Effect of topical dexamethasone in reducing dysfunction after facial nerve crush injury in the rat

Effect of Interventional Ultrasound in the Treatment of Postthyroidectomy Vocal Cord Dysfunction: A Preliminary Exploratory Study

PURPOSE

To explore the efficacy of interventional ultrasound treatment for hoarseness caused by nondisconnected recurrent laryngeal nerve injury after thyroidectomy.

MATERIALS AND METHODS

In this retrospective study, we analysed the clinical data of 21 patients who underwent interventional ultrasound therapy (ultrasound-guided injection of a Diprospan and saline mixture) for postthyroidectomy hoarseness at our hospital between August 1, 2023, and January 31, 2024 (the Diprospan group) and randomly selected 21 patients who did not receive any treatment for postthyroidectomy hoarseness during the same period as the control group. The average vocal cord activity improvement time for the Diprospan group was calculated and compared with that of untreated patients from previous studies. Vocal cord activity improvement rates were assessed at 1, 2, and 3 mo after thyroidectomy, and changes in the voice handicap index (VHI) and the subjective listening perception scale (GRBAS) scores before and after treatment were evaluated. Additionally, the efficacy was compared between patients treated within 2 wk (timely intervention group, TI group) and those treated 2 wk after thyroidectomy (delayed intervention group, DI group) to explore the impact of treatment timing on outcomes.

RESULTS

In the Diprospan group, the average vocal cord activity improvement time was 44.6 ± 4.7 d for those treated within 2 wk after thyroidectomy and 17.7 ± 1.5 d for those treated 2 wk after thyroidectomy, both of which were significantly shorter than the 6 mo to 1 y reported in the literature. The improvement rates at 1, 2, and 3 mo after thyroidectomy were significantly greater in the Diprospan group than in the control group (0.0% vs. 28.6%, 23.8% vs. 81.0%, 33.3% vs. 90.5%, p < 0.05). The VHI score (72.6 ± 21.2 vs. 12.6 ± 24.7, p < 0.001) and GRBAS score (12.0 vs. 0.0, p < 0.001) significantly improved after treatment. Compared with the DI group, the TI group also showed faster voice recovery (19.8 ± 5.8 d vs. 14.0 ± 2.6 d, p < 0.05). No treatment-related adverse reactions were observed.

CONCLUSION

Interventional ultrasound is a safe and effective treatment for hoarseness after thyroidectomy, as it effectively improves vocal cord mobility and accelerates voice recovery.

The functional and biological effects of systemic dexamethasone on mice with facial nerve crushing injury

BACKGROUND

Corticosteroid therapy is commonly recommended for acute facial nerve weakness; however, its effectiveness in treating traumatic nerve injuries remains controversial. This study investigated the functional recovery and cellular effects of systemic dexamethasone administration after facial nerve injury.

METHODS

C57BL/6 mice were assigned to two groups by intraperitoneal injection: the phosphate-buffered saline group and the dexamethasone group. Facial nerve crush injury was induced, followed by the functional grading of recovery. Cellular effects were investigated using transmission electron microscopy, flow cytometry, immunofluorescence, and intravital imaging.

RESULTS

Macrophage infiltration into the facial nerves was significantly inhibited by systemic dexamethasone administration. However, dexamethasone group slightly delayed the functional recovery of the facial nerve compared to the PBS group. In addition, the morphological changes in the nerve were not significantly different between the two groups at 14 days post-injury. Macrophage migration analysis in the intravital imaging also showed no difference between groups.

CONCLUSIONS

In summary, systemic dexamethasone successfully inhibited leukocyte infiltration; however, functional recovery was delayed compared to the PBS control group. Clinically, these findings indicate that more evidence and research are required to use steroid pulse therapy for the treatment of traumatic facial nerve injuries.

A systematic review of steroid use in peripheral nerve pathologies and treatment

Background

The use of corticosteroids has become a part of the standard of care in various pathologies but their use in peripheral nerve injury treatment is limited. Given corticosteroids' anti-inflammatory properties and their regulatory role in neuronal protein production and myelination, corticosteroids could serve as an adjunct therapy for peripheral nerve injuries. This review aims to systematically investigate the current use of corticosteroid treatment in peripheral nerve pathologies.

Methods

The systematic search was performed on PubMed, MEDLINE, EMBASE, Scopus, Cochrane, and Web of Science using keywords such as "corticosteroid treatment," "peripheral nerve damage," "peripheral neuropathy," and "complications." The PRISMA guidelines were used to conduct the systematic review and all articles were reviewed by the corresponding author. After the initial search, individual study titles and abstracts were further screened and categorized using an inclusion and exclusion criteria followed by a final full-text review.

Results

Out of the total 27,922 identified records, 203 studies were included based on the selection criteria. These studies focused on the use and efficacy of steroids across a spectrum of compression and non-compression peripheral neuropathies such as cubital tunnel syndrome and chronic inflammatory demyelinating polyradiculoneuropathy. Various studies noted the promising role of steroids in offering pain relief, nerve block, and nerve regeneration effects. Additionally, safety considerations and potential complications regarding steroid use in peripheral nerve injuries were analyzed.

Conclusion

While there is currently limited clinical utilization of corticosteroids in peripheral nerve pathologies, the anti-inflammatory and regenerative effects that steroids provide may be a beneficial tool in managing various peripheral neuropathies and their associated pain. Additional clinical trials and investigation into the mechanism of action could improve the reputation of steroid use as peripheral nerve injury treatment.

Establishment of a facial nerve trunk crush injury model and evaluation of facial nerve self-healing in rats

INTRODUCTION/AIMS

To facilitate further investigation into the mechanisms of facial nerve regeneration, a simple and reliable model of facial nerve crush injury is essential. Nevertheless, the establishment of such models lacks standardization and repeatability, while the healing capacity of the nerve is often overlooked, potentially affecting future studies.

METHODS

We made facial nerve trunk crush injury models with different pressing times and detected the changes from the distal nerves to the motoneurons via behavior analysis, electrophysiological test, and histomorphometry analysis.

RESULTS

It revealed a particular capacity for self-healing following facial nerve crush damage because there was almost no facial motoneuron apoptosis in the MC group during the observation period, and rats in MC group had total facial paralysis in behavioral tests following surgery and varying degrees of recovery 28 days postoperatively with no treatments. As the pressing time increased, the latency, wave amplitude, nerve fiber damage degree, nerve axon ratio, myelin thickness, electroneurograph (ENoG) value, ultrastructural damage, abnormal morphological changes, and the buccal muscle atrophy of each MC group gradually increased or got worse during the observation period. However, after 28 postoperative days, only the ENoG values of the M10min and M12min groups were beyond 90%, indicating no self-healing.

DISCUSSION

It suggests that a stable model of peripheral facial palsy may be created by applying a 12.5 cm mosquito clamped to the facial nerve trunk for at least 10 min, which laid the foundation for the subsequent research to objectively evaluate facial nerve regeneration.

Effect of Metformin on the Functional and Electrophysiological Recovery of Crush Injury-Induced Facial Nerve Paralysis in Diabetic Rats

The impact of metformin on the rat facial nerve following crush injury has only occasionally been documented to date. The purpose of the current investigation was to use functional and electrophysiological evaluations to investigate the effects of metformin administration on recovery following crush injury to the rat facial nerve. The rats were randomly divided into four groups: the nonDM/PBS group (n = 4), the nonDM/metformin group (n = 4), the DM/PBS group (n = 4), and the DM/metformin group (n = 4). Diabetes was generated by an intraperitoneal injection of streptozotocin. Facial nerve paralysis was induced by a crush injury 7 days after diabetes induction. The blood glucose levels of the DM/PBS and DM/metformin groups were maintained at over 300 mg/dL, whereas the blood glucose levels of the nonDM/PBS and nonDM/metformin groups were maintained at less than 150 mg/dL. There was no significant difference between the two nonDM groups. In comparison to the PBS group, the metformin group's recurrence of vibrissa fibrillation occurred noticeably sooner over time. The nonDM/metformin group showed the highest recovery rate in the second, third, and fourth weeks post-crush, respectively. The threshold of action potential 4 weeks after crush injury showed that the nonDM/metformin group had a significantly lower mean threshold of MAP compared to other groups. The short-term effect of metformin on the recovery of facial nerve blood flow (FNBF) was significantly increased compared to the DM/PBS group. However, there was no significant difference in FNBF between the nonDM/metformin and nonDM/PBS groups. A diabetic condition promoted a delay in FN regeneration. Metformin is able to accelerate functional recovery in diabetic or nondiabetic FN-injured rats. Further studies using a morphometric or molecular approach are planned to understand the pharmacologic mechanism of metformin.

Effects of platelet-rich fibrin and dexamethasone on nerve regeneration after acute facial-nerve injury

BACKGROUND

Acute facial-nerve injury.

OBJECTIVE

To investigate the effects of platelet-rich fibrin (PRF) and dexamethasone on nerve regeneration.

MATERIALS AND METHODS

Thirty-six rats were randomly divided into six groups. Facial-nerve injury was created using a full-thickness incision in all groups except Group E. Next, primary anastomosis, PRF application, topical dexamethasone application, primary anastomosis with topical PRF and dexamethasone application, and no facial-nerve repair were performed in Groups A, B, C, D, and F, respectively. Clinical, functional, and structural improvements were evaluated at eight weeks.

RESULTS

The mean eye-closure movement score in Group B was significantly higher than that in Group F (p < .001). The mean whisker-movement score in Group B was significantly higher than that in Group F (p = .001). The mean amplitude of whisker movement in Group F was significantly lower than those in Groups A, B, C, and E, and the mean amplitude in Group D was significantly lower than that in Group E (p < .001). Furthermore, an improvement in nerve ultrastructure was observed in Group B.

CONCLUSION

PRF application has a positive effect on nerve recovery after anastomosis.

SIGNIFICANCE

Contribute to the literature to improve nerve regeneration.

Review of Drug Therapy for Peripheral Facial Nerve Regeneration That Can Be Used in Actual Clinical Practice

Although facial nerve palsy is not a life-threatening disease, facial asymmetry affects interpersonal relationships, causes psychological stress, and devastates human life. The treatment and rehabilitation of facial paralysis has many socio-economic costs. Therefore, in cases of facial paralysis, it is necessary to identify the cause and provide the best treatment. However, until now, complete recovery has been difficult regardless of the treatment used in cases of complete paralysis of unknown cause and cutting injury of the facial nerve due to disease or accident. Therefore, this article aims to contribute to the future treatment of facial paralysis by reviewing studies on drugs that aid in nerve regeneration after peripheral nerve damage.

Tetrahedral framework nucleic acids facilitate neurorestoration of facial nerves by activating the NGF/PI3K/AKT pathway

The facial nerve is a crucial nerve in the maxillofacial region and is vulnerable to damage. As a consequence of the complications during nerve restoration, existing remedies have certain limitations, thus the treatment of facial nerve injury is always a perplexing task for people. Regulation of Schwann cells is always the breakpoint of neurorestoration since Schwann cells count a great deal in injured nerve repair. In this study, we presented proof that tetrahedral framework nucleic acids (tFNAs), a kind of nucleic acid nanomaterial, were capable of regulating the neurorestorative pathway NGF/PI3 K/AKT, resulting in the activation of a series of cell behaviors related to injured nerve restoration such as proliferation and migration. In vivo experiments also proved that tFNAs enhanced the expressions of axon and myelin marker proteins, impelled histological recovery, promoted the efficient restoration of nerve conduction and muscle movement. Additionally, tFNAs possessed excellent biocompatibility and superior endocytosis ability. Thus, there is good potential for tFNAs to be applied in the therapy of facial nerve injury or even peripheral nerve injury.

The effects of 4-aminopyridine and methylprednisolone on recovery of the facial nerve crush injury

OBJECTIVE

4-Aminopyridine (4-AP) is a potassium channel blocker that enhances nerve excitability. In this study, rat models that have facial nerve crush injury (FNCI) were grouped and treated with methylprednisolone (MP), 4-AP, and a combination of these two drugs. Electrophysiologic and histopathologic outcomes of these groups will be compared with a control group.

MATERIALS AND METHODS

Thirty healthy male Wistar rats (mean weight of 265 g) were used in this study. The rats were randomly divided into five groups with six subjects in each: Group 1 (sham group), Group 2 (control group), Group 3 (MP group), Group 4 (4-aminopyridine group), and Group 5 (4-AP + MP group). All groups except the sham group underwent crush injury to the right facial nerve. Electrophysiologic and histologic recovery was recorded three weeks postoperatively.

RESULTS

The 4-AP group and the combined group had a more significant recovery at Nerve Excitability Thresholds (NET) at the end of three weeks. The methylprednisolone group and the control group had a minimal recovery of NET. Histologically, when compared with the control group, the combined group was the only group that had significant recovery at all three of axonal degeneration, axon diameter, and myelin thickness.

CONCLUSION

In this experimental study, we demonstrated that a combination treatment of 4-AP and MP is more effective in the recovery of peripheric FNCI than in the no-treatment control group and in the 4-AP- or MP-alone groups. Moreover, our results suggested that 4-AP can be a potent alternative to MP in the treatment of the FNCI.

LEVEL OF EVIDENCE

N/A.

Recent Findings on the Effects of Pharmacological Agents on the Nerve Regeneration after Peripheral Nerve Injury

Peripheral nerve injuries (PNIs) are accompanied with neuropathic pain and functional disability. Despite improvements in surgical repair techniques in recent years, the functional recovery is yet unsatisfied. Indeed a successful nerve repair depends not only on the surgical strategy but also on the cellular and molecular mechanisms involved in traumatic nerve injury. In contrast to all strategies suggested for nerve repair, pharmacotherapy is a cheap, accessible and non-invasive treatment that can be used immediately after nerve injury. This study aimed to review the effects of some pharmacological agents on the nerve regeneration after traumatic PNI evaluated by functional, histological and electrophysiological assessments. In addition, some cellular and molecular mechanisms responsible for their therapeutic actions, restricted to neural tissue, are suggested. These findings can not only help to find better strategies for peripheral nerve repair, but also to identify the neuropathic effects of various medications and their mechanisms of action.

Effects of Melatonin and Dexamethasone on Facial Nerve Neurorrhaphy

OBJECTIVES

To investigate the effects of topical and systemic administrations of melatonin and dexamethasone on facial nerve regeneration.

MATERIALS AND METHODS

In total, 50 male albino Wistar rats underwent facial nerve axotomy and neurorrhaphy. The animals were divided into 5 groups: control, topical melatonin, systemic melatonin, topical dexamethasone, and systemic dexamethasone. Nerve conduction studies were performed preoperatively and at 3, 6, 9, and 12 weeks after drug administrations. Amplitude and latency of the compound muscle action potentials were recorded. Coapted facial nerves were investigated under light and electron microscopy. Nerve diameter, axon diameter, and myelin thickness were recorded quantitatively.

RESULTS

Amplitudes decreased and latencies increased in both the melatonin and dexamethasone groups. At the final examination, the electrophysiological evidence of facial nerve degeneration was not significantly different between the groups. Histopathological examinations revealed the largest nerve diameter in the melatonin groups, followed by the dexamethasone and control groups (p<0.05). Axon diameter of the control group was smaller than those of the melatonin (topical and systemic) and topical dexamethasone groups (p<0.05). The melatonin groups had almost normal myelin ultrastructure.

CONCLUSION

Electrophysiological evaluation did not reveal any potential benefit of dexamethasone and melatonin in contrast to histopathological examination, which revealed beneficial effects of melatonin in particular. These agents may increase the regeneration of facial nerves, but electrophysiological evidence of regeneration may appear later.

Intraoperative Corticosteroids for Voice Outcomes among Patients Undergoing Thyroidectomy: A Systematic Review and Meta-analysis

Objective

To determine if a preoperative dose of intravenous corticosteroids reduces the risk of postoperative recurrent laryngeal nerve palsy and improves subjective voice outcomes among patients undergoing thyroidectomy.

Data Sources

PubMed, Cochrane database, and EMBASE.

Review Methods

Randomized controlled trials comparing corticosteroids with placebo on voice outcomes in thyroid surgery were extracted with standardized search criteria. Systematic review and meta-analysis were performed. With random effects models, trial data were pooled to determine the overall rate of recurrent laryngeal nerve palsy as well as secondary outcomes of adverse events, including wound infection and hyperglycemia.

Results

Four studies with a total of 517 patients met inclusion criteria. The overall rate of recurrent laryngeal nerve palsy was 5.78%. There was no difference in the rate of palsy between the corticosteroid and placebo groups (risk ratio, 0.70; 95% CI, 0.34-1.44). There was also no difference between the groups in regard to wound infection, healing, or hyperglycemia.

Conclusions

Preoperative corticosteroids do not appear to reduce the risk of recurrent laryngeal nerve palsy following thyroid surgery. There is insufficient evidence to assess its effect on subjective voice outcomes. More robust randomized controlled trials are needed to assess the effectiveness of perioperative steroids in improving voice outcomes after thyroidectomy.

The effect of n-acetyl-cysteine on recovery of the facial nerve after crush injury

OBJECTIVE

Facial nerve dysfunction can vary in severity and recovery is dependent on the character of the injury. N-acetyl-cysteine prevents oxidative stress and cellular damage, and its use in the setting of nerve dysfunction from crush injury has not yet been established. In this study, rats with facial nerve crush injury will be treated with n-acetyl-cysteine or control and functional recovery and electrophysiologic outcome will be compared.

STUDY DESIGN

Prospective, randomized animal study.

METHODS

Twenty-four Wistar rats underwent unilateral facial nerve crush injury. Rats were implanted with a subcutaneous osmotic pump filled with saline (n = 12) or n-acetyl-cysteine 50 mg/kg/day (n = 12). Functional and electromyographic recovery was recorded at two and four weeks postoperatively.

RESULTS

When compared to untreated rats, n-acetyl-cysteine treated rats had a greater electromyography amplitude recovery at 2 weeks with regard to eye blink (p=0.006) but not vibrissae function. At four weeks, the electromyography amplitude recovery of the vibrissae function was greater in n-acetyl-cysteine treated rats (P=0.001), but the amplitude recovery difference in eye blink was only marginally significant between groups (p=0.07). The functional score was higher in n-acetyl-cysteine-treated rats than in untreated rats at all of the time points.

CONCLUSION

This study demonstrated that n-acetyl-cysteine facilitated facial nerve recovery with improved functional and electromyography outcomes in the setting of crush injury.

LEVEL OF EVIDENCE

NA.

Coadministration of Dexamethasone and Melissa officinalis Has Neuroprotective Effects in Rat Animal Model with Spinal Cord Injury

Objective

Spinal cord injury (SCI) causes inflammation, deformity and cell loss. It has been shown that Melissa officinalis (MO), as herbal medicine, and dexamethasone (DEX) are useful in the prevention of various neurological diseases. The present study evaluated combinational effects of DEX and MO on spinal cord injury.

Materials and Methods

Thirty six adult male Wistar rats were used in this experimental study. The weight-drop contusion method was employed to induce spinal cord injury in rats. DEX and MO were administrated alone and together in different treatment groups. Intra-muscular injection of DEX (1 mg/kg) was started three hours after injury and continued once a day for seven days after injury. Intra-peritoneal (I.P) injection of MO (150 mg/ kg) was started one day after injury and continued once a day for 14 days.

Results

Our results showed motor and sensory functions were improved significantly in the group received a combination of DEX and MO, compared to spinal cord injury group. Mean cavity area was decreased and loss of lower motor neurons and astrogliosis in the ventral horn of spinal cord was significantly prevented in the group received combination of DEX and Melissa officinalis, compared to spinal cord injury group. Furthermore, the findings showed a significant augmentation of electromyography (EMG) recruitment index, increase of myelin diameter, and up-regulation of myelin basic protein in the treated group with combination of DEX and MO.

Conclusion

Results showed that combination of DEX and MO could be considered as a neuroprotective agent in spinal cord injury.

The Effect of Insulin Like Growth Factor-1 on Recovery of Facial Nerve Crush Injury

OBJECTIVES

The aim of this study is to investigate the efficacy of locally applied insulin-like growth factor 1 (IGF-1) on the recovery of facial nerve functions after crush injury in a rabbit model.

METHODS

The rabbits were randomly assigned into three groups. Group 1 consisted of the rabbits with crush injury alone; group 2, the animals applied saline solution onto the crushed facial nerve and group 3, IGF-1 implemented to the nerve in the same manner. Facial nerve injury was first electrophysiologically studied on 10th and 42nd days of the procedure. The damage to the facial nerves was then investigated histopathologically, after sacrification of the animals.

RESULTS

In the electrophysiological study, compound muscle action potential amplitudes of the crushed nerves in the second group were decreased. In pathological specimens of the first and second groups, the orders of axons were distorted; demyelination and proliferation of Schwann cells were observed. However, in IGF-1 treated group axonal order and myelin were preserved, and Schwann cell proliferation was close to normal (P<0.05).

CONCLUSION

Local application of IGF-1 in a slow releasing gel was found efficacious in the recovery of the facial nerve crush injury in rabbits. IGF-1 was considered worthy of being tried in clinical studies in facial nerve injury cases.