Creating a stable tympanic membrane perforation using mitomycin C

OBJECTIVE

To determine the ability of topically applied mitomycin C to create a stable tympanic membrane perforation.

STUDY DESIGN AND SETTING

Twenty-four rats underwent subtotal removal of the tympanic membranes bilaterally. Forty ears received 0.2 mg/ml of mitomycin C. The remaining 8 received phosphate-buffered saline solution (control). Photographs taken every 3 to 5 days for 44 days were digitally scanned and computer analyzed to calculate the percentage of residual perforation. Application of solutions, photography, and data analysis were performed in a blinded fashion.

RESULTS

The mitomycin C treated ears had delayed closure time and healing rate (from day 0 to 25) compared to the control group. All controls healed by day 14. By day 44, 92.5% of the mitomycin C treated ears healed.

CONCLUSION

Mitomycin C prolongs the closure and healing rate of myringotomies in rat tympanic membranes.

SIGNIFICANCE

Myringotomy with concurrent mitomycin C application may be useful for creating an animal model for chronic tympanic membrane perforation and should be tested in human beings as a method to maintain myringotomy patency for long-term ventilation.

Short- and long-term outcomes of canalith repositioning for benign paroxysmal positional vertigo

This is a prospective, nonrandomized study of the canalith repositioning procedure (CRP) for treatment of benign paroxysmal positional vertigo (BPPV). CRP was used to treat 168 patients with BPPV. Patient data were gathered by yearly telephone interviews to determine whether symptoms of position-induced vertigo had returned. After 1 or 2 treatment sessions 91.3% of patients reported complete symptom resolution. Average follow-up for the study population after the initial treatment was 26 months. A recurrence rate of 26.8% was found among those patients who initially reported resolution of symptoms after CRP. Application of recurrence data to a Kaplan-Meier estimation suggests a 15% recurrence rate per year of BPPV, with a 50% recurrence rate of BPPV at 40 months after treatment. There was no significant association between cure or recurrence rate and sex, age, duration of symptoms, presumed cause, or treating physician.

Responses of vestibular nucleus neurons to tilt following chronic bilateral removal of vestibular inputs

Recordings were made from the vestibular nuclei of decerebrate cats that had undergone a combined bilateral labyrinthectomy and vestibular neurectomy 49-103 days previously and allowed to recover. Responses of neurons were recorded to tilts in multiple vertical planes at frequencies ranging from 0.05 to 1 Hz and amplitudes up to 15 degrees. Many spontaneously active neurons were present in the vestibular nuclei; the mean firing rate of these cells was 43 +/- 5 (SEM) spikes/s. The spontaneous firing of the neurons was irregular: the coefficient of variation was 0.86 +/- 0.14. The firing of 27% of the neurons was modulated by tilt. The plane of tilt that elicited the maximal response was typically within 25 degrees of pitch. The response gain was approximately 1 spikes/s/degree across stimulus frequencies. The response phase was near stimulus position at low frequencies, and lagged position slightly at higher frequencies (average of 35 +/- 9 degrees at 0.5 Hz). The source of the inputs eliciting modulation of vestibular nucleus activity during tilt in animals lacking vestibular inputs is unknown, but could include receptors in the trunk or limbs. These findings show that activation of vestibular nucleus neurons during vertical rotations is not exclusively the result of labyrinthine inputs, and suggest that limb and trunk inputs may play an important role in graviception and modulating vestibular-elicited reflexes.

Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo is a common disorder of the inner ear that should be suspected in all patients with a history of positionally provoked vertigo. The condition appears to be caused by free-floating debris in the posterior semicircular canal. The diagnosis is confirmed by eliciting characteristic symptoms and signs during the Dix-Hallpike test. Although benign paroxysmal positional vertigo is usually a self-limited disorder, treatment with a specific bedside maneuver is effective and can provide the patient immediate and long-lasting relief. Although many patients with positionally provoked vertigo have typical benign paroxysmal positional vertigo, physicians should be aware of nonbenign variants.

Approach to the vestibular patient and driving: A patient perspective

OBJECTIVES

To learn about the impact of dizziness on driving from a patient perspective and to present an approach to the vestibular patient and driving.

DESIGN

An anonymous questionnaire completed by 265 dizzy patients at 3 different centers.

RESULTS

The participants were experienced drivers who needed to drive to function normally (83%). Those with constant or severe dizziness comprised a higher risk group of drivers. Although few had ever been warned not to drive, 52% said that if they were warned to stop driving, they would not. Most thought that it was the doctor's role to report unsafe drivers to the authorities (P < 0.001, chi2 = 87.2670).

CONCLUSIONS

The diagnosis of a vestibular disorder should not alone be grounds to suspend a patient's driver's license. Legislation should be amended to better reflect the views of doctors and patients alike.

Effects of bilateral vestibular lesions on orthostatic tolerance in awake cats

Previous experiments in anesthetized or decerebrate cats showed that the vestibular system participates in adjusting blood pressure during postural changes. The present experiments tested the hypothesis that removal of vestibular inputs in awake cats would affect orthostatic tolerance. Before the lesion, blood pressure typically remained within 10 mmHg of baseline values during nose-up-pitch body rotations of up to 60 degrees in amplitude. In contrast, bilateral peripheral vestibular lesions altered the pattern of orthostatic responses in all animals, and blood pressure fluctuated >10 mmHg from baseline values during most 60 degrees nose-up tilts in five of six animals. The deficit in correcting blood pressure was particularly large when the animal also was deprived of visual cues indicating position in space. During this testing condition, either a decrease or increase in blood pressure >10 mmHg in magnitude occurred in >80% of tilts. The deficit in adjusting blood pressure after vestibular lesions persisted for only 1 wk, after which time blood pressure remained stable during tilt. These data show that removal of vestibular inputs alters orthostatic responses and are consistent with the hypothesis that vestibular signals are one of several inputs that are integrated to elicit compensatory changes in blood pressure during movement.

Management of facial nerve injury due to temporal bone trauma

OBJECTIVE

This article provides an overview of relevant data regarding the management of facial nerve injury due to temporal bone trauma.

DATA SOURCES

Sources used were relevant English language clinical and basic science publications.

STUDY SELECTION

A Medline search dating back to 1966 for articles concerning temporal bone trauma and facial nerve injury including both human and animal data was performed. Articles were included if they contained relevant data or were significant reviews on the subject. A retrograde bibliography search was then conducted to acquire any articles that may have been missed by the computerized search, including those papers published prior to 1966.

DATA EXTRACTION

The data from each paper were reviewed individually.

DATA SYNTHESIS

The data were not amenable to formal meta-analysis or valid data summarization.

CONCLUSIONS

Patients who should not require surgical intervention include those who have: documented normal facial nerve function after injury regardless of progression, presentation with incomplete facial nerve paralysis with no progression to complete paralysis, and degeneration <95% on ENoG. The remaining patients presumably have a poorer prognosis for return of facial nerve function although it remains unclear exactly how poor the return of function will be. Decompression surgery likely has a beneficial effect if performed within 14 days of injury, so those patients with expected poor natural outcomes may be offered this intervention. Late decompression surgery is not recommended. Late exploratory surgery is recommended only in those patients who do not experience adequate recovery of facial nerve function and likely require nerve repair. Despite the availability of a relatively large volume of published data, there remain many unanswered questions.

Treatment of benign positional vertigo using heels-over-head rotation

Particle repositioning, using either bedside techniques or whole-body manipulation devices, has been used effectively to treat benign positional vertigo (BPV). We assessed the efficacy of particle repositioning using a device designed and built specifically to treat BPV that rotated patients 360 degrees heels-over-head in their sagittal body plane while their heads were turned to align the posterior semicircular canal with the plane of rotation. Eye movements were monitored during the maneuver by an infrared video recording system that allowed subsequent review of the induced nystagmus. Our results indicate that 1) heels-over-head rotation is an extremely efficacious procedure for treating patients with BPV and 2) the pattern of nystagmus during repositioning is consistent with the theory that free-floating debris is highly likely to account for BPV.

A review of balance instruments for older adults

OBJECTIVE

The purpose of this article is to review balance instruments developed within the past 10 years that can be used in the clinic or home environment. The use of such instruments may assist in identifying older adults who are at risk for falling, a major problem that can result in impaired function and loss of independence.

METHOD

Six instruments were reviewed: the Berg Balance Scale (Berg), the Clinical Test of Sensory Interaction and Balance (CTSIB), the Functional Reach Test, the Tinetti Balance Test of the Performance-Oriented Assessment of Mobility Problems (Tinetti), the Timed "Up and Go" Test (TU&GT), and the Physical Performance Test (PPT). Considered were what aspects of balance are assessed, time needed to administer the instrument, tools or equipment needed, evidence of reliability and validity, advantages and disadvantages, and the target population.

RESULTS

The Berg, Tinetti, and PPT measure a variety of aspects of balance, whereas the Functional Reach, TU&GT, and CTSIB measure more narrow aspects of balance. All six instruments have been used with older adults and do not require much equipment. The instruments differ in their reliability and validity.

CONCLUSION

Familiarity with balance instruments can be helpful in selecting the one most appropriate for clinical setting and clients in order to institute appropriate prevention programs, such as environmental modifications and lifestyle adaptations.

The effect of acidic fibroblast growth factor and live yeast cell derivative on tympanic membrane regeneration in a rat model

The current treatment of choice for chronic tympanic membrane perforations is surgery. Recent studies using various polypeptide growth factors to accelerate closure of tympanic membrane perforations in model systems have produced mixed results. This study evaluates the effect of acidic fibroblast growth factor (AFGF) and live yeast cell derivative (LYCD) on the rate of healing of acute tympanic membrane perforations in a rat model. Thirty-seven rats had both ears separately randomized in a blinded fashion to receive AFGF in one of three concentrations, LYCD, or a control solution. The rats initially underwent subtotal removal of the tympanic membranes bilaterally. Solutions were applied to the randomized ears daily for 3 days, starting at the time of the surgical perforation. The ears were photographed every 3 to 8 days for 35 days. The photographs were digitally scanned and a computer analysis was used to calculate the percentage of residual perforation. No significant difference in the rate of healing was observed for ears treated with AFGF or LYCD versus the controls. Given the potential advantages of medical treatment of tympanic membrane perforations and the established efficacy of growth factors in other model systems, however, further research is warranted.

The effect of acidic fibroblast growth factor and live yeast cell derivative on tympanic membrane regeneration in a rat model

The current treatment of choice for chronic tympanic membrane perforations is surgery. Recent studies using various polypeptide growth factors to accelerate closure of tympanic membrane perforations in model systems have produced mixed results. This study evaluates the effect of acidic fibroblast growth factor (AFGF) and live yeast cell derivative (LYCD) on the rate of healing of acute tympanic membrane perforations in a rat model. Thirty-seven rats had both ears separately randomized in a blinded fashion to receive AFGF in one of three concentrations, LYCD, or a control solution. The rats initially underwent subtotal removal of the tympanic membranes bilaterally. Solutions were applied to the randomized ears daily for 3 days, starting at the time of the surgical perforation. The ears were photographed every 3 to 8 days for 35 days. The photographs were digitally scanned and a computer analysis was used to calculate the percentage of residual perforation. No significant difference in the rate of healing was observed for ears treated with AFGF or LYCD versus the controls. Given the potential advantages of medical treatment of tympanic membrane perforations and the established efficacy of growth factors in other model systems, however, further research is warranted.

Migraine-related vestibulopathy

Migraine has been associated with specific vestibular disorders, including benign paroxysmal vertigo of childhood and benign recurrent vertigo in adults. Migraine may also play a role in chronic nonspecific vestibulopathy. Because scant data exist that describe the clinical findings and vestibular function abnormalities in suspected migraine-related vestibulopathy, we reviewed the history, physical examination, vestibular tests (electronystagmography, rotational chair, posturography), and response to treatment of 100 patients with diagnoses of migraine-related vestibulopathy. Dominant clinical features included chronic movement-associated dysequilibrium, unsteadiness, space and motion discomfort, and occasionally, episodic vertigo as an aura prior to headache, or true vertigo without headache. Common vestibular test abnormalities included a directional preponderance on rotational testing, unilateral reduced caloric responsiveness, and vestibular system dysfunction patterns on posturography. Treatment was usually directed at the underlying migraine condition by identifying and avoiding dietary triggers and prescribing prophylactic anti-migraine medications. Symptomatic relief was also provided using anti-motion sickness medications, vestibular rehabilitation, and pharmacotherapy directed at any associated anxiety or panic disorder.

Functional outcome of vestibular rehabilitation in patients with abnormal sensory-organization testing

A goal of vestibular rehabilitation is to improve the functional status of patients with balance disorders. Despite the focus of vestibular rehabilitation on function, few objective data describe the outcome of vestibular rehabilitation in terms of balance function. In this prospective observational study, we tested a well-defined patient cohort (n = 67) with abnormal pretreatment sensory-organization testing who were undergoing vestibular rehabilitation. Patient outcomes were determined by using objective and subjective measures of function before and after rehabilitation. Overall, 60% of patients showed objective improvement of balance function; 25% of patients improved to normal. Analysis of success and failure of vestibular rehabilitation is important as an aid to appropriate patient counseling and efficient use of rehabilitation resources.

Update on skull base surgery

The field of skull base surgery has changed significantly during the past decade. Various surgical approaches have been developed, which when used alone or in combination provide optimal exposure for the resection of a given lesion with minimal morbidity. This recent evolution in the field of skull base surgery has allowed the surgical management of larger lesions in previously inaccessible locations. Furthermore, techniques in the preoperative, intraoperative, and postoperative management of the intrapetrous internal carotid artery have circumvented many prior limitations of cranial base resections. The goals of this article are to provide an overview of the postlateral skull base approaches in use today, discuss the regions of the skull base that are accessible, and describe the state of the art in management of the intrapetrous internal carotid artery.

Galvanic-induced postural movements as a test of vestibular function in humans

Galvanic stimulation produces a postural sway and eye movements in humans. Since galvanic currents are thought to exert their effect at the trigger zone of the vestibular nerve, an intact vestibular nerve should be necessary to produce a response. We have used galvanic stimulation in humans to test the hypothesis that intact vestibular nerve fibers are required to obtain a postural away response. Experimental subjects included normal subjects, patients who had undergone resection of an acoustic neuroma, and patients who had undergone vestibular neurectomy and surgical labyrinthectomy. Our results support the hypothesis that an intact vestibular nerve is necessary to produce a response. Moreover, two patients with recurrent vertigo following vestibular neurectomy and labyrinthectomy, who had absent ice-water caloric test responses in the operated ears, were found to have a positive galvanic response. This result suggested that their recurrent vertigo was based on intact residual vestibular nerve fibers. Although previous research has not yielded a routine clinical use for galvanic stimulation, our results suggest that galvanic stimulation of the vestibular system can provide unique and valuable diagnostic information.

A practical work-up for vertigo

Specific elements in the history and physical examination direct the work-up of the "dizzy" patient toward or away from a vestibular disorder. When a disorder of this type is suspected, the differential diagnosis includes benign positional vertigo, vestibular neuritis, vertebrobasilar insufficiency, migraine, and endolymphatic hydrops, which is the pathologic condition thought to underlie Meniere's disease. Anxiety is well recognized as a potential component of vestibular abnormalities or as the primary problem.

Excision of petroclival tumors by a total petrosectomy approach

The surgical removal of intradural petroclival tumors of any size is demanding because of the restricted surgical exposure and relation of the tumor with the brain stem, cranial nerves, and vertebrobasilar artery and branches. When petroclival tumors are large or giant sized and involve multiple areas of the clivus, adequate surgical exposure is difficult to achieve, yet is critical for safe tumor removal. In 17 patients with extensive petroclival tumors, total removal of the petrous bone was performed to gain a wide and shallow surgical exposure. This report details the intraoperative and postoperative complications, cranial nerve status, pre- and postoperative disability scores, and extent of tumor resection in these 17 patients. Deterioration of facial nerve function was the most common new cranial nerve injury following surgery. Three patients suffered major neurologic complications; six other patients suffered significant but temporary neurologic complications. Gross total tumor resection was accomplished in 9 of 17 patients, and most patients (15/17) maintained or improved their disability status. Tumor residual was related to cavernous sinus involvement, vascular encasement, or brainstem pial invasion. Total petrosectomy is an intensive and complex approach with inherent morbidity and thus should be reserved for extensive petroclival tumors that cannot be removed using less complicated approaches.

Combined approaches for resection of extensive glomus jugulare tumors. A review of 12 cases

Complete resection with conservation of cranial nerves is the primary goal of contemporary surgery for glomus jugulare tumors. This publication reports the value of combined surgical approaches in achieving this goal in 12 patients with extensive tumors. Eleven of these tumors were classified as Fisch Class C and/or D, while eight were categorized as Jackson-Glasscock Grade III or IV. Intracranial (intradural) extension was present in 10 patients; four patients had tumor extension into the clivus and two into the cavernous sinus. The petrous internal carotid artery (ICA) was involved in eight and the vertebral artery (VA) in one. Subtemporal-infratemporal, retrosigmoid, and/or extreme lateral transcondylar approaches were added to the usual transtemporal-infratemporal approach. This improved the exposure, provided early control of the petrous ICA, and facilitated tumor removal from the clivus, cavernous sinus, posterior fossa, and foramen magnum, allowing a single-stage resection in eight patients. Ten patients had a complete microscopic resection with no mortality. The facial nerve was preserved in nine cases, with tumor involvement requiring nerve resection followed by grafting in the remaining three. Mobilization of the facial nerve was avoided in five cases; of these, three had intact function and two had House-Brackmann Grade III function on follow-up review. Only one patient had a mild persistent swallowing difficulty. The ICA was preserved in 10 patients and resected in two, while the VA required reconstruction in one case. There were no instances of stroke, and blood transfusions were required in five patients who had tumors with nonembolizable ICA or VA feeders. While complete resection provides the best possibility for cure, the important role of adjuvant radiation therapy in cases with residual tumor is discussed. The importance of degrees of brain-stem compression and vascular encasement is emphasized in classifying the more extensive tumors.

Evolution and advances of the lateral surgical approaches to cranial base neoplasms

The evolution and advances of the lateral surgical approaches used for neoplasms of the cranial base involving the middle and posterior cranial fossa are reviewed. The lateral approaches available for access to the cranial base are diverse and are often used in combination. Approaches for tumors that are completely extradural, usually involving the temporal bone or infratemporal fossa, include the infratemporal fossa approach described by Fisch and the preauricular subtemporal-infratemporal fossa approach. Lateral approaches used to provide exposure of intradural tumors involving the clivus and traversing the middle and posterior cranial fossa are based on the following approaches: the frontotemporal orbitozygomatic, subtemporal/middle fossa, transpetrosal, lateral suboccipital, and transcondylar approaches. The great strides that have been made in the safe and effective surgical treatment of cranial base neoplasms are due, in part, to the availability of multiple surgical approaches and the ability to tailor the planned operative procedure to the precise location and extent of the cranial base tumor.

Clinical assessment of postural stability

It is important to evaluate both vestibulo-oculomotor and vestibulospinal pathways in patients with balance disorders. While moving-platform posturography can assess vestibulospinal function, the cost and time required to perform this test may limit its clinical use. A clinical office vestibulospinal evaluation that could be done quickly and inexpensively would be of benefit. In this study we used foam posturography to prospectively evaluate 50 patients with vestibular complaints to determine its predictive value in comparison with moving-platform posturography results. Our results demonstrate a significant correlation (p < 0.005) with a sensitivity and specificity of 95 percent and 90 percent, respectively, between the clinical office assessment using foam posturography and the results of moving-platform posturography. The ability of patients to utilize vestibular cues to maintain posture may be accurately assessed in a clinical office examination and should be useful to otolaryngologists to evaluate the vestibulospinal system.

Sources of error in use of beta-2 transferrin analysis for diagnosing perilymphatic and cerebral spinal fluid leaks

Beta-2 transferrin is a protein found in cerebral spinal fluid and inner ear perilymph, but not in blood, nasal, or ear secretions. The clinical use of this test has been previously demonstrated, but sources of test error have not been addressed. The purpose of this study was to evaluate sources of error related to this test in order to improve its clinical use. We reviewed the specimens submitted for beta-2 analysis over the first 12 months of test availability at our institution to identify potential factors leading to test error. Sources of error were categorized into the following groups: sample collection, delivery, and extraction factors; assay factors; physician-related factors; and patient-related factors. The test for beta-2 transferrin is a valuable diagnostic tool for the management of difficult clinical problems, provided the physician is aware of potential factors that can lead to test error and clinical mismanagement.

Neurotologic manifestations of Chiari 1 malformation

It is important for otolaryngologists to recognize Chiari malformations as part of the differential diagnosis of balance disorders because patients may initially be seen with symptoms referable to the vestibular system, including ataxia, nystagmus, or vertigo. The objective of this paper is to review the signs, symptoms, and vestibular test findings of a series of patients with Chiari 1 malformation. Six patients were identified by retrospective chart review with a diagnosis of Chiari malformation. Each patient had a complete otoneurologic examination and vestibular function testing. The results indicated that patients fell into two different vestibular test result profiles. First, patients with advanced symptoms demonstrated oculomotor dysfunction, central vestibular nystagmus, abnormal vestibular visual interaction, and abnormal tilt suppression of postrotatory nystagmus. On the other hand, a number of patients were identified with incidentally noted Chiari malformation on magnetic resonance imaging scan who had a vestibular test profile consistent with peripheral vestibulopathy without signs and symptoms of central nervous system dysfunction. Guidelines are provided to help determine the extent of the group of symptoms attributable to an incidentally discovered Chiari malformation.

Translabyrinthine approach to skull base tumors with hearing preservation

The improvement in surgical techniques and the experience gained in treatment of skull base tumors have stimulated more aggressive management of larger lesions. Patients presenting with limited preoperative deficits have challenged the surgeon to design the surgical approach so as to minimize postoperative morbidity and preserve function. Tumors of the middle fossa and clivus with extension into the posterior fossa are usually approached by a combined subtemporal, transtentorial, transpetrous approach. In patients with preoperative hearing, the surgical exposure is often limited by the labyrinthine portion of the otic capsule. The technique of partial labyrinthectomy, removing the posterior and/or superior semicircular canals, maximizes exposure with preservation of hearing. This report details our experience with the partial labyrinthectomy approach for 14 patients with large skull base lesions. All patients had hearing preserved despite sacrifice of one or two of the semicircular canals. Bone pure-tone averages and speech discrimination scores were maintained near their preoperative levels. The indications, benefits, techniques, and hearing results of this approach are reviewed.