Diminished plantar cutaneous sensation and postural control

Acupuncture for the treatment of diabetic peripheral neuropathy in the elderly: a systematic review and meta-analysis

Background

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus, often causing pain or numbness in the patient's limbs and even leading to amputation and death. Elderly patients with DPN usually have higher morbidity and more severe results. Acupuncture has been widely used as an effective treatment for DPN in China. However, the efficacy of acupuncture in the treatment of DPN remains unclear. In this review, we aimed to explore the impact of acupuncture in alleviating symptoms of DPN.

Method and analysis

Six databases were searched from inception to October 2023. We searched Medline, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and three Chinese databases, namely China National Knowledge Infrastructure (CNKI), SinoMed, and Wanfang. All randomized controlled trials related to the effect of acupuncture on DPN will be included. There was no restriction in language or publication year. The primary outcome is the response rate. The secondary outcomes are the Toronto clinical scoring system (TCSS), nerve conduction velocities (NCVs), and blood glucose before and after the treatment. Two researchers will be responsible for the selection of study, data extraction, and assessment of study quality independently. RevMan V5.1.0 software will be used to assess the risk of bias and generate data.

Results

We searched 4518 studies, among which 9 RCTs were considered eligible. Overall, acupuncture treatment had a higher response rate than controls (relative risk (RR), -2.87 [95% confidence interval (CI), -5.27 to -0.48], p = 0.02) and significantly alleviated the symptoms of DPN patients, reduced their blood glucose levels, and improved their NCVs compared to the control group. This study will provide a high-quality synthesis of current available evidence for the clinical treatment of DPN with this therapy.

Conclusion

The results suggested that acupuncture might be effective in improving symptoms of DPN in elderly patients. Owing to the overall low quality of the literature included, we need more large-sample, high-quality, and low-bias studies to prove it.

The effect of foot somatosensory loss in postural control during Functional reach test in patients with diabetic polyneuropathy: A controlled study

BACKGROUND

In patients with diabetic polyneuropathy (DPN), differences in postural control due to losing the lower limb somatosensory information were reported. However, it is still unclear by which mechanisms the dynamic postural instability is caused.

OBJECTIVES

This study aimed to investigate postural control differences and neuromuscular adaptations resulting from foot somatosensory loss due to DPN.

METHODS

In this controlled cross-sectional study, fourteen DPN patients and fourteen healthy controls performed the Functional Reach Test (FRT) as a dynamic task. The postural control metrics were simultaneously measured using force plate, motion capture system, and surface electromyography (sEMG). The main metrics including reach length (FR), FR to height ratio (FR/H), displacement of CoM and CoP, moment arm (MA), and arch height ratio. Also, kinematic (range of motion of ankle, knee, and hip joints), and sEMG metrics (latencies and root mean square amplitudes of ankle and hallux muscles) were measured. To compare variables between groups, the independent sample T-test for (normally distributed) and the Mann-Whitney U test (non-normally distributed) were used.

RESULTS

The subjects' reach length (FR), FR to height ratio, absolute MA, and displacement of CoM were significantly shorter than controls, while displacement of CoP was not significant. Arch height ratio was found significantly lower in DPN patients. We observed that CoM was lagging CoP in patients (MA = + 0.89) while leading in controls (MA = -1.60). Although, the muscles of patients showed significantly earlier activation, root mean square sEMG amplitudes were found similar. Also, DPN patients showed significantly less hip flexion, knee extension, and ankle plantar flexion.

CONCLUSIONS

This study presented that decreasing range of motion at lower limbs' joints and deterioration in foot function caused poor performance at motor execution during FRT in DPN patients.

The topographical attenuation of cutaneous input is modulated at the ankle joint during gait

The attenuation of sensory inputs via various methods has been demonstrated to impair balance control and alter locomotor behavior during human walking; however, the effects of attenuating foot sole sensation under distinct areas of the foot sole on lower extremity motor output remains poorly understood. Thus, the purpose of this study was to attenuate cutaneous feedback via regional hypothermia under five different areas of the foot sole and investigate the resultant modulation of kinematic and muscle activity during level walking. Electromyography from eight lower leg muscles, kinematics, and location of center of pressure was recorded from 48 healthy young adults completing walking trials with normal and reduced cutaneous sensation from bilateral foot soles. The results of this study highlight the modulatory response of the tibialis anterior in terminal stance (propulsion and toe-off) and medial gastrocnemius muscle throughout the entire stance phase of gait. The topographical organization of foot sole skin in response to the attenuation of cutaneous feedback from different areas of the foot sole significantly modified locomotor activity. Furthermore, the locomotor response to cutaneous attenuation under the same regions that we previously facilitated with tactile feedback do not oppose each other, suggesting different physiological changes to foot sole skin generate unique gait behaviors.

Does Impaired Plantar Cutaneous Vibration Perception Contribute to Axial Motor Symptoms in Parkinson's Disease? Effects of Medication and Subthalamic Nucleus Deep Brain Stimulation

OBJECTIVE

To investigate whether impaired plantar cutaneous vibration perception contributes to axial motor symptoms in Parkinson's disease (PD) and whether anti-parkinsonian medication and subthalamic nucleus deep brain stimulation (STN-DBS) show different effects.

METHODS

Three groups were evaluated: PD patients in the medication "on" state (PD-MED), PD patients in the medication "on" state and additionally "on" STN-DBS (PD-MED-DBS), as well as healthy subjects (HS) as reference. Motor performance was analyzed using a pressure distribution platform. Plantar cutaneous vibration perception thresholds (VPT) were investigated using a customized vibration exciter at 30 Hz.

RESULTS

Motor performance of PD-MED and PD-MED-DBS was characterized by greater postural sway, smaller limits of stability ranges, and slower gait due to shorter strides, fewer steps per minute, and broader stride widths compared to HS. Comparing patient groups, PD-MED-DBS showed better overall motor performance than PD-MED, particularly for the functional limits of stability and gait. VPTs were significantly higher for PD-MED compared to those of HS, which suggests impaired plantar cutaneous vibration perception in PD. However, PD-MED-DBS showed less impaired cutaneous vibration perception than PD-MED.

CONCLUSIONS

PD patients suffer from poor motor performance compared to healthy subjects. Anti-parkinsonian medication in tandem with STN-DBS seems to be superior for normalizing axial motor symptoms compared to medication alone. Plantar cutaneous vibration perception is impaired in PD patients, whereas anti-parkinsonian medication together with STN-DBS is superior for normalizing tactile cutaneous perception compared to medication alone. Consequently, based on our results and the findings of the literature, impaired plantar cutaneous vibration perception might contribute to axial motor symptoms in PD.

Effects of a Single Electrical Stimulation Session on Foot Force Production, Foot Dome Stability, and Dynamic Postural Control

CONTEXT

Mounting evidence suggests neuromuscular electrical stimulation (NMES) as a promising modality for enhancing lower limb muscle strength, yet the functional effects of a single electrical stimulation session for improving the function of the intrinsic foot muscles (IFM) has not been evaluated.

OBJECTIVE

To investigate the immediate effects of an NMES session compared with a sham stimulation session on foot force production, foot dome stability, and dynamic postural control in participants with static foot pronation.

DESIGN

Randomized controlled clinical trial.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 46 participants (23 males, 23 females) with static foot pronation according to their Foot Posture Index (score ≥ 6) were randomly assigned to an NMES (n = 23) or control (n = 23) group.

INTERVENTION(S)

The NMES group received a single 15-minute NMES session on the dominant foot across the IFM. The control group received a 15-minute sham electrical stimulation session.

MAIN OUTCOME MEASURE(S)

All outcome measurements were assessed before and after the intervention and consisted of foot force production on a pressure platform, foot dome stability, and dynamic postural control. Statistical analysis was based on the responsiveness of the outcome measures and responder analysis using the minimum detectable change scores for each outcome measure.

RESULTS

In the NMES group, 78% of participants were classified as responders for at least 2 of the 3 outcomes, compared with only 22% in the control group. The relative risk of being a responder in the NMES group compared with the control group was 3.6 (95% CI = 1.6, 8.1]. Interestingly, we found that all participants who concomitantly responded to foot strength and navicular drop (n = 8) were also responders in dynamic postural control.

CONCLUSIONS

Compared with a sham stimulation session, a single NMES session was effective in immediately improving foot function and dynamic postural control in participants with static foot pronation. These findings support the role of NMES for improving IFM function in this population.

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.

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.

The relationship between plantar sensation and muscle onset during automatic postural responses in people with multiple sclerosis and healthy controls

BACKGROUND

Plantar sensation is critical for balance control in people with multiple sclerosis (PwMS). While previous research has described its impact on standing balance, the influence of plantar sensation during automatic postural responses (APRs) is not well understood in PwMS. The purpose of this study was to characterize the relationship between plantar sensation and APRs in PwMS and controls. A secondary aim was to determine whether the relationship between plantar sensation and APRs is different across PwMS and control groups.

METHODS

122 PwMS and 48 age-matched controls underwent forward and backward support-surface perturbations from stance. The onset of the tibialis anterior (TA) and medial gastrocnemius (MG) were the primary reactive balance outcome measures for backward and forward losses of balance, respectively. Plantar sensation was measured as the vibration sensation threshold (VT).

RESULTS

As expected, PwMS had significantly higher (i.e., worse) VT (p<0.001) and an increased MG and TA onset latency (TA: p<0.001, MG: p = 0.01) compared to the control group. A higher VT was related to increased MG (p<0.001) and TA latency (p<0.001) across all participants. However, no moderating effect of group (control or PwMS) was observed for the relationship between VT and muscle onset (MG: p = 0.14; TA: p = 0.34).

CONCLUSION

PwMS demonstrated poorer plantar sensation and delayed muscle onset during APRs compared to controls. Plantar sensation was also related to muscle onset after perturbations in all participants. Although this relationship was not moderated by group, this may be related to the lack of dynamic range of VT scores in controls. These results indicate that plantar sensation may be related to reactive balance and provides insight into a potential contributing factor of delayed automatic postural responses in people with MS.

Effects of offloading devices on static and dynamic balance in patients with diabetic peripheral neuropathy: A systematic review

Patients with diabetic peripheral neuropathy (DPN) usually have reduced somatosensory information and altered perception in feet and ankles. Somatosensory information acts as feedback for movement control and loss of somatosensation leads to altered plantar pressure patterns during gait and stance. Offloading devices are used to reduce peak plantar pressure and prevent diabetic foot ulcers. However, offloading devices can unfortunately have negative effects on static and dynamic balance. It is important to investigate these unwanted effects, since patient with DPN already are at high risk of falling and offloading devices could potentially increase this risk. The aim of this systematic review is to investigate the effects of plantar offloading devices used for ulcer prevention on their role in static and dynamic balance control in patients with DPN. PubMed and Embase were systematically searched using relevant search terms. After title selection, abstract selection, and full-text selection only five articles could be included for further analysis. Two articles included static balance measurements, two articles included dynamic balance measurements, and one article included both. Results suggested that static balance control is reduced when rocker bottom shoes and different insole configurations are used, however, toe-only rockers showed less evidence for reduced static balance control. There was no evidence for reduced dynamic balance control in combination with offloading devices. However, these results should be interpreted with care, since the number of studies was very small and the quality of the studies was moderate. Future research should evaluate balance in combination with different offloading devices, so that clinicians subscribing them are more aware of their potential unwanted consequences.

Comparison of the Intrinsic Foot Muscle Activities between Therapeutic and Three-Dimensional Foot-Ankle Exercises in Healthy Adults: An Explanatory Study

Background: In recent years, a three-dimensional ankle exercise has been proposed as a practice for strengthening the intrinsic foot muscles, however this topic still requires further research. This study aimed to compare the activities of the intrinsic muscles in healthy participants during 3D foot–ankle exercises, namely, short foot (SF), and toe spread out (TSO). Methods: Prior to the experiment, 16 healthy adults were trained on how to perform SF, TSO, and 3D foot–ankle exercises for an hour. Once all participants passed the foot–ankle exercise performance test, we randomly measured the activity of the intrinsic foot muscles using electromyography while the patients were performing foot–ankle exercises. Results: The abductor hallucis (AbH), extensor hallucis longus (EHL), and flexor hallucis brevis (FHB) activities showed significant differences among the exercises for intrinsic foot muscle strengthening (p < 0.01). Additionally, the AbH/AdH (adductor hallucis) ratio showed significant differences among the exercises for strengthening the intrinsic foot muscles (p < 0.01). Conclusions: Our results showed that the 3D extension exercise is as effective as the therapeutic exercise in terms of the AbH and FHB activities, and the AbH/AdH ratio. On the contrary, the 3D flexion exercise showed superiority in terms of the EHL activity.

Comparison of Postural Sway, Plantar Cutaneous Sensation According to Saccadic Eye Movement Frequency in Young Adults

The crossover trial study aimed to identify the saccadic eye movement (SEM) frequency to improve postural sway (PS) and plantar cutaneous sensation (PUS) in young adults. The 17 participants randomly performed 0.5-, 2-, and 3-Hz SEM. The SEM frequency was determined to allow the target to appear once per 2 s (0.5 Hz), twice per second (2 Hz), or thrice per second (3 Hz). SEM performance time was 3 min with a washout period of 5 min. PS and PUS were measured at baseline and during 0.5-Hz, 2-Hz, and 3-Hz SEMs using a Zebris FDM 1.5 force plate. PS was determined by measuring the sway area, path length, and speed of center of pressure (COP) displacement, and PUS was determined via the plantar surface area (PSA). In PS parameters, there was a significant difference among the SEM frequencies in the COP_{sway area} PSA_{left foot} and PSA_{right foot}. Compared to that at baseline, COP_{sway area} decreased at 0.5 Hz and 2 Hz, while PSA_{left foot} and PSA_{right foot} increased at 2 Hz. These results suggest that 2 Hz SEM may improve PS and PSA.

Influence of tactile sensitivity in the finger on postural control while using the light touch effect

Providing additional tactile sensory input, such as light finger touch, improves postural control while standing. This phenomenon is called light touch (LT) effect. The present study investigated influences of tactile sensitivity in a finger on the magnitude of improvement in postural sway owing to LT. The participants were 16 healthy men (20-33 years). They performed two upright postures with their eyes closed; their feet 1) comfortably apart (normal stance) and 2) together in a side-by-side stance (Romberg stance). These tasks were performed both with and without LT. The participants let their right index finger lightly touch a fixed surface. The tactile sensitivity in the finger was evaluated using a two-point discrimination test. Although postural sway decreased owing to the LT, the association between tactile sensitivity in the finger and the percentage change in postural sway was not statistically significant, regardless of the difficulty of the upright tasks. These results suggested that the person might not be able to perceive a change in direction in their posture through LT; however, the LT might be recognized as a reference point to detect relative changes in the alignment of the body. Therefore, tactile sensitivity in the finger might not be necessary to achieve the LT effect.

Influence of posture on blink reflex prepulse inhibition induced by somatosensory inputs from upper and lower limbs

BACKGROUND

Prepulse inhibition (PPI) is a neurophysiological phenomenon whereby a weak stimulus modulates the reflex response to a subsequent strong stimulus. Its physiological purpose is to avoid interruption of sensory processing by subsequent disturbing stimuli at the subcortical level, thereby preventing undesired motor reactions. An important hub in the PPI circuit is the pedunculopontine nucleus, which is also involved in the control of posture and sleep/wakefulness.

OBJECTIVE

To study the effect of posture (supine versus standing) on PPI, induced by somatosensory prepulses to either upper or lower limb. PPI was measured as the percentage inhibition of the blink reflex response to electrical supraorbital nerve (SON) stimulation.

METHODS

Sixteen healthy volunteers underwent bilateral blink reflex recordings following SON stimulation either alone (baseline) or preceded by an electrical prepulse to the median nerve (MN) or sural nerve (SN), both in supine and standing. Stimulus intensity was 8 times sensory threshold for SON, and 2 times sensory threshold for MN and SN, respectively. Eight stimuli were applied in each condition.

RESULTS

Baseline blink reflex parameters did not differ significantly between the two postures. Prepulse stimulation to MN and SN caused significant inhibition of R2. In supine but not in standing, R2 was significantly more inhibited by MN than by SN prepulses. In standing, SN stimulation caused significantly more inhibition of R2 than in supine, while the inhibition caused by MN prepulses did not differ significantly between postures.

SIGNIFICANCE

PPI induced by lower limb afferent input may contribute to postural control while standing.

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.

Is there a relationship between plantar foot sensation and static balance, physical performance, fear of falling, and quality of life in hemodialysis patients?

INTRODUCTION

This study was conducted to investigate the relationship between plantar foot sensation and static balance, physical performance, fear of falling, and quality of life in hemodialysis patients.

MATERIALS AND METHODS

The study involved 24 hemodialysis patients and 20 healthy volunteers. Light touch-pressure sensation (Semmes Weinstein Monofilament test kit), two-point discrimination sensation (esthesiometer) and vibration sensation (128 Hz diapason) were used to evaluate plantar foot sensation. Static balance was assessed by the one-leg standing balance test, physical performance by the Timed Up and Go test, fear of falling with the Fall Efficacy Scale, and quality of life with the Ferrans and Powers Quality of Life Index Dialysis Version.

FINDINGS

There was a significant difference in plantar foot sensation, static balance, and physical performance of the patients compared to the healthy controls (P < 0.05). There was a strong correlation between static balance and physical performance with foot sensation in the hemodialysis patients (P < 0.05). There was also a strong correlation between static balance, physical performance, and fear of falling in hemodialysis patients (P < 0.05). The correlation between static balance, physical performance, and quality of life in the hemodialysis patients was strong (P < 0.05).

DISCUSSION

The most important result of this study is that light touch-pressure sensation, vibration sensation, two-point discrimination sensation, static balance, and physical performance, all of which involve the activity of cutaneous sensory receptors on the sole of the foot, are reduced in individuals who undergo hemodialysis. The findings of this study suggest potential rehabilitation strategies that could be applied to this patient group.

Transitions sit to stand and stand to sit in persons post-stroke: Path of centre of mass, pelvic and limb loading - A pilot study

BACKGROUND

To explore the movement patterns utilized by persons post stroke from the simultaneous perspective of pelvic and limb loading with the path of centre of mass during the movement transitions sit to stand and stand to sit.

METHODS

A descriptive pilot study where kinetic and kinematic data were collected and compared between the contribution made by the less affected versus more affected lower limb and trunk during sit to stand and stand to sit following stroke. Movement analysis was undertaken using force-plates and a 3D VICON motion capture system.

FINDINGS

Data were successfully collected on nine subjects of whom four presented with left side more affected and eight were male. Two patterns were demonstrated for pelvic loading, four patterns for limb loading and five patterns for deviation of centre of mass. There were no consistent patterns of movement demonstrated dependent upon the more or less affected side. There was no consistent relationship between pelvic and limb loading and deviation of centre of mass throughout the movement phases.

INTERPRETATION

In contrast to assumptions often made with respect to limb loading, we found large variability in movement patterns utilized by person's with a hemiparetic presentation during sit to stand and stand to sit. The findings suggest that movement problems encountered by persons post-stroke are complex and identifies limitations with respect to current measurement techniques.

Characterizing postural oscillation in children and adolescents with hereditary sensorimotor neuropathy

Charcot Marie Tooth disease (CMT) has negative functional impact on postural control of children; however, it has not been widely studied. Stabilometry can provide insights about postural control and guide preventive interventions in immature perceptual and musculoskeletal systems as those seen in children with CMT. This cross-sectional study aimed to identify and interpret stabilometric variables that reflect the postural control of children with CMT. 53 subjects (age 6-17) were assigned to one of the two groups: CMT (15 males and 14 females with CMT) or Control (13 males and 11 females healthy). Quiet standing was tested in different conditions: with open and closed eyes on regular surface (open-regular, closed-regular) and foam surface (open-foam, closed-foam) using a force platform. The minimum of 2 and maximum of 3 trials of 30 seconds for each test condition provided the classical stabilometric variables and Romberg Quotient (RQv). CMT group showed increase of confidence ellipse area, mean velocity, mediolateral and anteroposterior velocities associated with decreased mean body oscillation frequency, as the complexity of tasks increased. CMT postural deficit was identified by greater and faster sway associated with these lower frequencies, when compared to Control.

Cutaneous afferent innervation of the human foot sole: what can we learn from single-unit recordings?

Cutaneous afferents convey exteroceptive information about the interaction of the body with the environment and proprioceptive information about body position and orientation. Four classes of low-threshold mechanoreceptor afferents innervate the foot sole and transmit feedback that facilitates the conscious and reflexive control of standing balance. Experimental manipulation of cutaneous feedback has been shown to alter the control of gait and standing balance. This has led to a growing interest in the design of intervention strategies that enhance cutaneous feedback and improve postural control. The advent of single-unit microneurography has allowed the firing and receptive field characteristics of foot sole cutaneous afferents to be investigated. In this review, we consolidate the available cutaneous afferent microneurographic recordings from the foot sole and provide an analysis of the firing threshold, and receptive field distribution and density of these cutaneous afferents. This work enhances the understanding of the foot sole as a sensory structure and provides a foundation for the continued development of sensory augmentation insoles and other tactile enhancement interventions.

A comparison of balance control during stance and gait in patients with inflammatory and non-inflammatory polyneuropathy

Introduction

We compared changes in balance control due to chronic inflammatory demyelinating polyneuropathy (CIDP) and non-inflammatory (non-inf) polyneuropathy (PNP) to each other and with respect to healthy controls (HCs). Differences in patients’ subjective impressions of balance capabilities were also compared.

Methods

Balance control of 11 CIDP patients (mean age 61.1±(sd) 11, 8 male) and 10 non-inf PNP patients (mean age 68.5±11.7, all male) was examined and compared to that of 18 age- and gender-matched healthy controls. Balance control during stance and gait tasks was measured as trunk sway angles and angular velocities with body-worn gyroscopes. Patients’ subjective impressions of balance were obtained using the Dizziness Handicap Inventory (DHI). The Neuropathy Impairment Score in the Lower Limbs (NIS-LL) was used to measure clinical disease status.

Results

Non-inf PNP patients had slightly lower NIS-LL (13.5±7.2 vs. 17.9±15.1) and DHI scores (22.6±17.1 vs 27.6±16.3). Gait tasks showed a significant decrease in gait speed with respect to HCs for both patient groups but reduced trunk sway for non-inf PNP patients. Trunk sway during tandem walking and walking on the heels was greater for both groups than that of HCs. Sway during 2-legged stance tasks with eyes closed on a firm or foam surface was also greater than for HCs.

Discussion

Compared to HCs both groups of patients have significantly greater sway for most stance and gait tasks accompanied by reduced gait speed. As for HCs, non-inf PNP patients reduced trunk sway with slower gait speed. In CIDP patients this compensatory strategy was absent, possibly due to a greater deficit of efferent and motor nerve fibers. An interpretation of these findings is that CIDP patients have reduced ability to decrease trunk sway with slower gait speed and is possibly associated with an increased risk of falls.

How does cryotherapy effect ankle proprioception in healthy individuals?

Objectives To investigate how a 15-min cryotherapy intervention effects proprioception by measuring joint positional sense (JPS) and static single legged balance. Design Repeated measures design. Setting Laboratory. Participants Eighteen healthy university sports team students (11 males, 7 females) aged between 20 and 21 years old. Main outcome measures Participants were treated with 15 min of Aircast Cryo-cuff. The subject's skin temperature was measured before and immediately after 15 min of cryotherapy treatment. Ankle active joint positional sense (A-JPS) and passive joint positional sense (P-JPS) were measured at pre-test, immediately post-test, and 5 min post-test. Static balance was measured by centre of pressure (CoP) mean path length, medial-lateral (ML) CoP mean deviation, and anterior-posterior (AP) CoP mean deviation and mean time-to-boundary (TtB) minima for AP and ML directions. Results No significant differences were found for the variables of JPS and static single balance testing after 15 min of cryotherapy treatment. However, mean differences for CoP mean path length and ML mean deviation were shown to improve following cryotherapy treatment, results not previously found in the literature. Conclusion Results suggest that 15 min of Cryo-cuff treatment does not significantly affect proprioception. Although the effect of cryotherapy on proprioception depends on cooling modality used, time frame applied, and joint applied to.

Influence of light finger touch on postural stability during upright stance with cold-induced plantar hypoesthesia

The present study investigated the influence of light finger touch on postural stability during an upright stance with or without cold-induced plantar hypoesthesia. Participants were 21 healthy right-handed men (20-33 years), randomly assigned to a normal temperature group (NML-group; n = 11) or cold-induced plantar hypoesthesia group (COLD-group; n = 10). Participants performed two standing tasks with their eyes closed: 1) stand upright with the feet comfortably apart (normal standing); and 2) with the feet together in a side-by-side stance (Romberg standing). The order of the tasks was randomized across participants. After a rest period, they were asked to perform each standing task and let their right index finger lightly touch the fixed surface. Before the each task, participants in the COLD group were conducted a plantar intermediate hypothermic exposure. Postural sway was decreased by providing additional haptic sensory input through the light touching regardless of standing task difficulty with a normal plantar temperature. Although postural sway under plantar hypoesthesia is decreased by light touching, the effect was greater during the difficult posture task. These results suggest that, when the sensory information from the plantar surface is decreased, additional haptic input from the hand or finger might provide supplementary information about the relative changes in one's own body orientation. Therefore, sensory information provided by touching became relatively more important to maintaining postural control during the relatively difficult postural task performed under the reduced plantar sensitivity condition.

Should Ballet Dancers Vary Postures and Underfoot Surfaces When Practicing Postural Balance?

BACKGROUND

Postural balance (PB) is an important component skill for professional dancers. However, the effects of different types of postures and different underfoot surfaces on PB have not adequately been addressed.

PURPOSE

The main aim of this study was to investigate the effect of different conditions of footwear, surfaces, and standing positions on static and dynamic PB ability of young ballet dancers.

METHODS

A total of 36 male and female young professional ballet dancers (aged 14-19 years) completed static and dynamic balance testing, measured by head and lumbar accelerometers, while standing on one leg in the turnout position, under six different conditions: (1) "relaxed" posture; (2) "ballet" posture; (3) barefoot; (4) ballet shoes with textured insoles; (5) barefoot on a textured mat; and (6) barefoot on a spiky mat.

RESULTS

A condition effect was found for static and dynamic PB. Static PB was reduced when dancers stood in the ballet posture compared with standing in the relaxed posture and when standing on a textured mat and on a spiky mat (p < .05), and static PB in the relaxed posture was significantly better than PB in all the other five conditions tested. Dynamic PB was significantly better while standing in ballet shoes with textured insoles and when standing on a spiky mat compared with all other conditions (p < .05).

CONCLUSIONS

The practical implications derived from this study are that both male and female dancers should try to be relaxed in their postural muscles when practicing a ballet aligned position, including dance practice on different types of floors and on different types of textured/spiky materials may result in skill transfer to practice on normal floor surfaces, and both static and dynamic PB exercises should be assessed and generalized into practical dance routines.

Effects of active and passive warming of the foot sole on vibration perception thresholds

OBJECTIVE

Skin temperatures are known to increase cutaneous sensitivity. However, it is unclear whether the amount of improved sensitivity differs depending on the protocol of heat application. Therefore, this study aimed to investigate the effects of active (treadmill walking) and passive (infrared radiator) warming of the foot sole on vibration perception thresholds.

METHODS

Sixty healthy and injury-free subjects voluntarily participated in this study. Vibration perception thresholds (200 Hz) and plantar temperatures were measured at the hallux and 1st metatarsal head. In experiment 1, warming and mechanically stimulating the skin was achieved by walking on a treadmill for 30 min. In a follow-up study (experiment 2), external plantar heat was administered via an infrared radiator (30 min).

RESULTS

In both experiments, increasing temperatures led to increased plantar sensitivity. However, the amount of improved sensitivity was greater in experiment 1, although plantar temperature increases were lower compared to experiment 2.

CONCLUSIONS

Warming in conjunction with mechanical stimulation seems to have a greater potential to enhance plantar sensitivity compared to external heat supply only.

SIGNIFICANCE

The possible influence of mechanical stimulation and warming towards superior plantar afferent feedback highlights its importance regarding human posture and fall prevention.

Therapeutic interventions for improving self-reported function in patients with chronic ankle instability: a systematic review

OBJECTIVE

To identify which therapeutic intervention may be most effective for improving self-reported function in patients with chronic ankle instability (CAI).

DESIGN

Systematic literature review. Articles were appraised using the Downs and Black Checklist by 3 reviewers.

DATA SOURCES

PubMed along with CINAHL, MEDLINE and SPORTDiscus within EBSCOhost for pertinent articles from their inception through August 2016.

ELIGIBILITY CRITERIA FOR SELECTED STUDIES

Articles included were required to (1) be written in English, (2) report adequate data to calculate effect sizes, (3) identify patients with CAI, (4) use some form of therapeutic intervention and (5) use a self-reported questionnaire as a main outcome measurement.

RESULTS

A broad spectrum of therapeutic interventions were identified related to balance training, multimodal rehabilitation, joint mobilisation, resistive training, soft-tissue mobilisation, passive calf stretching and orthotics. All of the articles included in the balance training category had moderate-to-strong Hedges g with none of the 95% CIs crossing 0. Hedges g effect sizes ranged from -0.67 to -2.31 and -0.51 to -1.43 for activities of daily living and physical activity, respectively. The multimodal rehabilitation category also produced moderate-to-strong Hedges g effect sizes but with large CIs crossing 0. Hedges g effect sizes ranged from -0.47 to -9.29 and -0.62 to -24.29 for activities of daily living and physical activity, respectively.

CONCLUSIONS

The main findings from this systematic review were balance training provided the most consistent improvements in self-reported function for patients with CAI.

Effects of hypothermically reduced plantar skin inputs on anticipatory and compensatory balance responses

Background

Anticipatory and compensatory balance responses are used by the central nervous system (CNS) to preserve balance, hence they significantly contribute to the understanding of physiological mechanisms of postural control. It is well established that various sensory systems contribute to the regulation of balance. However, it is still unclear which role each individual sensory system (e.g. plantar mechanoreceptors) plays in balance regulation. This becomes also evident in various patient populations, for instance in diabetics with reduced plantar sensitivity. To investigate these sensory mechanisms, approaches like hypothermia to deliberately reduce plantar afferent input have been applied. But there are some limitations regarding hypothermic procedures in previous studies: Not only plantar aspects of the feet might be affected and maintaining the hypothermic effect during data collection. Therefore, the aim of the present study was to induce a permanent and controlled plantar hypothermia and to examine its effects on anticipatory and compensatory balance responses. We hypothesized deteriorations in anticipatory and compensatory balance responses as increased center of pressure excursions (COP) and electromyographic activity (EMG) in response to the hypothermic plantar procedure. 52 healthy and young subjects (23.6 ± 3.0 years) performed balance tests (unexpected perturbations). Subjects’ foot soles were exposed to three temperatures while standing upright: 25, 12 and 0 °C. COP and EMG were analyzed during two intervals of anticipatory and one interval of compensatory balance responses (intervals 0, 1 and 2, respectively).

Results

Similar plantar temperatures confirmed the successful implementation of the thermal platform. No significant COP and EMG differences were found for the anticipatory responses (intervals 0 and 1) under the hyperthermia procedure. Parameters in interval 2 showed generally decreased values in response to cooling.

Conclusion

No changes in anticipatory responses were found possibly due to sensory compensation processes of other intact afferents. Decreased compensatory responses may be interpreted as the additional balance threat, creating a more cautious behavior causing the CNS to generate a kind of over-compensatory behavior. Contrary to the expectations, there were different anticipatory and compensatory responses after reduced plantar inputs, thereby, revealing alterations in the organization of CNS inputs and outputs according to different task difficulties.

Plantar cooling does not affect standing balance: A systematic review and meta-analysis

The purpose of this systematic review with meta-analysis was to critically appraise and synthesize the literature to determine if cooling the plantar surface of the foot is an effective method of inducing postural control alterations in healthy individuals. Specific variables that were evaluated within the meta-analysis included (1) the duration of the plantar cooling intervention, (2) the stance type during postural control assessment, and (3) the role of visual input. A computerized search of four electronic databases from inception to March 2015 was performed to identify studies which examined the effects of plantar cooling on postural control in healthy individuals. A critical appraisal of the methodological quality of the included studies was performed using an appraisal criteria instrument previously used for assessing biomechanics studies. The literature search yielded 88 references of which 7 were deemed relevant and included in the systematic review and meta-analysis. A single, overall random-effects model meta-analysis of all study variables were performed; as well as, separate meta-analyses for each study variable. Across the 7 studies, the overall effect was 0.028 (95% CI=-0.177, 0.234; p=0.78) indicating that cooling the plantar surface had a very small effect on postural control. Similar results were obtained when data were examined based on study quality, plantar cooling intervention duration, stance type during postural control assessment, and the presence of visual input. Therefore, cooling the plantar surface of the foot had a very weak, non-significant effect on standing balance despite the anesthetic effects identified in each study.

Effect of experimentally reduced distal sensation on postural response to hip abductor/ankle evertor muscle vibration

This study assessed whether postural responses induced by vibratory perturbations of the hip abductors and ankle evertors, were modified when distal tactile sensation was experimentally reduced through cooling. Sixteen healthy subjects were investigated pre and post cooling. Subjects stood with their eyes closed with a stance width of 4 cm. A 2s vibratory stimulus was applied to the left or right hip abductor or ankle evertor muscle. The order of the site and side of the stimulation was randomised. The postural response to hip abductor and ankle evertor vibration was recorded using 3D motion analysis (Codamotion, Leicestershire). Medio-lateral centre of pressure motion was simultaneously recorded during quiet standing via a force plate (Kistler, UK). Pre-cooling people responded to unilateral ankle vibration with an ipsilateral translation and tilt of the pelvis, and an ipsilateral tilt of the trunk. People responded to unilateral hip vibration with a contralateral translation and tilt of the pelvis, and an ipsilateral tilt of the trunk. Following an experimental reduction in distal tactile sensation there was a significant reduction in the amplitude of pelvic tilt in response to ankle vibration (F(6.2)=P<0.05) and a significant increase in amplitude of pelvic tilt in response to hip vibration (F(5.2)=P<0.05). This suggests that the sensitivity to artificial stimulation of hip proprioception increases with distal cooling, possibly indicating a change in the gain/weighting placed upon sensory information from the hips.

The effect of textured ballet shoe insoles on ankle proprioception in dancers

BACKGROUND

Impaired ankle inversion movement discrimination (AIMD) can lead to ankle sprain injuries. The aim of this study was to explore whether wearing textured insoles improved AIMD compared with barefoot, ballet shoes and smooth insoles, among dancers.

METHODS

Forty-four adolescent male and female dancers, aged 13-19, from The Australian Ballet School were tested for AIMD while barefoot, wearing ballet shoes, smooth insoles, and textured insoles.

RESULTS

No interaction was found between the four different footwear conditions, the two genders, or the two levels of dancers in AIMD (p > .05). An interaction was found between the four different footwear conditions and the three tertiles when tested in ballet shoes (p = .006). Although significant differences were found between the upper tertiles and the lower tertiles when tested with ballet shoes, barefoot and with smooth insoles (p < .001; p < .001; p = .047, respectively), when testing with textured insoles dancers in the lower tertile obtained similar scores to those obtained by dancers in the upper tertile (p = .911).

CONCLUSION

Textured insoles improved the discrimination scores of dancers with low AIMD, suggesting that textured insoles may trigger the cutaneous receptors in the plantar surface, increasing the awareness of ankle positioning, which in turn might decrease the chance of ankle injury.

Contribution of the sural nerve to postural stability and cutaneous sensation of the lower limb

BACKGROUND

The sural nerve is a cutaneous nerve of the lower limb that innervates the posterolateral aspect of the lower leg, ankle, and foot. Considering this pattern, it is plausible that it contributes to the maintenance of postural stability. However, the implications of sensory loss following sural nerve injury have yet to be thoroughly investigated. Therefore, the aim of this study was to investigate the immediate effect of sural nerve sensory loss on postural stability and its variability of innervation to the lower limb.

METHODS

Twenty-five healthy adult subjects participated in an observational study with a repeated-measures design. Each participant underwent a postural stability assessment using the Neurocom Balance Master under 2 conditions: 1) with the sural nerve functioning normally and 2) following a bilateral ultrasound-guided sural nerve block. The cutaneous distribution of the sural nerve was mapped for descriptive purposes.

RESULTS

There were no statistically significant differences between conditions for the primary outcome measure (unilateral stance on the dominant leg with eyes closed). A statistically significant reduction in postural stability was detected during unilateral stance on the nondominant leg (with eyes closed) following the nerve block (mean increase, 2.25 deg/s; 95% confidence interval, -0.48 to 2.91; t = 2.75; df = 24; P = .01). The mean area of plantar skin innervated by the sural nerve was 17% ± 11%, and the mean area of lateral skin was 50% ± 6%.

CONCLUSION

Our findings demonstrate that a loss in sural nerve function is unlikely to reduce postural stability during daily activities. The sural nerve has a variable innervation pattern that can involve the third digit and the plantar medial border of the heel.

CLINICAL RELEVANCE

Practitioners should consider this variability when assessing for potential sensory deficits and when planning procedures requiring anesthesia to the plantar surface of the foot.

Reduced plantar sole sensitivity induces balance control modifications to compensate ankle tendon vibration and vision deprivation

The aim of this study was to investigate if sensory reweighting occurred to control balance when the sensitivity of the plantar sole is reduced using cooling. To address this question, visual information was manipulated and/or ankle proprioception was altered by Achilles tendon vibration. It was expected that Achilles tendon vibration and vision deprivation would induce greater center of pressure (CoP) excursions and/or increase of electromyographic (EMG) activity of the ankle muscles (triceps surea and tibialis anterior) with than without cooling of the plantar sole. To verify these hypotheses, the CoP and EMG activity of the ankle muscles were simultaneously recorded during quiet standing trials of 30s before and after feet cooling procedure. Results showed that plantar sole sensitivity alteration did not lead to larger CoP excursions even during Achilles tendon vibration in absence of vision. This could be explained by an increase in the EMG activity of the triceps surae after the cooling procedure without modification of tibialis anterior EMG activity. This study suggests that to compensate alteration in plantar sole sensitivity, the central nervous system increased the muscular activity of the triceps surae to limit CoP excursions.

Cooling reduces the cutaneous afferent firing response to vibratory stimuli in glabrous skin of the human foot sole

Skin on the foot sole plays an important role in postural control. Cooling the skin of the foot is often used to induce anesthesia to determine the role of skin in motor and balance control. The effect of cooling on the four classes of mechanoreceptor in the skin is largely unknown, and thus the aim of the present study was to characterize the effects of cooling on individual skin receptors in the foot sole. Such insight will better isolate individual receptor contributions to balance control. Using microneurography, we recorded 39 single nerve afferents innervating mechanoreceptors in the skin of the foot sole in humans. Afferents were identified as fast-adapting (FA) or slowly adapting (SA) type I or II (FA I n = 16, FA II n = 7, SA I n = 6, SA II n = 11). Receptor response to vibration was compared before and after cooling of the receptive field (2-20 min). Overall, firing response was abolished in 30% of all receptors, and this was equally distributed across receptor type (P = 0.69). Longer cooling times were more likely to reduce firing response below 50% of baseline; however, some afferent responses were abolished with shorter cooling times (2-5 min). Skin temperature was not a reliable indicator of the level of receptor activation and often became uncoupled from receptor response levels, suggesting caution in the use of this parameter as an indicator of anesthesia. When cooled, receptors preferentially coded lower frequencies in response to vibration. In response to a sustained indentation, SA receptors responded more like FA receptors, primarily coding "on-off" events.

Reduced input from foot sole skin through cooling differentially modulates the short latency and medium latency vestibular reflex responses to galvanic vestibular stimulation

Sensory afferent information from the skin of the foot sole and information from the vestibular system converge within the central nervous system; however, their mode of interaction remains unknown. The purpose of this study was to investigate the effect of reduced cutaneous foot sole information on the ability of the vestibular system to evoke short latency (SL) and medium latency (ML) lower limb muscle reflex responses. Galvanic vestibular stimulation (GVS; bipolar; binaural; 25 ms; 2 mA square-wave pulse) was applied to standing human subjects (four women, eight men, average age 21.1 ± 3.0 years) both before and after cooling the foot soles in 1°C ice water (15 min initially, followed by 5 min between blocks of 200 GVS pulses). Changes in soleus reflex amplitude were examined. Following ice water immersion, there was a 35.16% increase in the size of the ML response in the soleus muscle when expressed as a percentage of pre-stimulus electromyographic (EMG) activity (control 26.48 ± 4.91%; ice 36.16 ± 6.52%) with no change in size of the SL response (control 7.42 ± 1.12%; ice 8.72 ± 1.10%). These results support the previously proposed dissociation of the SL and ML responses with respect to their circuitry and functions. The results also suggest a greater role for cutaneous-vestibular interaction in the modulation of the ML than the SL response and at a location prior to the motoneuron pool.

The effect of age, movement direction, and target size on the maximum speed of targeted COP movements in healthy women

Rapid center of pressure (COP) movements are often required to avoid falls. Little is known about the effect of age on rapid and accurate volitional COP movements. We hypothesized that COP movements to a target would be slower and exhibit more submovements in older versus younger adults, particularly in posterior versus anterior movements. Healthy older (N=12, mean age=76 years) and young women (N=13, mean age=23 years) performed anterior and posterior lean movements while standing on a force plate, and were instructed to move their COP 'as fast and as accurately as possible' using visual feedback. The results showed that rapid posterior COP movements were slower and had an increased number of submovements and ratio of peak-to-average velocity, in comparison to anterior movements (p<.005). Moreover, older compared to younger adults were 27% slower and utilized nearly twice as many compensatory submovements (p<.005), particularly when moving posteriorly (p<.05). Older women also had higher ratios of peak-to-average COP velocity than young (p<.05). Thus, despite moving more slowly, older women needed to take more frequent submovements to maintain COP accuracy, particularly posteriorly, thereby providing evidence of a compensatory strategy that may be used for preventing backward falls.

Effects of experimentally induced pain of the plantar soles on centre of foot pressure displacements during unperturbed upright stance

BACKGROUND

Although impaired balance control during quiet standing has repeatedly been reported in persons suffering from foot pain, a better understanding of the effect of foot pain on unperturbed postural control is needed in order to propose and implement efficient podiatry treatments/interventions into clinical practice. The present study was hence designed to address this issue.

METHODS

Ten young healthy adults were asked to stand upright, eyes closed, as still as possible in three experimental conditions: (1) a no-pain condition, (2) a condition when a painful stimulation was applied to the plantar surfaces of both feet, and (3) a condition in which painful stimulation was applied to another body part, the palms of both hands. The centre of foot pressure displacements was recorded using a force platform.

FINDINGS

For the same perceived intensity of the pain, the severe painful stimulation applied to the plantar surfaces of both feet increased centre of foot pressure displacements, whereas the severe painful stimulation applied to the palms of both hands did not.

INTERPRETATION

These results reveal the deleterious effect of experimentally induced pain on the plantar soles on unperturbed bipedal postural control. At this point, it is conceivable that these effects of experimental pain could generalise to the effects of pain in patients. Accordingly, the present findings suggest that clinical and/or instrumental interventions designed to mitigate pain in patients suffering from plantar foot pain (e.g., podiatry treatments/interventions) could improve postural control.

Postural balance under normal and altered sensory conditions in normal-weight and overweight children

BACKGROUND

little or no research has been done in the overweight child on the relative contribution of multisensory information to maintain postural stability. Therefore, the purpose of this study was to investigate postural balance control under normal and experimentally altered sensory conditions in normal-weight versus overweight children.

METHODS

sixty children were stratified into a younger (7-9yr) and an older age group (10-12yr). Participants were also classified as normal-weight (n=22) or overweight (n=38), according to the international BMI cut-off points for children. Postural stability was assessed during quiet bilateral stance in four sensory conditions (eyes open or closed, normal or reduced plantar sensation), using a Kistler force plate to quantify COP dynamics. Coefficients of variation were calculated as well to describe intra-individual variability.

FINDINGS

removal of vision resulted in systematically higher amounts of postural sway, but no significant BMI group differences were demonstrated across sensory conditions. However, under normal conditions lower plantar cutaneous sensation was associated with higher COP velocities and maximal excursion of the COP in the medial-lateral direction for the overweight group. Regardless of condition, higher variability was shown in the overweight children within the 7-9yr old subgroup for postural sway velocity, and more specifically medial-lateral velocity.

INTERPRETATION

in spite of these subtle differences, results did not establish any clear underlying sensory organization impairments that may affect standing balance performance in overweight children compared to normal-weight peers. Consequently, it is believed that other factors account for overweight children's functional balance deficiencies.

The effect of reduced somatosensation on standing balance: a systematic review

The objective of this review is to identify and review publications describing the impact of reduced somatosensation on balance. Based on knowledge of the association between specific somatosensory loss and deterioration of balance, conclusions can be made about role of somatosensation in standing balance. A systematic literature review is presented in which publications from the years 1993 through 2007 were searched in Medline and Embase. Medical Subject Headings (MESH) terms and free text words (related to balance, somatosensory loss, and lower limb) were used to perform the searches. Fifteen articles were selected for detailed review based on predetermined inclusion criteria, and three of the included articles described the effect of experimentally reduced somatosensation on balance in healthy subjects. Ten of the articles described balance in diabetic neuropathy (DN). The last two included articles described balance in Charcot-Marie-Tooth (CMT) disease type 1A (CMT1A) or type 2 (CMT2). The literature indicates that the tactile sensation is reduced in DN, CMT1A, and CMT2 and when the plantar surface of the feet was hypothermically anesthetized. Joint motion sensation seems to be impaired in patients with DN, and passive joint position sensation appears to be reduced in healthy subjects with anesthesia of ankle and foot from prolonged ischemia. This reduced somatosensation seems to have a negative effect on balance in patients with DN and CMT2; however, this appeared not to be the case in patients with CMT1A and in healthy subjects.

Plantar cutaneous sensory stimulation improves single-limb support time, and EMG activation patterns among individuals with Parkinson's disease

Parkinson's disease is a chronic neurological disorder that results in gait and posture impairment. There is increasing evidence that these motor impairments may be partially due to deficits within the sensory system. In this study, the effects of a facilitatory insole that provides increased plantar sensory stimulation, was evaluated during gait, in a group of individuals with Parkinson's disease in comparison with healthy age-matched controls. Spatial-temporal parameters of gait were evaluated using an instrumented carpet, and muscle activation patterns were evaluated using surface EMG. All participants were tested with both a facilitatory (ribbed) insole and a conventional (flat) insole while walking 20 feet. Results indicated that the use of the facilitatory insole produced a significant increase in single-limb support time. Additionally, the muscle activation sequence of the tibialis anterior was normalized by the facilitatory insole, at the time of initial ground contact. These changes may lead to an overall improvement in gait pattern and stability, and suggest that the use of this type of facilitatory insole may be a useful treatment strategy for improving the gait of individuals with Parkinson's disease. This also provides support for the role of facilitation of the sensory system in improving motor output in individuals with Parkinson's disease.

The effect of immersion cryotherapy on medial-lateral postural sway variability in individuals with a lateral ankle sprain

BACKGROUND AND PURPOSE

Postural stability has been shown to be impaired after a lateral ankle sprain (LAS) and after immersion cryotherapy in healthy ankles. This study was performed to determine the effects of cryotherapy on postural stability after LAS.

METHOD

A single-session, repeated measures design was used. Fifteen 18- to 29-year-old males (mean age 21.33 +/- 3.54, height 71.23 +/- 2.50 cm, mass 170.33 +/- 19.77 kg) with relatively recent grade I LAS volunteered. Medial-lateral postural sway variability was assessed during single-leg barefoot stance using a Bertec force platform. Sway was tested before cryotherapy ('Pre'), immediately after 20 minutes of lower-leg immersion cryotherapy ('Post(0)'), and 10 and 20 minutes after cryotherapy ('Post(10)' and 'Post(20)'). Both legs were tested (individually) before cryotherapy; the involved leg was tested alone after cryotherapy. The uninvolved leg served as a control.

RESULTS

Postural sway variability of the involved le was significantly greater than the uninvolved le before cryotherapy (p = 0.001). Postural sway variability of the involved leg was also significantly greater than the uninvolved LE during Post(0) (p = 0.000), Post(10) (p = 0.000) and Post(20) testing (p = 0.003) with the largest increase in sway variability occurring at Post(0).

CONCLUSIONS

Medial-lateral postural sway variability was greater after LAS. This effect was augmented by immersion cryotherapy.