H-index is important for postural control for people with impaired foot sole sensation

The effect of loss of foot sole sensitivity on H-reflex of triceps surae muscles and functional gait

Objective: To investigate the effects of foot sole insensitivity on the outcomes of the triceps surae muscle H-reflex and functional gait. Material and Methods: People with peripheral neuropathy were recruited and divided into two groups: people with more (n = 13, 73.3 ± 4.3 years old) or less (n = 10, 73.5 ± 5.3) sensitive tactile sensation. Their monofilament testing scores were 9.0 ± 1.5 (range: 7-10) and 2.3 ± 2.4 (range: 0-6) out of 10, respectively. H-reflex of the triceps surae muscles during quiet standing and their relationship with functional gait, 6 min walking distance (6MWD), and timed-up-and-go duration (TUG), were compared between groups. Results: No significant difference was detected for H-reflex parameters between the groups. The less sensitive group showed reduced (p < .05) functional gait capacity compared to the other group, 38.4 ± 52.7 vs. 463.5 ± 47.6 m for 6MWD, and 9.0 ± 1.5 vs. 7.2 ± 1.1s for TUG, respectively. A significant correlation (p < .05), worse functional gait related to greater H/M ratio, was observed in the less sensitive group, not the other group. Conclusion: Although there was no significant H-reflex difference between the groups, more pronounced tactile sensation degeneration affected functional gaits and their relationship with H-reflex.

The Impact of Hoffmann Reflex on Standing Postural Control Complexity in the Elderly with Impaired Plantar Sensation

In people with peripheral neuropathy (PN), impaired plantar sensation can cause adaptive changes in the central nervous system (CNS), resulting in changes in the standing postural control, which is reflected in the variability of standing output signals. Standard deviation (SD) and entropy are reliable indicators of system variability, especially since entropy is highly sensitive to diseased populations. The relation between SD and entropy, CNS and center of pressure (COP) variability is unclear for people with severe PN. The purpose of this study was to explore the adaptability of the CNS to the severe of PN and its effect on the degree and complexity of COP variability. Here, people with PN were divided into less affected (LA) and more affected (MA) groups based on plantar pressure sensitivity. We studied Hoffmann reflex (H-reflex) and standing balance performance with the control group (n = 8), LA group (n = 10), and MA group (n = 9), recording a 30 s COP time series (30,000 samples) of double-leg standing with eyes open. We observed that the more affected group had less COP complexity than people without PN. There is a significant negative correlation between the SD and sample entropy in people without PN, less affected and more affected. The COP complexity in people without PN was inversely correlated with H-reflex. We concluded that: (1) The complexity of COP variability in patients with severe plantar sensory impairment is changed, which will not affect the degree of COP variability; (2) The independence of the COP entropy in the AP and ML directions decreased, and the interdependence increased in people with PN; (3) Although the CNS of people with PN has a greater contribution to standing balance, its modulation of standing postural control is decreased.

Conduction Velocity of Spinal Reflex in Patients with Acute Lateral Ankle Sprain

Recent literature has highlighted altered spinal-reflex excitability following acute lateral ankle sprain (ALAS), yet there is little information on the conduction velocity of spinal reflex pathways (CV-SRP) in these patients. Therefore, we aimed to investigate the effects of ALAS on the CV-SRP. We employed a cross-sectional study with two groups: ALAS (n = 30) and healthy controls (n = 30). The CV-SRP of the soleus, fibularis longus, and tibialis anterior was assessed using the H-index method. As secondary outcomes, H-reflex and M-wave latencies were assessed as well as acute symptoms including ankle swelling, pain, and self-reported ankle function. Separate group-by-limb ANOVA with repeated measures revealed a significant interaction for soleus CV-SRP (p < 0.001) and H-reflex latency (p < 0.001), showing significant slower CV-SRP and longer H-reflex latency in the involved limb of the ALAS group compared with both limbs in the control group. However, there was no significant interaction or main effect in any other ankle muscles (p > 0.05). A further correlation analysis showed a significant relationship between CV-SRP and acute symptoms, including ankle swelling (r = −0.37, p = 0.048) and self-reported ankle function (r = 0.44, p = 0.017) in ALAS patients. These results suggest a disrupted functionality of the afferent pathway and/or synaptic transmission following ALAS. Level of Evidence: 4.

Exploring the effects of peripheral sensibility on visuospatial and postural capacities during goal-directed movements in long-term Tai Chi practitioners

Background

Falls are directly related to visuospatial ability and postural stability. Perturbations of upper body movements pose a challenge to older adults and may cause falls. This study investigated visuospatial ability and postural stability during goal-directed upper body movements between the Tai Chi and control groups and tried to connect them with their sensations.

Materials and methods

Thirty-seven older adults were recruited to perform the touch (TT) and blind touch (BTT) tasks. The target positioning error (TPE), ankle proprioception, tactile sensation, time to stabilization (TTS), and maximum displacement (D_max) of the center of pressure trajectory were compared between the groups during the tasks. The relationships of visuospatial ability and postural stability to proprioception and tactile sensation were investigated.

Results

D_max in the mediolateral (D_maxML) direction decreased during BTT compared to TT among the Tai Chi group but not the control group. Compared to the control group, less D_max in the anterio-posterior (D_maxAP) direction, and shorter TTS in AP/ML (TTS_AP/TTS_ML) directions were observed among the Tai Chi group. Compared to TT, D_maxAP decreased during the BTT. The Tai Chi group had less TPE in the vertical (TPE_V) direction and in three-dimensional space. Among the Tai Chi group, TPE_V, TTS_ML, and D_maxAP were correlated to their proprioception during plantarflexion; TTS_AP was correlated to tactile sensation at the great toe during the TT and BTT; D_maxAP was correlated to tactile sensation at the great toe during the TT. Among the control group, TTS_ML was correlated to ankle proprioception during dorsiflexion and plantarflexion during the BTT.

Conclusion

Long-term Tai Chi practitioners exhibited superior visuospatial ability and postural stability during goal-directed upper body movements, which was associated with sensitive proprioception and tactile sensation.

The Reduced Adaptability of H-Reflex Parameters to Postural Change With Deficiency of Foot Plantar Sensitivity

Purpose: The project was to examine the influence of peripheral neuropathy (PN) severity on the relationship between Hoffmann-reflex (H-reflex) and postures.

Methods: A total of 34 participants were recruited. H-reflex (H/M ratio and H-index) during prone, standing, and the heel-contact phase of walking was tested, along with foot sole sensitivity.

Results: The participants were divided into three groups based on the severity of the foot sole sensitivity deficit: control, less (LA), and more (MA) affected with both feet 5.07 monofilament test scores ranging 10, 0–5, and 6–9, respectively. A significant group by the posture interaction was observed in the H/M ratio (F_{3.0, 41.9} = 2.904, p = 0.046, η_p² = 0.172). In the control group, the H/M ratio of prone (22 ± 7%) was greater than that of the standing (13 ± 3%, p = 0.013) and heel-contact phase (10 ± 2%, p = 0.004). In the MA group, the H/M ratio of standing (13 ± 3%) was greater than that of the heel-contact phase (8 ± 2%, p = 0.011). The H-index was significantly different among groups (F_2,28 = 5.711, p = 0.008, and η_p²= 0.290). Post hoc analysis showed that the H-index of the control group (80.6 ± 11.3) was greater than that of the LA (69.8 ± 12.1, p = 0.021) and MA groups (62.0 ± 10.6, p = 0.003).

Conclusion: In a non-PN population, the plantar sensory input plays an important role in maintaining standing postural control, while as for the PN population with foot sole sensitivity deficiency, type Ⅰ afferent fibers reflex loop (H-reflex) contributes more to the standing postural control. The H-index parameter is an excellent method to recognize the people with and without PN but not to distinguish the severity of PN with impaired foot sole sensitivity.

Relationship between Muscular Activity and Postural Control Changes after Proprioceptive Focal Stimulation (Equistasi®) in Middle-Moderate Parkinson's Disease Patients: An Explorative Study

The aim of this study was to investigate the effects of Equistasi^®, a wearable device, on the relationship between muscular activity and postural control changes in a sample of 25 Parkinson’s disease (PD) subjects. Gait analysis was carried out through a six-cameras stereophotogrammetric system synchronized with two force plates, an eight-channel surface electromyographic system, recording the activity of four muscles bilaterally: Rectus femoris, tibialis anterior (TA), biceps femoris, and gastrocnemius lateralis (GL). The peak of the envelope (PoE) and its occurrence within the gait cycle (position of the peak of the envelope, PPoE) were calculated. Frequency-domain posturographic parameters were extracted while standing still on a force plate in eyes open and closed conditions for 60 s. After the treatment with Equistasi^®, the mid-low (0.5–0.75) Hz and mid-high (0.75–1 Hz) components associated with the vestibular and somatosensory systems, PoE and PPoE, displayed a shift toward the values registered on the controls. Furthermore, a correlation was found between changes in proprioception (power spectrum frequencies during the Romberg Test) and the activity of GL, BF (PoE), and TA (PPoE). Results of this study could provide a quantitative estimation of the effects of a neurorehabilitation device on the peripheral and central nervous system in PD.

Effectiveness of Active Therapy-Based Training to Improve the Balance in Patients with Fibromyalgia: A Systematic Review with Meta-Analysis

Balance impairment is a frequent disorder in patients with fibromyalgia (FMS), increasing the risk of falls and decreasing physical function and quality of life. In recent years, the use of active therapy-based training (ATBT) has increased, with the aim of improving balance in women with FMS. Our study aimed to assess the effect of ATBT to improve different balance outcomes in subjects with FMS. A systematic review with meta-analysis was carried out. We searched PubMed Medline, SCOPUS, Web of Science, CINAHL, and PEDro (Physiotherapy Evidence Database) databases up to September 2020. We included randomized controlled trials (RCT) that assessed the balance in patients with FMS after ATBT and compared to other treatments or no intervention. In a random-effects model, the standardized mean difference (SMD) was used to calculate the effect size. Ten studies were included in the review providing data from 546 FMS patients with a mean age of 52.41 ± 2.90 years old (98% females). Our results showed a medium effect favors ATBT with respect to other therapies for monopedal static balance (SMD = 0.571; 95% CI = 0.305, 0.836; p < 0.001), dynamic balance (SMD = 0.618; 95% CI = 0.348, 0.888; p < 0.001), and functional balance (SMD = 0.409; 95% CI = 0.044, 0.774; p = 0.028). No statistically significant differences were found for balance on unstable support. The present meta-analysis showed moderate-quality evidence of a medium effect of ATBT to improve dynamic and functional balance and low-quality evidence of a medium effect to improve monopedal static balance with respect to other therapies or no intervention.

The contribution of small and large sensory afferents to postural control in patients with peripheral neuropathy

Peripheral neuropathy (PN) is a multifarious disorder that is caused by damage to the peripheral nerves. Although the symptoms of PN vary with the etiology, most cases are characterized by impaired tactile and proprioceptive sensation that progresses in a distal to proximal manner. Balance also tends to deteriorate as the disorder becomes more severe, and those afflicted are substantially more likely to fall while walking compared with those who are healthy. Most patients with PN walk more cautiously and with greater stride variability than age-matched controls, but the majority of their falls occur when they must react to a perturbation such as a slippery or uneven surface. The purpose of this study was to first describe the role of somatosensory feedback in the control of posture and then discuss how that relationship is typically affected by the most common types of PN. A comprehensive review of the scientific literature was conducted using MEDLINE, and the relevant information was synthesized. The evidence indicates that the proprioceptive feedback that is conveyed primarily through larger type I afferents is important for postural control. However, the evidence indicates that the tactile feedback communicated through smaller type II afferents is particularly critical to the maintenance of balance. Many forms of PN often lead to chronic tactile desensitization in the soles of the feet and, although the central nervous system seems to adapt to this smaller type II afferent dysfunction by relying on more larger type I afferent reflex loops, the result is still decreased stability. We propose a model that is intended both to help explain the relationship between stability and the smaller type II afferent and the larger type I afferent feedback that may be impaired by PN and to assist in the development of pertinent rehabilitative interventions.

Global methaemoglobinaemia research output (1940-2013): a bibliometric analysis

Bibliometric studies, which involve the use of statistical methods, are increasingly being used for research assessment. A bibliometric analysis was conducted to evaluate the publication pattern of methaemoglobinaemia research output at the global level based on the Scopus database. We analysed selected documents with "methemoglobinemia", or "methaemoglobinaemia" as a part of the title and reported the following parameters: trends of publication output, country of publication, journal pattern, collaborative measures, citations pattern, and institute productivity. A total of 1770 articles were published worldwide. The time trend for the number of articles showed an increase after 2000. The highest number of articles related to methaemoglobinaemia was from the USA (24.8 %), followed distantly by the UK (4.5 %), India (3.7 %), and France (3.7 %). No data related to methaemoglobinaemia were published from 152 countries. The total number of citations at the date of data collection was 10,080, with an average of 5.7 citations per document. The USA and UK had the highest h-index of 31 and 14, respectively, and six countries had an h-index of 9-14. It is notable that Canada was ranked eighth in the number of publications but fourth in h-index and India was ranked third in the number of publications but eighth in h-index. Furthermore, Canada produced the most internationally collaborated papers out of the total number of publications for each country (16.1 %), followed by the UK (13.9 %). This bibliometric analysis provides data contributing to a better understanding of the methaemoglobinaemia research field. The number of publications on methaemoglobinaemia increased significantly after 2000. The USA was the most productive country as measured by total publications. The USA and UK achieved the highest h-index in the field of methaemoglobinaemia research, signifying a higher quality of research than other countries.

Postural Steadiness and Ankle Force Variability in Peripheral Neuropathy

INTRODUCTION

The purpose was to determine the effect of peripheral neuropathy (PN) on motor output variability for ankle muscles of older adults, and the relation between ankle motor variability and postural stability in PN patients.

METHODS

Older adults with (O-PN) and without PN (O), and young adults (Y) underwent assessment of standing postural stability and ankle muscle force steadiness.

RESULTS

O-PN displayed impaired ankle muscle force control and postural stability compared with O and Y groups. For O-PN, the amplitude of plantarflexor force fluctuations was moderately correlated with postural stability under no-vision conditions (r = .54, p = .01).

DISCUSSION

The correlation of variations in ankle force with postural stability in PN suggests a contribution of ankle muscle dyscontrol to the postural instability that impacts physical function for older adults with PN.