Long-term follow-up of transtympanic gentamicin for Ménière's syndrome.

OBJECTIVE: Recent studies have shown that transtympanic gentamicin for Ménière's syndrome is effective. Current treatment protocols vary. One concept has been to perform a chemical ablation; the other has been to perform a chemical alteration. Ablation requires multiple injections and is effective in controlling the vertigo, but it is associated with a significant incidence of hearing loss. Chemical alteration uses a minimal dose to reduce vestibular function without affecting cochlear function. STUDY DESIGN: Prospective. SETTING: Tertiary medical center. PATIENTS: Patients had classic unilateral Ménière's syndrome that was unresponsive to medical therapy. INTERVENTION: A single injection of gentamicin is given, and the patient is seen 1 month after injection. If indicated, the patient receives another injection and is reevaluated 1 month later. MAIN OUTCOME MEASURES: Control of vertigo and maintenance of hearing using the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines (1995). RESULTS: Fifty-six patients have documented follow-up for 2 years or more, and 21 have 4 years or more of follow-up. This article presents the 4-year results as outlined by the AAO-HNS guidelines. Vertigo classes A and B were seen in 82% of patients. The patients followed 2 to 4 years had 86% vertigo class A and B results. Those followed 4 years or more show 76% with a vertigo class A or B result. In this study there has been minimal cochlear loss. There was vestibular change clinically, which was documented by electronystagmography. CONCLUSIONS: It appears that a single transtympanic gentamicin injection is effective in controlling the vertigo of Ménière's syndrome. Cochlear impact has been minimal. It is most useful for those patients who have failed medical management and are severely affected but not totally incapacitated by the disease.

Audiometric findings in patients with acoustic neuroma.

OBJECTIVE: Hearing loss remains the most common symptom associated with acoustic neuroma. This study documents the audiometric findings from 721 acoustic neuroma procedures. STUDY DESIGN: This was a retrospective study. The preoperative audiometric data were compiled and were analyzed by patient age, gender, tumor size, time of surgery, and neurofibromatosis Type 2 (NF 2). Postoperative audiometric data were arranged and compiled in the same way. The hearing classification proposed by the AAO-HNS was applied to all preoperative and postoperative cases. SETTING: Tertiary referral center. PATIENTS: Surgically confirmed acoustic neuroma patients who had not previously received surgical or radiosurgical therapy. Patients underwent surgery by the retrosigmoid approach. INTERVENTION: Surgical removal of an acoustic neuroma. MAIN OUTCOME RESULT: Provision of pure tone and speech data from a group of acoustic neuroma patients, including application of the recently introduced and accepted AAO-HNS hearing classification system. RESULTS: Preoperative audiometric data were obtained from 694 of 721 patients (96%), of whom 619 had measurable hearing. Postoperative audiometry was performed on 606 patients; 152 had usable data. The combined preoperative audiometric data revealed a high frequency sensorineural hearing loss. Word recognition was servicable. The postoperative pure tones and word recognition scores were worse than preoperative scores. Age, gender, tumor size, and time of surgery had some impact on the preoperative hearing and the postoperative result; NF 2 did not. CONCLUSIONS: The study confirms that hearing alteration is almost universal in acoustic neuroma patients. Hearing preservation is possible in a significant number of cases; however, the postoperative auditory function tends to be worse.

Assessment of dysequilibrium after acoustic neuroma removal.

OBJECTIVE: Published data evaluating the rate of dysequilibrium after acoustic neuroma removal are inconsistent. The purpose of this investigation was to determine the incidence and severity of dysequilibrium and quality of life in a group of patients after acoustic neuroma surgery. STUDY DESIGN: The study design was a retrospective chart review and survey that included demographic and medical history questions, the Dizziness Handicap Inventory (DHI), the UCLA Dizziness Questionnaire (UCLA-DQ), and the Health Status Questionnaire (HSQ). SETTING: The study was conducted in a multispecialty tertiary care clinic. PATIENTS: Two hundred thirty-seven subjects who underwent initial surgical removal of an acoustic neuroma between January 1990 and June 1997 were studied. MAIN OUTCOME MEASURES: Correlation of dysequilibrium with age, gender, and tumor size was measured. Survey analysis including DHI, UCLA-DQ, and HSQ scores. RESULTS: Sixty-five percent of patients reported persistent dysequilibrium after surgery. A majority of those with dysequilibrium had DHI, UCLA-DQ, and HSQ scores that suggested minimal impact on the quality of life. The HSQ scores were statistically significantly poorer for the patients with dysequilibrium than for those without dysequilibrium. CONCLUSIONS: Sixty-five percent of patients reported dysequilibrium after acoustic neuroma removal. The quality-of-life impact was mild.

Transtympanic gentamicin for Meniere's syndrome.

OBJECTIVES: Study the impact of transtympanic gentamicin on patients with unilateral Meniere's syndrome. Partial chemical labyrinthectomy is a relatively recent concept for the treatment of Meniere's syndrome. It uses the ototoxic effect of gentamicin to reduce the symptom of vertigo and maintain cochlear function. STUDY DESIGN: A prospective study using transtympanic gentamicin was begun in January 1994. Patients selected had failed medical therapy, but were not incapacitated. Patients had preinjection audiometric and electronystagmography data. Most had an imaging study. All had one injection, about half had more than one. Patients were seen 1 month after therapy and repeat studies were obtained. Repeat injection was performed if indicated. Follow-up from the chart or by telephone was obtained. Data were tabulated using the 1995 American Academy of Otologaryngology-Head and Neck Surgery guidelines. RESULTS: Through December 1996 43 patients with unilateral Meniere's syndrome were treated. The pretherapy function level was 3 through 5. After therapy the function level was 1 or 2. There was almost no change in cochlear function and no patient became deaf. Many patients had mild ataxia or dysequilibrium during the first 2 weeks following therapy. Most patients showed some decrease in labyrinthine function measured on electronystagmography. No attempt was made to ablate labyrinthine function. Seventeen of 18 patients had a vertigo index in the class A or B category after 2 years. CONCLUSIONS: Transtympanic gentamicin has become the treatment of choice for patients who fail medical therapy for Meniere's syndrome at the authors' institution.

Preoperative identification of patients at risk of developing persistent dysequilibrium after acoustic neuroma removal.

OBJECTIVE: This study aimed to identify preoperative signs or symptoms that correlate with poor postoperative vestibular compensation after acoustic neuroma removal. STUDY DESIGN: The study design was a retrospective chart review. SETTING: The study was conducted at a tertiary care center. PATIENTS: A total of 210 patients who had acoustic neuromas removed via the retrosigmoid approach from January 1, 1990, to July 1, 1995, participated. MAIN OUTCOME MEASURES: Persistent dysequilibrium for > 3 months after surgery was measured. RESULTS: Age (p = 0.002), gender (p = 0.007), presence of preoperative dysequilibrium (p = 0.005), duration of preoperative dysequilibrium > 3.5 months (p = 0.003), and central findings on electronystagmography ( p < 0.001) were related to poor outcome. CONCLUSIONS: The authors found 31% of patients to have dysequilibrium lasting > 3 months after surgical removal of an acoustic neuroma. Age > 55.5 years, female gender, constant preoperative dysequilibrium present for > 3.5 months, and central findings on electronystagmography were associated with a worse outcome.

Venous air embolism in sitting and supine patients undergoing vestibular schwannoma resection.

OBJECTIVE: This study retrospectively compares the incidence of venous air embolism (VAE) detection and morbidity in the sitting and supine positions. All patients underwent vestibular schwannoma resection via the retrosigmoid approach by a single surgical team. METHODS: A total of 432 consecutive operations were reviewed, 222 of which were performed with the patients in the sitting position and 210 of which were performed with the patients in the supine position. Charts were reviewed for evidence of intraoperative VAE, intraoperative hypotension secondary to VAE, postoperative morbidity related to VAE, and other variables to compare the groups. RESULTS: This study demonstrated a 28% incidence of VAE detection when patients were in the sitting position compared to a 5% incidence of VAE detection when patients were in the supine position (P < 0.0001). Intraoperative hypotension secondary to VAE was noted in 1.8% of the sitting patients and 1.4% of the supine patients (P=0.72, no significant difference). Postoperative morbidity caused by VAE was noted in one sitting patient (0.5%) (pulmonary edema) and in no supine patients (P=0.48, no significant difference). Blood loss was slightly greater in the supine group, and operative times were similar in both groups, despite that the average tumor size of patients operated on in the sitting position was 2.8 cm versus 2.2 cm in the supine group (P < 0.0001). CONCLUSION: Our results indicate that although there is a higher incidence of VAE detection in sitting patients, the morbidity is not statistically greater. We conclude that because morbidity from VAE is similar in either position, patient positioning should be based on surgical team preference.

Nonsurgical factors predictive of postoperative hearing for patients with vestibular schwannoma.

OBJECTIVE: The purposes of the study were to determine whether preoperative cochlear reserve as measured by evoked otoacoustic emissions (EOAE) as well as other hearing variables often associated with hearing preservation are correlated with hearing preservation after tumor removal and to determine whether any hearing variables are independent of tumor size as a predictor of hearing preservation. STUDY DESIGN: Preoperative audiologic data for 104 patients having vestibular nerve schwannomas removed via a retrosigmoid surgical approach were reviewed and subjected to factor analysis. SETTING: All patients were seen at the Mayo Clinic, Rochester, Minnesota. PATIENTS: The patient sample was divided into two groups based on hearing thresholds after surgery. Group I consisted of 73 ears without hearing preservation. The remaining 31 ears, group II, had preserved hearing (defined as average postoperative pure-tone thresholds < or = 85-dB HL for 0.5, 1, 2, and 3 kHz). MAIN OUTCOME MEASURES: Variables not predictive of hearing preservation were age, gender, tumor laterality, and cochlear reserve (EOAE). Variables predictive of hearing preservation were small tumor size, pure-tone hearing sensitivity, speech reception thresholds, word recognition scores, integrity of cochlear nerve (acoustic reflex thresholds, and auditory brain stem response [ABR] waveforms). RESULTS: A multivariate logistic regression analysis showed that only word recognition scores at 40-dB sensation level were independent of tumor size as a predictor of hearing preservation.

Low-dose intratympanic gentamicin and the treatment of Meniere's disease: preliminary results.

The most disabling symptom for most patients with unilateral Meniere's disease is vertigo. Eradication of the diseased end organ is effective in eliminating the vertigo. Labyrinthectomy remains the "gold standard"; unfortunately, residual hearing is sacrificed to obtain this end. The purpose of this study is to evaluate low-dose intratympanic gentamicin for the control of vertigo and for the preservation of hearing. A single dose of gentamicin (10-80 mg) was injected into the middle ear space of 23 patients with unilateral Meniere's disease as an office procedure. Eighty-four percent of the patients had no episodes of vertigo during the last 6 months of follow-up. Pure tone average and word discrimination scores were unchanged as a group. Ninety-five percent of patients had a hearing loss at 6 and 8 kHz that averaged 7.5 dB. Caloric function was reduced in 93%. Low-dose intratympanic gentamicin is a safe, simple, office procedure that is effective in controlling the definitive vertiginous episodes in most patients with unilateral Meniere's disease. Control of vertigo can be obtained with preservation of hearing.

Iatrogenic facial paralysis prevention.

Iatrogenic facial paralysis occurs in less than 4% of major otologic procedures. The prevention of iatrogenic injuries involves study, training and experience. These concepts are carefully woven into residency training, fellowship and, ultimately, into peer review. The reasons for injury may be errors of omission, such as inadequate preparation for the procedure, or errors of commission, such as inadequate surgical exposure. Currently, there appear to be enough surgical cases for training programs and the core training of otolaryngology residents prepares them to handle most facial nerve problems. Included in this article is a more detailed description of the anatomy in and around the facial nerve, particularly in the mastoid, with suggestions on how to avoid problems and reduce injuries.

Conservative management of acoustic neuroma: an outcome study.

OBJECTIVE: This study analyzed selection criteria, clinical outcome, and tumor growth rates in patients with acoustic neuromas in whom the initial management strategy was observation. METHODS: A retrospective review of patients with conservatively managed unilateral acoustic neuromas was conducted. Minimum follow-up was 6 months. Patients with neurofibromatosis Type II were excluded. Differences in tumor growth rates were analyzed by use of the Wilcoxon rank sum test. RESULTS: Sixty-eight patients (31 men and 37 women) with a mean age of 67.1 years were followed for an average of 3.4 years after diagnosis. The reasons for a trial of observation included advanced age (55%), patient preference (21%), minimal symptoms (9%), poor general medical condition (7%), asymptomatic tumor (4%), and tumor in the only hearing ear (4%). Fifty-eight patients (85%) were successfully managed with observation alone. Ten patients (15%) ultimately required treatment (nine received microsurgical treatment and one patient underwent radiosurgical intervention) at a mean time interval of 4.0 years after diagnosis. Forty-eight tumors (71%) showed no growth and 20 (29%) enlarged during the study period. The mean tumor growth rate at the 1-year follow-up was significantly higher in the group requiring treatment (3.0 mm) than in the group not requiring treatment (0.36 mm) (P < 0.0001). Thus, the tumor growth rate at the 1-year follow-up was a strong predictor of the eventual need for treatment. CONCLUSION: Observation is a reasonable management strategy in carefully selected patients with acoustic neuromas. Diligent follow-up with serial magnetic resonance imaging is recommended, because some tumors will enlarge to the point at which active treatment is required.

Far-field auditory brainstem response in neurotologic surgery.

This is a review of our experience using far-field auditory brainstem monitoring during acoustic neuroma removal. The observations are based on 144 consecutive cases beginning in 1986. The factors of importance are tumor size, preoperative auditory function, and the preoperative presence of a wave V on the auditory brainstem response. Our experience suggests that preservation of hearing in tumors > 2.5 cm is rare. It was observed that preserving wave V does not guarantee preservation of hearing. Conversely, loss of wave V does not preclude preservation of hearing. It has also been noted that the presence of only wave I preoperatively does offer some hope that hearing can be preserved postoperatively. Finally, postoperative hearing function is usually equal to or worse than the preoperative function. Only rarely does the postoperative function improve.

Stereotactic radiosurgery using the gamma knife for acoustic neuromas.

PURPOSE: To assess the efficacy and toxicity of stereotactic radiosurgery using the gamma knife for acoustic neuromas. METHODS AND MATERIALS: Between January 1990 and January 1993, 36 patients with acoustic neuromas were treated with stereotactic radiosurgery using the gamma knife. The median maximum tumor diameter was 21 mm (range: 6-32 mm). Tumor volumes encompassed within the prescribed isodose line varied from 266 to 8,667 mm3 (median: 3,135 mm3). Tumors < or = 20 mm in maximum diameter received a dose of 20 Gy to the margin, tumors between 21 and 30 mm received 18 Gy, and tumors > 30 mm received 16 Gy. The dose was prescribed to the 50% isodose line in 31 patients and to the 45%, 55%, 60%, 70%, and 80% isodose line in one patient each. The median number of isocenters per tumor was 5 (range: 1-12). RESULTS: At a median follow-up of 16 months (range: 2.5-36 months), all patients were alive. Thirty-five patients had follow-up imaging studies. Nine tumors (26%) were smaller, and 26 tumors (74%) were unchanged. No tumor had progressed. The 1- and 2-year actuarial incidences of facial neuropathy were 52.2% and 66.5%, respectively. The 1- and 2-year actuarial incidences of trigeminal neuropathy were 33.7% and 58.9%, respectively. The 1- and 2-year actuarial incidence of facial or trigeminal neuropathy (or both) was 60.8% and 81.7%, respectively. Multivariate analysis revealed that the following were associated with the time of onset or worsening of facial weakness or trigeminal neuropathy: (a) patients < age 65 years, (b) dose to the tumor margin, (c) maximum tumor diameter > or = 21 mm, (d) use of the 18 mm collimator, and (e) use of > five isocenters. The 1- and 2-year actuarial rates of preservation of useful hearing (Gardner-Robertson class I or II) were 100% and 41.7% +/- 17.3, respectively. CONCLUSION: Stereotactic radiosurgery using the gamma knife provides short-term control of acoustic neuromas when a dose of 16 to 20 Gy to the tumor margin is used. Preservation of useful hearing can be accomplished in a significant proportion of patients.

Olfactory neuroblastoma. An immunohistochemical, ultrastructural, and flow cytometric study.

BACKGROUND: Olfactory neuroblastoma is an uncommon neuroectodermal tumor of the upper nasal cavity, microscopic features of which are not always homogeneous. No morphologic features have been found to correlate reliably with prognosis. METHODS: Twenty-six olfactory neuroblastomas occurring in 14 females and 12 males, ages 18-78 years, were studied by immunohistochemistry, electron microscopy, and DNA flow cytometry. Survival rates were statistically analyzed relative to several variables. RESULTS: Microscopically, 22 tumors formed a morphologic spectrum intermediate between paraganglioma (PG) and neuroblastoma (NB). Others included two ganglioneuroblastomas (GNB), one lesion exhibited biphasic (neuronal and epithelial) differentiation, and one tumor showed predominantly epithelial features. Immunoreactivity for neuronal and neuroendocrine markers included synaptophysin in 77%, neurofilament protein in 38%, class III beta-tubulin in 81%, and chromogranin A in 77%. In 88% of cases, elongated S-100 protein-positive cells surrounded tumor lobules. Cytokeratin and epithelial membrane antigen immunoreactivity were noted in six (23%) and two (8%) tumors, respectively. Aberrant p53 expression was detected in 16 tumors (62%). The Ki-67 labeling index (LI) varied from 0%-43.8% (mean, 7.4%). Ultrastructurally, 80-230 nm dense core granules were noted within perikarya and as in microtubule-containing processes in all of the 11 tumors studied by electromicroscopy. Lobules of seven tumors were surrounded by electron-dense sustentacular cells. Epithelial tumors exhibited obviously epithelial features in addition to neuronal differentiation. DNA flow cytometry demonstrated a high incidence of polyploidy and aneuploidy (78%) and a wide range of percent S phase fractions (1.5%-21.8%; mean, 9.0%). The study showed that longer survival rates are related significantly to (1) the occurrence of metastases which was linked to tumor subtype, (2) to a higher incidence of S-100 protein-positive cells, and (3) to a low (< 10%) Ki-67 labeling index. CONCLUSIONS: The present study indicates that (1) although typical olfactory neuroblastomas exhibit PG/NB differentiation, they more closely resemble PG, (2) occasional tumors show GNB and/or epithelial differentiation, and (3) survival rates may correlate with S-100 protein immunoreactivity and Ki-67 LI. Cancer 1995; 76:4-19.

Impact of cranioplasty on headache after acoustic neuroma removal.

We reported previously the incidence of headache after the retrosigmoid removal of an acoustic neuroma as 23% at 3 months, declining to 9% at 2 years after surgery. In an attempt to reduce the incidence and the severity of these headaches, we made one change in our surgical procedure, which was to perform a cranioplasty with methyl methacrylate. Twenty-four patients underwent the cranioplasty and were followed for at least 3 months postoperatively. These patients were matched to 24 patients who did not undergo a cranioplasty. We found a 4% incidence of headache in the cranioplasty group and a 17% incidence in the matched group. No complications were related to this change in our procedure.

Middle ear adenoma and adenocarcinoma.

Adenomas and adenocarcinomas originating from the middle ear are few in number and have met with significant controversy in the literature. Our experience with 11 previously described patients is updated and five new cases are added. These tumors were seen in persons whose ages ranged from 7 to 77 years. The most common initial symptom was decreased hearing (11 cases), followed by otorrhea (4 cases), and otalgia (4 cases). At the time of diagnosis, facial nerve weakness was present in several patients (seven), and this was a poor prognostic sign. These glandular tumors engender controversy regarding histologic origin and the pathologic demarcation between adenoma and adenocarcinoma. In this review, we show that otorrhea, bone erosion, facial nerve involvement, and aggressive clinical behavior can be the result of lesions that appear microscopically benign. Furthermore, we present evidence of the similarity of these glandular lesions to paragangliomas and carcinoid tumors. Finally, pathologic data are presented to develop the previously unreported theory that the origin for this group of tumors is paraganglionic tissue.

Headache after acoustic neuroma excision.

The retrosigmoid approach to acoustic neuroma removal has recently been criticized for causing frequent and severe headache postoperatively. We review 331 patients who had acoustic neuroma removal by the retrosigmoid approach at one institution. The incidence of postoperative headache was 23 percent at 3 months, 16 percent at 1 year, and 9 percent at 2 years. Management was primarily with analgesics, physiotherapy, and reassurance. No patient had additional surgical treatment. Information available indicates that the incidence of postoperative headache associated with the translabyrinthine approach is similar to that of the retrosigmoid approach. Perhaps filling the craniectomy defect will decrease further the incidence of headache postoperatively.

Does the distribution of Schwann cells correlate with the observed occurrence of acoustic neuromas? .

Acoustic neuromas account for 75 to 80 percent of cerebellopontine angle tumors and 8 to 10 percent of all intracranial neoplasms. These tumors arise from the Schwann cell sheath that surrounds the peripheral portion of the facial, cochlear, superior, and inferior vestibular nerves. Theoretically, a schwannoma may arise from Schwann cells anywhere along these nerves from the glial-Schwann cell junction to the end organ. Clinically, however, they most frequently originate from the vestibular nerves, occasionally from the facial, and only rarely from the cochlear nerve. This investigation utilized light microscopy, immunochemistry, and digital optical morphologic analysis to determine the distribution of Schwann cells along the facial and vestibulocochlear nerves in an attempt to explain the observed distribution of tumors, and to evaluate currently accepted theories. No direct correlation between the distribution of Schwann cells and the observed distribution of schwannomas was found. Thus, this study did not confirm the currently held theories regarding schwannoma distribution in these nerves.

Acoustic neuroma and pregnancy.

From January 1978 through July 1989, 360 patients underwent primary removal of an acoustic neuroma at the Mayo Clinic. Seventy of these patients were women under the age of 46 years; six of them were pregnant between the time of onset of their symptoms and the removal of their tumor. A review of the records of these six women revealed the presenting complaint in most to be central neurologic symptoms rather than labyrinthine symptoms. All had unilateral tumors. These tumors tended to be larger and more vascular than those in the nonpregnant cohort, and to have greater surgical morbidity. The pure-tone hearing levels were normal in four of these patients. All women experienced normal vaginal delivery without complication. Based on our experience with these women, we believe that acoustic neuroma present during pregnancy may be managed by close observation until the postpartum period, provided there are no impending neurologic complications.