Facial nerve palsy after reactivation of herpes simplex virus type 1 in diabetic mice

Elevated TRPV2 expression in the facial nerve of rats by cold stimulation: Implications for Bell's palsy

OBJECTIVE

Bell's palsy, also referred to as clinical manifestations of unilateral facial nerve palsy, encompasses downward angling of the corners of the mouth, the absence of forehead creases, and unilateral incomplete eyelid closure. The incidence of Bell's palsy has increased progressively in recent years, but the underlying mechanism of its occurrence remains unknown; therefore, it is essential to investigate both the cause and treatment of Bell's palsy. Member 2 of the Subfamily V Transient Receptor Potential Cation Channel is a mechanically and thermally sensitive ion channel that plays a crucial role in neural growth and development. Using a novel modeling technique, we endeavored to develop an animal model of Bell's palsy and determine whether TRPV2 expression is altered throughout the course of a facial nerve injury.

MATERIALS AND METHODS

The rats were categorized into 3 groups, and their facial nerve function was assessed using RT-qPCR, WB, and pathologic testing, respectively, after undergoing unilateral cold air stimulation for 1, 3, and 7 days. TRPV2 expression was identified using these techniques.

RESULTS

In response to cold stimulation, rats exhibited facial nerve paralysis symptoms, demyelinating lesions in the facial nerve, and increased TRPV2 expression.

CONCLUSIONS

Extended cold stimulation of the facial nerve in rats may lead to an imbalance in facial nerve homeostasis and increased TRPV2 expression. These findings will contribute to the understanding of the potential mechanism by which cold stimulation affects the facial nerve. Moreover, this finding implies that TRPV2 could possibly function as an additional diagnostic marker or therapeutic target in the context of Bell's palsy.

Acute Onset of Delayed Facial Nerve Paralysis After an Uncomplicated Total Parotidectomy for an Oncocytoma

Facial nerve injury is one of the most substantial potential sequelae of parotid surgery. Pulling, stretching, and otherwise disturbing the facial nerve during parotid surgery can lead to post-surgical neural paresis and consequential deficits in facial movement. Furthermore, transection of the main facial nerve trunk or its branches, either purposeful or incidental, can lead to complete paralysis of the related facial musculature. Facial nerve injury is often diagnosed immediately post-operatively as evident by deficits in ipsilateral facial motion on examination of the patient in the recovery unit or, at most, by one week post-operatively. Although delayed onset facial nerve paralysis is seen in traumatic injury and otologic surgery, it is uncommon that facial nerve paralysis presents late after parotid surgery in the absence of hematoma development, viral reactivation, or secondary insult. Here, we present the case of a 70-year-old man developing a delayed acute onset of hemi-facial paralysis 12 days after right-sided total parotidectomy for an oncocytoma; a facial nerve examination done immediately post-operatively and at the one-week post-operative follow-up was found to be normal. The patient was treated with two courses of high-dose oral steroids with close-to-complete resolution.

Recurrent Bell's palsy: outcomes and correlation with clinical comorbidities

Recurrent Bell’s palsy (RBP) has been reported to range from 2.6 to 15.2% of primary Bell’s palsy (BP) and has been associated with systemic comorbidities such as diabetes and hypertension. A retrospective analysis of patients affected by BP and RBP were performed to define the signs and symptoms associated with recurrence and the outcomes. Clinical and subjective characteristics of 341 patients affected by facial palsy were analysed. Facial function was assessed via House-Brackmann and Sunnybrook grading system. Characteristics of the palsy and systemic comorbidities (diabetes, hypertension, herpetic infections, autoimmunity disorders, audio-vestibular symptoms) were analysed in BP and RBP patients applying Fisher exact and the Mann-Whitney U tests, while time to recovery was explored with univariate and multivariate analysis. Twenty-four patients presented two or more episodes of facial palsy, representing a recurrence rate of 7%. Associated symptoms (e.g. retroauricular pain, taste disorder, dry eye etc.) were similar between BP and RBP patients. RBP occurred at older age than primary episode (p = 0.03). Recurrence was a risk factor for delayed recovery (p = 0.02), although final facial function was similar between the two groups. In conclusion, no significant differences were found between primary BP patients and RBP patients in terms of symptoms, palsy severity and presence of comorbidities. Delayed facial nerve function recovery in RBP did not affect the final outcome. Treatment of facial nerve recurrences must be the same of the primary episode, although the presence of prodromal symptoms may alert the patient and early corticosteroid treatment may be commenced even before the onset of paresis.

The etiology of Bell's palsy: a review

Bell’s palsy is the most common condition involving a rapid and unilateral onset of peripheral paresis/paralysis of the seventh cranial nerve. It affects 11.5–53.3 per 100,000 individuals a year across different populations. Bell’s palsy is a health issue causing concern and has an extremely negative effect on both patients and their families. Therefore, diagnosis and prompt cause determination are key for early treatment. However, the etiology of Bell’s palsy is unclear, and this affects its treatment. Thus, it is critical to determine the causes of Bell’s palsy so that targeted treatment approaches can be developed and employed. This article reviews the literature on the diagnosis of Bell’s palsy and examines possible etiologies of the disorder. It also suggests that the diagnosis of idiopathic facial palsy is based on exclusion and is most often made based on five factors including anatomical structure, viral infection, ischemia, inflammation, and cold stimulation responsivity.

Nerve Regeneration in Conditions of HSV-Infection and an Antiviral Drug Influence

Herpes simplex virus type I (HSV-I) is a latent neuroinfection which can cause focal brain lesion. The role of HSV-infection in nerve regeneration has not been studied so far. The aim of the work was to study sciatic nerve regeneration in the presence of HSV-infection and the influence of an antiviral drug. BALB/c line mice were divided into five groups. Group 1 animals were infected with HSV-I. After resolution of neuroinfection manifestations the sciatic nerve of these animals was crushed. Group 2 mice were administered acyclovir following the same procedures. Groups 3-5 mice served as controls. Thirty days after the operation distal nerve stumps and m.gastrocnemius were studied morphologically and biochemically. Ultrastructural organization of the sciatic nerve in control animals remained intact. Morphometric parameters of the nerves from the experimental groups have not reach control values. However, in the group 1 diameter of nerve fibers was significantly smaller than in the group 2. Both nerve regeneration and m.gastrocnemius reinnervation were confirmed. The muscle hypotrophy was found in groups 1, 2, and 3 (the muscle fibers diameter decreased). Metabolic changes in the muscles of the infected animals (groups 1 and 2) were more pronounced than in control groups 3 and 4. The levels of TBA-active products, conjugated dienes, carbonyl and SH-groups were reduced in m.gastrocnemius of the experimental groups, however no significant difference associated with acyclovir administration was found. HSV-infection is not limited to the local neurodegenerative changes in the CNS but affects regeneration of the injured sciatic nerve. Anat Rec, 301:1734-1744, 2018. © 2018 Wiley Periodicals, Inc.

[Bell's palsy]

Idiopathic peripheral facial palsy, also named Bell's palsy, is the most common cause of peripheral facial palsy in adults. Although it is considered as a benign condition, its social and psychological impact can be dramatic, especially in the case of incomplete recovery. The main pathophysiological hypothesis is the reactivation of HSV 1 virus in the geniculate ganglia, leading to nerve edema and its compression through the petrosal bone. Patients experience an acute (less than 24 hours) motor deficit involving ipsilateral muscles of the upper and lower face and reaching its peak within the first three days. Frequently, symptoms are preceded or accompanied by retro-auricular pain and/or ipsilateral face numbness. Diagnosis is usually clinical but one should look for negative signs to eliminate central facial palsy or peripheral facial palsy secondary to infectious, neoplastic or autoimmune diseases. About 75% of the patients will experience spontaneous full recovery, this rate can be improved with oral corticotherapy when introduced within the first 72 hours. To date, no benefit has been demonstrated by adding an antiviral treatment. Hemifacial spasms (involuntary muscles contractions of the hemiface) or syncinesia (involuntary muscles contractions elicited by voluntary ones, due to aberrant reinnervation) may complicate the disease's course. Electroneuromyography can be useful at different stages: it can first reveal the early conduction bloc, then estimate the axonal loss, then bring evidence of the reinnervation process and, lastly, help for the diagnosis of complications.

Comparison of Treatment Outcomes Following Either Prefrontal Cortical-only or Dual-site Repetitive Transcranial Magnetic Stimulation in Chronic Tinnitus Patients: A Double-blind Randomized Study

OBJECTIVES

We evaluated treatment outcomes following single-site repetitive transcranial magnetic stimulation (rTMS) in the dorsolateral prefrontal cortex (DLPFC) and dual-site rTMS in the auditory cortex (AC) and DLPFC (AC + FC).

STUDY DESIGN AND PATIENTS

This prospective randomized double-blind trial initially included 19 patients with chronic tinnitus and 17 of these patients received rTMS on the left AC and left DLPFC or only the left DLPFC. The subjects were randomly allocated to either the dual-site rTMS (AC + FC) protocol (Group 1, n = 9) or the singlesite rTMS (DLPFC) protocol (Group 2, n = 8). Group 1 received daily treatments with 2,000 pulses applied to the AC and 1,000 pulses applied to the DLPFC for 4 days (total of 12,000 pulses) and Group 2 received daily treatments with 3,000 pulses applied the DLPFC for 4 days (total of 12,000 pulses).

MAIN OUTCOME MEASURES

The severity of tinnitus was assessed before rTMS treatment using the Tinnitus Handicap Inventory (THI) and the self-rated Visual Analog Scale. These measures were used to determine the awareness, loudness, annoyance, and effects of tinnitus on daily life at 1, 2, 4, and 12 weeks after treatment.

RESULTS

The improvement in THI score was significantly better in Group 1 than in Group 2, even after controlling for the between-group differences in pretreatment THI score. In terms of psychological factors, Group 1 exhibited significant improvements in scores on the State-Trait Anxiety Inventory (STAI) for both state anxiety (STAI-X1) and trait anxiety (STAI-X2) at 12 weeks posttreatment and scores on the Pittsburgh Sleep Quality Index at 4 weeks posttreatment. Group 2 showed an improvement in only the STAI-X2 score at 12 weeks posttreatment.

CONCLUSIONS

The rTMS protocol effectively suppressed tinnitus in the dual-site rTMS (AC+FC) group but not in the single-site rTMS (DLPFC) group. Although recent evidence has shown that non-auditory cortices in the tinnitus network play an important role in the generation of tinnitus, our findings indicate that rTMS on non-auditory cortical sites alone may not be sufficient for treatment. Thus, dual-site rTMS in the AC and DLPFC may be preferable for controlling this condition.