Steer by ear: Myoelectric auricular control of powered wheelchairs for individuals with spinal cord injury.

PURPOSE: Providing mobility solutions for individuals with tetraplegia remains challenging. Existing control devices have shortcomings such as varying or poor signal quality or interference with communication. To overcome these limitations, we present a novel myoelectric auricular control system (ACS) based on bilateral activation of the posterior auricular muscles (PAMs). METHODS: Ten able-bodied subjects and two individuals with tetraplegia practiced PAM activation over 4 days using visual feedback and software-based training for 1 h/day. Initially, half of these subjects were not able to voluntarily activate their PAMs. This ability was tested with regard to 8 parameters such as contraction rate, lateralized activation, wheelchair speed and path length in a virtual obstacle course. In session 5, all subjects steered an electric wheelchair with the ACS. RESULTS: Performance of all subjects in controlling their PAMs improved steadily over the training period. By day 5, all subjects successfully generated basic steering commands using the ACS in a powered wheelchair, and subjects with tetraplegia completed a complex real-world obstacle course. This study demonstrates that the ability to activate PAM on both sides together or unilaterally can be learned and used intuitively to steer a wheelchair. CONCLUSIONS: With the ACS we can exploit the untapped potential of the PAMs by assigning them a new, complex function. The inherent advantages of the ACS, such as not interfering with oral communication, robustness, stability over time and proportional and continuous signal generation, meet the specific needs of wheelchair users and render it a realistic alternative to currently available assistive technologies.

[Injury of polyester grafts by vascular clamps]. / Schädigung von Polyestergefässprothesen durch Gefässklemmen.

UNLABELLED: Protected vascular clamps are not new. Clamp associated damage of human arteries has already been published over 20 years ago. The necessity of protective clamps seems to have been forgotten. In our explant archive (230 explants) we have observed an accumulation of graft ruptures in the groin (13 of 25 ruptures). We presume a multifactorial process. Clamp damage could be part of it. The aim of this study is to prove the clamp induced damage of polyester vascular grafts and to examine whether protected clamps can reduce this. METHOD: Five unprotected (Aesculap(R) FB512R, FB502, FB517, Ulrich CC1235, CV3535) and 5 protected vascular clamp types (Aesculap(R) FB667, FB668, Edwards(R) - formally Baxter(R) - Fogarty(R) CV5050, CV5201, Edwards(R) Cosgrove(R) CV1033) were tested. A longitudinal burst test was performed after maximal clamp closure on 6 different, multifilament polyester yarns of 2 different vascular grafts manufacturers (B. Braun(R), Edwards(R)). RESULTS: The yarn tests with protected clamps showed no difference to those of the unclamped yarns. After clamping with unprotected vascular clamps the stress-strain-diagrams differed significantly. The mean, maximum burst strength was up to 75 % lower. Video documentation revealed filament ruptures. Damage of the yarn surface was seen on a simple woven graft in scanning electron microscopy (SEM). DISCUSSION: The application of unprotected vascular clamps on polyester vascular grafts is common in Germany (56 %). The observed damage of multifilament polyester yarns makes it necessary to re-consider the use of unprotected vascular clamps. The benefit for biological vessels has already been shown.

[Late complications after alloplastic vascular replacement]. / Spätkomplikationen nach alloplastischem Gefässersatz.

The follow-up of 273 AAA patients operated 1981-1985 showed a mean dilation of polyester grafts of 17.4% in 12 days and 34.8% in 3 years. This early dilation is due to mesh expansion of the warp knitted grafts. It has no clinical relevance. In contrary the late dilation after approximately 10 years is due to degradation. The evaluation of 436 explanted grafts attained from 75 hospitals showed graft rupture to be the cause of the explanation for 42/255 (16%) polyester grafts and 2/42 (5%) PTFE grafts. The most ruptures were observed in the surrounding of the inguinal ligament after 10 to 20 years of duration. In comparison to modern endovascular grafts the conventional polyester and PTFE grafts still are the gold standard of durability.

Prognosis of patients with juvenile chronic arthritis and juvenile spondyloarthropathy.

OBJECTIVE: Evaluation of the course and the prognosis of juvenile chronic arthritis (JCA) and juvenile spondyloarthropathy (JSpA). METHODS: The entire medical histories of 171 patients with JCA or JSpA were reviewed. The study cohort comprised 102 patients with oligoarticular, 17 with systemic, and 24 with polyarticular onset of JCA; 28 patients had a SpA; 91 patients with JCA from a population based cohort were included in that study cohort. The mean period of followup was 7.4 years. The probability of remission was estimated by survival analysis methods (Kaplan-Meier method). RESULTS: After a disease duration of 10 years the highest probability of complete remission was estimated for patients with oligoarticular or systemic onset of JCA (54% and 38%, respectively). In the oligoarthritis group with late onset of JCA, a lower probability of remission was found for the HLA-B27+ patients compared with HLA-B27- patients. Patients with polyarticular onset of JCA had the poorest prognosis, with a significantly lower probability of complete remission (15%) within 10 years, more secondary injuries, and a lower functional capacity at followup. Patients with JSpA showed a 17% probability of remission after a disease duration of 5 years and ranged between the remission rates for oligoarticular and polyarticular JCA. The estimated remission rates for the patients with JCA in the population based cohort and in the whole cohort were quite similar. CONCLUSION: Our data suggest a favorable prognosis for JCA and JSpA in general, but with differences among the subtypes. It seems that more than 50% of the patients with JCA and JSpA reach adulthood with active arthritis and need further rheumatological care.

Incidence and prevalence of juvenile chronic arthritis in East Berlin 1980-88.

OBJECTIVE: To estimate the incidence and prevalence rates of juvenile chronic arthritis (JCA). METHODS: The study population was children under 16 years of age living in the East Berlin area (part of the former German Democratic Republic). By admission order that was effective up to 1990, all children with symptoms of a rheumatic disease living in the East Berlin area had to be referred to the 2nd Children's Hospital at Berlin-Buch. This specific condition allowed us to ascertain cases from the clinical records and to calculate population rates. Based upon this data, the results of surveys with different methods of case ascertainment are compared. RESULTS: An incidence rate of 3.5 per 100,000 and a prevalence rate of 2.0 per 10,000 children were calculated. The frequency of JCA is higher for girls, with an incidence of 4.3 per 100,000 and a prevalence of 2.3 per 10,000. The figures for boys are 2.7 per 100,000 and 1.7 per 10,000, respectively. CONCLUSION: Because of the specific prerequisites, the population rates of prevalence and incidence that were based on clinical records can be regarded as valid in this study. Deviant results of other surveys can be explained by differences in the study design or in the diagnostic procedures used.

[Somatostatin receptor scintigraphy in the primary diagnosis and follow-up care of gastrinoma]. / Somatostatinrezeptor-Szintigraphie in der Primärdiagnostik und Nachsorge bei Gastrinomen.

Somatostatin receptor scintigraphy (SRS) was performed in 14 patients (five men, nine women; mean age 51.5 [20-71] years) with Zollinger-Ellison syndrome (ZES), a gastrinoma proven in 7 and suspected on clinical or biochemical grounds in 7. The results were compared with those obtained by other methods (ultrasound, computed tomography, angiography). All 12 known tumour manifestations were demonstrated by SRS in seven patients with histologically confirmed gastrinoma. In four patients previously non-localized tumour was revealed by SRS, while in seven other patients the procedure led to modification of the treatment (primary tumour resection: n = 3, resection of metastases: n = 2, percutaneous radiation or chemoembolization: one each). These results suggest the following indications for SRS: (1) staging or re-staging in histologically proven gastrinoma and (2) search for primary tumour in clinically and biochemically suspected ZES.