Facial nerve neurorrhaphy due to unexpected facial nerve injury during parotid gland tumor surgery

Controlled release of ciliary neurotrophic factor from bioactive nerve grafts promotes nerve regeneration in rats with facial nerve injuries

It is critical to repair severed facial nerves, as lack of treatment may cause long-term motor and sensory impairments. Ciliary neurotrophic factor (CNTF) plays an important role in terms of enhancing nerve axon regrowth and maturation during peripheral nerve regeneration after injury. However, simple application of CNTF to the transected nerve site does not afford functional recovery, because it is rapidly flushed away by bodily fluids. The aim of the present study was the construction of a new, bioactive composite nerve graft facilitating persistent CNTF delivery to aid the reconstruction of facial nerve defects. The in vitro study showed that the bioactive nerve graft generated sustainable CNTF release for more than 25 days. The bioactive nerve graft was then transplanted into the injury sites of rat facial nerves. At 6 and 12 weeks post-transplantation, functional and histological analyses showed that the bioactive nerve graft featuring immobilized CNTF significantly enhanced nerve regeneration in terms of both axonal outgrowth and Schwann cell proliferation in the rat facial nerve gap model, compared to a collagen tube with adsorbed CNTF that initially released high levels of CNTF. The bioactive nerve graft may serve as novel, controlled bioactive release therapy for facial nerve regeneration.

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).

Endoscopic versus conventional parotid gland excision: a systematic review and meta-analysis

The objective of this review was to conduct a systematic review and meta-analysis to compare endoscopic with conventional parotid tumour excision. Online databases including MEDLINE, EMBASE, EMCare, CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), the World Health Organization International Clinical Trials Registry (ICTRP), and the ISRCTN registry were all searched. All randomised controlled trials and observational studies comparing endoscopic with conventional parotid tumour excision were included. Five studies were identified and analysis was reported in forest plots with 95% confidence intervals. Outcomes of interest included operating time, cosmesis, blood loss, facial nerve injury, Frey syndrome, duration of hospital stay, and tumour recurrence. Endoscopic tumour excision had a comparable operating time to conventional resection with an insignificant mean difference (p=0.08). Scar cosmesis in the endoscopic group was superior (mean difference: 2.95, p<0.05) and it also reported a lower volume of blood loss (mean difference: -31.84, p<0.05). No significant difference was found in the incidence of facial nerve injury or Frey syndrome between the two groups, but overall, fewer miscellaneous complications were observed in the endoscopic cohorts. Endoscopic parotid surgery reported a shorter duration of hospital stay, and tumour recurrence was similar in both treatment arms. Endoscopic parotid gland surgery is an effective alternative to conventional approaches with comparable operating times, reduced blood loss and fewer complications, as well as shorter inpatient stay and improved cosmesis. Further studies are, however, required with longer follow-up periods to assess outcomes between different subtypes of parotid tumour.