The pathology of facial and vestibular neuronitis

Influenza A virus infection of human Schwann cells in vitro

OBJECTIVES

Sudden sensorineural hearing loss, vestibular neuronitis, vocal fold paralysis and Bell's palsy have been associated with a viral etiology, due to the infection of nerve cells. The goal of this research was to ascertain whether Schwann cells can support infection with human influenza A virus and thereby represent a plausible alternative site for virus-host interaction. Viral infection of Schwann cells may lead to secretion of inflammatory mediators, leukocyte recruitment, demyelination and nerve damage.

MATERIAL AND METHODS

Cultured human Schwann cells were exposed to human influenza A virus. Infection was assayed at various times post-inoculation (0, 24, 48 and 72 h) using light microscopy, immunocytochemistry and influenza A virus-specific reverse transcriptase polymerase chain reaction (RT-PCR). A group of unexposed cells served as controls.

RESULTS

Following exposure to the virus, vacuolization, cellular expansion and detachment from the dish were seen as early as 24 h post-inoculation. The exposed cells demonstrated positive immunocytochemical staining for influenza A virus antigen at 24, 48 and 72 h. Using RT-PCR, a sharp rise in influenza A virus-specific mRNA was detected.

CONCLUSIONS

Human Schwann cells can be infected with human influenza A virus. Further studies will assess the inflammatory response in this model.

Management of cerebrospinal fluid leaks involving the temporal bone: report on 92 patients

OBJECTIVE

To investigate the success of different surgical and nonsurgical techniques in the management of cerebrospinal fluid otorrhea or otorhinorrhea.

STUDY DESIGN

Retrospective case analysis.

METHODS

Ninety-two patients with confirmed diagnosis of cerebrospinal fluid otorrhea or otorhinorrhea treated at our institution between 1976 and 1998 were followed up long-term by retrospective chart review and patient interviews.

RESULTS

Conservative treatment was successful in most cases of cerebrospinal fluid otorrhea or otorhinorrhea resulting from head injury (26 of 29 patients). In contrast, surgical intervention was required in all but 1 of 53 patients with cerebrospinal fluid otorrhea or otorhinorrhea caused surgically. The primary operative success rate was 76.9%. When relapse occurred, the interval ranged from 0 days to 24 months (mean interval, 3.9 mo; median, 1.3 mo). All leaks requiring surgery eventually were closed successfully. Surgical results were chronologically dependent. Before 1989, 11 failures occurred in 37 primary procedures. After 1989, only 4 failures occurred in 28 primary procedures. Of seven patients undergoing primary dural closure alone, three (43%) had recurrence of the leak. Closure rates were highest among patients in whom a multilayer technique for leak closure was used: combining a primary graft or sealing material such as bone wax, free muscle, or fascia for closure of the defect with additional autologous free grafts or allogenic materials. This resulted in a 2-year closure rate of 100% compared with a 2-year rate of 75.4% for patients whose primary closure was supported by a single layer of autologous or allogenic material (P =.034). Fibrin glue with primary closure alone did not have additional benefit. Postoperative meningitis occurred in two patients and was treated without sequelae.

CONCLUSIONS

Conservative treatment should be reserved for cerebrospinal fluid otorrhea or otorhinorrhea resulting from head injury. Postoperative and nontraumatic cerebrospinal fluid otorrhea or otorhinorrhea should have early operative intervention. A multilayer technique combining allogenic materials with free autologous grafts is recommended.

Skull base cerebrospinal fluid fistulas: a comprehensive diagnostic algorithm

OBJECTIVE

Our goal was to assess the efficacy of current diagnostic modalities in the management of skull base cerebrospinal fluid (CSF) fistulas.

METHODS

We conducted a retrospective review of all patients presenting to our institution over the past 6 years with skull base CSF fistulas.

RESULTS

Fifty-two patients were included in the study. beta2-Transferrin analysis of collected specimen was the most efficacious means of confirming a CSF leak. High-resolution computed tomography was the most informative radiographic study, yielding a sensitivity and an accuracy of 87%. Magnetic resonance cisternography, yielding a sensitivity and an accuracy of 78%, was instrumental in localizing the site of leak for a few cases but was most commonly corroborative. Using a graduated diagnostic approach, successful repair was attained in 88% of cases after 1 attempt and 98% after 1 or 2 attempts.

CONCLUSION

For patients with skull base CSF fistulas, a graduated diagnostic approach with emphasis on confirmation of leak by beta2-transferrin analysis and precise localization by high-resolution computed tomography is both efficacious and cost effective.

The three faces of vestibular ganglionitis

We present temporal bone and clinical evidence that common syndromes of recurrent vertigo are caused by a viral infection of the vestibular ganglion. In the present series, histopathologic and radiologic changes in the vestibular ganglion and meatal ganglion were consistent with a viral inflammation of ganglion cells in cases of Meniere's disease, benign paroxysmal positional vertigo, and vestibular neuronitis. Clinical observations of multiple neuropathies involving cranial nerves V, VII, and VIII on the same side in patients with recurrent vertigo are best explained by a cranial polyganglionitis caused by a neurotrophic virus, which is reactivated by a stressful event later in life. The reactivation of the latent virus may manifest as one of the above vertigo syndromes, depending on the part of the vestibular ganglion that is inflamed, the type and strain of the virus, and host resistance.

Evaluation and treatment of dural tears in lumbar spine surgery: a review

Incidental durotomy is a frequent complication of lumbar spinal surgery. The number and complexity of spinal procedures is increasing, leading to a greater prevalence of dural tears; therefore, it is imperative that spine surgeons be familiar with safe and effective closure techniques. Occasionally, a tear may not be recognized during the procedure, so that one must recognize the signs and symptoms of a cerebrospinal fluid leak postoperatively. Several newer treatment concepts show promise. The current study represents an extensive review of the recent literature on the prevalence, mechanism, diagnosis, treatment, and outcomes of dural tears. The authors provide an overview of the problem, an update on current treatment strategies, and describe the senior author's technique of repair, which is easy to do and is effective in stopping additional leakage of cerebrospinal fluid.

Menière's disease as a manifestation of vestibular ganglionitis

OBJECTIVE

To present morphologic evidence of viral-induced vestibular nerve pathology in Menière's Disease (MD). MATERIAL STUDIED: Twelve temporal bones (TB) from 8 patients with the clinical symptoms of MD.

RESULTS

There was endolymphatic hydrops (EH) and perilymphatic fibrosis in 10 of the 12 TB from MD patients. Of the 10 TB with EH of the pars inferior, 3 also contained outpouchings in the pars superior (utricle and canals), and 3 showed apical spiral ganglion cell loss. Focal vestibular nerve axonal degeneration was observed in all but one TB.

CONCLUSION

Morphologic changes in TB of patients with MD, and clinical observations in patients with recurrent vestibulopathy, support the concept that the pathologic mechanism responsible for auditory and vestibular symptoms in MD may be reactivation of a latent viral vestibular ganglionitis.

Isolated vestibular areflexia after blunt head trauma

The sudden unilateral loss of vestibular function is a frequent cause of vertigo. This condition is called vestibular neuronitis or vestibular neuritis. Its cause remains unknown, but many authors consider it to be a sequel of vestibular viral infection. We report the history and clinical findings of 5 patients in whom a unilateral vestibular loss occurred after head trauma. None of these patients complained of hearing loss. In all cases, the vertigo gradually subsided over days or weeks. The follow-up showed the partial recovery of vestibular function in 2 cases, while vestibular areflexia persisted in 3. The clinical course and findings were similar in every respect to those in patients with classic idiopathic vestibular neuronitis.

Middle cranial fossa approach for the repair of spontaneous cerebrospinal fluid otorrhoea using autologous bone pate

Tegmen plate defects causing cerebrospinal fluid (CSF) leaks and brain hernias have conventionally been repaired using soft tissue grafts by a transmastoid approach. A review of the literature reveals that the results of transmastoid repairs have been less than satisfactory. We present here four patients with spontaneous CSF otorrhoea who had tegmen defects repaired using the middle cranial fossa approach. An autologous bone pate slab mixed with fibrin glue with additional temporalis fascia reinforcement was used for the repairs. All four patients had uneventful postoperative periods and have had no subsequent CSF leak (follow-up range: 1-3 years). We believe that the middle cranial fossa approach is more effective than the transmastoid approach for the repair of CSF leaks and brain hernias through tegmen plate defects. An important additional benefit is hearing preservation. We also recommend the use of bone pate along with soft tissue for the repair in order to achieve a secure seal. Bone pate can effectively seal multiple defects in the tegmen plate without any risk of migration.

Vestibular neuritis: three-dimensional videonystagmography and vestibular evoked myogenic potential results

Eight patients diagnosed with vestibular neuritis received the newly developed three-dimensional videonystagmography (3D VNG) and vestibular evoked myogenic potential (VEMP) examination in order to localize the lesion site. Two (25%) of the 8 patients exhibited spontaneous nystagmus with 3 components, indicating that both the horizontal semicircular canal (HSCC) and anterior semicircular canal (ASCC) were affected. The remaining 6 patients (75%) displayed only horizontal nystagmus, meaning that only the HSCC was involved. Seven (88%) of the 8 patients had bilateral normal VEMPs, revealing sparing of the posterior semicircular canal (PSCC). In a comparative study, another seven patients with vestibular neuritis 1 year post-treatment also received the caloric test, 3D VNG and VEMP examination. Only one patient exhibited spontaneous nystagmus. An absent caloric response of the lesioned side persisted in 5 (71%) of the 7 patients. However, all patients showed normal VEMPs bilaterally. 3D VNG and VEMP examination indicates that vestibular neuritis mainly affects the superior division of the vestibular nerve, which innervates the HSCC and ASCC. Meanwhile, the function of the PSCC and saccule, innervated by the inferior vestibular nerve, is preserved.