Establishing a natural communication interface between the user and the terminal device is one of the central challenges of hand neuroprosthetics research. Surface electromyography (EMG) is the most common source of neural signals for interpreting a user’s intent in these interfaces. However, how the capacity of EMG generation is affected by various clinical parameters remains largely unknown. In this study, we examined the EMG activity of forearm muscles recorded from 11 transradially amputated subjects who performed a wide range of movements. EMG recordings from 40 able-bodied subjects were also analyzed to provide comparative benchmarks. By using non-negative matrix factorization, we extracted the synergistic EMG patterns for each subject to estimate the dimensionality of muscle control, under the framework of motor synergies. We found that amputees exhibited less than four synergies (with substantial variability related to the length of remaining limb and age), whereas able-bodied subjects commonly demonstrate five or more synergies. The results of this study provide novel insight into the muscle synergy framework and the design of natural myoelectric control interfaces.

The proper management of a prolapsed rectal mass in a child or teenager is challenging. Given that the underlying etiology of a prolapsed rectal mass in this population is not always immediately clear, interdisciplinary assessment is often required. Juvenile polyps, more commonly presenting with bleeding than a prolapsed mass, can mimic the appearance of both hemorrhoids and the rectum itself -making a purely clinical diagnosis difficult. Presented here is a case of a prolapsed colorectal polyp in a teenage boy, who underwent manual reduction of the mass, followed by colonoscopy and endoscopic ligation. Further histological evaluation revealed it to be a juvenile retention polyp. Despite the rarity of polyp prolapse as a presenting symptom, this case underscores the importance of considering colonic polyps as the etiology of a prolapsed anorectal mass in a teenager.

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Dapsone is an antibiotic used in the management of dermatologic infections and opportunistic infection prophylaxis in developed countries. Methemoglobinemia (MetHb) is a known complication of dapsone use that can result in cyanosis. MetHb is an aberrant form of hemoglobin produced physiologically by autooxidation. An impairment in the process of auto-oxidation due to genetic defects or the use of drugs/toxins causes its levels to rise. Management involves timely recognition and the use of methylene blue (MB) or ascorbic acid. We describe the diagnosis and management of a patient with acquired MetHb as a result of dapsone use.