Plantar Cutaneous Sensitivity Research Articles

Reduced menthol sensitivity in a prodromal Parkinson's disease model induced by intranasal rotenone treatment.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms, and it is associated with several prodromal non-motor symptoms, including an impaired sense of smell, taste and touch. We previously reported that bitter taste impairments occur independently of olfactory impairments in an early-stage PD animal model using short-term intranasal rotenone-treated mice. Cool temperatures also affect bitter taste perception, but it remains unclear whether or not bitter taste impairments result from an altered sensitivity for intraoral cool stimuli. We examined disturbances in the intraoral menthol sensitivity, such as coolness at low concentrations of menthol, using a brief-access test. Once a day, one solution from the 7-concentration series of (-)-menthol (0-2.3 mM) or the bitter taste quinine-HCl (0.3 mM) was randomly presented 20 times for 10 s to water-deprived mice before and 1 week after rotenone treatment. The total number of licks within 20 times was significantly decreased with the presentation of 2.3 mM menthol and quinine-HCl, compared to distilled water in untreated mice, but not in rotenone-treated mice. The correlation between the licks for quinine-HCl and that for menthol was increased after rotenone treatment. In contrast, the 2-bottle choice test for 48 h clarified that menthol sensitivity was increased after rotenone treatment. Furthermore, a thermal place preference test revealed that seeking behavior toward a cold-floored room was increased in the rotenone-treated mice despite the unchanged plantar cutaneous cold sensitivity. These results suggest that taste impairments in this model mice are at least partly due to intraoral somatosensory impairments, accompanied by peripheral/central malfunction.

Age-related differences in the capacity and neuromuscular control of the foot core system during quiet standing.

The foot core system is essential for upright stability. However, aging-induced changes in the foot core function remain poorly understood. The present study aimed to examine age-related differences in postural stability from the perspective of foot core capacity and neuromuscular control during quiet standing. Thirty-six older and 25 young adults completed foot core capacity tests including toe flexion strength, muscle ultrasonography, and plantar cutaneous sensitivity. The center of pressure (COP) and electromyography (EMG) of abductor hallucis (ABH), peroneus longus (PL), tibialis anterior (TA) and medial gastrocnemius (GM) were simultaneously recorded during double-leg and single-leg standing (SLS). EMG data were used to calculate muscle synergy and intermuscular coherence across three frequency bands. Compared to young adults, older adults exhibited thinner hallucis flexors, weaker toe strength, and lower plantar cutaneous sensitivity. The ABH thickness and plantar cutaneous sensitivity were negatively associated with the COP mean peak velocity in older adults, but not in young adults. Besides, older adults had higher cocontraction of muscles spanning the arch (ABH-PL) and ankle (TA-GM), and had lower beta- and gamma-band coherence of the ABH-PL and TA-PL during SLS. Foot core capacities became compromised with advancing age, and the balance control of older adults was susceptible to foot core than young adults in balance tasks. To compensate for the weakened foot core, older adults may adopt arch and ankle stiffening strategies via increasing muscle cocontraction. Furthermore, coherence analysis indicated that aging may increase the demand for cortical brain resources during SLS.

Ankle complex proprioception and plantar cutaneous sensation in older women with different physical activity levels

Ankle complex proprioception and plantar sole sensitivity have been separately reported to be essential sensory components in balance control among the elderly. However, their inter-relationship is still unknown. Further, although optimal proprioceptive ability has been related to regular physical exercise, the association between physical activity (PA) levels, ankle proprioceptive acuity and plantar cutaneous sensation is unclear. Therefore, this study aims to compare ankle proprioceptive acuity and plantar cutaneous sensitivity scores between groups of older women with different PA levels, and to determine any relationships between plantar sole cutaneous sensitivity, ankle proprioceptive performance and PA levels. 68 older female participants were recruited who were distributed over three PA levels: highly active, moderately active, and inactive. PA level was assessed by the International Physical Activity Questionnaire. Ankle proprioceptive acuity was tested in full weight-bearing stance using the ankle Active Movement Extent Discrimination Apparatus (AMEDA) and plantar cutaneous sensitivity was assessed with the Nylon Semmes-Weinstein monofilaments test. Results showed that ankle proprioceptive acuity scores were strongly positively related to plantar sole sensitivity scores (r = 0.80, p < 0.001; effect size: η2 = 0.715), and both scores correlated with PA level. In conclusion, plantar cutaneous sensitivity and ankle complex proprioception were strongly correlated in older females with different levels of physical activity, suggesting that the former may be an integral part of the latter. Given the previously reported contribution of AMEDA ankle proprioceptive acuity to sport performance level, the health of the plantar sole of the foot may be important as a performance determinant.

Non-ambulatory measures of lower extremity sensorimotor function are associated with walking function in Multiple Sclerosis

BackgroundDisease progression of multiple sclerosis (MS) is often monitored by ambulatory measures, but how non-ambulatory sensorimotor measures differentially associate to walking measures in MS subtypes is unknown. We determined whether there are characteristic differences between relapsing-remitting MS (RRMS), progressive MS (PMS), and non-MS controls in lower extremity sensorimotor function and clinical walking tasks and the sensorimotor associations with walking function in each group. Methods18 RRMS, 13 PMS and 28 non-MS control participants were evaluated in their plantar cutaneous sensitivity (vibration perception threshold, Volts), proprioception during ankle joint position-matching (|∆°| in dorsiflexion), motor coordination (rapid foot-tap count/10 s), and walking function with three tests: Timed 25-foot walk (T25FW) at preferred and fast speeds (s), and timed-up-and-go (TUG, s). ResultsFoot-tapping (p = 0.039, Mean difference (MD)= 5.65 taps) and plantar cutaneous sensation (p = 0.026, MD= -10.30 V) differed between the MS subtypes. For the RRMS group faster walking was related to better proprioceptive function (preferred T25FW: p = 0.019, Root mean square error (RMSE)=1.94; fast T25FW: p = 0.004, RMSE=1.65; TUG: p = 0.001, RMSE=2.12) and foot-tap performance (preferred T25FW: p = 0.033, RMSE = 2.74; fast T25FW: p = 0.010, RMSE=2.02). These associations were not observed in the PMS group. ConclusionsFoot-tap performance and plantar cutaneous sensitivity but not ankle proprioception differed between MS subtypes. Lower walking performance was associated with lower foot-tapping and plantar cutaneous sensitivity in the RRMS but not the PMS group. This result suggests a change in the relationship of lower extremity sensorimotor function to walking performance in the PMS subtype.

Optimization of the Effects of Physical Activity on Plantar Sensation and Postural Control With Barefoot Exercises in Institutionalized Older Adults: A Pilot Study

Increasing somatosensory information from the foot by exercising barefoot can potentially optimize the effectiveness of physical exercise interventions on falls prevention in the older adults. This pilot study was then undertaken to explore the effects of increased somatosensory information from the foot by exercising barefoot on balance, gait, and plantar cutaneous sensitivity in institutionalized older adults involved in multimodal exercise intervention. Participants were assigned to three groups: a control group which did not perform any physical exercise and two groups in which they were involved in a multimodal exercise program performed barefoot or shod. Postural, gait, and plantar cutaneous sensitivity parameters were collected. The results showed that the exercise program produced larger effects on balance and plantar cutaneous sensitivity when exercises were performed barefoot, without any noticeable effect on gait. Hence, barefoot exercising could be a relevant means to optimize the fall-prevention exercise programs in institutionalized older adults.

Influência de estímulos cutâneos plantares sobre a sensibilidade e controle postural em idosos

A diminuição da sensibilidade cutânea plantar pode resultar na redução do controle postural em idosos, tornando-os mais suscetíveis a quedas. O objetivo deste estudo foi verificar a influência de um programa de estimulação cutânea plantar, sobre o limiar de sensibilidade e controle postural em indivíduos idosos. Este foi um estudo clínico prospectivo, randomizado e simples-cego, no qual participaram 36 indivíduos idosos acima de 60 anos de idade de ambos os sexos, submetidos ao teste Timed Up and Go (TUG), para mensurar a mobilidade funcional, teste de apoio unipodal para avaliar o equilíbrio estático, e avaliação da sensibilidade plantar por estesiometria com monofilamentos de nylon. Os idosos foram divididos em dois grupos. O grupo-controle não passou por nenhuma intervenção e foi orientado a não mudar o estilo de vida. Já o grupo-experimental foi orientado a realizar intervenções domiciliares por 3 semanas. Após esse período, todos os participantes foram reavaliados. Os resultados revelaram que ambos os grupos apresentaram maior sensibilidade cutânea plantar após 3 semanas; porém, não foram observadas alterações no controle postural. Ambos os grupos demonstraram melhora em relação à sensibilidade cutânea plantar, e não houve diferença entre eles.Palavras-chave: Idoso; Equilíbrio Postural; Envelhecimento.

Reactive balance control in older adults with diabetes

Diabetes mellitus is a major health problem for older adults worldwide and could be associated with impaired ability to recover balance after postural disturbances. This study compared reactive balance control in three groups of adults, young (YA), healthy non-diabetes older (nonDM-OA) and diabetes older (DM-OA). Twenty participants in each group completed a series of vision, plantar cutaneous sensitivity, grip power and lower limb strength tests. In the reactive balance test, participants stood on a force platform and used the dominant hand to pull the handle of a cord that could be suddenly released to create an imbalancing force. The anteroposterior (AP) and mediolateral (ML) motion of the center of pressure (COP) immediately after the sudden release was calculated to represent the level of imbalance experienced by the participants. Regression analysis entering big toe plantar sensitivity and grip power as independent variable was conducted for COP range for the three groups separately. The results showed that, except for the knee extensor, DM-OA had significantly poorer muscle strength and plantar sensitivity, and greater COP ML motion than YA and nonDM-OA. DM-OA also had significantly greater COP AP motion than YA. Grip power alone and together with plantar sensitivity explained a significant amount of variance in the AP and ML COP motion respectively (r2 = 0.334 and 0.582, respectively) for DM-OA. These findings indicated that diabetes in older adults was associated with declines in reactive balance control, and these changes may be related to muscle weakness and plantar insensitivity.

Effects of reduced plantar cutaneous sensation on static postural control in individuals with and without chronic ankle instability.

The purpose of this study was to determine how reduced plantar cutaneous sensation influences static postural control in individuals with and without CAI. A case-control study design. Twenty-six individuals with self-reported CAI and 26 matched healthy controls participated in this study. The plantar aspect of the participants' foot was then submersed in ice water (0°C) for 10min to reduce plantar sensation. Before and after the cooling procedure, plantar cutaneous sensation thresholds and single leg balance with eyes open and closed were assessed. Significantly, higher scores were observed in both groups after ice water submersion (p<0.001) indicating a significant reduction in the plantar cutaneous sensitivity after the cooling procedure. In single limb balance with eyes open, there were significant intervention main effects for the TTB ML mean (p<0.001), TTB AP mean (p=0.035) and TTB ML SD (p=0.021); indicating postural control improvement in both groups post-cooling. In single limb balance with eyes closed, Group×Intervention interactions were observed for the TTB AP mean (p=0.003) and TTB AP SD (p=0.017); indicating postural control deficits in CAI group post-cooling, but no changes in the control group. The main finding of this study was that reduced plantar cutaneous sensation induced by an ice submersion procedure caused eyes closed postural control impairments in those with CAI but not healthy controls. The present investigation demonstrated that the ability to dynamically reweight among sensory inputs to maintain postural stability appears to be diminished in CAI patients compared to healthy controls.

Plantar Cutaneous Sensitivity With and Without Cognitive Loading in People With Chronic Ankle Instability, Copers, and Uninjured Controls.

Controlled laboratory study. Deficits in light touch have recently been identified on the plantar surface of the foot in those with chronic ankle instability (CAI) but not in uninjured controls. It is unknown whether copers display similar deficits. Similarly, cognitive loading has been shown to impact postural control in different populations, but it is unclear how it may impact sensory perception. To evaluate the difference in cutaneous sensation thresholds at rest and under cognitive loading, using Semmes-Weinstein monofilaments (SWMs), among uninjured controls, copers, and those with CAI. A total of 45 participants (mean ± SD age, 20.2 ± 2.8 years; height, 167.6 ± 9.9 cm; mass, 66.3 ± 14.7 kg) were recruited and categorized to a CAI, coper, or control group, based on Ankle Instability Instrument scores. Participants were assessed with SWMs for cutaneous thresholds using a 4-2-1 stepping algorithm at the head of the first metatarsal, base of the fifth metatarsal, calcaneus, and sinus tarsi. Each participant was then retested while generating random digits to the beat of a metronome in order to simulate cognitive loading. Participants with CAI displayed significantly higher SWM thresholds at the head of the first metatarsal, base of the fifth metatarsal, and sinus tarsi than those of the control participants, and significantly higher thresholds at the base of the fifth metatarsal and calcaneus than those of copers (all, P<.05). Copers showed higher thresholds than those of controls at the sinus tarsi only (P<.05). A main effect of cognitive loading was identified at all 4 sites (P<.05). People with CAI have deficits in plantar sensation relative to controls and copers. Cognitive loading increases plantar cutaneous sensation thresholds irrespective of CAI status.

Balance and plantar cutaneous sensitivity functional assessment in community-dwelling elderly

SummaryImpaired balance is one of several factors that increase an elderly's susceptibility to falls. Balance assessment can be performed using postural tests and plantar cutaneous sensitivity tests.AimTo assess balance disorders and loss of plantar cutaneous sensitivity in the elderly and look for association between these alterations.Materials and MethodsA descriptive cross-sectional study involving 45 elderly submitted to the Berg Balance Scale (BBS) and the plantar sensitivity test with nylon monofilament. We used chi-square and Fisher's exact tests, and ROC curves were created in order to study the sensitivity and specificity of BBS.ResultsTwo and 4 individuals showed balance and cutaneous sensation disorders, respectively. There was a significant association between the complaint of impaired balance and loss of skin sensitivity (p = 0.047), and there was a reasonable agreement (Kappa: 0.6457) between the BBS and the sensorial test. A significant association was also found among 6 of the 14 BBS tasks and the sensitivity test.ConclusionMost of the elderly living independently in the community showed normal balance and plantar cutaneous sensation. When impaired, these functions appeared associated in a way that if the tests are performed together, the accuracy of the evaluation of the balance increases.

Plantar Cutaneous Sensitivity and Balance in Individuals With and Without Chronic Ankle Instability

To determine if plantar cutaneous sensation and postural control differ between individuals with and without chronic ankle instability (CAI). Case-control. Laboratory. Ten subjects with CAI and 10 subjects with no ankle sprain history participated. Light touch was evaluated at 3 sites (heel, base of fifth metatarsal, and head of first metatarsal) on the plantar aspect of the foot using Semmes-Weinstein Monofilaments (SWMs). Postural control was assessed using the single leg firm and foam conditions of the Balance Error Scoring System (BESS) and during eyes open and eyes closed static postural control on a force plate. Semmes-Weinstein Monofilament detection thresholds, BESS errors, and the mean of time-to-boundary (TTB) minima (TTB-mean) and the SD of TTB minima (TTB-SD) in the anterior-posterior (AP) and medial-lateral directions were evaluated for each subject. Subjects with CAI demonstrated increased SWM detection thresholds at the heel (P = 0.009), head of the first (P = 0.01), and base of the fifth metatarsal (P < 0.001) and postural control deficits on the BESS firm (P = 0.04) and foam (P = 0.001) conditions and with eyes open TTB-mean AP (P = 0.007) and TTB-SD AP (P = 0.02). When combining groups, a negative moderate correlation was observed between the base of the fifth metatarsal detection threshold and eyes open TTB-mean AP (r = -0.50; P = 0.03). Light touch and postural control deficits were observed in individuals with CAI. The correlation between light touch over the base of the fifth metatarsal and eyes open TTB-mean AP suggests that there may be a relevant relationship between these measures. Individuals with CAI demonstrated deficits in light touch over the plantar aspect of the foot. The relationship between base of the fifth metatarsal sensation and TTB-mean AP may provide a starting point to link plantar cutaneous sensory deficits to changes in other aspects of sensorimotor function.

足底への感覚刺激が足底感覚および足趾把持力に及ぼす影響

足底への感覚刺激が足底感覚および足趾把持力に及ぼす影響

Plantar cutaneous sensitivity as a risk for falls in the elderly

The risk factors for falls in the elderly are many and may be due to syncope and pre-syncope caused by cardiovascular diseases; neurological diseases, such as epilepsy and Parkinson’s disease; dementia disorders; and dependence in activities of daily life 1 . Other risk factors that also cause syncope and fall include the adverse effect or inappropriate use of several concurrent medications, drugs which are central nervous system-depressant, or act on the cardiocirculatory system 1 . Systemic diseases combined with sensorineural degeneration and neuromuscular disorders due to aging accentuate the risk of falling, particularly in the frail elderly. Vertigo and imbalance are also frequent causes of falls, often associated with metabolic disorders, mainly uncontrolled diabetes without the well-known clinical manifestations of the disease 2,3 . Diabetes leads to glucose fluctuations in metabolically active structures of the inner ear, interfering with the sodiumpotassium pump activity. This pump creates the electrical potentials of the cochlear and vestibular neuroepithelial cells that, when altered, produce auditory and vestibular signs and symptoms. Among the causes of change in body balance there are also the reduced number of mechanoreceptors located in the feet, and the increase in the vibrational excitation threshold of the plantar cutaneous mechanoreceptors due to aging. Plantar sensitivity is an important source of information for balance control, as it codifies the changes in pressure under the feet, especially during gait. This information reaches the brain, which senses the body position and, if necessary, generates postural reflexes to maintain an upright position 4 . This sensitivity loss may be due to several diseases, particularly diabetes 5 . About 50% of diabetic patients over 60 years of age have this disorder, with or without complaint. Moreover, even the healthy elderly may have subclinical neuropathy. It has been widely demonstrated that this loss plays an important role in balance disorders in the elderly population 4-6 . Change in plantar cutaneous sensitivity is an independent predictor of falls; 30% of the elderly people aged 65, and 40% of those aged 75 and over have fallen at least once 7 . Two or more falls in six months significantly increases the risk of falls in the frail elderly. Quality of life is compromised by a sense of instability that causes fear of falling, especially if the elder has fallen recently 7 . Fear of falling leads to reduced mobility, increasing sedentary lifestyle and creating a vicious cycle that further increases the risk 7,8 . Frequent falls often

Plantar cutaneous sensitivity as a risk for falls in the elderly

Plantar cutaneous sensitivity as a risk for falls in the elderly

Peripheral Neuropathy Alters Variability but not Finite-Time Lyapunov Exponents during Treadmill Walking

Peripheral neuropathy (PN) is marked by diminished plantar cutaneous sensitivity, reduced preferred walking speed (PWS), and increased risk of falls. Predisposition to falls may result from an inability to adapt to challenging walking speeds. The PURPOSE: of this study was to compare the dynamics of treadmill walking at different speeds between individuals with PN and age-matched controls. METHODS: Eleven individuals with PN (mean ± SD age=67.0 ± 10.9 yr, height =172 ± 11 cm, body mass=86.8 ± 23.6 kg) and 11 healthy controls (age=69.1 ± 10.0 yr, height=168 ± 6 cm, body mass=83.0 ± 18.8 kg) gave informed consent as approved by the university's IRB. The 6-min walk test was used to determine "maximal walking speed" (100%MWS). Multiple treadmill walking trials were then completed at 100%MWS, 80%MWS, and 60%MWS. During the middle 2 min of each trial, motion analysis (60 Hz) was used to collect sagittal plane hip, knee, and ankle joint kinematics. Stride duration variability (SDvar) was calculated from 30 consecutive strides. Joint angle variability (JTvar) was calculated for each joint from the ensemble curves of the same 30 strides. Short-and long-term Finite-Time Lyapunov Exponents (ST, LT) were computed for each joint from ensemble curves of 100 consecutive strides. Factorial ANOVA with repeated measures was used for statistical analysis. Tukey's pos-hoc tests were used wherever appropriate. RESULTS: In general, faster walking speeds were associated with increased SDvar, JTvar, ST and LT. The PN group walked slower than the control group (100%MWS=1.25 ± 0.17 vs. 1.45 ± 0.29 m/s, F1,21=4.41, p<0.001). Despite controlling for the variance in walking speed, the PN group exhibited increased SDvar (32.9 ± 2.2 vs. 23.7 ± 1.4 ms, F1, 65=6.77, p=.02) and JTvar (2.64 ± 0.10 vs. 1.87 ± 0.07 deg, F1, 65=29.1, p=.01). No group or group × speed interactive effects were observed for ST or LT. CONCLUSIONS: Compared to controls, the PN group exhibited increased variability (SDvar and JTvar) over and above that elicited by group differences in walking speed. However, no difference in the time dependent Lyapunov Exponents were observed. While effects were not exaggerated when walking at challenging speeds, the results nevertheless highlight the disturbed control of walking in this population.

Sensitivity of plantar cutaneous sensation and postural stability

Background Impaired plantar cutaneous sensation is often seen clinically and can lead to postural instability. It is not clear if the severity of such sensory loss would be associated with postural stability, and if such an association would be affected by sensory redundancy and task difficulty. The purpose of this study was to investigate the association of the degree of somatosensory loss and postural stability by experimentally induced somatosensory loss in healthy young adults. Methods Twenty-one healthy young adults performed four quiet standing tasks (normal or narrow base, and eyes open or closed) on a force platform under three somatosensory conditions induced by ischemic blocking of afferent conduction below the ankle, normal, partial loss and complete loss. Differences in the standing center of pressure motion between the three sensory loss conditions were compared. Findings There was a significant trend of greater center of pressure motion with increasing severity of sensory loss in all task conditions. The differences in the center of pressure motion between partial and total loss conditions were significant only in conditions where vision was removed and the support surface was narrow. Interpretation Increased severity of experimentally induced loss of plantar cutaneous sensitivity was associated with greater postural sway. Such an association was affected by the availability of visual input and the size of the support surface. Clinically for patients with somatosensory impairments of the foot, postural stability should be given special attention.

1208 Advanced, computerised cold cap for preventing chemotherapy induced alopecia

The purpose of this study was to determine how reduced plantar cutaneous sensation influences static postural control in individuals with and without CAI.A case-control study design.Twenty-six individuals with self-reported CAI and 26 matched healthy controls participated in this study. The plantar aspect of the participants’ foot was then submersed in ice water (0 °C) for 10 min to reduce plantar sensation. Before and after the cooling procedure, plantar cutaneous sensation thresholds and single leg balance with eyes open and closed were assessed.Significantly, higher scores were observed in both groups after ice water submersion (p < 0.001) indicating a significant reduction in the plantar cutaneous sensitivity after the cooling procedure. In single limb balance with eyes open, there were significant intervention main effects for the TTB ML mean (p < 0.001), TTB AP mean (p = 0.035) and TTB ML SD (p = 0.021); indicating postural control improvement in both groups post-cooling. In single limb balance with eyes closed, Group × Intervention interactions were observed for the TTB AP mean (p = 0.003) and TTB AP SD (p = 0.017); indicating postural control deficits in CAI group post-cooling, but no changes in the control group.The main finding of this study was that reduced plantar cutaneous sensation induced by an ice submersion procedure caused eyes closed postural control impairments in those with CAI but not healthy controls. The present investigation demonstrated that the ability to dynamically reweight among sensory inputs to maintain postural stability appears to be diminished in CAI patients compared to healthy controls.