David Cioncoloni

Time Course of Corticospinal Excitability and Autonomic Function Interplay during and Following Monopolar tDCS.

While polarity-specific after-effects of monopolar transcranial direct current stimulation (tDCS) on corticospinal excitability are well-documented, modulation of vital parameters due to current spread through the brainstem is still a matter of debate, raising potential concerns about its use through the general public, as well as for neurorehabilitation purposes. We monitored online and after-effects of monopolar tDCS (primary motor cortex) in 10 healthy subjects by adopting a neuronavigated transcranial magnetic stimulation (TMS)/tDCS combined protocol. Motor evoked potentials (MEPs) together with vital parameters [e.g., blood pressure, heart-rate variability (HRV), and sympathovagal balance] were recorded and monitored before, during, and after anodal, cathodal, or sham tDCS. Ten MEPs, every 2.5-min time windows, were recorded from the right first dorsal interosseous (FDI), while 5-min epochs were used to record vital parameters. The protocol included 15 min of pre-tDCS and of online tDCS (anodal, cathodal, or sham). After-effects were recorded for 30 min. We showed a polarity-independent stabilization of cortical excitability level, a polarity-specific after-effect for cathodal and anodal stimulation, and an absence of persistent excitability changes during online stimulation. No significant effects on vital parameters emerged both during and after tDCS, while a linear increase in systolic/diastolic blood pressure and HRV was observed during each tDCS condition, as a possible unspecific response to experimental demands. Taken together, current findings provide new insights on the safety of monopolar tDCS, promoting its application both in research and clinical settings.

Using the robotic sixth finger and vibrotactile feedback for grasp compensation in chronic stroke patients

This paper presents a wearable robotic extra finger used by chronic stroke patients to compensate for the missing hand functions of the paretic limb. The extra finger is worn on the paretic forearm by means of an elastic band, and it is coupled with a vibrotactile ring interface worn on the healthy hand. The robotic finger and the paretic hand act like the two parts of a gripper working together to hold an object. The human user is able to control the flexion/extension of the robotic finger through a switch placed on the ring, while being provided with vibrotactile feedback about the forces exerted by the robotic finger on the environment. To understand how to control the vibrotactile interface to evoke the most effective cutaneous sensations, we carried out perceptual experiments to evaluate its absolute and differential thresholds. Finally, we performed a qualitative experiment, the Franchay Arm Test, with a chronic post-stroke patient presenting a partial loss of sensitivity on the paretic limb. Results show that the proposed system significantly improves the performance of the considered test.

Compensating Hand Function in Chronic Stroke Patients Through the Robotic Sixth Finger

A novel solution to compensate hand grasping abilities is proposed for chronic stroke patients. The goal is to provide the patients with a wearable robotic extra-finger that can be worn on the paretic forearm by means of an elastic band. The proposed prototype, the Robotic Sixth Finger, is a modular articulated device that can adapt its structure to the grasped object shape. The extra-finger and the paretic hand act like the two parts of a gripper cooperatively holding an object. We evaluated the feasibility of the approach with four chronic stroke patients performing a qualitative test, the Frenchay Arm Test. In this proof of concept study, the use of the Robotic Sixth Finger has increased the total score of the patients by two points in a five points scale. The subjects were able to perform the two grasping tasks included in the test that were not possible without the robotic extra-finger. Adding a robotic opposing finger is a very promising approach that can significantly improve the functional compensation of the chronic stroke patient during everyday life activities.

Relationship between the modified Rankin Scale and the Barthel Index in the process of functional recovery after stroke.

OBJECTIVE The modified Rankin Scale (mRS) and the Barthel Index (BI) are the most common clinimetrical instruments for measuring disability after stroke. This study investigated the relationship between the BI and the mRS at multiple time points after stroke. The BI, which is a widely used instrument for longitudinal follow-up post-stroke, was used as reference to determine the effect of time on the sensitivity of the mRS in differentiating functional recovery. METHODS Ninety-two patients with first stroke and hemispheric brain lesion were evaluated using the BI and mRS at 10 days, 3 and 6 months. The Kruskal-Wallis test was applied to examine median differences in BI among the mRS levels at 10 days, 3 and 6 months with Dunns correction for multigroup comparison. The Mann and Whitney test was used to compare median differences in BI scores between two aggregations of mRS grades (mRS=0-2, mRS=3-5) at the same time periods after stroke. RESULTS BI score distribution amongst mRS grades overlapped at 10 days, differentiating only between extreme grades (no disability vs severe disability). At 3 months, independent patients with slight disability could be distinguished from dependent patients with marked disability. At 6 months, grade 2 and 3 overlapped no more, differentiating independence (class 0-2) from dependence (class 3-5). The largest transition to an independent functional status occurred from grade 4, at 3 months. CONCLUSION Maximum sensitivity of mRS in differentiating functional recovery is reached at six months post-stroke.

Sensory axons excitability changes in carpal tunnel syndrome after neural mobilization

Increased mechanosensitivity of the median nerve in carpal tunnel syndrome (CTS) has been demonstrated during upper limb tension test 1 (ULTT1) when the nerve is passively elongated. However, the neurophysiological changes of the sensory axons during stressing activities are unknown. The aim of present study was to verify possible changes in the excitability of median nerve afferent axons following nerve stress in elongation, in subjects with and without CTS. Eight CTS hands and eight controls were selected. Recruitment properties of the median nerve were studied by analyzing the relationship between the intensity of electrical stimulation and the size of motor response, before and after intermittent-repetitive neural mobilization. Only in CTS hands, after the intervention, the stimulus–response curve was strikingly abnormal: both plateau and slope values were significantly lower. During anatomical stress across the median nerve in elongation, compressive forces may exert mechanical traction on the median nerve, since it is ‘tethered’ at the carpal tunnel, resulting inactivation of Na+ channels at the wrist, or impairment of energy-dependent processes which affect axonal conduction block. We conclude that in entrapment neuropathies, neural mobilization during nerve elongation may generate conduction failure in peripheral nerve. Our study supports specific considerations for patient education and therapeutic approaches.

Meaningful improvement in walking performance after Botulinum Neurotoxin A (BoNT-A) in chronic spastic patients

BACKGROUND Botulinum neurotoxin A (BoNT-A) may reduce lower limb spasticity but its role in improving walking ability remains to be established. OBJECTIVE To investigate the efficacy of simultaneous BoNT-A injections into several targeted spastic muscles of different joints on gait speed and on functional gains in gait performance in chronic stroke and MS patients. METHODS Twenty patients affected by stroke or multiple sclerosis were tested before, one and three months after BoNT-A administration. Gait was evaluated by the 10 Meter Walk Test; patients were stratified into functional ambulation classes accordingly. Spasticity was assessed using the modified Ashworth Scale. RESULTS At final assessment, spasticity was reduced in hip adductors and ankle plantar-flexors, gait speed improved and, 1/3rd of patients transitioned to a higher ambulation class. The pre-post difference in Level of Spasticity of the hips was a predictor for an increase in gait speed. CONCLUSIONS A meaningful improvement in walking performance can be obtained in chronic spastic patients after BoNT-A injection into several muscles, specifically the hip adductors.

Predictors of long-term recovery in complex activities of daily living before discharge from the stroke unit.

BACKGROUND AND PURPOSE There is a need for individuating those post-stroke patients who may benefit from an optimal and customised rehabilitation plan aiming at early reintegration in community life participation. This study investigated whether the gain of independence in complex Activities of Daily Living (ADL) may be predicted before the discharge from the stroke unit using simple bedside determinants. METHODS In 104 first-ever stroke patients with no previous disability, ten determinants at 10 days after stroke were selected. Multivariable logistic regression analysis was applied to identify the prognostic determinants able to predict independence in complex ADL, as measured by modified Rankin Scale grade ≤2. RESULTS The model shows that having a Barthel Index ≥9, a Motricity Index- Upper Limb ≥75, an age ≤70 and being a male resulted in 100% probability of achieving independence in complex ADL. If three of the four determinants were present, the probability was more than 90%. With the presence of two of the four determinants, the probability ranged from 87% to 28%. With the presence of only one determinant, the probability was 13%. CONCLUSIONS Accurate prediction of independence in complex ADL can be made before the discharge from the stroke unit. The strength of the paretic upper limb, age, gender, and the ability of performing basic ADL are the significant variables. The probability of favorable prognosis depends on the presence and on the robustness of each single determinant.

Individual factors enhance poor health-related quality of life outcome in multiple sclerosis patients. Significance of predictive determinants.

BACKGROUND Individual factors in multiple sclerosis (MS) patients may modify the reliability of health-related quality of life (HRQOL) assessment. Knowledge of these effects may enable physicians to identify patients at risk for poor perceived health. OBJECTIVE To investigate what individual factors may interact with MS symptoms and their severity to modify the reliability of HRQOL assessment; to explore the predictive values of the significant variables identified. METHODS HRQOL was assessed in 57 patients by the 36-Item Short Form Health Survey (SF-36). The Physical Component Summary and Mental Component Summary were dichotomized and applied as dependent variables for logistic regression analysis. The Functional Independence Measure (FIM), Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), Cognitive Behavioral Assessment (CBA) and specific individual factors were tested as independent variables. Two-way contingency tables were used to calculate the predictive values. RESULTS Unemployment, smoking, and night waking were the most significant individual factors. Introversion, physical pain and difficulty falling asleep were also significant. EDSS-total ≥2, EDSS-pyramidal ≥2, FIM ≤123, FSS ≥5, depressive manifestations and bowel/bladder dysfunction were significant MS-related determinants. Sensitivity and specificity differed widely for each variable. CONCLUSIONS Individual factors have relevance in HRQOL assessment. Their identification may help physicians construct the patients risk profile. Sensitivity and specificity add weight to the significance of variables.

A soft supernumerary robotic finger and mobile arm support for grasping compensation and hemiparetic upper limb rehabilitation

In this paper, we present the combination of our soft supernumerary robotic finger i.e.Soft-SixthFinger with a commercially available zero gravity arm support, the SaeboMAS. The overall proposed system can provide the needed assistance during paretic upper limb rehabilitation involving both grasping and arm mobility to solve task-oriented activities. The Soft-SixthFinger is a wearable robotic supernumerary finger designed to be used as an active assistive device by post stroke patients to compensate the paretic hand grasp. The device works jointly with the paretic hand/arm to grasp an object similarly to the two parts of a robotic gripper. The SaeboMAS is a commercially available mobile arm support to neutralize gravity effects on the paretic arm specifically designed to facilitate and challenge the weakened shoulder muscles during functional tasks. The proposed system has been designed to be used during the rehabilitation phase when the arm is potentially able to recover its functionality, but the hand is still not able to perform a grasp due to the lack of an efficient thumb opposition. The overall system also act as a motivation tool for the patients to perform task-oriented rehabilitation activities.With the aid of proposed system, the patient can closely simulate the desired motion with the non-functional arm for rehabilitation purposes, while performing a grasp with the help of the Soft-SixthFinger. As a pilot study we tested the proposed system with a chronic stroke patient to evaluate how the mobile arm support in conjunction with a robotic supernumerary finger can help in performing the tasks requiring the manipulation of grasped object through the paretic arm. In particular, we performed the Frenchay Arm Test (FAT) and Box and Block Test (BBT). The proposed system successfully enabled the patient to complete tasks which were previously impossible to perform.

A Soft Robotic Extra-Finger and Arm Support to Recover Grasp Capabilities in Chronic Stroke Patients

In this paper, we present the combination of the Soft-SixthFinger, a wearable robotic extra-finger designed to be used by chronic stroke patients to compensate for the missing hand function, with a robotic arm that is used as an assistive device to support the patient arm. The extra-finger is a tendon-driven modular structure worn at the paretic forearm. The robotic extra-finger is used jointly with the paretic hand/arm to grasp an object similarly to the two parts of a robotic gripper. The flexion/extension of the robotic finger is controlled by the patient using an Electromyography (EMG) interface embedded in a cap. The robotic arm is controlled to partially compensate for the weight of the paretic arm, while not interfering with the user arm motion. The system has been designed as a tool that can be used by chronic stroke patients to compensate for grasping in many Activities of Daily Living (ADL). We performed a pilot test to demonstrate that the proposed system can significantly improve the performance and the autonomy in ADL.