ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Speech perception skills of prelingually deafened children who used the multichannel Tactaid 7 (n = 10) were compared to those of a matched group of children who used the Nucleus 22 channel cochlear implant (n = 10). Group scores were compared on a closed-set test of word recognition and on an open-set test of phrase recognition in the pre-device condition and at a post-device interval after an average of 1.5 years of multichannel device use. The results revealed that the scores of the implant users improved significantly between the pre- and post-device intervals on all measures. Moreover, the scores of the implant users were significantly higher than those of the tactile aid users on all measures. In contrast, the scores of the tactile aid users showed negligible change over time, except on a test that evaluated open-set recognition of phrases with both auditory and visual cues. The results suggest that children can learn to recognize words and understand speech without lipreading with a multichannel implant, whereas children who used the multichannel tactile aid demonstrate limited speech recognition skills only if auditory/tactile cues are combined with lipreading.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The focus of the present investigation was to study, via molecular biology techniques, the character of the DNA present in individual archival celloidin-embedded human temporal bone sections. Polymerase chain reaction (PCR) amplification of 92 base pair (bp), 121 bp, and 471 bp regions of mitochondrial DNA (mtDNA) extracted from a single archival celloidin-embedded human temporal bone section was used to assess the length of the template DNA extracted. The effects of digestion time and sample motion during the extraction method on DNA concentration was also studied. These data are crucial to determine the limits of applying PCR technology to amplify specific genomic DNA targets located within the human inner ear. Further development of these methods will allow additional molecular temporal bone pathologic studies to be completed and, more specifically, hypotheses regarding the molecular etiopathogenesis of many auditory, vestibular, and facial nerve disorders, such as autoimmune hearing loss, congenital hearing losses, Meniere's disease, otosclerosis, or Bell's palsy could be tested. The results described should be of great value to those investigators extracting DNA from archival individual human temporal bone sections for PCR assays of specific genetic alterations or infectious agents associated with temporal bone pathologies.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The authors present their combined experience with large cartilage-perichondrial composite grafts used to reconstruct total tympanic membrane perforations in 294 ears. Patients chosen for this procedure had failed earlier tympanoplasty surgery or were identified as poor candidates for conventional fascial tympanoplasty because of the perforation size. Successful perforation closure was achieved in 97% of ears with chronic otitis media characterized by absence of the tympanic membrane, including portions of the anterior annular ligament. Hearing results in general were good, considering the advanced stage of the disease, which required the use of alloplastic ossicular prostheses (PORP and TORP) in 76% of ears. Hearing improvement was maximal at 2000 Hz regardless of the method of ossicular reconstruction. Closure of the air-bone gap at this frequency to within 10 dB was achieved in 87% of type I tympanoplasties, 73% of type III (PORP), and 70% of type III (TORP) tympanoplasties. Although cartilage autografts have also been promoted to reverse tympanic membrane atelectasis, the authors believe that the above preoperative conditions are strong indications for this grafting technique, which is described in detail.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Auditory brainstem responses (ABRs) were recorded in 64 ears with radiographically confirmed Paget's disease involving the skull. Responses were absent in eight ears, all of which had elevated high pure-tone thresholds. Auditory brainstem responses were interpreted as normal in 56 ears; none were abnormal. Computed tomography and digital image analysis were used to quantify internal auditory canal (IAC) dimensions. The midlength diameter and minimum diameter of the IAC of 68 temporal bones from subjects with Paget's disease were found to have no statistically significant relation to hearing thresholds. Increased IAC length showed a limited relation to reduced hearing level in pagetic subjects, possibly consistent with bossing adjacent to the poms acusticus. Findings support the principle that hearing loss in Paget's disease of bone is generally associated with intact auditory nerve function and also support a cochlear site of lesion.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Some forms of dizziness, imbalance, and hearing change have been suspected to result from a vertebral basilar artery circulatory deficit. Microvascular hypoperfusion of the central nervous system (CNS) is proposed as a more likely mechanism than thromboembolic phenomena of the parent arteries. Symptoms of end-organ pathology must be differentiated from CNS causes to assure implementation of an appropriate treatment strategy. Guidelines for the evaluation of these patients are provided. Changes in platelet and red and white blood cell morphology are proposed as more significantly influencing blood flow than blood pressure or vessel caliber. Medications that alter blood rheology, have been found to alleviate the acute symptoms of microvascular hypoperfusion. Residual balance deficits from presumed long-term CNS ischemia have then been relieved by balance rehabilitation training. With the recognition of this disease entity there appears another means of aiding patients with dizziness and balance problems who have previously experienced long-term disability. The results of a preliminary study of 378 patients merits further investigation of the proposed pathophysiology and treatment measures.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Intradural tumors that are situated anterior to the midbrain, pons, and medulla have historically been among the most inaccessible of all intracranial lesions. The classic approaches to the posterior fossa (e.g., suboccipital, retrosigmoid) provide only limited access to the anterior midline, primarily due to interposition of the cerebellum, brain stem, and numerous cranial nerves between the tumor and the viewpoint of the surgeon. A variety of techniques have been developed in recent years that create a craniotomy by removal of a portion of the lateral skull base. These procedures enhance exposure of the ventral surface of the brain stem while markedly reducing the need for brain retraction. An underlying theme of transbasal craniotomy is judicious removal of a portion of the petrous pyramid. The most radical form of petrosectomy, the extended transcochlear approach, involves removal of the entire petrous pyramid along with the lateral aspect of the clivus. This provides an unimpeded view of the ventral surface of the pons, including the basilar artery, vertebrobasilar junction, and both abducens nerves. Whereas this technique provides splendid exposure along the midsegment of the brain stem, it carries substantial morbidity, including hearing loss and transient facial palsy, which typically recovers incompletely and with synkinesis. Over the past few years transcochlear procedures have been gradually supplanted, at the University of California Medical Center, by techniques that involve creating a simultaneous craniotomy of both the middle and posterior fossae fashioned around a more limited petrosectomy. These versatile procedures, in particular the middle fossa/retrolabyrinthine approach, provide excellent exposure of the region ventral to the midbrain and pons with less morbidity than the transcochlear approach. When tumors extend inferiorly, ventral to the lower medulla and/or upper cervical spinal cord, augmented inferior exposure is required. Approaches to ventrally situated lesions at the craniovertebral junction include the far lateral (transcondylar) approach to the foramen magnum and the transjugular approach, both of which involve removal of the inferior portion of the petrous bone. To efficiently utilize these innovative surgical options the surgeon must decide which of the potential approaches optimizes resection while minimizing morbidity. An analysis of the anatomy of the tumor, the functional integrity of cranial nerves, and the extent of resection planned provides the surgeon with the information needed to arrive at a rational choice.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Although most third-party payors presently fund cochlear implantation, some do not, and many cite the current lack of cost-effectiveness data as a major concern. Cost-utility analysis is a widely used method of medical technology assessment that permits cost-effectiveness comparisons between medical interventions by determining the cost per quality-adjusted life-year (QALY) they provide. The cost per QALY for the cochlear implant was determined using clinical cost data and a health-utility outcome model based on the established communication gains attained with the device. Cochlear implantation costs approximately $15,600 per QALY provided. Sensitivity analysis, a technique that systematically varies the assumptions underlying the calculations, suggests a range for the true value of between $12,000 and $30,000. This compares favorably with other medical interventions, such as coronary artery bypass grafting ($10,431 for three-vessel disease, $64,033 for single-vessel disease), the implantable defibrillator ($29,200), and cardiac transplantation ($38,970). This analysis indicates that the cochlear implant lies well within the cost-effectiveness range currently accepted by the American medical system.

ISSN:0192-9763    

出版商:OVID    

年代:1995

数据来源: OVID