Stance Postural Strategies in Patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

INTERPRETATION

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

Romberg's test revisited: Changes in classical and advanced sway metrics in patients with pure sensory neuropathy

OBJECTIVES

The Romberg test, undoubtedly a classical and well-established method in physical neurological assessment of patients with sensory ataxia, has long been suspected to be prone to several limitations. Here, we quantified upright stance before and after visual deprivation in a selected cohort of patients with pure sensory neuropathy.

METHODS

Static balance was assessed in sensory neuropathy patients during quiet stance on a force platform under different visual and proprioceptive feedback conditions. Sural nerve neurography was employed to evaluate the severity of peripheral neuropathy. Conventional and advanced postural sway metrics were investigated to draw a quantitative analogy to the clinical Romberg test.

RESULTS

Posturographic analyses showed that patients displayed Romberg and vestibular Romberg quotient values around 2, indicating an approximately twofold increase in body sway in the absence of vision. However, the diagnostic discrimination ability between patients and controls was only modest. Even less impactful were the diagnostic contributions of frequency domain and non-linear sway analyses. This was primarily attributed to the heightened body sway exhibited by patients with sensory neuropathy under 'eyes open' conditions, diminishing the contrast with the 'eyes closed' condition as assessed in the classical Romberg test.

CONCLUSION

We conclude that the Romberg test, even in its quantitative form with the aid of an apparatus, had an unsatisfactory classification value in terms of distinguishing patients from healthy controls. Instead, it should be interpreted within the comprehensive context of the broader neurological examination and the electrodiagnosis of peripheral nerve function.

Imbalance and lower limb tremor in chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND AND AIMS

Imbalance is a prominent symptom of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Although upper limb tremor in CIDP is described, lower limb tremor has not been assessed. The aim of this study was to determine whether lower limb tremor was present in CIDP and assess potential relationships with imbalance.

METHODS

This was a cross-sectional observational study of prospectively recruited consecutive patients with typical CIDP (N = 25). Clinical phenotyping, lower limb nerve conduction and tremor studies, and posturography analyses were performed. The Berg Balance Scale (BBS) divided CIDP patients into those with "good" and "poor" balance.

RESULTS

Lower limb tremor was evident in 32% of CIDP patients and associated with poor balance (BBSTremor 35 [23-46], BBSNo Tremor 52 [44-55], p = .035). Tremor frequency was 10.2-12.5 Hz with legs outstretched and on standing, apart from four patients with a lower frequency tremor (3.8-4.6 Hz) while standing. Posturography analysis revealed a high-frequency spectral peak in the vertical axis in 44% of CIDP patients (16.0 ± 0.4 Hz). This was more likely in those with "good" balance (40% vs. 4%, p = .013).

INTERPRETATION

Lower limb tremor is present in one third of CIDP patients and is associated with poor balance. A high-frequency peak on posturography is associated with better balance in CIDP. Lower limb tremor and posturography assessments could serve as important biomarkers of balance in a clinical setting.

Validity, responsiveness, floor and ceiling effects of the Berg Balance Scale in patients with Guillain-Barré syndrome

We investigated the measurement properties of the Berg Balance Scale in patients with Guillain-Barré syndrome. A retrospective analysis was performed of 81 patients with Guillain-Barré syndrome of age 17-84 years who had completed inpatient rehabilitation over a 5-year period. They were assessed with the Berg Balance Scale, the 10 Meter Walk Test, and the 6 Minute Walk Test at admission and discharge. The concurrent validity of the Berg Balance Scale was confirmed by very good correlations with the 10 Meter Walk Test at admission and discharge (ρ = 0.83 and 0.78, respectively) and by excellent and very good correlations with the 6 Minute Walk Test at admission (ρ = 0.91) and discharge (ρ = 0.77). The predictive validity of the Berg Balance Scale for the 10 Meter Walk Test and the 6 Minute Walk Test at discharge was moderate (ρ = 0.62 and 0.61, respectively) and very good (ρ = -0.87) for length of stay. The minimal clinically important difference of the Berg Balance Scale was estimated to be 10 points. The scale was highly responsive to changes in balance (Cohen's d 0.9). No floor effect was identified. A ceiling effect was identified only at discharge. The Berg Balance Scale is feasible in patients with Guillain-Barré syndrome at admission and discharge from rehabilitation. However, a ceiling effect may occur at discharge in patients with high levels of balance.

Posturography as a biomarker of intravenous immunoglobulin efficacy in chronic inflammatory demyelinating polyradiculoneuropathy

INTRODUCTION/AIMS

Imbalance is a common feature of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Intravenous immunoglobulin (IVIg) exerts clinical benefit in CIDP, including improving balance, although objective markers of efficacy are lacking. Posturography is an established objective marker of balance; therefore, this study aimed to determine the utility of posturography as an objective marker of treatment efficacy in CIDP.

METHODS

Posturography was performed on 18 CIDP patients, established on IVIg infusions, and results were compared to age-matched healthy controls. CIDP patients were assessed just prior to IVIg infusion and at the mid-point of the cycle. Center of pressure (CoP) was measured and the total path traveled by CoP (Sway Path, SP) was calculated for five different conditions: feet placed in parallel 16 cm apart at the medial border with eyes open (16cmEO) and eyes closed (16cmEC); medial borders of the feet touching with eyes open (0cmEO) and eyes closed (0cmEC); and tandem stance.

RESULTS

The sway path (SP) was significantly increased in CIDP patients (mean SP 1191 ± 104 mm) when compared to healthy controls (mean SP 724 ± 26 mm, P < .001). The increase was most prominent during eyes closed and tandem stance conditions. Treatment with IVIg significantly reduced SP when assessing 0cmEC (1759 ± 324 mm vs. 1081 ± 134 mm, P = .019) and tandem stance (1775 ± 290 mm vs. 1152 ± 113 mm, P = .027).

DISCUSSION

Posturography detected significant improvements in balance following IVIg in CIDP patients established on maintenance therapy. As such, posturography may be considered an objective marker of treatment response in clinical management and therapeutic trials.

Cutaneous and muscular afferents from the foot and sensory fusion processing: Physiology and pathology in neuropathies

The foot-sole cutaneous receptors (section 2), their function in stance control (sway minimisation, exploratory role) (2.1), and the modulation of their effects by gait pattern and intended behaviour (2.2) are reviewed. Experimental manipulations (anaesthesia, temperature) (2.3 and 2.4) have shown that information from foot sole has widespread influence on balance. Foot-sole stimulation (2.5) appears to be a promising approach for rehabilitation. Proprioceptive information (3) has a pre-eminent role in balance and gait. Reflex responses to balance perturbations are produced by both leg and foot muscle stretch (3.1) and show complex interactions with skin input at both spinal and supra-spinal levels (3.2), where sensory feedback is modulated by posture, locomotion and vision. Other muscles, notably of neck and trunk, contribute to kinaesthesia and sense of orientation in space (3.3). The effects of age-related decline of afferent input are variable under different foot-contact and visual conditions (3.4). Muscle force diminishes with age and sarcopenia, affecting intrinsic foot muscles relaying relevant feedback (3.5). In neuropathy (4), reduction in cutaneous sensation accompanies the diminished density of viable receptors (4.1). Loss of foot-sole input goes along with large-fibre dysfunction in intrinsic foot muscles. Diabetic patients have an elevated risk of falling, and vision and vestibular compensation strategies may be inadequate (4.2). From Charcot-Marie-Tooth 1A disease (4.3) we have become aware of the role of spindle group II fibres and of the anatomical feet conditions in balance control. Lastly (5) we touch on the effects of nerve stimulation onto cortical and spinal excitability, which may participate in plasticity processes, and on exercise interventions to reduce the impact of neuropathy.

Wearable Health Technology to Quantify the Functional Impact of Peripheral Neuropathy on Mobility in Parkinson's Disease: A Systematic Review

The occurrence of peripheral neuropathy (PNP) is often observed in Parkinson’s disease (PD) patients with a prevalence up to 55%, leading to more prominent functional deficits. Motor assessment with mobile health technologies allows high sensitivity and accuracy and is widely adopted in PD, but scarcely used for PNP assessments. This review provides a comprehensive overview of the methodologies and the most relevant features to investigate PNP and PD motor deficits with wearables. Because of the lack of studies investigating motor impairments in this specific subset of PNP-PD patients, Pubmed, Scopus, and Web of Science electronic databases were used to summarize the state of the art on PNP motor assessment with wearable technology and compare it with the existing evidence on PD. A total of 24 papers on PNP and 13 on PD were selected for data extraction: The main characteristics were described, highlighting major findings, clinical applications, and the most relevant features. The information from both groups (PNP and PD) was merged for defining future directions for the assessment of PNP-PD patients with wearable technology. We established suggestions on the assessment protocol aiming at accurate patient monitoring, targeting personalized treatments and strategies to prevent falls and to investigate PD and PNP motor characteristics.

Stimulus Prediction and Postural Reaction: Phase-Specific Modulation of Soleus H-Reflexes Is Related to Changes in Joint Kinematics and Segmental Strategy in Perturbed Upright Stance

Anticipation determines the timing and efficiency of human motor performance. This study aimed to evaluate the effect of stimulus anticipation on proactive (prior to the event) and reactive (after the event) postural adjustments in response to perturbations. Postural set was manipulated by providing either (i) predictable, (ii) unpredictable, or (iii) cheated perturbations which require balance corrections to maintain postural stability. In 29 subjects, a protocol of anterior and posterior perturbations was applied for the conditions (i–iii). Center of pressure (COP) displacement, ankle, knee, and hip joint kinematics and electromyographic activity (EMG) of the soleus (SOL) and tibialis anterior (TA) muscles were recorded prior (PRE) and after posterior perturbations. SOL H-reflexes at the peak of the short-, medium- ,and long-latency responses (SLR, MLR, LLR) were assessed. For conditions (i to iii) EMG activity and COP differed prior to perturbation onset (p < 0.05). After perturbation, results demonstrated a progressively increased H-reflex amplitude in the MLR and LLR (p < 0.05), delayed muscle activities (p < 0.05), and shifted activation patterns, with muscles of the proximal segment being more involved in the compensatory postural response (p < 0.05). COP displacements and ankle, knee, and hip joint deflections progressively increased (p < 0.05). Neuromechanical coupling showed positive correlations for the anticipation-induced changes in EMG activity and H-reflex amplitude with that of COP displacement (p < 0.05). In conclusion, proactive and reactive postural responses indicated setting dependent modulations of segmental and phasic muscle activation. A shift to proximal muscle groups and facilitated late reflex responses compensating for cheated or unpredicted perturbations was found to recover a safe body equilibrium. In consideration of the phase-specific adaptation and its interrelationship to the kinematics, it suggested that changes in stimulus prediction challenged the central nervous system to appropriately counteract the higher postural challenges. The outcomes of this experiment are of functional relevance for experimental and training settings involving perturbation stimuli. These findings provide fundamental information of the mechanisms underlying postural adjustments in response to external perturbations.

An Initial Passive Phase That Limits the Time to Recover and Emphasizes the Role of Proprioceptive Information

In the present experiments, multiple balance perturbations were provided by unpredictable support-surface translations in various directions and velocities. The aim of this study was to distinguish the passive and the active phases during the pre-impact period of a fall. It was hypothesized that it should be feasible if one uses a specific quantitative kinematic analysis to evaluate the dispersion of the body segments trajectories across trials. Moreover, a multi-joint kinematical model was created for each subject, based on a new 3-D minimally invasive stereoradiographic X-ray images to assess subject-specific geometry and inertial parameters. The simulations allowed discriminating between the contributions of the passive (inertia-induced properties) and the active (neuromuscular response) components during falls. Our data show that there is limited time to adjust the way one fall from a standing position. We showed that the pre-impact period is truncated of 200 ms. During the initial part of a fall, the observed trajectory results from the interaction between the destabilizing external force and the body: inertial properties intrinsic to joints, ligaments and musculotendinous system have then a major contribution, as suggested for the regulation of static upright stance. This passive phase is later followed by an active phase, which consists of a corrective response to the postural perturbation. We believe that during a fall from standing height, it takes about 300 ms for postural responses to start correcting the body trajectory, while the impact is expected to occur around 700 ms. It has been argued that this time is sufficient to change the way one falls and that this makes it possible to apply safer ways of falling, for example by using martial arts fall techniques. Also, our results imply visual and vestibular information are not congruent with the beginning of the on-going fall. This consequence is to be noted as subjects prepare to the impact on the basis of sensory information, which would be uniquely mainly of proprioceptive origin at the fall onset. One limitation of the present analysis is that no EMG was included so far but these data are the subject of a future study.

Peripheral nerve disease

Polyneuropathies are common neurologic disorders affecting the peripheral nerves. There are a number of causes of damage to these structures, such as genetic and metabolic factors, autoimmune disorders, infection, drug or environmental toxicity, and malignancy. Motor and sensory impairments are commonly encountered in these conditions, leading to altered balance and gait with increased risk of falling. Diabetic neuropathy is the most common cause of peripheral nerve disease and extensive investigation of balance and walking function revealed greater postural instability and delayed activation of distal muscles during walking. Although classically thought to be due to sensory impairment, it is now recognized that a motor contribution to balance and gait impairment cannot be ruled out in diabetic neuropathy. Inflammatory and inherited neuropathies have had less investigation. Variations in static and dynamic balance and depend on the sensory afferents affected and the degree of motor impairment. Motor impairment is a major contributor to alterations in gait pattern. Exercise is an effective rehabilitation approach that can improve muscle strength and postural responses. The gains can carry over into improved functional balance and walking. Orthotic interventions are also promising in supporting joints where there is significant muscle weakness, but newer devices are being developed that provide sensory feedback, e.g., vibration, which may be effective where sensory impairment is a key contributor to postural instability.

Vestibular impairment in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a common, treatable, autoimmune peripheral neuropathy considered to produce imbalance by weakness and proprioceptive impairment rather than vestibular impairment. We measured semicircular canal vestibular function in 21 CIDP patients (15M/6F) by the video head impulse test and postural stability with a battery comprising the modified Clinical Test of Sensory Integration and Balance, the Berg Balance Scale, the Dynamic Gait Index, the Fall Efficiency Scale, and the International Cooperative Ataxia Rating Scale. Of the 21 patients, 16 had vestibular impairment, ranging from mild-affecting just a single semicircular canal, to severe-affecting all 6 canals. Although the severity of the vestibular impairment did not correlate either with the severity of the postural imbalance or of the peripheral neuropathy, our data show that vestibular impairment is an additional challenge to balance that some CIDP patients will face.

F. CARACTERIZACIÓN TEMPORO-ESPACIAL DEL PATRÓN DE MARCHA EN ROEDORES COMO MODELO ANIMAL DE LESIÓN CEREBRAL CEREBROVASCULAR

En la investigación sobre movimiento, la experimentación animal ha proporcionado fundamentación científica para la investigación clínica, mejorando procedimientos diagnósticos y de rehabilitación. Lesiones cerebrales en roedores pueden ser usadas para modelar síntomas locomotores, sensoriales y/o cognitivos. Con el propósito de determinar la funcionalidad locomotriz y sensorial en roedores, se han propuesto varios métodos de evaluación y pronóstico clínico para identificar y evaluar adaptaciones estructurales y mecanismos de neuro-recuperación. Esto ha permitido que métodos de intervención terapéutica, como el ejercicio físico, sean utilizados para restaurar funciones sensitivo-motoras y cognitivas en roedores y humanos. La extrapolación (translación) de los resultados de investigaciones en ciencias básicas a áreas clínicas supone la continua cooperación y retroalimentación entre investigadores y profesionales de la salud, favoreciendo la formulación de intervenciones terapéuticas más eficaces basadas en resultados obtenidos de la experimentación animal. El objetivo de esta revisión es exponer las principales deficiencias motoras y los métodos empleados para determinar la dificultad motriz en la marcha en roedores con lesión cerebrovascular, para lo cual se realizó una revisión de literatura, sobre términos definidos (MeSH), en las bases de datos PsychINFO, Medline y Web of Science, entre enero de 2000 y enero de 2017. Se excluyeron artículos de carácter cualitativo o narrativo, sin revisión por pares, disertaciones, tesis o trabajos de grado y resúmenes de conferencias. Se revisan algunas manifestaciones clínicas, su efecto en la locomotricidad en roedores, algunas metodologías usadas para generar lesiones y para estudiar la función motriz, los principales métodos de medición y algunos aspectos translacionales. 

Assessing Somatosensory Utilization during Unipedal Postural Control

Multisensory-visual, vestibular and somatosensory information is integrated for appropriate postural control. The primary goal of this study was to assess somatosensory utilization during a functional motor task of unipedal postural control, in normal healthy adults. Assessing individual bias in the utilization of individual sensory contributions during postural control may help customization of rehabilitation protocols. In this study, a test paradigm of unipedal stance control in supine orientation with and without vision was assessed. Postural control in this test paradigm was hypothesized to utilize predominantly contributions of somatosensory information from the feet and ankle joint, with minimal vestibular input. Fourteen healthy subjects "stood" supine on their dominant leg while strapped to a backpack frame that was freely moving on air-bearings, to remove available otolith tilt cues with respect to gravity that influences postural control when standing upright. The backpack was attached through a cable to a pneumatic cylinder that provided a gravity-like load. Subjects performed three trials each with Eyes-open (EO) and Eyes-closed (EC) while loaded with 60% body weight. There was no difference in unipedal stance time (UST) across the two conditions with EC condition challenging the postural control system greater than the EO condition. Stabilogram-diffusion analysis (SDA) indicated that the critical mean square displacement was significantly different between the two conditions. Vestibular cues, both in terms of magnitude and the duration for which relevant information was available for postural control in this test paradigm, were minimized. These results support our hypothesis that maintaining unipedal stance in supine orientation without vision, minimizes vestibular contribution and thus predominantly utilizes somatosensory information for postural control.