Pathophysiology of facial nerve paralysis induced by herpes simplex virus type 1 infection

Cathelicidin-derived antiviral peptide inhibits herpes simplex virus 1 infection

Herpes simplex virus 1 (HSV-1) is a widely distributed virus. HSV-1 is a growing public health concern due to the emergence of drug-resistant strains and the current lack of a clinically specific drug for treatment. In recent years, increasing attention has been paid to the development of peptide antivirals. Natural host-defense peptides which have uniquely evolved to protect the host have been reported to have antiviral properties. Cathelicidins are a family of multi-functional antimicrobial peptides found in almost all vertebrate species and play a vital role in the immune system. In this study, we demonstrated the anti-HSV-1 effect of an antiviral peptide named WL-1 derived from human cathelicidin. We found that WL-1 inhibited HSV-1 infection in epithelial and neuronal cells. Furthermore, the administration of WL-1 improved the survival rate and reduced viral load and inflammation during HSV-1 infection via ocular scarification. Moreover, facial nerve dysfunction, involving the abnormal blink reflex, nose position, and vibrissae movement, and pathological injury were prevented when HSV-1 ear inoculation-infected mice were treated with WL-1. Together, our findings demonstrate that WL-1 may be a potential novel antiviral agent against HSV-1 infection-induced facial palsy.

Structural remodeling secondary to functional remodeling in advanced-stage peripheral facial neuritis

BACKGROUND

Structural remodeling is a classic manifestation of disease decompensation. Facial synkinesis is the most troubling sequela of peripheral facial neuritis, and its structural remodeling, especially in white matter (WM), is still poorly understood. Therefore, understanding WM microstructure is important for predicting WM pathology and for early intervention in facial synkinesis patients.

METHODS

A total of 20 facial synkinesis patients (18 men and 2 women; mean age, 33.35 ± 6.97 years old) and 19 healthy controls (17 men and 2 women; mean age, 33.21 ± 6.75 years old) were enrolled in this study. rs-fMRI data, diffusion tensor imaging (DTI) data, and Beck's Depression Inventory (BDI) data were collected, and tract-based spatial statistics (TBSS) and voxel-mirrored homotopic connectivity (VMHC) values were used to analyze changes in WM microstructure and interhemispheric coordination.

RESULTS

Compared with the healthy controls, facial synkinesis patients exhibited significantly lower regional fractional anisotropy (FA) in the genu of the corpus callosum and the body of the corpus callosum, significantly higher regional FA in the retrolenticular part of the internal capsule, and significantly decreased VMHC values bilaterally in the orbital inferior frontal gyri, the fusiform gyri, the superior temporal gyri, the superior frontal gyri, and the supplementary motor areas. Furthermore, a lower regional FA in the genu of the corpus callosum was correlated with higher BDI scores in facial synkinesis patients.

CONCLUSION

Structural remodeling, especially changes in white matter microstructure, may be the central mechanism for severe sequelae of peripheral facial neuritis.

Recurrent facial palsy: The prognostic value of electrophysiological tests according to recurrence interval

OBJECTIVE

The prognostic value of nerve excitability tests (NET) and electroneurography (ENoG) for recurrent peripheral facial palsy is poorly understood. This study aimed to evaluate the association between NET/ENoG results for the current palsy and recovery.

METHODS

We extracted data on patients who were referred to our hospital (2005-2017). Adult patients with recurrent peripheral facial palsy who underwent NET and ENoG within 3 weeks of onset were retrospectively analyzed (n = 26). Favorable recovery was defined as the achievement of either House-Brackmann grade I/II or the same level of facial movement as before the current palsy. We evaluated the predictive NET/ENoG results by making comparison between the favorable recovery group and the unfavorable recovery group, which were subdivided based on the length of time after the previous palsy.

RESULTS

In terms of patients with a >4-year recurrent interval, 8 out of 12 patients achieved favorable recovery. Compared to the favorable recovery group, the unfavorable recovery group had significantly higher NET results (9.03 mA vs. -1.08 mA, p = 0.017). Also, the unfavorable recovery group had significantly higher NET results in patients with a >2-year recurrent interval (9.03 mA vs. 1.06 mA, p = 0.036). However, other test results (NET in ≤4-year recurrent interval/all 26 patients, and ENoG in >4-year recurrent interval/≤4-year recurrent interval/all 26 patients) did not differ significantly between patients with favorable and unfavorable recovery.

CONCLUSION

NET might be a useful prediction method in patients with at least a few years interval between the previous and the current palsy.

Facial paralysis induced by ear inoculation of herpes simplex virus in rat

OBJECTIVE

Bell's palsy is caused by the reactivation of herpes simplex virus type 1 (HSV-1). Using Balb/c mice inoculated with the KOS strain of HSV-1, we previously developed an animal disease model that simulated mild Bell's palsy. The current study developed an animal disease model of more severe facial palsy than that seen in the mouse model.

METHODS

Three-week-old female Wister rats weighing 60-80g were inoculated on the auricle with HSV-1 and acyclovir was administered intraperitoneally to deactivate the infected HSV-1. Instead of HSV-1, phosphate-buffered saline was used for inoculation as a negative control. Quantitative polymerase chain reaction (PCR), behavior testing (blink reflex), electroneuronography, histopathology of the peripheral nerve, and immunohistochemistry of the facial nerve nucleus were evaluated.

RESULTS

Facial palsy occurred 3-5 days after virus inoculation, and the severity of the facial palsy progressed for up to 7 days. Quantitative PCR showed an increase in HSV-1 DNA copies in the facial nerve from 24 to 72h, suggesting that HSV-1 infection occurred in the nerve. Electroneuronography values were 33.0±15.3% and 110.0±18.0% in HSV-1-inoculated and control rats, respectively. The histopathology of the peripheral nerve showed demyelination and loss of the facial nerve, and the facial nerve nucleus showed degeneration.

CONCLUSION

Facial palsy developed in Wister rats following inoculation of the KOS strain of HSV-1 onto the auricles. The behavioral, histopathological, and electroneuronography data suggested that the severity of facial palsy was greater in our rats than in animals in the previous mouse disease model.

The alteration of SHARPIN expression in the mouse brainstem during herpes simplex virus 1-induced facial palsy

Bell's palsy presents a unilateral weakness or paralysis of the face due to acute dysfunction of the peripheral facial nerve with no readily identifiable cause. Although data show that herpes simplex virus type 1 (HSV-1) may be the possible causative agent of Bell's palsy, the precise mechanism of the paralysis is still unknown. SHANK-associated RH domain-interacting protein (SHARPIN) is thought to play a role in the control of inflammatory responses. In order to clarify the molecular pathway of SHARPIN involved in the facial palsy caused by HSV-1 in mice and the inhibitory effect of corticosteroids, we used 4-week-old Balb/c mice inoculated with HSV-1 for experiments. The expression and location of SHARPIN in the facial nucleus of brainstem were detected respectively by quantitative real-time polymerase chain reaction, western blot and immunofluorescence. Expression level of SHARPIN increased and peaked at 2 days and then decreased in the facial nucleus of brainstem after the manifestation of the facial paralysis. After the administration of MPSS, the protein expression of SHARPIN at the peak point was down-regulated. Our results suggest that SHRPIN were activated during the inflammatory reaction in the HSV-1-induced facial paralysis. MPSS can effectively inhibit the expression of SHARPIN that may contribute to attenuate HSV-1-mediated nervous system damage.

Effects of Electroacupuncture on Facial Nerve Function and HSV-1 DNA Quantity in HSV-1 Induced Facial Nerve Palsy Mice

Acupuncture is a common and effective therapeutic method to treat facial nerve palsy (FNP). However, its underlying mechanism remains unclear. This study was aimed to investigate the effects of electroacupuncture on symptoms and content of HSV-1 DNA in FNP mice. Mice were randomized into four groups, an electroacupuncture treatment group, saline group, model animal group, and blank control group. Electroacupuncture was applied at Jiache (ST6) and Hegu (LI4) in electroacupuncture group once daily for 14 days, while electroacupuncture was not applied in model animal group. In electroacupuncture group, mice recovered more rapidly and HSV-1 DNA content also decreased more rapidly, compared with model animal group. We conclude that electroacupuncture is effective to alleviate symptoms and promote the reduction of HSV-1 in FNP.

The facial nerve canal in patients with Bell's palsy: an investigation by high-resolution computed tomography with multiplanar reconstruction

Facial nerve edema is an important finding in Bell's palsy patients. Inflammation may cause facial nerve edema, and mechanical compression and ischemic change of the facial nerve may occur in the facial nerve canal. A few studies have reported the dimensions of the facial nerve canal using conventional computed tomography or human temporal bone sections. However, the cross-sectional area of the facial nerve canal has not been fully understood. Therefore, the cross-sectional area of the facial nerve canal was measured in patients with unilateral Bell's palsy by computer tomography with multiplanar reconstruction. Sixteen patients with unilateral Bell's palsy were enrolled. Computed tomography of the temporal bone was performed, and perpendicular images to the facial nerve canal were reconstructed by the multiplanar reconstruction technique. The cross-sectional area of the facial nerve canal on the affected and unaffected sides was measured at the labyrinthine segment, the horizontal segment, and the mastoid segment. Both in the labyrinthine and horizontal segments, the mean cross-sectional area of the facial nerve canal was significantly smaller on the affected side than on the unaffected side. There was no significant difference between the affected and unaffected sides in the cross-sectional area of the facial nerve canal in the mastoid segment. The labyrinthine segment was the narrowest segment in the facial nerve canal. These findings suggest that the facial nerve is vulnerable, especially in the labyrinthine segment of the facial nerve canal, and a narrow facial nerve canal may be one of the risk factors for Bell's palsy.

Hepatocyte growth factor incorporated into herpes simplex virus vector accelerates facial nerve regeneration after crush injury

Hepatocyte growth factor (HGF) promotes regeneration of the central nervous system, but its effects on the peripheral nervous system remain unclear. This study was conducted to elucidate the effect of HGF on regeneration of the murine facial nerve after crush injury. To do so, a replication-defective herpes simplex virus vector that incorporated HGF was prepared (HSV-HGF). The main trunk of the facial nerve was compressed by mosquito hemostats, and HSV-HGF, control vector or medium was then applied to the compressed nerve. We found that mice in the HGF group required significantly fewer days for complete recovery from nerve compression. Furthermore, the amplitude of the evoked buccinator muscle compound action potential increased following HSV-HGF application. HGF expression in and around the compressed nerve was demonstrated by enzyme-linked immunoassay and immunohistochemistry. In addition, HSV-HGF introduction around the damaged nerve significantly accelerated recovery of function of the facial nerve. These data suggest a possible role of HGF in promoting facial nerve regeneration after nerve damage. Furthermore, this viral delivery method may be applied clinically for many types of severe facial palsy during facial nerve decompression surgery.

Facial nerve decompression for idiopathic Bell's palsy: report of 13 cases and literature review

INTRODUCTION

The prognosis for cases of idiopathic facial palsy is usually good. However, some cases develop disabling sequelae, such as synkinesis or severe facial hemispasm, despite targeted medical treatment.

OBJECTIVES

The authors try to achieve that electromyography is useful to identify patients with severe palsy and an unfavourable prognosis. These patients would probably benefit from facial nerve decompression.

SETTING

The otolaryngology-head and neck surgery department of Pitié-Salpêtrière Hospital, Paris, a tertiary referral centre.

PARTICIPANTS

Thirteen cases undergoing surgery between January 1997 and March 2007.

MAIN OUTCOME MEASURES

We describe the electromyographic findings that led to surgery. All patients underwent surgery via a subpetrous approach, within four months of the onset of palsy. Decompression involved the first and second portions of the nerve and the geniculate ganglion.

RESULTS

Recovery to House-Brackmann grade III was obtained in all cases at one year follow up.

CONCLUSION

These results compared favourably with previous reports. A new therapeutic procedure may allow improved results.

Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study

OBJECTIVE

To investigate the effects of valacyclovir and prednisolone in comparison with those of placebo and prednisolone for the treatment of Bell's palsy, excluding zoster sine herpete.

STUDY DESIGN

Prospective, multicenter, randomized placebo-controlled study.

SETTING

Six academic tertiary referral centers.

PATIENTS

Ultimately, 221 patients with Bell's palsy who were treated within 7 days of the onset. Serological and polymerase chain reaction examinations were performed to distinguish Bell's palsy from zoster sine herpete.

INTERVENTION

The patients were treated with either valacyclovir (dosage, 1,000 mg/d for 5 days) plus prednisolone (VP [n = 114]) or placebo plus prednisolone (PP [n = 107]) administered orally.

MAIN OUTCOME MEASURE

Recovery from the palsy was defined as a score higher than 36 using Yanagihara 40-point scoring system without facial contracture or synkinesis. The patients were followed up until complete recovery occurred or for more than 6 months in cases with a poor prognosis.

RESULTS

The overall rate of patient recovery among those treated with VP (96.5%) was significantly better (p < 0.05) than the rate among those treated with PP (89.7%). The rate of patient recovery was also analyzed by classifying the initial severity of facial palsy. In cases of complete or severe palsy, the rates of patients treated with VP and PP who recovered were 95.7% (n = 92) and 86.6% (n = 82), respectively; the recovery rate for treatment with VP was significantly better than that with PP (p < 0.05).

CONCLUSION

The valacyclovir and prednisolone therapy was more effective in treating Bell's palsy, excluding zoster sine herpete, than the conventional prednisolone therapy. To our knowledge, this is the first controlled study of an antiviral agent in the treatment of a sufficient number of Bell's palsy cases based on an etiologic background.

Modified Procedure for Secondary Facial Rehabilitation Following Total Bilateral Irreversible Peripheral Facial Palsy

We present the case of a middle-aged gentleman who developed total bilateral irreversible peripheral facial palsy over a period of 10 years, starting with palsy of the marginal mandibular and buccal branches of the facial nerve and progressing to the zygomatic and temporal branches. The patient did not develop any other neurological symptoms, and all neurological and other tests have remained negative over the last 10 years. Dripping of saliva and inability to close the mouth necessitated reanimation of the perioral region with the help of a fascia lata graft fixed to the fascia of the masseter muscles. The increasing lagophthalmos and associated eye problems were alleviated with a temporal muscle transposition combined with a lengthening procedure using the temporal fascia, passed through the upper and lower eyelids and hooked around the medial canthal ligament. The fascia strips were sutured not to the canthal ligament itself, but to each other, thereby placing equal self-adjusted tension on the upper and lower eyelids. Both operations were successful and improved eating and eye closure functions, allowing resolution of the eye symptoms.

The role of viruses in idiopathic peripheral facial palsy and cellular immune response

PURPOSE

The purpose of this study is to investigate the role of viruses on the idiopathic peripheral facial palsy and show the interaction of immune system.

MATERIALS AND METHODS

The levels of immunoglobulin (Ig) G and IgM antibodies against to varicella-zoster virus (VZV), herpes simplex virus (HSV), cytomegalovirus (CMV), Ebstein-Barr virus (EBV), and mumps virus in venous blood taken from patients in the amount of 10 mL have been investigated by enzyme-linked immunosorbent assay method. Tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and transforming growth factor-beta (TGF-beta) were also examined. Of lymphocyte subpopulation, antibodies of CD3(+), CD4(+), CD8(+), CD19(+), and CD16(+) plus 56(+) were analyzed.

RESULTS

Ten of the patients had HSV-1 IgG; 1 of the patients IgM, 5 of the patients EBV IgG, 6 of the patients VZV IgG, 1 of the patients IgM, 9 of the patients mumps IgG, 1 of the patients IgM, and finally in 7 of the patients CMV IgG antibodies were obtained. It was found that CD4(+) cell and ratio of CD4(+)/CD8(+) lower and the percentage of the CD8(+) and CD16(+) plus 56(+) cells higher compared with the control group (P < .05). The levels of TNF-alpha were lower, whereas IFN-gamma and TGF-beta1 were higher.

CONCLUSION

It may be concluded from these results that VZV, HSV-1, CMV, EBV, and mumps virus play a significant role in the etiology of idiopathic peripheral facial palsy and activate the cellular immunity.