Biomechanical Analysis of Body Movements of Myoelectric Prosthesis Users During Standardized Clinical Tests.

OBJECTIVE: The objective clinical evaluation of user's capabilities to handle their prosthesis is done using various tests which primarily focus on the task completion speed and do not explicitly account for the potential presence of compensatory motions. Given that the excessive body compensation is a common indicator of inadequate prosthesis control, tests which include subjective observations on the quality of performed motions have been introduced. However, these metrics are then influenced by the examiner's opinions, skills, and training making them harder to standardize across patient pools and compare across different prosthetic technologies. Here we aim to objectively quantify the severity of body compensations present in myoelectric prosthetic hand users and evaluate the extent to which traditional objective clinical scores are still able to capture them. METHODS: We have instructed 9 below-elbow prosthesis users and 9 able-bodied participants to complete three established objective clinical tests: Box-and-Blocks-Test, Clothespin-Relocation-Test, and Southampton-Hand-Assessment-Procedure. During all tests, upper-body kinematics has been recorded. RESULTS: While the analysis showed that there are some correlations between the achieved clinical scores and the individual body segment travel distances and average speeds, there were only weak correlations between the clinical scores and the observed ranges of motion. At the same time, the compensations were observed in all prosthesis users and, for the most part, they were substantial across the tests. CONCLUSION: The sole reliance on the currently available objective clinical assessment methods seems inadequate as the compensatory movements are prominent in prosthesis users and yet not sufficiently accounted for.

Simultaneous and proportional control of wrist and hand degrees of freedom with kinematic prediction models from high-density EMG.

To improve intuitive control and reduce training time for active upper limb prostheses, we developed a myocontrol system for 3 degrees of freedom (DoFs) of the hand and wrist. In an offline study, we systematically investigated movement sets used to train this system, to identify the optimal compromise between training time and performance. High-density surface electromyography (HDsEMG) and optical marker motion capture were recorded concurrently from the lower arms of 8 subjects performing a series of wrist and hand movements activating DoFs individually, sequentially, and simultaneously. The root mean square (RMS) feature extracted from the EMG signal and kinematics obtained from motion capture were used to train regression and classification models to predict the kinematics of wrist movements and opening and closing of the hand, respectively. Results showed successful predictions of kinematics when training with the complete training set (r2 = 0.78 for wrist regression and recall = 0.85 for hand closing/opening classification). In further analysis, the training set was substantially reduced by removing the simultaneous movements. This led to a statistically significant, but relatively small reduction of the effectiveness of the wrist controller (r2 = 0.70, p<0.05), without changes for the hand controller (closing recall = 0.83). Reducing the training time and complexity needed to control a prosthesis with simultaneous wrist control as well as detection of intention to close the hand can lead to improved uptake of upper limb prosthetics.

Intramuscular EMG-Driven Musculoskeletal Modelling: Towards Implanted Muscle Interfacing in Spinal Cord Injury Patients.

OBJECTIVE: Surface EMG-driven modelling has been proposed as a means to control assistive devices by estimating joint torques. Implanted EMG sensors have several advantages over wearable sensors but provide a more localized information on muscle activity, which may impact torque estimates. Here, we tested and compared the use of surface and intramuscular EMG measurements for the estimation of required assistive joint torques using EMG driven modelling. METHODS: Four healthy subjects and three incomplete spinal cord injury (SCI) patients performed walking trials at varying speeds. Motion capture marker trajectories, surface and intramuscular EMG, and ground reaction forces were measured concurrently. Subject-specific musculoskeletal models were developed for all subjects, and inverse dynamics analysis was performed for all individual trials. EMG-driven modelling based joint torque estimates were obtained from surface and intramuscular EMG. RESULTS: The correlation between the experimental and predicted joint torques was similar when using intramuscular or surface EMG as input to the EMG-driven modelling estimator in both healthy individuals and patients. CONCLUSION: We have provided the first comparison of non-invasive and implanted EMG sensors as input signals for torque estimates in healthy individuals and SCI patients. SIGNIFICANCE: Implanted EMG sensors have the potential to be used as a reliable input for assistive exoskeleton joint torque actuation.

Intramuscular Stimulation of Muscle Afferents Attains Prolonged Tremor Reduction in Essential Tremor Patients.

This study proposes and clinically tests intramuscular electrical stimulation below motor threshold to achieve prolonged reduction of wrist flexion/extension tremor in Essential Tremor (ET) patients. The developed system consisted of an intramuscular thin-film electrode structure that included both stimulation and electromyography (EMG) recording electrodes, and a control algorithm for the timing of intramuscular stimulation based on EMG (closed-loop stimulation). Data were recorded from nine ET patients with wrist flexion/extension tremor recruited from the Gregorio Marañón Hospital (Madrid, Spain). Patients participated in two experimental sessions comprising: 1) sensory stimulation of wrist flexors/extensors via thin-film multichannel intramuscular electrodes; and 2) surface stimulation of the nerves innervating the same target muscles. For each session, four of these patients underwent random 60-s trials of two stimulation strategies for each target muscle: 1) selective and adaptive timely stimulation (SATS) - based on EMG of the antagonist muscle; and 2) continuous stimulation (CON) of target muscles. Two patients underwent SATS stimulation trials alone while the other three underwent CON stimulation trials alone in each session. Kinematics of wrist, elbow, and shoulder, together with clinical scales, were used to assess tremor before, right after, and 24 h after each session. Intramuscular SATS achieved, on average, 32% acute (during stimulation) tremor reduction on each trial, while continuous stimulation augmented tremorgenic activity. Furthermore, tremor reduction was significantly higher using intramuscular than surface stimulation. Prolonged reduction of tremor amplitude (24 h after the experiment) was observed in four patients. These results showed acute and prolonged (24 h) tremor reduction using a minimally invasive neurostimulation technology based on SATS of primary sensory afferents of wrist muscles. This strategy might open the possibility of an alternative therapeutic approach for ET patients.

Morphological characteristics of optical coherence tomography defined plaque fissure in patients with acute coronary syndrome.

We assessed the plaque disruption in 245 consecutive patients with acute coronary syndrome undergoing percutaneous coronary intervention. The plaque fissure was diagnosed with optical coherence tomography, and intravascular ultrasound was used to determine arterial remodeling. Of them, 26 fissures were found in this study. The definite fissure was seen in 17 (65.4%) and probable fissure was seen in 9 (34.6%) patients. In 18 (69.2%), plaque fissure component was lipidic or thin-capped fibroatheroma. Eighteen (69.2%) of fissured plaque were seen within 30 mm of coronary ostium. Combined plaque fissure with plaque rupture/erosion was seen in 21 (80.8%) cases. The isolated fissure was seen in 5 (19.2%). Compared to the maximal necrotic core site of the ruptured plaque, the fissure site showed a smaller %necrotic core (p = 0.012), however, greater in fissure site than minimal lumen area site (24.93 ± 11.50% vs 15.34 ± 10.40%, p < 0.0001). The remodeling index was higher at fissure site as compared to minimal lumen area site (1.02 ± 0.22 vs 0.94 ± 0.27; p = 0.047), but similar to the rupture plaque (p = 0.31). The frequency of positive remodeling was 34.6% (9/26) at the plaque fissure. Although the plaque fissure can be interchangeable with the rupture in acute coronary syndrome, the limited extension to the small lipid core might and less positive remodeling provoke a fissuring of the plaque. Further study is necessary to assess the plaque fissure.

Choroidal and skin metastases from colorectal cancer.

Choroidal and skin metastasis of colon cancer is rare. In women, the frequency of cutaneous metastasis from colon cancer as the primary lesion in is 9% and skin metastasis occurs in 0.81% of all colorectal cancers. We report a patient with colonic adenocarcinoma who presented with visual disorder in her right eye and scalp pain as her initial symptoms. Contrast-enhance orbital magnetic resonance imaging with fat suppression revealed an infrabulbar mass, and skin biopsy of the posterior parietal scalp confirmed adenocarcinoma. These symptoms were diagnosed as being caused by choroidal and skin metastases of colonic adenocarcinoma. We started palliative chemotherapy with oral capecitabine (1000 mg/m2, twice a day, on days 1-14) every 3 wk, which was effective at shrinking the brain masses and improving the visual disorder. This is the first report that capecitabine is effective at reducing a choroidal and cutaneous metastatic lesion from right-sided colorectal cancer.

Prevalence of Barrett's esophagus in Korea.

BACKGROUND: In contrast to Western countries, the prevalence of Barrett's esophagus (BE) is still believed to be very low in the Far East. The aim of the present paper was to assess the prevalence of BE in Korea. METHODS: Nine hundred and ninety-two consecutive patients undergoing their first diagnostic upper gastrointestinal endoscopies due to various indications were included from four university hospitals in Korea. Esophagus of each patient was examined during insertion of the endoscope with minimum air inflation. From subjects who were found, during endoscopy, to have columnar-lined esophagus, at least two biopsy samples were taken from the columnar epithelium. Patients exhibiting specialized columnar epithelium on histological examination were diagnosed as having BE. RESULTS: Among 992 patients, 108 cases (10.9%) were endoscopically diagnosed as short-segment BE, and three cases (0.3%) were endoscopically diagnosed as long-segment BE. However, only 36 patients (3.6%) met the histological criteria for BE. Among these patients, only one (0.1%) was histologically diagnosed as having long-segment BE. Reflux esophagitis, mostly in a mild degree, was found in 25.0% of the BE group, and 8.6% of the non-BE group (P = 0.0022). Hiatal hernias were more commonly found in the BE group than in the non-BE group (22.2% vs 8.9%, P = 0.0163). CONCLUSIONS: Although the prevalence of BE in Korea appears to be lower than the reported rates from Western countries, it may not be as low as was previously thought.

Biliary drainage by endoscopic choledochoduodenal fistulotomy in patients with papillary carcinoma.

BACKGROUND: There are few reports of endoscopic choledochoduodenal fistulotomy (endoscopic fistulotomy) in patients with papillary carcinoma by using a needle-knife. METHODS: Among 35 patients with papillary carcinoma requiring biliary drainage, 14 with a suprapapillary bulge underwent endoscopic fistulotomy alone or with widening of the fistula by using a standard sphincterotome or dilation balloon catheter. OBSERVATIONS: Transfistula bile duct cannulation was successful on the first attempt in 13 of 14 patients (93%) and temporary biliary drainage through the fistula was successfully established in all 13 patients. The single complication was minor bleeding (7%) in 1 patient. In 6 patients with biliary obstruction who were not operative candidates, endoscopic fistulotomy was used for palliation, and all remained asymptomatic for a mean period of 3.2 months. CONCLUSIONS: Endoscopic fistulotomy is an effective, relatively safe biliary drainage procedure. It should be considered in selected patients with bile duct obstruction caused by papillary carcinoma and a suprapapillary bulge caused by the dilated bile duct.