Bursts of vagus nerve stimulation paired with auditory rehabilitation fail to improve speech sound perception in rats with hearing loss.

Hearing loss can lead to long-lasting effects on the central nervous system, and current therapies, such as auditory training and rehabilitation, show mixed success in improving perception and speech comprehension. Vagus nerve stimulation (VNS) is an adjunctive therapy that can be paired with rehabilitation to facilitate behavioral recovery after neural injury. However, VNS for auditory recovery has not been tested after severe hearing loss or significant damage to peripheral receptors. This study investigated the utility of pairing VNS with passive or active auditory rehabilitation in a rat model of noise-induced hearing loss. Although auditory rehabilitation helped rats improve their frequency discrimination, learn novel speech discrimination tasks, and achieve speech-in-noise performance similar to normal hearing controls, VNS did not enhance recovery of speech sound perception. These results highlight the limitations of VNS as an adjunctive therapy for hearing loss rehabilitation and suggest that optimal benefits from neuromodulation may require restored peripheral signaling.

Vagus nerve stimulation during training fails to improve learning in healthy rats.

Learning new skills requires neuroplasticity. Vagus nerve stimulation (VNS) during sensory and motor events can increase neuroplasticity in networks related to these events and might therefore serve to facilitate learning on sensory and motor tasks. We tested if VNS could broadly improve learning on a wide variety of tasks across different skill domains in healthy, female adult rats. VNS was paired with presentation of stimuli or on successful trials during training, strategies known to facilitate plasticity and improve recovery in models of neurological disorders. VNS failed to improve either rate of learning or performance for any of the tested tasks, which included skilled forelimb motor control, speech sound discrimination, and paired-associates learning. These results contrast recent findings from multiple labs which found VNS pairing during training produced learning enhancements across motor, auditory, and cognitive domains. We speculate that these contrasting results may be explained by key differences in task designs, training timelines and animal handling approaches, and that while VNS may be able to facilitate rapid and early learning processes in healthy subjects, it does not broadly enhance learning for difficult tasks.

Mid to Long-Term Outcomes of Grade III-B Open Tibial Fractures Definitively Managed With a Circular Frame: A 13-Year Prospective Database Study at a Major Trauma Center.

OBJECTIVES: The aim of this study was to report experience of a major trauma center utilizing circular frames as definitive fixation in patients sustaining Gustilo-Anderson 3B open tibial fractures. DESIGN: A prospectively maintained database was retrospectively interrogated. SETTING: Single major trauma center in the United Kingdom. PATIENT SELECTION CRITERIA: All patients over the age of 16 sustaining an open tibial fracture with initial debridement performed at the study center. All patients also received orthoplastic care for a soft tissue defect (via skeletal deformation or a soft tissue cover procedure) and subsequent definitive management using an Ilizarov ring fixator. Patients who received primary debridement at another center, had preexisting infection, sustained a periarticular fracture, or those who did not afford a minimum of 12-month follow-up were excluded. Case notes and radiographs were reviewed to collate patient demographics and injury factors. OUTCOME MEASURES AND COMPARISONS: The primary outcome of interest was deep infection rate with secondary outcomes including time to union and secondary interventions. RESULTS: Two hundred twenty-five patients met inclusion criteria. Mean age was 43.2 year old, with 72% males, 34% smokers, and 3% diabetics. Total duration of frame management averaged 6.4 months (SD 7.7). Eight (3.5%) patients developed a deep infection and 41 (20%) exhibited signs of a pin site infection. Seventy-nine (35.1%) patients had a secondary intervention, of which 8 comprised debridement of deep infection, 29 bony procedures, 8 soft tissue operations, 30 frame adjustments, and 4 patients requiring a combination of soft tissue and bony procedures. Bony union was achieved in 221 cases (98.2%), 195 (86.7%) achieved union in a single frame without the need for secondary intervention, 26 required frame adjustments to achieve union. Autologous bone grafts were used in 10 cases. CONCLUSIONS: Orthoplastic care including circular frame fixation for Gustilo-Anderson-3B fractures of the tibia resulted in a low rate of deep infection (3.5%) and achieved excellent union rates (98.2%). LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.