Risk, III.

Despite modern technological advances, the most widely available prostheses provide little functional recovery beyond basic grasping. Although sophisticated upper extremity prostheses are available, optimal prosthetic interfaces which give patients high-fidelity control of these artificial limbs are limited. We have developed a novel Regenerative Peripheral Nerve Interface (RPNI), which consists of a unit of free muscle that has been neurotized by a transected peripheral nerve. In conjunction with a biocompatible electrode on the muscle surface, the RPNI facilitates signal transduction from a residual peripheral nerve to a neuroprosthetic limb. The purpose of this study was to explore signal quality and reliability in an RPNI following an extended period of implantation. Following a 14-month maturation period, electromyographic signal generation was evaluated via electrical stimulation of the innervating nerve. The long-term RPNI was viable and healthy, as demonstrated by evoked compound muscle action potentials as well as histological tissue analysis. Signals exceeding 4 mV were successfully acquired and amplitudes were consistent across multiple repetitions of applied stimuli. There were no evident signs of muscle denervation, significant scar tissue, or muscle necrosis. This study provides further evidence that after a maturation period exceeding 1 year, reliable and consistent signals can still be acquired from an RPNI.

SUMMARYDuodenal varices are an unexpected source of upper gastrointestinal haemorrhage associated with high mortality. The prevalence of ectopic variceal bleeding accounts for 2-5% of all variceal bleeding; of this, only 17% occurs in the duodenum. Diagnosis is difficult, and insufficient evidence exists to demonstrate the best treatment option when haemorrhage occurs. We report the case of a 69-year-old man with a history of chronic alcoholism who presented to the emergency department (ED) with nausea, vomiting and several episodes of haematochezia. Diagnostic workup in the ED included CT with multiplanar reconstruction, which revealed a network of large tortuous blood vessels running near the second portion of the duodenum between the inferior vena cava and portal vein. The patient was emergently treated with endoscopic therapy and clipping of the vessel. This failed, and he was subsequently taken to the operating room for suture ligation of the bleeding duodenal varices. BACKGROUND