, it brings a risk of injurious falls, especially among populations with diabetes and metabolic syndrome-related distal neuromuscular decline and frank neuropathy. Those who stand to benefit most from walking are at greatest risk. Development of practical clinical tools to more precisely quantify neuromuscular function and link it to mobility outcomes will help clinicians target interventions toward those at risk for falls. Electrodiagnosis, with inclusion of several newer techniques, serves as a promising tool for objective evaluation of distal neuromuscular function.

The reactive leg drop: a simple and novel sensory-motor assessment to predict fall risk in older individuals

There is need for a functional ability test that appropriately assesses the rapid integration of the sensory and motor systems required for older adults to recover from a slip. The purpose of this study was to assess the efficacy and reliability of a novel test, the reactive leg drop, for assessing sensory-motor function in older adults. Fourteen young (YW; mean age = 20 yr) and 11 older women (OW; mean age = 76 yr) participated in this study. For each drop, the leg was passively moved to full extension and then released. The subjects had to recognize their leg was free-falling and reactively kick up as quickly as possible during varying sensory conditions. To assess the leg drop's reliance on proprioception, other proprioceptive tests (e.g., patellar tendon reflexes and balance) were separately performed. Leg drops performed with the eyes closed ( P = 0.011) and with a blocked view of the leg ( P = 0.033) showed significant differences in drop angle between YW and OW. Significant relationships between leg drop conditions and balance were observed in OW that were not present within YW. When collapsed across groups, reflex latency was correlated with drop angle when the eyes were closed. The reactive leg drop was age sensitive, reliable, and likely reliant on proprioception, as shown by relationships to other sensory-motor assessments, such as balance and the patellar reflex. Although more research is needed, we propose that the reactive leg drop is an effective tool to assess sensory-motor integration in a manner that may mimic fall recovery. NEW & NOTEWORTHY The reactive leg drop was age sensitive and was significantly related to other sensory-motor assessments. The ability to accurately assess sensory-motor integration may aid clinicians, practitioners, and researchers in developing new interventions. The reactive leg drop presented in the current study is a potentially effective tool to assess sensory and motor integration in a manner that may mimic fall recovery.

Complex and Simple Clinical Reaction Times Are Associated with Gait, Balance, and Major Fall Injury in Older Subjects with Diabetic Peripheral Neuropathy

OBJECTIVE

The aim of this work was to identify relationships between complex and simple clinical measures of reaction time (RTclin) and indicators of balance in older subjects with and without diabetic peripheral neuropathy (DPN).

DESIGN

Prospective cohort design. Complex RTclin accuracy, simple RTclin latency, and their ratio were determined using a novel device in 42 subjects (mean ± SD age, 69.1 ± 8.3 yrs), 26 with DPN and 16 without. Dependent variables included unipedal stance time (UST), step width variability and range on an uneven surface, and major fall-related injury over 12 months.

RESULTS

In the DPN subjects, the ratio of complex RTclin accuracy to simple RTclin latency was strongly associated with longer UST (R/P = 0.653/0.004), and decreased step width variability and range (R/P = -0.696/0.001 and -0.782/<0.001, respectively) on an uneven surface. Additionally, the 2 DPN subjects sustaining major injuries had lower complex RTclin accuracy:simple RTclin latency than those without.

CONCLUSIONS

The ratio of complex RTclin accuracy:simple RTclin latency is a potent predictor of UST and frontal plane gait variability in response to perturbations and may predict major fall injury in older subjects with DPN. These short latency neurocognitive measures may compensate for lower limb neuromuscular impairments and provide a more comprehensive understanding of balance and fall risk.