听神经瘤临床行为与其磁共振信号和病理特征之间的相关性研究

目的　分析听神经瘤的大小、生长速率及增殖与其磁共振信号、组织学特征之间的相互关系。方法　回顾分析听神经瘤 4 3例 ,依MR信号分为均匀、不均匀及囊性变 ,组织学包括AntoniA、AntoniB以及纤维化、含铁血黄素沉淀、黄色瘤样细胞。结果　信号均匀的听神经瘤肿瘤较小、生长较慢、增殖指数较低 ,组织学以AntoniA结构占优 ;不均匀和囊性听神经瘤肿瘤较大、生长较快、增殖指数较高 ,以混合型结构占优 ;不均匀和囊性听神经瘤中含铁血黄素沉淀、黄色瘤样细胞以及不均匀听神经瘤的纤维化明显增多 ,它们均有统计学意义。结论　较大的听神经瘤不仅MR表现为不均匀信号 ,而且组织学主要表现混合型结构 ,也可能有其他变化 ,主要是含铁血黄素沉淀和囊性变。     

Microsurgical results with large vestibular schwannomas with preservation of facial and cochlear nerve function as the primary aim

Summary Objective. To evaluate our microsurgical results in dealing with vestibular schwannomas (VS) greater than or equal to 30 mm when preservation of cranial nerve function was considered more important than total tumour removal.Methods. Sixteen consecutive cases were operated on by the same neurosurgeon according to a prospective protocol using intraoperative neuro-monitoring (IONM) based on electromyographic and brain stem auditory evoked potential recordings. Facial nerve function was evaluated on the House-Brackmann Scale and cochlear nerve function on the Gardner-Robertson Scale. Someone not involved in the clinical management of our patients collected all data.Results. Fifteen patients showed facial nerve (FN) function of House-Brackmann grade (HBG) I or II at one year postoperatively and one kept the HBG IV she had preoperatively. Two patients of four maintained a cochlear nerve function of Gardner-Robertson grade (GRG) II. The tumour excision rates were: total, 68.7%; near total, 6.3%; subtotal, 18.7%, and partial, 6.3%. The average follow-up was 55 months (1–106). Three patients underwent radiotherapy later with growth stabilisation and no additional morbidity.Conclusion. When dealing with VS greater than or equal to 30 mm, microsurgery guided by IONM, with a rate of total or near-total tumour excision of about 75%, can retain socially acceptable facial nerve function (HBG I or II) in all cases and serviceable hearing (GRG I or II) in two cases out of four. Maintaining serviceable cranial nerve function should take precedence over total tumour excision.     

The current state of the radiological diagnosis of acoustic neuroma

Summary Thin, overlapping section, contrast-enhanced, axial and coronal CT, with additional highresulution (HR) treatment of the sections through the internal auditory canal, was performed on 31 patients clinically suspected of acoustic neuroma. With this technique 13 acoustic neuromas protruding more than 10 mm and eight acoustic neuromas protruding between 2 and 10 mm outside the internal auditory canal were unequivocally diagnosed. O₂CT cisternography was performed on ten patients. An intracanalicular neuroma was diagnosed in three cases with this technique, also a small extracanalicular neuroma in one case, and an acoustic neuroma was definitely excluded in six cases. It is concluded that O₂CT cisternography is the diagnostic procedure of choice for the detection of purely intracanalicular neuromas and the definite exclusion of acoustic neuroma. HR CT proved superior to polytomography for the evaluation of the internal auditory canal and should be performed in every case suspected of acoustic neuroma. A protocol for the radiological investigation of patients suspected of acoustic neuroma is given     

Abnormalities of axon growth in human olfactory mucosa

OBJECTIVES/HYPOTHESIS: Random biopsies of the human adult olfactory mucosa often demonstrate degenerative changes in the olfactory epithelium (OE) in both dysosmic and normosmic patients and, consequently, have limited diagnostic usefulness. However, detailed analysis of the subepithelial tissue with specific attention to the fascicles of the olfactory nerve and abnormalities of axonal growth may improve the correlation of histopathology with sensory function. STUDY DESIGN: Retrospective review of human OE biopsies. METHODS: Mucosal biopsies from the olfactory area obtained from 27 subjects were examined by light and electron microscopy, with particular attention to the olfactory nerve fascicles; results were correlated with clinical status. Immunohistochemical analysis was used to characterize the extent of axonal depletion, relative maturity of the parent population, and aberrant axonal growth. RESULTS: As expected, there are areas of respiratory metaplasia and neuronal depletion in normosmic as well as dysosmic patients. The degree of axon degeneration within the fascicles correlates better with individual olfactory status. Immature neurons predominate, and re-entrant neuromas develop in patients with olfactory loss caused by disconnection from the olfactory bulb. Individuals with olfactory loss caused by epithelial damage as with chronic rhinosinusitis display evidence of nerve fascicle degeneration and intraepithelial neuromas. CONCLUSION: The status of olfactory axons provides useful information on the overall condition of the olfactory periphery and improves the diagnostic usefulness of mucosal biopsies. In addition to an assessment of the epithelium per se, the fascicles of the olfactory nerve need to be characterized for a complete analysis of the olfactory mucosa.     

Patient perception of comorbid conditions after acoustic neuroma management: survey results from the acoustic neuroma association

OBJECTIVES/HYPOTHESIS: Based on survey results of the Acoustic Neuroma Association, the patient ratings of the most difficult aspects of acoustic neuroma management were reported and a review of the literature was made regarding comorbid conditions associated with acoustic neuroma treatment and their impact on patient quality of life. STUDY DESIGN: Cohort study of 1940 patients who were members of the Acoustic Neuroma Association. METHODS: A detailed questionnaire was mailed to 2372 members of the Acoustic Neuroma Association to identify preoperative and postoperative symptoms, complications, and long-term effects on physical and psychosocial function. For 1940 respondents (81.8%) who reported the "most difficult aspect of the AN [acoustic neuroma] experience," the responses were analyzed by tumor size, surgical approach, and patient age and sex. Statistical analysis was performed using SPSS software. RESULTS: Respondents reported that the most difficult aspect of the acoustic neuroma experience was hearing loss (25.8%), followed by facial weakness (17.9%), eye problems (10.8%), and headache (10.5%). In order of frequency, men reported hearing loss, balance problems, perioperative surgical experience, and eye and facial weakness, and women reported hearing loss, facial weakness, eye problems, and headache. Facial weakness was a morbidity more often reported for men and women who had large tumors, who were young, or who had undergone the retrosigmoid approach. Balance dysfunction was significant in patients older than 75 years of age. In patients with small tumors, headaches and balance problems were frequently reported. CONCLUSION: In the large cohort study of patients with acoustic neuroma, perceptions regarding the impact of treatment illustrated why it is incumbent on physicians to understand the sentiments of patients with acoustic neuroma when counseling them and recommending optimal management strategies.     

Auditory brainstem response versus magnetic resonance imaging for the evaluation of asymmetric sensorineural hearing loss

OBJECTIVES/HYPOTHESIS: Auditory brainstem response (ABR) testing and magnetic resonance imaging (MRI) are compared for the evaluation of patients with asymmetric sensorineural hearing loss (SNHL). MRI with gadolinium administration is the current gold standard for identifying retrocochlear lesions causing asymmetric SNHL. The study seeks to determine the sensitivity and specificity of ABR in screening for possible retrocochlear pathology. Most important among SNHL etiologies are neoplastic lesions such as vestibular schwannomas, cerebellopontine angle (CPA) tumors, as well as multiple sclerosis, stroke, or other rare nonneoplastic causes. The study results will allow the author to recommend a screening algorithm for patients with asymmetric SNHL. STUDY DESIGN: The study is a multi-institutional, institutional review board approved, prospective, nonrandomized comparison of ABR and MRI for the evaluation of patients with asymmetric SNHL. METHODS: Three hundred twelve patients (between the ages of 18 and 87) with asymmetric SNHL completed the study. Asymmetric SNHL was defined as 15 dB or greater asymmetry in two or more frequencies or 15% or more asymmetry in speech discrimination scores (SDS). These patients prospectively underwent both ABR and MRI. The ABR and MRI were interpreted independently in a blinded fashion. In addition to the ABR and MRI results, a variety of clinical and demographic data were collected. RESULTS: Thirty-one (9.94%) patients of the study population of 312 were found on MRI to have lesions causing their SNHL. Of the 31 patients with causative lesions on MRI there were 24 vestibular schwannomas, 2 glomus jugulare tumors, 2 ectatic basilar arteries with brainstem compression, 1 petrous apex cholesterol granuloma, 1 case of possible demyelinating disease, and 1 parietal lobe mass. Twenty-two of the 31 patients had abnormal ABRs, whereas 9 patients (7 with small vestibular schwannomas) had normal ABRs. This gives an overall false-negative rate for ABR of 29%. The false-positive rate was found to be 76.84%. Sensitivity of ABR as a screening test was 71%, and specificity was 74%. CONCLUSIONS: Ten percent of patients with asymmetric SNHL (by this study's criteria) are likely to have causative lesions found on MRI. Although the recently reported annual incidence of vestibular schwannoma in the general population is 0.00124%, for patients with asymmetric SNHL in this study, the incidence was 7.7% (nearly 4 orders of magnitude higher). ABR has been demonstrated to have low sensitivity and specificity in the evaluation of these patients and cannot be relied on as a screening test for patients with asymmetric SNHL. Keeping the use of MRI conditional on the results of ABR will annually result in missed or delayed diagnosis of causative lesions in 29 patients per 1,000 screened. The author recommends abandoning ABR as a screening test for asymmetric SNHL and adoption of a focused MRI protocol as the screening test of choice (within certain guidelines).     

Hearing preservation in acoustic neuroma surgery: the impact of different patient selection criteria

OBJECTIVES/HYPOTHESIS: The aim of the present study was to assess whether applying the various selection criteria for hearing preservation surgery on the same group of patients with acoustic neuroma leads to significantly different numbers of patients being considered suitable for this kind of surgery. STUDY DESIGN: We used different selection criteria for hearing conservation surgery based on a range of studies in the published literature. We applied these criteria to a consecutive group of patients presenting to our unit with acoustic neuroma. We then calculated the numbers of patients deemed suitable for hearing preservation surgery as a function of these different selection criteria. METHODS: Studies with published selection criteria, total numbers of patients, and numbers of patients suitable for hearing preservation surgery were found in the literature. These selection criteria were applied to our patient data. A chi2 statistical analysis was used to assess whether applying different selection criteria to the same group of patients (the subjects of the present study) resulted in different numbers of patients suitable for hearing preservation surgery. RESULTS: The numbers of patients suitable for hearing preservation showed wide variation, ranging from 8 (10%) to 45 (56%) patients (of the total number of 80 patients in the present study). The chi2 statistical analysis revealed that the various selection criteria did have an effect on the numbers of patients suitable for hearing preservation surgery, and the statistical significance reached the level of P<.001. CONCLUSIONS: Different selection criteria lead to significantly different numbers of patients being considered suitable for hearing preservation surgery. Consensus and agreed selection criteria would help set patient expectations, refine candidate selection, and facilitate the comparison of outcomes across centers.     

An objective method of analyzing cochlear versus noncochlear patterns of distortion-product otoacoustic emissions in patients with acoustic neuromas

OBJECTIVES: To objectify the effects of retrocochlear disease on distortion-product otoacoustic emissions (DPOAEs) by developing a computer-based software strategy for classifying DPOAE patterns as cochlear or noncochlear and to evaluate the sensitivities of these techniques in a large series of patients with unilateral acoustic neuromas. STUDY DESIGN: Development of a novel, software-based method of DPOAE analysis, which was evaluated with data obtained from a retrospective review of the results from audiometric tests performed in a series of patients. METHODS: A computer-based software strategy was developed, using frequency-specific data from normal-hearing adults, for the purpose of distinguishing cochlear from noncochlear patterns of hearing loss, by determining the discrepancies between DPOAEs and behavioral audiometry. Preoperative pure-tone thresholds and DPOAEs from 97 patients with surgically confirmed acoustic neuroma were compared using an objective method and a standard, subjective technique that was considered to be the gold standard. The effects of bilateral hearing losses, such as noise-induced hearing loss and presbycusis, were accounted for during the analysis to isolate the effects of the tumors on hearing thresholds and DPOAEs. RESULTS: Overall, 55 (57%) of the tumor ears were assigned to the cochlear group (i.e., DPOAEs consistent with hearing thresholds), 40 (41%) to the noncochlear group (i.e., DPOAEs inconsistent with hearing thresholds), and 2 (2%) to an indeterminate group, using the subjective technique for classifying DPOAEs. There was no significant difference in the categorization of the patients with acoustic neuroma when employing the objective strategy. The objective algorithm, when modified to maximize the number of noncochlear identifications, led to assignments of 36 (37%) to the cochlear, 57 (59%) to the noncochlear, and 4 (4%) to the indeterminate categories. CONCLUSIONS: Subjective analysis of a large series patients with acoustic neuromas showed that the majority of ears with tumors demonstrated cochlear (57%), rather than non-cochlear (41%), patterns of DPOAEs. The computerized, software-based algorithm developed for differentiating cochlear from noncochlear patterns of DPOAEs in patients with retrocochlear disease had a maximum sensitivity of 59%. This value was significantly higher than that reported in previous studies.     

Wittmaacks Theorie vom „Hören ohne Cortisches Organ“

Summary 1911 Wittmaack had shown by experiments in cats that the organ of Corti is independent from the cochlear nerve but dependent from a normal internal auditory artery. Similar findings he could observe in his temporal bone collection in cases of acoustic nerve tumors.On the other hand many human cases with the compression phenomenon of the organ of Corti had intact cochlear nerve fibers and neurons, and nearly normal hearing. Thus Wittmaack concluded that some parameters of hearing are transmitted by the nerve endings in the organ of Corti without the haircells. This hypothesis is discussed by means of examples of Wittmaack's temporal bone collection in the light of our present knowledge.

Frl. I. Lehmann danke ich herzlich für die photographische Assistenz.