ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The present study was designed to investigate the type and extent of degeneration occurring in the human central auditory system subsequent to profound hearing loss. The authors have examined the size of one population of neurons in the ventral cochlear nucleus in seven subjects with profound hearing loss (audiometric responses poorer than 90–100 dB HL). Six normal subjects, ages 35–78, were used as controls. Cell size in the hearing-impaired subjects ranged from normal to reduced by more than 50 percent. Two factors appear to contribute to the variability in cell size reduction. The correlation coefficient (Spearman rs) of cell size with duration of profound deafness was −0.48, indicating a moderate tendency for neurons to become smaller with longer periods of deafness. The correlation coefficient of cell size with number of surviving cochlear ganglion cells was 0.73, indicating a stronger tendency for neurons to be larger with greater eighth nerve innervation of the cochlear nucleus. Two cases of Scheibe degeneration showed the most severe degenerative change in the central auditory system.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Clinical interest in otoacoustic emissions (OAEs) is increasing. These can be elicited rapidly in a number of test paradigms that reflect the functional status of the outer hair cells of the organ of Corti. Distortion product otoacoustic emissions (DPOEs) have been well described in infants, and adults, but not in the elderly. The value of DPOE testing as a means of objective assessment of cochlear function is still being studied. The authors obtained DPOEs in 129 ears of 71 elderly volunteer subjects (age 56–93 yr) and in 16 ears of eight young adults (age 19–26 yr) with normal pure-tone thresholds (PTTs). The relation between DPOEs and PTTs, as expressed by the r2statistic, was 0.18, 0.46, and 0.30 at 1,2, and 4 kHz, respectively. Ampl itudes of DPOEs did not decrease significantly with age, when adjusted for PTTs. Sensitivity and specificity, receiver operating characteristic curves, as well as posterior probabilities were analyzed to elucidate the relation between DPOEs and PTTs. At 2 kHz 90 percent of ears with PTTs 40 dB HL or less exhibited DPOEs of – 4 dB SPL or greater, and all ears with PTTs greater than 40 dB HL had either no measurable DPOEs or DPOE amplitude less than 4 dB SPL.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Cochlear osteoneogenesis may result from a variety of pathologic conditions, including cochlear implantation. The etiology of cochlear osteoneogenesis following implantation, however, is not known. Cochlear implant-related osteoneogenesis has been demonstrated in laboratory animals, but the specific cause, extent, or time-course of this process has not been determined. In this preliminary study, fluorescent bone labels were used to assess osteoneogenesis in six chinchillas in three experimental categories: surgical trauma to the cochlea, chronic nonstimulated cochlear implantation, and intrascalar neomycin infusion. Computer image analysis was used to measure the area of labeled bone on representative mid-modiolar histologic sections. The amount of bone deposition was greatest in ears treated with intracochlear neomycin (mean = 2.3835 mm2, SD = 3.7308). Surgical trauma alone (mean = 0.9549 mm2, SD = 1.384) and chronic implantation without stimulation did not produce substantial bone growth when compared to contralateral control ears (mean = 0.0574 mm2, SD = 0.0731). Fluorochrome labeling was also used to differentiate types of bone deposition. The morphology and timing of new bone growth appeared to be related to the type of cochlear injury. These results confirm that intracochlear neomycin may contribute to osteoneogenesis in animal studies of cochlear implantation. This study supports the use of fluorescent bone labeling in the evaluation of cochlear osteoneogenesis.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

AGENDA: The primary focus of this panel was to explore the attitudes of a group of experienced otologic surgeons on the utility of contemporary cranial nerve monitoring techniques. The emphasis was not upon how to do cranial nerve monitoring (CNM), but rather for which procedures the panelists felt it to be useful and their reasons for holding these beliefs. An attempt was made to categorize the panelist's viewpoints according to whether, for any given procedure, they felt that the value of CNM was (1) well proved through outcome analysis of comparative data derived from monitored and unmonitored cases, (2) well proved through anecdotal experience, (3) promising, but as of yet unproved, or (4) unhelpful or otherwise not indicated. At the outset, the panel was cautioned that its mandate was not to attempt to establish a “standard of care” for the use of CNM, but rather to share their own personal attitudes toward the utility of this surgical tool as a means of educating fellow otologic surgeons on the relevant issues to consider. It is anticipated that each practitioner will use the insights of these panelists, along with their own experience, to help arrive at an informed decision as to the utility and criteria for selective application of CNM to employ in their own practice.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

With the increased use of gadolinium-enhanced magnetic resonance imaging studies to detect acoustic neuromas, smaller tumors are discovered more frequently. The middle fossa craniotomy approach for removal of small tumors is ideal for hearing preservation. The authors report hearing preserved at or near the preoperative levels in 71 percent of a series of 24 consecutive patients in whom the middle fossa craniotomy approach was employed. Several technical modifications, including more extensive bony exposure medially, tumor dissection in a medial-to-lateral direction, and topical application of papaverine to the cochlear nerve at the modiolus, have enhanced the ability to preserve hearing.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Postoperative facial function was compared for middle cranial fossa and translabyrinthine removal of acoustic tumors. Included were 164 primary acoustic tumor surgeries performed between 1988 and 1991 in patients with normal preoperative facial function; postoperative House-Brackmann facial function grade available immediately postoperatively, at time of discharge and at 1 year or more postoperatively; and a tumor 1.5 cm or smaller. There were 116 translabyrinthine surgeries and 48 middle fossa surgeries. There was no significant difference in facial function results between the two surgical approaches at any of the three postoperative time intervals. Immediate postoperative facial function grade I or II was present in 90 percent of patients who underwent the middle cranial fossa approach, and in 90 percent of those with translabyrinthine surgery. By long-term follow-up, grade I or II function was recorded after 96 percent of middle fossa, and 91 percent of translabyrinthine surgeries. Results were similar when evaluating subgroups of those with tumors measuring 1.0 cm or smaller and 1.1–1.5 cm. There was also no difference in facial function result between superior and inferior vestibular nerve tumors with either approach. The authors conclude that, in an experienced center, long-term postoperative facial function outcome is not a basis for selecting surgical approach for tumors measuring 1.5 cm or less.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

This retrospective study describes the use of transcranial Doppler (TCD) and history for further defining and diagnosing cerebral blood flow (CBF) disorders in patients with central dizziness. Central dizziness was defined as dizziness of nonlabyrinthine, non-peripheral causes. It was believed that at least some of the causes for central dizziness are not unknown but are associated with CBF disorders. Fifty patients who presented with central dizziness were examined and subsequently tested with TCD. In 33 of 50 cases (66%) a diagnosis could be assigned after TCD; whereas, on the basis of both history and TCD a diagnosis was assigned to 38 patients (76%).

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Progressive sensorineural hearing loss has been associated with Chiari type I malformation. Retrocochlear features on auditory brainstem response testing have been reported; however, debate exists over the exact location of the defect. Surgical decompression may be beneficial if brainstem or vascular compression have played a significant role in the pathophysiology of the hearing loss. Lack of specific audiologic data before and after surgical decompression has kept surgical decision making theoretic. This report presents the case of a 10-year-old boy with a progressive, asymmetric sensorineural hearing loss without other neurologic abnormalities. He underwent a posterior fossa decompression that resulted in stable hearing over the 2 years he was followed postoperatively. Preoperative and postoperative audiologic and evoked response features are described, and the rationale for operating with symptoms limited to hearing loss is discussed.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Neurotropic viruses have been postulated to play a role in the development of Meniere's disease (MD). The purpose of this study was to evaluate the endolymphatic sacs of patients undergoing surgery for MD in a single-blind study for evidence of herpes simplex virus (HSV), varicella zoster (VZ), or cytomegalovirus (CMV) DNA. Polymerase chain reaction (PCR) was used as the method of detection because of its sensitivity, specificity, and applicability to fresh, as well as fixed tissues. Twenty-two patients with MD and 11 control patients with vestibular schwannomas had a portion of the endolymphatic sac removed at the time of surgery. The specimens were then evaluated for herpes simplex type 1 and 2, varicella zoster, and cytomegalovirus DNA. Herpes simplex virus DNA was detected in 2 of the 22 extracts from the endolymphatic sacs obtained from patients with MD. There was no evidence of a positive signal obtained with any of the other viral DNA probes when PCR was performed on the control tissue extracts or the other MD tissue extracts. These results do not demonstrate a significant difference and do not statistically support the postulate that ongoing viral infection in the endolymphatic sac is a frequent factor in the development of Meniere's disease.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID