Herpes simplex virus and Bell palsy

Association of Overweight and Obesity With Bell Palsy in Children

BACKGROUND

In the Division of Pediatric Neurology at the University Medical Center Göttingen we observed that many patients with Bell palsy are overweight or obese. To evaluate whether overweight and obesity are associated with increased risk of Bell palsy in children we conducted this single-centered retrospective study by performing a database search for International Classification of Diseases (ICD)-10 primary and secondary diagnosis of G51.0 (facial nerve palsy) between January 1, 2010, and December 31, 2020.

METHODS

For risk assessment, patients' body mass indices (BMIs) were compared with BMI data of controls from a nationwide child health survey.

RESULTS

In total, 202 patients with peripheral facial nerve palsies (pFPs) were included, of which nearly half were classified as Bell palsies; 38% and 24% of the patients with Bell palsy and pFP had a BMI above the 90th percentile, respectively. High BMI was associated with statistically increased odds of Bell palsy in the group of overweight and obese patients (BMI >90th percentile; odds ratio [OR], 2.42; 95% confidence interval [CI], 1.6 to 3.8; P < 0.001) and solely obese patients (BMI >97th percentile; OR, 2.43; 95% CI, 1.4 to 4.3; P = 0.003).

CONCLUSIONS

We could confirm our observation that overweight and obesity are associated with increased risk of Bell palsy in children.

Oropharyngeal shedding of herpesviruses before and after BNT162b2 mRNA vaccination against COVID-19

INTRODUCTION

Concerns were raised over an increase in Bell's palsy, herpes simplex and herpes zoster after BNT162b2 vaccination, all are manifestations of herpesviruses reactivation. As herpesviruses commonly reactivate in the oropharynx, we have hypothesized that oropharyngeal shedding of herpesviruses will increase after vaccination.

METHODS

Immune-competent Adults, excluding those using topical steroids or manifesting symptomatic herpesvirus infection, were sampled before BNT162b2 vaccination and one week after. Herpesviruses 1-7 shedding was tested with a multiplexed PCR.

RESULTS

In 103 paired samples the prevalence of herpesviruses was similar before and after vaccination: HSV1, 3.9% vs. 5.8% (p = 0.75); HSV2, 0% vs. 1% (p = not applicable, NA); VZV, 0% vs. 0% (p = NA); EBV, 14.6% vs. 17.5% (p = 0.63); CMV, 0% vs. 0% (p = NA); HHV6, 4.9% vs. 7.8% (p = 0.55); HHV7, 71.8% vs. 72.8% (p = 1); any herpesvirus, 73.8% vs. 74.8% (p = 1).

DISCUSSION

We did not find evidence for increased oropharyngeal reactivation of herpesviruses one week after BNT162b2.

Bell Palsy and the Risk of Cardio-Cerebrovascular Disease: A Population-Based Follow-Up Study

OBJECTIVE

To evaluate the risk of cardio-cerebrovascular disease (CCVD), such as ischemic stroke and acute myocardial infarction (AMI), in patients diagnosed with Bell palsy STUDY DESIGN: Population-based follow-up study.

METHODS

We used the National Sample Cohort 2002 to 2013 data from the Korea National Health Insurance Service. The Bell palsy group comprised all patients diagnosed with Bell palsy (n = 730). The comparison group comprised patients selected randomly using propensity score matching (n = 1,460). The Kaplan-Meier survival analysis, log-rank test, and Cox proportional-hazards regression models were used to calculate the disease-free survival rate and hazard ratio (HR) of CCVD for each group.

RESULTS

Of the total study population, ischemic stroke developed in 15.7% of patients with Bell palsy and 9% of patients in the comparison group during the 12-year follow-up period. After adjusting for other factors, the HR of ischemic stroke during the 12-year follow-up period was 1.84 times greater in the Bell palsy group than in the comparison group (95% confidence interval [CI], 1.43-2.36). However, the adjusted HR of developing ischemic stroke for patients with Bell palsy treated concurrently with antiviral agents and steroids was 1.12 (95% CI, 0.62.-2.04). There was no significant relationship between Bell palsy and risk of AMI development (HR, 1.13; 95% CI, 0.71-1.82).

CONCLUSION

Bell palsy is linked with an increased incidence of ischemic stroke. Our data suggest that Bell palsy may be used as an indicator of increased stroke risk, and concurrent treatment with antiviral agents and steroids may be effective in preventing ischemic stroke.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2371-2377, 2019.

The neurologist's dilemma: a comprehensive clinical review of Bell's palsy, with emphasis on current management trends

Background

Recent advances in Bell’s palsy (BP) were reviewed to assess the current trends in its management and prognosis.

Material/Methods

We retrieved the literature on BP using the Cochrane Database of Systematic Reviews, PubMed, and Google Scholar. Key words and phrases used during the search included ‘Bell’s palsy’, ‘Bell’s phenomenon’, ‘facial palsy’, and ‘idiopathic facial paralysis’. Emphasis was placed on articles and randomized controlled trails (RCTs) published within the last 5 years.

Results

BP is currently considered the leading disorder affecting the facial nerve. The literature is replete with theories of its etiology, but the reactivation of herpes simplex virus isoform 1 (HSV-1) and/or herpes zoster virus (HZV) from the geniculate ganglia is now the most strongly suspected cause. Despite the advancements in neuroimaging techniques, the diagnosis of BP remains one of exclusion. In addition, most patients with BP recover spontaneously within 3 weeks.

Conclusions

Corticosteroids are currently the drug of choice when medical therapy is needed. Antivirals, in contrast, are not superior to placebo according to most reliable studies. At the time of publication, there is no consensus as to the benefit of acupuncture or surgical decompression of the facial nerve. Long-term therapeutic agents and adjuvant medications for BP are necessary due to recurrence and intractable cases. In the future, large RCTs will be required to determine whether BP is associated with an increased risk of stroke.

Alpha-Defensin Overexpression in Patients with Bell's Palsy and Ramsay Hunt Syndrome

Objectives:

To investigate the biological factors related to the onset of Bell's palsy, we sought to identify differentially expressed genes in peripheral blood mononuclear cells (PBMCs) and plasma of patients with Bell's palsy and Ramsay Hunt syndrome (RHS).

Methods:

We carried out DNA microarray analyses using PBMCs taken from patients with Bell's palsy at their initial visit and 2 to 4 weeks later. To validate these analyses, we measured the relative messenger RNA levels of α-defensin in paired PBMCs by reverse transcription–polymerase chain reaction. The plasma concentrations of α-defensin in patients and healthy volunteers were quantified by enzyme-linked immunosorbent assay.

Results:

The DNA microarray analysis identified α-defensin as a candidate gene related to the onset of Bell's palsy. Reverse transcription–polymerase chain reaction analysis showed that the relative α-defensin messenger RNA levels in PBMCs from the later visit were increased at least twofold in 9 of 13 patients (69%) with Bell's palsy and in 4 of 6 patients (67%) with RHS. The plasma α-defensin concentrations in the patients with RHS were significantly higher than those in healthy volunteers (p = 0.0013) and in the patients with Bell's palsy (p = 0.0306). Elevations of plasma α-defensin were observed in 5 of the 9 patients with Bell's palsy who demonstrated α-defensin overexpression in PBMCs.

Conclusions:

α-Defensin may be one of the biological factors related to the onset of Bell's palsy and RHS.

An unusual presentation of Bell's palsy: A case report and review of literature

In clinical medicine there may be times when clinical conditions manifest differently both when they present individually or concomitantly. Such scenarios warrant a broader differential diagnosis with thorough investigations. We present one such case of a patient of Bell's palsy with unexplained eye pain on the ipsilateral side. The patient had a chronic retinal detachment which became worse due to the concomitant Bell's palsy.

Management of recurrent oral herpes simplex infections

The literature has been reviewed for evidence of the efficacy of antiviral agents in both the prophylaxis and treatment of recurrent oral herpes simplex virus (HSV) infections and discussed by a panel of experts. Emphasis was given to randomized controlled trials. Management of herpes-associated erythema multiforme and Bell palsy were also considered. The evidence suggests that 5% acyclovir (ACV) in the cream base may reduce the duration of lesions if applied early. Recurrent herpes labialis (RHL) and recurrent intraoral HSV infections can be effectively treated with systemic ACV 400 mg 3 times a day or systemic valacyclovir 500 to 1000 mg twice a day for 3 to 5 days (longer in the immunocompromised). RHL in the immunocompetent can be effectively prevented with (1) sunscreen alone (SPF 15 or above), (2) systemic ACV 400 mg 2 to 3 times a day, or (3) systemic valacyclovir 500 to 2000 mg twice a day. Valacyclovir 500 mg twice a day is also effective in suppressing erythema multiforme triggered by HSV. Further studies are needed to compare treatment efficacy between topical penciclovir, docosanol, and ACV cream for RHL.

Ophthalmic Management of Facial Nerve Palsy: A Review

Facial nerve palsy affects individuals of all ages, races, and sexes. Psychological and functional implications of the paralysis present a devastating management problem to those afflicted, as well as the carriers. Since Sir Charles Bell's original description of facial palsy in 1821, our understanding and treatment options have expanded. It is essential that a multidisciplinary approach, encompassing ophthalmologists; Ear, Nose, and Throat surgeons; plastic surgeons; and psychologists work closely to optimize patient management in a staged approach. Although the etiology remains unknown, strong histological, cerebral spinal fluid, and radiological evidence suggests a possible association with herpes simplex virus in idiopathic facial nerve palsy (Bell's palsy). The use of steroids has been suggested as a means of limiting facial nerve damage in the acute phase. Unfortunately, no single randomized control trial has achieved an unquestionable benefit with the use of oral steroid therapy and thus remains controversial. In the acute phase, ophthalmologists play a pivotal role in preventing irreversible blindness from corneal exposure. This may be successfully achieved by using intensive lubrication, medical therapy (botulinum toxin), or surgery (upper lid weighting or tarsorraphy). Once the cornea is adequately protected and recovery deemed unlikely, longer term planning for eyelid and facial reanimation may take place in an individualized manner. Onset is sudden and management potentially lengthy. Physician empathy, knowledge, and experience are essential in averting long-term lifestyle and psychological discomfort for patients.

Acute lymphoblastic leukemia presenting as acute renal failure

BACKGROUND

A 42-year-old previously healthy man presented with acute-onset headache and facial paralysis. He was treated for Bell's palsy with corticosteroids and valaciclovir. One week later, he developed acute renal failure requiring hospitalization.

INVESTIGATION

Physical examination, laboratory tests, urinalysis, renal ultrasound, renal biopsy, bone marrow biopsy, lumbar puncture, CT of the chest, abdomen and pelvis, MRI of the brain, and whole-body PET scan.

DIAGNOSIS

Acute lymphoblastic leukemia, bilateral renal enlargement secondary to leukemic infiltration, acute renal failure, tumor lysis syndrome, and leukemic involvement of the facial nerve.

MANAGEMENT

The patient was treated with a modified induction chemotherapy regimen. He was given allopurinol for hyperuricemia and hydrated with alkalized intravenous fluids to prevent uric acid precipitation in the renal tubules. The profound tumor lysis that occurred after the cytotoxic chemotherapy required hemodialysis.

Skin manifestations of herpesvirus infections

Currently there are eight human herpesviruses identified that cause disease in both adults and children. Although the manifestations of disease differ with each herpesvirus, cutaneous presentations are common among almost all of them. These skin manifestations may be visually similar among several of these viruses, occasionally making it challenging to diagnose the patient's illness. Laboratory diagnostic testing is commercially available for most of these viruses. Because many herpesvirus infections are self-limiting in immunocompetent hosts, patients require only supportive care. Effective antiviral therapy is available for the more severe cases of infection caused by herpes simplex virus (HSV), varicella zoster virus (VZV), or cytomegalovirus (CMV). Healthcare practitioners should become familiar with the different cutaneous manifestations these viruses may exhibit.

Comparisons of steroid, acyclovir, lipoprostoglandin E1 and steroid + acyclovir treatments in facial paralysis: a rat study

OBJECTIVE

To induce experimental peripheral facial paralysis by inoculation of HSV1 and to compare the effects of steroid, acyclovir, lipoprostoglandin E2 and steroid + acyclovir treatments in terms of clinical recovery, electrophysiologically and histopathologically.

MATERIALS AND METHODS

A total of 132 adult female rats were used in this study. HSV type 1 strain was inoculated at the back of the left ear by using 27 gauge needle. Of all animals, 70 (53%) rats which developed facial paralysis were divided into five groups (n = 14 for each group) as control, steroid + acyclovir, lipoprostaglandin E1, steroid only and acyclovir only. At the end of the 21 days period, the rats were clinically examined and electrophysiological tests were performed, then decapitated and the nerve specimens were obtained.

RESULTS

A modified electroneurography (ENoG) test was performed and the latencies and the amplitudes were compared. The findings of the intact side were better, but with no significant difference. Histopathologicaly edema was significantly smaller in all groups compared to the controls (p < 0.05). Similarly, no difference was seen in terms of vacuolar degeneration and Schwann cell hyperchromatisation among the groups and no significant difference in recovery period and rate of facial paralysis when all groups were compared.

CONCLUSION

Facial paralysis induced by HSV1 recovered spontaneously within a week. In the treatment of facial paralysis, steroid alone, acyclovir alone, steroid + acyclovir, or lipoprostaglandin E1 all reduced edema in the infected facial nerve but there was no statistical difference in of the rate or degree of recovery.

Clinical characteristics of patients with ischemic ocular nerve palsies and lacunar brain infarcts: a retrospective comparative study

BACKGROUND

Ischemic ocular motor nerve palsies (IOMP) and lacunar brain infarcts share a similar pathological mechanism. The clinical characteristics of patients as well as the protective role of aspirin should therefore be similar in both conditions.

METHODS

The medical records of 107 consecutive patients with IOMP and 160 patients with lacunar cerebrovascular accidents (CVA) were reviewed and analyzed with respect to patient characteristics, vascular risk factors, and aspirin intake. The data on patients with and without aspirin were compared within each group as well as between both groups.

RESULTS

Hyperlipidemia, smoking, high carotid stenosis (>70%) and the presence of more than one vascular risk factor in an individual patient were found to be more common in patients with lacunar brain infarcts regardless of aspirin intake. Absence of vascular risk factors was encountered more in IOMP patients. The recurrence of lacunar CVA was significantly higher than recurrence of IOMP. A history of Bell's palsy was more common in IOMP patients than in patients with lacunar CVA. Within the IOMP group, the prevalence of vascular risk factors did not differ between the aspirin and non-aspirin group. Ischemic heart disease (IHD), CVA and recurrence were found more often in the aspirin group. Within the CVA group hypertension, IHD, cardiac arrhythmia and recurrence rate were more common in the aspirin group whereas smoking was found to be more common in the non-aspirin group of patients.

CONCLUSIONS

Arteriosclerosis is the main cause of lacunar CVA and IOMP. However, IOMP depends less on the presence of vascular risk factors than does lacunar CVA. Furthermore, aspirin - at least at low doses - does not seem to have a protective effect on either of these conditions, but more extensive prospective studies of homogeneous groups of patients are needed to clarify the preventive role of antiplatelet agents in IOMP.

Varicella-zoster virus reactivation is an important cause of acute peripheral facial paralysis in children

BACKGROUND

Reactivation of herpes simplex virus type 1 is thought to be a major cause of adult idiopathic peripheral facial paralysis or Bell's palsy. However, few studies have examined the pathogenesis of this condition in children. Serologic assays and polymerase chain reaction (PCR) analysis of paired sera and saliva samples were used here to investigate the causes of acute peripheral facial paralysis in pediatric patients.

METHODS

A total of 30 children with acute peripheral facial paralysis were recruited. Paired sera were assayed for evidence of herpesvirus, mumps virus or Borrelia infection. PCR was used to detect herpes simplex virus type 1 and varicella-zoster virus (VZV) DNA in saliva samples.

RESULTS

Ramsay Hunt syndrome with accompanying zoster lesions was diagnosed clinically in 2 patients, and VZV reactivation was confirmed serologically. VZV reactivation in the absence of zoster (zoster sine herpete) was diagnosed in 9 patients with either serologic assays or PCR. Thus VZV reactivation was demonstrated in 11 of 30 (37%) patients. The prevalence of VZV reactivation among patients between 6 and 15 years of age was significantly higher than in those younger than 5 years of age (53% versus 9%, P = 0.023).

CONCLUSIONS

Our data indicate that VZV reactivation is an important cause of acute peripheral facial paralysis in children, especially those between 6 and 15 years of age.

Herpes virus reactivation and gadolinium-enhanced magnetic resonance imaging in patients with facial palsy

OBJECTIVE

This study investigated whether magnetic resonance imaging (MRI) patterns were different between patients with Bell's palsy and those with herpetic facial palsy in whom varicella-zoster virus (VZV) or herpes simplex virus type 1 (HSV-1) reactivation had been confirmed by polymerase chain reaction (PCR) or serologic assay.

STUDY DESIGN

A retrospective study of 15 patients with acute peripheral facial palsy was performed to compare virologic tests and gadolinium (Gd)-enhanced MRI findings.

RESULTS

Ramsay Hunt syndrome was diagnosed in one patient. By use of virologic tests, zoster sine herpete (VZV reactivation without zoster) was diagnosed in four patients and HSV-1 reactivation in three. Bell's palsy was diagnosed in the remaining seven patients. No significant difference in the frequency of Gd-enhanced MRI was observed between herpetic facial palsy and Bell's palsy. However, in those patients who underwent MRI on the day viral reactivation was confirmed by PCR, Gd enhancement of the meatal fundus was observed infrequently. In addition, when MRI was performed within 10 days of the onset of palsy, Gd enhancement was not detected at the geniculate ganglion in any patients with herpetic facial palsy. By contrast, both the meatal fundus and the geniculate ganglion were enhanced in all patients with Bell's palsy, regardless of when MRI was performed with respect to the onset of palsy.

CONCLUSION

This study shows a difference in the pattern of Gd enhancement at the meatal fundus and the geniculate ganglion between patients with Bell's palsy and those with herpetic facial palsy. The results suggest that the meatal fundus or the geniculate ganglion may be affected first by virus reactivation in patients with herpetic facial palsy.

Aspirin use and the prevention of acute ischemic cranial nerve palsy

PURPOSE

To assess the relationship of aspirin use and ischemic cranial nerve palsies among patients with diabetes mellitus and hypertension.

METHODS

This retrospective case-control study involved 100 patients with ischemic cranial nerve palsies in association with diabetes, hypertension, or both (palsy cases) and 163 age-matched and sex-matched patients with diabetes, hypertension, or both but without ischemic cranial nerve palsies (nonpalsy control subjects). Comparisons were made with respect to duration of diabetes, dose and duration of aspirin use, dose and duration of tobacco use, and presence of cardiac or cerebrovascular disease.

RESULTS

There were 20 oculomotor, 33 trochlear, 37 abducens, and 10 facial nerve palsy cases. The median duration of diabetes was 6 years for cases and 7 years for control subjects. There were 34 cases (34%) who had used aspirin for a mean duration of 5.5 years before the onset of the cranial nerve palsy and 49 control subjects (30.1%) who had used aspirin for a mean duration of 4.3 years. There were no significant differences between cases and control subjects for duration of diabetes (P =.94); aspirin use (P =.51), duration (P =.50), and dosage (P =.89); tobacco use (P =.73) and consumption (P =.45); and proportion of cardiac disease (P =.17). Cerebrovascular disease was significantly less common among palsy cases than nonpalsy control subjects (P<.001). There was no significant difference in the odds of a patient having cranial nerve palsy in the aspirin group compared with the nonaspirin group (odds ratio, 1.12; 95% confidence interval, 0.70-2.04).

CONCLUSION

Aspirin use was not associated with a reduced rate of ischemic third, fourth, sixth, and seventh nerve palsies among patients with diabetes mellitus and hypertension. Aspirin appears to be ineffective in preventing ischemic third, fourth, sixth, and seventh cranial nerve palsies. Patients with ischemic cranial nerve palsy have a significantly lower rate of strokes and transient ischemic attacks than patients who have diabetes or hypertension but who do not have a history of cranial nerve palsy.

High prevalence of varicella-zoster virus reactivation in herpes simplex virus-seronegative patients with acute peripheral facial palsy

Varicella-zoster virus (VZV) and herpes simplex virus (HSV) are considered to be the major causes of acute peripheral facial palsy (APFP). One hundred and forty-two patients with APFP were analyzed by serological assays and polymerase chain reaction analysis. Ramsay Hunt syndrome was diagnosed in 21 patients. Of the remaining 121 patients clinically diagnosed with Bell's palsy, VZV reactivation without zoster (zoster sine herpete) was detected in 35 patients (29%). The prevalence of antibodies to HSV among patients with Bell's palsy was significantly higher than the prevalence among those with VZV reactivation (Ramsay Hunt syndrome or zoster sine herpete). In contrast, a high incidence (88%) of VZV reactivation among HSV-seronegative patients with APFP was observed. Our data indicate that VZV is one of the major etiologic agents of clinically diagnosed Bell's palsy and that VZV reactivation causes APFP in most patients who lack antibodies to HSV.

Bell's palsy and herpes viruses: to (acyclo)vir or not to (acyclo)vir?

The majority of peripheral seventh cranial nerve palsy cases remain without an identified etiology and will eventually be diagnosed as idiopathic or Bell's palsy. Some features of this condition may be characteristic of a viral infection. Indeed, several herpes viruses have been implicated as potential causative pathogens. Besides varicella-zoster virus, shown to cause Bell's palsy under the Ramsay-Hunt syndrome, recent years have seen an increased interest and focus on the possible herpes simplex virus type 1 (HSV-1) etiology in idiopathic facial paralysis. We review the clinical, biological and virological basis for the potential herpetic cause of Bell's palsy and the rational for antiviral therapy in this condition.

The facial nerve. Current trends in diagnosis, treatment, and rehabilitation

Facial paralysis is a potentially devastating disorder with numerous implications. Multiple entities must be considered in its etiology, and recent advances in microbiology, radiographic imaging, electrodiagnostic testing, and microsurgery have provided great insight into the pathophysiology, diagnosis, treatment, and rehabilitation of the facial nerve. Recent DNA PCR testing has shed new insight into the potential cause for Bell's palsy. This article focuses on the evaluation, differential diagnosis, medical treatment, and rehabilitation of facial nerve pathology with primary emphasis on facial paralysis. Surgical management is also discussed, including reanimation of the paralyzed face.

A case of facial diplegia associated with herpes simplex reactivation

Facial nerve palsy is the commonest cranial neuropathy affecting 40/100 000 people in the Western World but is idiopathic in 50-70% of cases. This report describes a case of recurrent facial nerve palsy in association with herpes simplex virus (HSV) reactivation. HSV may be a major cause of racial nerve palsy. Further research is required to clarify this issue in order that targeted treatment strategies can be developed for this common problem.Copyright Lippincott-Raven Publishers

Idiopathic facial paralysis: a randomized, prospective, and controlled study using single-dose prednisone versus acyclovir three times daily

In a prospective, controlled, and randomized study, we compared the outcome of 101 Bell's palsy patients treated with acyclovir (54 patients) or prednisone (47 patients). The acyclovir dosage was 2400 mg (800 mg three times a day) for 10 days, and prednisone was given as a single daily dose of 1 mg/kg of body weight for 10 days and tapered to 0 over the next 6 days. Minimum follow-up was 3 months in all patients. Patients in the prednisone group had better clinical recovery than those treated with acyclovir. Less degree of neural degeneration was observed in the prednisone group compared with acyclovir patients. The incidence of sequelae was the same in both groups. According to these results, in a 10-day treatment cycle acyclovir given 800 mg three times is not as useful as prednisone given 1 mg/kg of body weight once a day in patients with idiopathic facial nerve paralysis.

Reactivation of herpes simplex virus type 1 in patients with Bell's palsy

Reactivation of herpes simplex virus type 1 (HSV-1) has been implicated in the pathogenesis of idiopathic peripheral facial palsy (Bell's palsy). The present study used the polymerase chain reaction (PCR) to analyze the saliva of patients with Bell's palsy for the presence of shed HSV-1. The study involved 47 patients with Bell's palsy, 24 patients with Ramsay Hunt syndrome, and 16 healthy HSV-seropositive volunteers. HSV-1 DNA was not detected in the saliva samples from HSV-seronegative patients. The prevalence of shed HSV-1 in patients with Bell's palsy (50%) was significantly higher than that in healthy volunteers (19%, p<0.05). When saliva samples were tested within 7 days after the onset of palsy, the prevalence of shed HSV-1 in patients with Bell's palsy (40%) was significantly higher than that in patients with Ramsay Hunt syndrome (7%, p<0.05). Furthermore, HSV-1 usually became undetectable by the second week after the onset of Bell's palsy when HSV-1 was detected during the acute phase of the disease. These findings strongly suggest that reactivation of HSV-1 is involved in the pathogenesis Bell's palsy, and indicate that PCR is a useful tool for early diagnosis of HSV-1 reactivation in patients with Bell's palsy.

Bell's palsy and herpes simplex virus

Bell's palsy, which is defined as idiopathic peripheral facial paralysis of sudden onset, accounts for > 50% of all cases of facial paralysis. Different theories on the etiology of Bell's palsy have been proposed and investigated. Various clinical studies have suggested an etiological link between Bell's palsy and herpes simplex virus (HSV). In addition, animal experiments have shown the ability of HSV to induce facial paralysis. In our opinion, the possible link between Bell's palsy and HSV can only be explored properly by studying the human facial nerve, and especially the geniculate ganglion itself. Different groups have tried to detect hypothetically reactivated and hypothetically latent HSV in the facial nerves of Bell's palsy patients and control patients, respectively. The isolation of infectious HSV from facial nerve tissue by conventional cell culture methods appeared to be very difficult, also when Bell's palsy patients were tested. Instead, modern molecular methods, such as in situ hybridization and the polymerase chain reaction (PCR) could easily detect HSV DNA in geniculate ganglia. The detection of HSV-specific latency-associated transcripts in the ganglia of control patients provided further evidence for the hypothetically latent state of HSV in the geniculate ganglia in these patients. Recent PCR experiments performed by a Japanese group strongly suggest that the area adjacent to the geniculate ganglia does not usually contain any HSV at all, except in patients with Bell's palsy. This well-controlled study provides conclusive evidence that reactivation of HSV genomes from the geniculate ganglia is the most important cause of Bell's palsy. Consequently, it has been suggested that "Bell's palsy" be renamed as "herpetic facial paralysis".