Recent experiments in rats have demonstrated significant effects of VNS on hippocampal excitability but were partially attributed to hypothermia, induced by the applied VNS parameters. To allow meaningful preclinical research on the mechanisms of VNS and translation of rodent results to clinical VNS trials, we aimed to identify non-hypothermia inducing VNS parameters that significantly affect hippocampal excitability. VNS was administered in cycles of 30 s including either 0.1, 0.16, 0.25, 0.5, 1.5, 3 or 7 s of VNS ON time (biphasic pulses, 250μs/phase, 1 mA, 30 Hz) and the effect of different VNS ON times on brain temperature was evaluated. VNS paradigms with and without hypothermia were compared for their effects on hippocampal neurophysiology in freely moving rats. Using VNS parameters with an ON time/OFF time of up to 0.5 s/30 s did not cause hypothermia, while clear hypothermia was detected with ON times of 1.5, 3 and 7 s/30 s. Relative to SHAM VNS, the normothermic 0.5 s VNS condition significantly decreased hippocampal EEG power and changed dentate gyrus evoked potentials with an increased field excitatory postsynaptic potential slope and a decreased population spike amplitude. VNS can be administered in freely moving rats without causing hypothermia, while profoundly affecting hippocampal neurophysiology suggestive of reduced excitability of hippocampal neurons despite increased synaptic transmission efficiency.

The invasive nature of brain implants remains a major limitation in neuromodulation strategies, often leading to chronic inflammation. To address this, soft coatings are applied on rigid probes to reduce the mechanical mismatch at the interface, or flexible probes are implemented accompanied by temporary stiffeners. This study presents a hybrid strategy integrating both approaches by applying a permanent hydrogel coating onto flexible neural probes. Moreover, we utilise the applied coatings as tool for post-operative non-invasive imaging via functionalisation of the hydrogel with 5-acrylamido-2,4,6-triiodoisophthalic acid (AATIPA), a monomer that increases radiodensity. Rheological measurements confirmed that AATIPA incorporation did not significantly alter the hydrogels’ mechanical properties (storage moduli ranging from 139 ± 33.5 to 186 ± 55.5 kPa). Subsequently, we show that coated flexible probes exhibited a two-fold increase in critical buckling force compared to uncoated counterparts, indicating improved mechanical robustness evidenced through enhanced insertion performance in agarose brain phantoms. The mechanical contrast supports the dual purpose of the material in our application: the coatings provide stiffness to facilitate probe insertion in the dry state, while transitioning to a compliant, soft interface upon swelling, post-implantation. Finally, the radiodense coating enabled successful visualization of the probes in the hippocampus of a mouse model using μ-CT imaging. This approach offers a promising route for improving the mechanical and imaging performance of neural implants, potentially reducing reliance on post-mortem histology and enhancing real-time feedback in neuromodulation research.

The COVID-19 pandemic highlighted the need for efficient use of hospital infrastructure. The hypothesis was that a rapid shift to outpatient surgery after hip or knee arthroplasty could be implemented without compromising quality of care. The aim of this study was to assess the safety, pain management and patient-reported outcomes before and after the implementation of an accelerated discharge program using a digital follow-up tool. A retrospective cohort design was used to compare 97 patients who received primary total hip or knee arthroplasty during the pandemic (early discharge) to comparable 194 pre-pandemic patients (normal discharge). Both cohorts had the same inclusion criteria and were closely monitored using the digital follow-up tool. The accelerated discharge program reduced length of stay from a median of 3 days (before the pandemic) to a median of 1 day (during the pandemic) (p < 0.001). The complication rate of 2% was the same for both groups (p > 0.05). Patient-reported outcomes for matched samples of hip (n = 100) and knee (n = 82) arthroplasty patients were similar before, at 6 weeks and 3 months after surgery for both groups (p > 0.05). There were no differences in pain and medication consumption for the first 6 weeks (p > 0.05). This study demonstrates that reducing length of stay from three to one night after total knee or hip arthroplasty, with the help of a digital follow-up tool, results in a stable rate of complications, readmission, and comparable clinical outcomes, while reducing the socio-economic burden on the health system.