Mouse model of Bell's palsy induced by reactivation of herpes simplex virus type 1.

In order to investigate the mechanism of Bell's palsy, we developed an animal model of facial nerve paralysis induced by the reactivation of herpes simplex virus type 1 (HSV-1). Eight weeks after recovery from facial nerve paralysis caused by inoculation with HSV-1, the mice were treated with auricular skin scratch at the site of the previous inoculation, or with intraperitoneal injection of anti-CD3 monoclonal antibody (mAb), or combination of both procedures. No mice developed facial nerve paralysis when they were treated with either auricular scratch or mAb injection alone. In contrast, 20% of mice developed facial nerve paralysis with the combined treatment. With one exception, no mouse treated with either auricular scratch or mAb injection showed HSV-I DNA in their facial nerve tissue, whereas 4 out of 6 mice receiving both treatments showed HSV-1 DNA on day 10 after treatment. Histopathological findings showed neuronal degeneration in the geniculate ganglion and demyelination of the facial motor nerve in paralyzed mice. These findings suggest that a combination of stimuli, local skin irritation, and general immunosuppression is essential for successfully inducing facial nerve paralysis in mice with latent HSV-1 infection.

Acoustic role of the buttress and posterior incudal ligament in human temporal bones.

OBJECTIVES: In middle ear surgery using intact ear canal wall techniques, the buttress, which is the bony bridge at the medial end of the posterior-superior bony ear canal, is commonly retained during posterior tympanotomy. In some cases, the surgical exposure may be improved by resectioning the buttress, and this requires sectioning the posterior incudal ligament. To date, the acoustic effects of removing the buttress with sectioning of the attached ligament have not been studied. METHOD: Using a laser Doppler vibrometer system, 15 human cadaver temporal bones were measured with 80 dB sound pressure level at the tympanic membrane over the 0.1 to 10 kHz frequency range. RESULT: The resection of the buttress and sectioning the posterior incudal ligament had no effect on stapes footplate velocity. CONCLUSION: These results suggest that the posterior incudal ligament does not play a significant role in the acoustic function of the ossicles.

Transmastoid decompression as a treatment of Bell palsy.

OBJECTIVE: We sought to assess the efficacy of transmastoid decompression after steroid treatment. STUDY DESIGN: One hundred one adults with Bell palsy having denervation exceeding 95% after steroid treatment were divided into 2 groups. In 58 patients decompression from the labyrinthine segment to the stylomastoid foramen was performed, and the remaining 43 patients were only followed up. Using the Yanagihara score and House Brackmann grading system, the recovery from the palsy was assessed. RESULTS: There was a statistically significant difference in the final facial score of the 2 groups. Within 60 days after the onset, the chance of better recovery from the palsy was higher in the patients with decompression. CONCLUSION: In the era of steroid treatment, we cannot discard the transmastoid decompression of the facial nerve in the treatment of severe Bell palsy with profound denervation, although further effort is needed to obtain definitive evidence to show the benefit of the operation.

Herpes simplex virus in the vestibular ganglion and the geniculate ganglion-role of loose myelin.

This study presents the first direct evidence for herpes simplex virus type 1 (HSV-1) infection in the neurons of the vestibular ganglion. Although many investigators have reported electron microscopic evidence of HSV-1 infection in sensory ganglia, HSV-1 infection in the vestibular ganglion has not been described. Vestibular ganglion neurons have a unique structure, with a loose myelin sheath instead of the satellite cell sheath that is seen in other ganglia. This loose myelin is slightly different from compact myelin which is known as too tight for HSV-1 to penetrate. The role of loose myelin in terms of HSV-1 infection is completely unknown. Therefore, in an attempt to evaluate the role of loose myelin in HSV-1 infection, we looked for HSV-1 particles, or any effects mediated by HSV-1, in the vestibular ganglion as compared with the geniculate ganglion. At the light microscopic level, some neurons with vacuolar changes were observed, mainly in the distal portion of the vestibular ganglion where the communicating branch from the geniculate ganglion enters. At the electron microscopic level, vacuoles, dilated rough endoplasmic reticulum and Golgi vesicles occupied by virus were observed in both ganglia neurons. In contrast, viral infections in Schwann and satellite cells were observed only in the geniculate ganglion, but not in the vestibular ganglion. These results suggest that loose myelin is an important barrier to HSV-1 infection, and it must play an important role in the prevention of viral spread from infected neurons to other cells.

Edematous swelling of the facial nerve in Bell's palsy.

Surgical decompression of the intratemporal facial nerve from the geniculate ganglion to the stylomastoid foramen was carried out in 91 patients with Bell's palsy. All of the patients had denervation exceeding 95%, and a suprastapedial lesion. Edematous swelling of the nerve was assessed using the following three grades: + +, nerve swells beyond the bony facial canal; +, nerve swells beyond the nerve sheath, but within the bony canal, and -, no notable swelling observed. Varying degrees of swelling of the nerve were noted in all of the patients from onset to the end of the ninth week. The incidence of + + swelling was highest within 3 weeks of onset and then declined. + + swelling was most often noted in the vicinity of the geniculate ganglion, and was thought to be a manifestation of inflammation due to herpes simplex virus infection. There was a clear time dependency of the swelling in the horizontal and pyramidal segments, but not in the mastoid segment. After the ninth week, the incidence of swelling decreased sharply and no swelling of the nerve was observed in about one-third of the patients. Considering the etiology and the analysis of edematous swelling, we propose that the course of Bell's palsy be differentiated into an acute phase (the first 3 weeks after onset), a subacute phase (from the fourth to ninth weeks) and a chronic phase (after the tenth week).

Ramsay Hunt syndrome in children.

In a retrospective study, 52 children were diagnosed with Ramsay Hunt syndrome. The facial palsy was milder and complete recovery of the function was achieved in 78.6% of patients. Associated cranial neuropathies were less common in children than in adults. The timing of vesicle appearance tended to be delayed in children. In preschool children, Ramsay Hunt syndrome was rare, although the frequency has recently increased. The syndrome is relatively common in older children. This study suggested that vaccination can prevent or reduce the occurrence of Ramsay Hunt syndrome.

[Treatment of Bell's palsy with acyclovir and prednisolone].

Many current studies have suggested that herpes simplex virus is a probable cause of Bell's palsy, and that treatment with antiviral agents such as acyclovir might benefit the patients. In the present study, 69 patients with Bell's palsy were treated with oral administration of acyclovir (2000 mg/day) and prednisolone (60-40 mg/day) at Ehime University Hospital between Oct. 1995 and Dec. 1998. Patients enrolled in this study met the following criteria: 1) severe or complete paralysis with a score lower than 20 by the 40-point Japanese grading system, and 2) treatment started within 7 days of onset. The overall recovery rate was 95.7% (66/69). The rate in patients who started this treatment within 3 days after disease onset was 100%, and this early treatment was highly efficacious in the prevention of nerve degeneration and resulted in a significantly better recovery. By comparison, the recovery rate in patients whose treatment was started 4 days or more after onset was only 84.2%. All patients who were given a diagnosis of zoster sine herpete and treated with acyclovir-prednisolone had a good outcome. These results suggest that early treatment, within 3 days after palsy onset, is necessary for effective acyclovir-prednisolone therapy of Bell's palsy.

Rapid diagnosis of varicella zoster virus infection in acute facial palsy.

Patients with zoster sine herpete and Ramsay Hunt syndrome without pathognomonic vesicles at the initial visit are often misdiagnosed with Bell's palsy and treated without antiviral agents. With PCR, we found that varicella zoster virus genomes were frequently detectable in auricular skin exudate from patients with zoster sine herpete or Ramsay Hunt syndrome before the appearance of vesicles.

[Radiotherapy combined with daily administration of low-dose cisplatin for squamous cell carcinomas of the head and neck].

The effects of radiotherapy combined with daily administration of low-dose cisplatin (CD DP) and radiotherapy alone for squamous cell carcinomas of the head and neck were compared clinically and histologically. There was no difference in the response rate between two groups with and without CDDP for pre-operative irradiation (30-40 Gy). However, the complete response rate in the radical irradiation group (60-70 Gy) with CDDP was significantly higher than without CDDP. In the histologic effect assessed by the classification of Shimozato in 9 of 19 patients undergoing radical irradiation with CDDP, 3 patients in this group showed a grade III effect, and the other 6 a grade IV effect. Only 5 of 11 patients having irradiation alone showed grade III or IV effect. In conclusion, full-dose radiotherapy combined with CDDP provided a high level of organ preservation and local control because of the high clinical and histological complete response rate at the primary site.

Immunologic aspects of facial nerve paralysis induced by herpes simplex virus infection in mice.

This immunologic aspects of facial nerve paralysis due to herpes simplex virus type 1 (HSV-1) infection were investigated in a mouse model system. Half of the 4- to 5-week-old mice developed facial nerve paralysis, whereas none of the 6-week-old mice died or developed facial nerve paralysis on inoculation with HSV-1. Six-week-old mice showed significantly higher titers of anti-HSV-1 neutralizing antibody than did 4-week-old animals. Passive transfer of either anti-HSV-1 antibody or HSV-1-immunized splenic T cells into 4-week-old mice 3 hours after HSV-1 inoculation prevented development of facial nerve paralysis and death, whereas such transfers 48 or 96 hours after HSV-1 inoculation did not prevent or exacerbate facial nerve paralysis. These results demonstrate that the age and the immunologic potency of mice are closely related to the pathogenesis of facial nerve paralysis. That facial nerve paralysis developed even in 6-week-old mice whose T-cell function was suppressed with anti-CD3 antibody suggests that virus-induced cellular demyelination is unlikely as a cause of facial nerve paralysis in this animal model.

Varicella-zoster virus distribution in Ramsay Hunt syndrome revealed by polymerase chain reaction.

The pathogenesis of facial nerve paralysis and vestibulo-cochlear dysfunction of Ramsay Hunt syndrome remains unclear as varicella-zoster virus (VZV) has not been demonstrated in the lesions. Using the polymerase chain reaction, we detected VZV genomes not only in the vesicles on the auricles or oral cavity but also in the facial nerve sheath, middle ear mucosa and cerebrospinal fluid from patients with Ramsay Hunt syndrome. The VZV genome was undetectable in the same kinds of clinical samples obtained from control patients with facial nerve paralysis of other etiologies. The results indicated that VZV spreads widely in the neural components, mucocutaneous tissue and cerebrospinal fluid. The present study will facilitate better understanding of the pathogenesis of facial nerve paralysis, vertigo, hearing impairment and other cranial nerve dysfunction of Ramsay Hunt syndrome.

Treatment of Ramsay Hunt syndrome with acyclovir-prednisone: significance of early diagnosis and treatment.

Although the antiviral agent acyclovir is currently used for the treatment of Ramsay Hunt syndrome, its effects on facial nerve and hearing recovery remain controversial. We retrospectively analyzed the effects of acyclovir-prednisone treatment in 80 Ramsay Hunt patients. Of 28 patients for whom treatment was begun within 3 days of the onset of facial paralysis, the recovery from paralysis was complete in 21 (75%). By comparison, of 23 patients for whom treatment was begun more than 7 days after onset, recovery from facial paralysis was complete in only 7 (30%). A significant difference in facial nerve recovery was found between these groups. Early administration of acyclovir-prednisone was proved to reduce nerve degeneration by nerve excitability testing. Hearing recovery also tended to be better in patients with early treatment. There was no significant difference in facial nerve outcome between intravenous and oral acyclovir treatment.

[Clinical features and prognosis of facial palsy and hearing loss in patients with Ramsay Hunt syndrome].

Clinical studies were performed on 325 patients with Ramsay Hunt syndrome who were treated in the Facial Nerve Clinic at Ehime University Hospital between 1976 and 1995. The clinical manifestations of Ramsay Hunt syndrome were various. Three major symptoms, auricular vesicles, facial paralysis and vestibulo-cochlear dysfunction, were found in 57.6% of the patients although these symptoms did not always appear simultaneously. Auricular vesicles appeared before (19.3%), during (46.5%), or after (34.2%) the onset of facial paralysis. Hearing loss was observed subjectively in only 20% but objectively in 48.2% of the patients. Hearing loss appeared before (34.3%), during (34.3%), or after (31.3%) the onset of facial paralysis. Complete recovery from facial paralysis was achieved in 52.4% of the patients. Good recovery of the facial nerve function was achieved in patients who had zoster vesicles or vestibulo-cochlear dysfunction preceding the development of facial paralysis. Complete recovery of hearing was also achieved in 45.4% of the patients, and the recovery was better in patients having light hearing loss, less than 35dB. The patients younger than 16 years old showed better recovery from both facial paralysis and hearing loss than the patients older than 60 years. Glossopharyngeal nerve or vagal nerve paralysis concomitant with facial paralysis was found in 8 (2.5%) patients. The outcome of glossopharyngeal nerve paralysis was good but that of the vagal nerve was poor.

[Immunological determinants and the spread of viral infection in facial nerve paralysis induced by herpes simplex virus in mice].

Herpes simplex virus type 1 (HSV-1) infection of the facial nerve has been strongly suggested as a cause of Bell's palsy. The author's group have produced a transient and homolateral facial paralysis in Balb/c mice by inoculating HSV-1 onto the auricle, simulating the symptoms of Bell's palsy. To clarify whether and how age and specific immunity against HSV-1 are involved in the pathogenesis of facial nerve paralysis, age dependent susceptibility to the virus and passive immunization with anti-HSV-1 antibody or immunized splenic T cells were investigated in a mouse model system. Following inoculation of HSV-1 into 3-week-old mice, 80% of the animals died whereas only 13% of 4-to 5-week-old mice died, and 50% developed facial nerve paralysis 1 week after the inoculation. No 6-week-old mice died and 6% developed facial nerve paralysis. Although all mice showed seroconversion of neutralizing antibody regardless of the presence of facial nerve paralysis, six-week-old mice and 4-week-old mice without facial nerve paralysis produce higher titers of anti-HSV-1 antibody than 4-week-old-mice with facial nerve paralysis. These results suggested that the age and the immunological potential of mice are closely related to the pathogenesis of facial nerve paralysis. Passive transfer of either anti-HSV-1 antibody or HSV-1 immunized splenic T cells into 4-week-old mice prevented development of facial nerve paralysis and death if they were transferred within 3 hours postinoculation. However, a similar transfer 48 or 96 hours after HSV-1 inoculation did not produce such protection. HSV-1 DNAs were detected in the facial nerve as early as 48 hours postinoculation by polymerase chain reaction (PCR). These results indicate that the passive immunization, providing both cellular and humoral immunity, is effective for preventing facial nerve paralysis if performed before virus infects the facial nerve. The nervous system has a blood-nerve barrier (BNB) which privileges it from the peripheral immune system. Therefore, once the virus infects the facial nerve, passive immunity transferred from peripheral vessel might be excluded from the virus or virus-infected cells unless the BNB is broken down. Bell's palsy is thought to occur during the course of HSV-1 latency in the geniculate ganglion. If we could reactivate latently infected virus and produce facial nerve paralysis again in the animal model, this might provide clues to clarify not only the pathological mechanism of Bell's palsy but also the interaction between immune system and virus reactivation.

Role of herpes simplex virus infection in the pathogenesis of facial paralysis in mice.

To clarify the role and site of herpes simplex virus (HSV) infection in the pathogenesis of facial paralysis, we examined the viral genome by the polymerase chain reaction and the neutralization antibody titer using microplates in an animal model. Following inoculation with HSV type 1 of the KOS strain into mouse auricles, HSV DNA appeared in the ipsilateral facial nerve on the 3rd day, and in bilateral facial nerves and the brain stem on the 10th day only in animals with facial paralysis. In animals without facial paralysis, no HSV DNA was detected in these tissues. The neutralization antibody titer was elevated between 4 and 20 days in all animals, with or without facial paralysis. Facial paralysis developed only on the inoculated side, even though HSV DNA was also present in the contralateral facial nerve. We conclude that HSV infection in the facial nerve and brain stem is prerequisite for facial paralysis, and suggest that an immunologic reaction following viral infection plays a key role in the pathogenesis.

Bell palsy and herpes simplex virus: identification of viral DNA in endoneurial fluid and muscle.

OBJECTIVE: To determine whether herpes simplex virus type 1 (HSV-1) causes Bell palsy. DESIGN: Prospective study. SETTING: University inpatient service. PATIENTS: 14 patients with Bell palsy, 9 patients with the Ramsay-Hunt syndrome, and 12 other controls. MEASUREMENTS: Viral genomes of HSV-1, varicella-zoster virus, and Epstein-Barr virus were analyzed in clinical samples of facial nerve endoneurial fluid and posterior auricular muscle using polymerase chain reaction (PCR) followed by hybridization with Southern blot analysis. RESULTS: Herpes simplex virus type 1 genomes were detected in 11 of 14 patients (79%) with Bell palsy but not in patients with the Ramsay-Hunt syndrome or in other controls. The nucleotide sequences of the PCR fragments were identical to those of the HSV-1 genome. CONCLUSIONS: Herpes simplex virus type 1 is the major etiologic agent in Bell palsy.

Proteus syndrome.

Proteus syndrome is a rare hamartomatous syndrome with a variety of abnormalities. A 6-year-old Japanese boy without apparent abnormalities at birth developed by 1 year of age cerebriform skin tumors on the right sole, soft masses on the left sole, palms and fingers, brownish verrucous lesions and whorled brownish patches on the right side of the neck, chest, external genitals and extremities, hemihypertrophy of the right lower extremity, lordoscoliosis, protuberance of the skull, epileptic seizures, hydrocephalus and mental retardation. This patient appears to be the second Japanese case of Proteus syndrome.