Micropatterned Poly(D,L-Lactide-Co-Caprolactone) Conduits With KHI-Peptide and NGF Promote Peripheral Nerve Repair After Severe Traction Injury

Severe traction injuries after stretch to peripheral nerves are common and challenging to repair. The nerve guidance conduits (NGCs) are promising in the regeneration and functional recovery after nerve injuries. To enhance the repair of severe nerve traction injuries, in this study KHIFSDDSSE (KHI) peptides were grafted on a porous and micropatterned poly(D,L-lactide-co-caprolactone) (PLCL) film (MPLCL), which was further loaded with a nerve growth factor (NGF). The adhesion number of Schwann cells (SCs), ratio of length/width (L/W), and percentage of elongated SCs were significantly higher in the MPLCL-peptide group and MPLCL-peptide-NGF group compared with those in the PLCL group in vitro. The electromyography (EMG) and morphological changes of the nerve after severe traction injury were improved significantly in the MPLCL-peptide group and MPLCL-peptide-NGF group compared with those in the PLCL group in vivo. Hence, the NGCs featured with both bioactive factors (KHI peptides and NGF) and physical topography (parallelly linear micropatterns) have synergistic effect on nerve reinnervation after severe traction injuries.

Functional and electron-microscopic changes after differential traction injury in the sciatic nerve of a rat

Background During maxillofacial trauma or oral cancer surgery, peripheral nerve might be damaged by traction injury. The purpose of this study was to evaluate functional and histomorphometric changes after traction nerve injury in the sciatic nerve of a rat model. Methods A total of 24 Sprague-Dawley rats were equally divided into three groups: unstretched (sham/control, group A), stretched with 0.7N (group B) and 1.5N (group C). Traction injury was performed for 10 min in B and C groups. Functional recovery of the sciatic nerve was evaluated by walking track analysis, toe spread test, and pinprick test 2 weeks after injury. The weight of gastrocnemius muscles of both sides was measured to evaluate weight ratio (ipsilateral/contralateral). Total number of axons, axon fiber size, myelin thickness, G-ratio, axon number/mm2, diameter of fiber, changes of longitudinal width, and formation of the edema and hematoma were evaluated by transmission electron microscopy. Results The sciatic function indexes were −11.48±4.0, −15.11±14.84, and −49.12±35.42 for groups A, B, and C, respectively. Pinprick test showed 3.0, 2.86±0.38, and 1.38±0.52 for A, B, and group C. Muscle weight ratios were 0.98±0.13 for group A, 0.70±0.10 for group B, and 0.54±0.05 for group C. There were significant differences in toe spread test, pinprick test, and muscle weight ratio between control group and experimental group (p<0.001). In the experimental group, fiber number, fiber size, G-ratio, fiber number/mm2, myelin thickness, diameter of fiber, and longitudinal width were decreased with statistical significance. Conclusion The present study demonstrated that the nerve traction injury in the rat sciatic nerve damaged the motor and sensory function and axonal integrity. The amount of functional nerve damage was proportional to the amount of traction power and dependent on the initial tensile strengths (0.7N and 1.5N).

Application of Novel Intraoperative Neuromonitoring System Using an Endotracheal Tube With Pressure Sensor During Thyroid Surgery: A Porcine Model Study

Objectives. The loss of signal during intraoperative neuromonitoring (IONM) using electromyography (EMG) in thyroidectomy is one of the biggest problems. We have developed a novel IONM system with an endotracheal tube (ETT) with an attached pressure sensor instead of EMG to detect laryngeal twitching. The aim of the present study was to investigate the feasibility and reliability of this novel IONM system using an ETT with pressure sensor during thyroidectomy in a porcine model.Methods. We developed an ETT-attached pressure sensor that uses the piezoelectric effect to measure laryngeal muscle twitching. Stimulus thresholds, amplitude, and latency of laryngeal twitching evaluated using the pressure sensor were compared to those measured using transcartilage needle EMG. The measured amplitude changes by EMG and the pressure sensor during recurrent laryngeal nerve (RLN) traction injury were compared.Results. No significant differences in stimulus threshold intensity between EMG and the pressure sensor were observed. The EMG amplitude detected at 0.3 mA, increased with increasing stimulus intensity. When the stimulus was more than 1.0 mA, the amplitude showed a plateau. In a RLN traction injury experiment, the EMG amplitude did not recover even 20 minutes after stopping RLN traction. However, the pressure sensor showed a mostly recovery.Conclusion. The change in amplitude due to stimulation of the pressure sensor showed a pattern similar to EMG. Pressure sensors can be feasibly and reliably used for RLN traction injury prediction, RLN identification, and preservation through the detection of laryngeal muscle twitching. Our novel IONM system that uses an ETT with an attached pressure sensor to measure the change of surface pressure can be an alternative to EMG in the future.