This study demonstrates the feasibility of detecting motor intent from brain activity of chronic stroke patients using an asynchronous electroencephalography (EEG)-based brain machine interface (BMI). Intent was inferred from movement related cortical potentials (MRCPs) measured over an optimized set of EEG electrodes. Successful intent detection triggered the motion of an upper-limb exoskeleton (MAHI Exo-II), to guide movement and to encourage active user participation by providing instantaneous sensory feedback. Several BMI design features were optimized to increase system performance in the presence of single-trial variability of MRCPs in the injured brain: (1) an adaptive time window was used for extracting features during BMI calibration; (2) training data from two consecutive days were pooled for BMI calibration to increase robustness to handle the day-to-day variations typical of EEG, and (3) BMI predictions were gated by residual electromyography (EMG) activity from the impaired arm, to reduce the number of false positives. This patient-specific BMI calibration approach can accommodate a broad spectrum of stroke patients with diverse motor capabilities. Following BMI optimization on day 3, testing of the closed-loop BMI-MAHI exoskeleton, on 4th and 5th days of the study, showed consistent BMI performance with overall mean true positive rate (TPR) = 62.7 ± 21.4% on day 4 and 67.1 ± 14.6% on day 5. The overall false positive rate (FPR) across subjects was 27.74 ± 37.46% on day 4 and 27.5 ± 35.64% on day 5; however for two subjects who had residual motor function and could benefit from the EMG-gated BMI, the mean FPR was quite low (< 10%). On average, motor intent was detected −367 ± 328 ms before movement onset during closed-loop operation. These findings provide evidence that closed-loop EEG-based BMI for stroke patients can be designed and optimized to perform well across multiple days without system recalibration.

Stroke is one of the leading causes of long-term disability today; therefore, many research efforts are focused on designing maximally effective and efficient treatment methods. In particular, robotic stroke rehabilitation has received significant attention for upper-limb therapy due to its ability to provide high-intensity repetitive movement therapy with less effort than would be required for traditional methods. Recent research has focused on increasing patient engagement in therapy, which has been shown to be important for inducing neural plasticity to facilitate recovery. Robotic therapy devices enable unique methods for promoting patient engagement by providing assistance only as needed and by detecting patient movement intent to drive to the device. Use of these methods has demonstrated improvements in functional outcomes, but careful comparisons between methods remain to be done. Future work should include controlled clinical trials and comparisons of effectiveness of different methods for patients with different abilities and needs in order to inform future development of patient-specific therapeutic protocols.

BackgroundPlatelet function disorders (PFDs) have emerged as an important etiology of heavy menstrual bleeding (HMB) in adolescents. However, neither clinical nor laboratory data have been methodically analyzed in this population subset. The objective of this study was to evaluate these parameters in order to distinguish characteristics of the disorder that in turn will lead to earlier diagnosis and therapy initiation.MethodsRetrospective review of medical records from postmenarcheal adolescents with documented PFDs referred to a hemophilia treatment center and university faculty practices for bleeding diatheses with their clinical and laboratory data evaluated.ResultsOf 63 teens with documented PFDs, HMB was the most common clinical manifestation of PFD (43; 68.3%). Of these, 37 (86%) were diagnosed with PFD either at or after menarche with the diagnosis based on HMB symptoms alone. Only 6 (14%) were diagnosed with a PFD prior to menarche, based on associated bleeding, i.e., epistaxis, ecchymosis, and all developed HMB after menstruation onset. Interestingly, 20 girls were diagnosed with a PFD prior to menarche and of these, only 6 (30%) went on to develop HMB after pubertal transition, while the majority (14; 70%) did not. The average age-at-PFD diagnosis was 14.5yrs, significantly differing from the 10.9yrs average age-at-PFD diagnosis in their counterparts that, after menarche, did not develop HMB (P<.01) Blood type O occurred significantly more frequently (76%) than national norms (P <.037). Incidence of δ-Storage Pool deficiency (δ-SPD) was significantly higher (74%) than their non-HMB cohorts (45%) (P <.007). Coagulation and von Willebrand factor studies were all normal. Abnormal closure times and aggregation studies were observed in 42% and 60%, respectively, of tested girls. In 25.6% for whom standard platelet studies were normal, electron microscopy detected reduced platelet δ-granules numbers (δ-SPD).ConclusionsAdolescents with PFDs and HMB appear to be clinically distinct from their non-HMB counterparts. This group of girls is characterized by HMB the major bleeding symptom, significantly high incidences of blood group O and the δ-SPD with a PFD diagnosed well after menarche. High false negative standard platelet function study results indicate additional diagnostic strategies, particularly for δ-SPD, should be considered.

This paper presents the performance characterization of the MAHI Exo-II, an upper extremity exoskeleton for stroke and spinal cord injury (SCI) rehabilitation, as a means to validate its clinical implementation and to provide depth to the literature on the performance characteristics of upper extremity exoskeletons. Individuals with disabilities arising from stroke and SCI need rehabilitation of the elbow, forearm, and wrist to restore the ability to independently perform activities of daily living (ADL). Robotic rehabilitation has been proposed to address the need for high intensity, long duration therapy and has shown promising results for upper limb proximal joints. However, upper limb distal joints have historically not benefitted from the same focus. The MAHI Exo-II, designed to address this shortcoming, has undergone a static and dynamic performance characterization, which shows that it exhibits the requisite qualities for a rehabilitation robot and is comparable to other state-of-the-art designs.