Advances in Oto-Rhino-Laryngology最新文献

The indications for cochlear implantation (CI) have expanded over the last few years. There is evidence that some adult patients with pre- or perilingual onset of deafness may gain from implantation. Similarly, CI in patients with single-sided deafness may offer significant benefits in terms of quality of life and social as well as academic development. In this setting, directional hearing may be restored and speech comprehension, especially in noise, may be optimized. In patients with intractable tinnitus and profound hearing loss, CI not only improves speech perception, but also helps to reduce the tinnitus in the deaf ear.

Approximately 2% of congenital profound deafness cases are due to cochlear nerve (CN) deficiency. MRI is essential to confirm if the nerve is deficient, but because of limitations with resolution, especially when the internal auditory canal is narrowed, it is often unable to distinguish between hypoplasia and aplasia. A full audiometric test battery should always be performed, even if the MRI suggests CN aplasia, as there will sometimes be evidence of audition. Electrically evoked auditory brainstem response testing can be carried out transtympanically via the round window or using an intracochlear test electrode to help determine the status of the CN. If any test suggests the presence of a CN, then cochlear implantation (CI) should be considered. Children should be followed up closely with audiometric, electrophysiological and language assessments to determine the benefits. They may initially show benefit but fail to progress. CI results are variable and often result in poor outcomes with Categories of Auditory Perception scores of <5. Auditory brainstem implantation (ABI) can be considered when CI is contraindicated or fails to provide adequate benefit. This may provide better outcomes, but this form of surgery has greater risks and future device replacement (in case of device failure) may be complicated. Careful patient selection is required when considering ABI as significant learning difficulties make programming extremely challenging. Patients should be given the option of CI first and then ABI. A small minority of patients presenting late (around 2-3 years of age) may be candidates for simultaneous CI and ABI.

Perilymphatic fistula (PLF) is defined as an abnormal communication between the fluid (perilymph)-filled space of the inner ear and the air-filled space of the middle ear and mastoid, or cranial spaces. PLF is located in the round or oval window, fractured bony labyrinth, microfissures, anomalous footplate, and can occur after head trauma or barotrauma, chronic inflammation, or in otic capsule dehiscence. This clinical entity was initially proposed more than a century ago, yet it has remained a topic of controversy for more than 50 years. The difficulty of making a definitive diagnosis of PLF has caused a long-standing debate regarding its prevalence, natural history, management and even its very existence. In this present study, we will discuss the symptoms, physiological tests (focusing on vestibular assessment) and imaging studies. Referring to a previous criticism, we will share our classification of PLF into 4 categories. Furthermore, we will summarize a nationwide survey using a novel and widely used biomarker (Cochlin-tomoprotein [CTP]) for PLF diagnosis in Japan and present the results of the new diagnostic criteria. PLF is surgically correctable by sealing the fistula, and appropriate recognition and treatment of PLF can improve hearing and balance, and in turn, improve the quality of life of afflicted patients. Therefore, PLF is an especially important treatable disease for otologists.

Hearing implant technology is evolving at a rapid rate and more than ever patients with hearing loss are benefiting from these emerging hearing devices. Active middle ear implants are alternatives to hearing aids and bone conducting devices, offering patients an expanded range in improving their hearing. This chapter looks at the devices currently available, their indications and the literature regarding their outcomes.

Despite steady improvements in cross-sectional imaging of the ear, current technologies still have limitations in terms of resolution, diagnosis, functional assessment and safety. In this chapter, state-of-the-art imaging techniques in current clinical practice are presented including cone-beam computerized tomography, non-echo planar imaging magnetic resonance imaging, imaging for labyrinthine hydrops and imaging of the central auditory pathways. Potential future imaging modalities are also presented, including optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) of the ear. These experimental modalities offer new opportunities for the assessment of ear structure and function. For example, middle ear structures can be visualized through the tympanic membrane, basilar membrane vibrations can be assessed through the round window and the passage of cochlear implants can be assessed in decalcified cochlear. Functional assessment of the middle ear using Doppler techniques are also discussed, including measurement of tympanic membrane and middle ear vibration amplitudes, visualization of dynamic changes, such as tensor tympani movements and movement of the tympanic membrane with breathing. These new modalities currently have limitations that preclude mainstream clinical use. For example, OCT is limited by the optical scattering of the thickened tympanic membrane and HFUS needs a coupling medium such as gel or fluid from the transducer to the imaged structure although it can visualize through thicker tissues. Nevertheless, further development of these novel techniques may provide an enhanced ability to assess the ear in conjunction with current technologies.

The number of marketed bone-conduction hearing implants (BCHIs) has been steadily growing, with multiple percutaneous devices and transcutaneous devices now available. However, studies assessing efficacy often have small sample sizes and employ different assessment methodologies. Thus, there is a paucity of evidence to guide clinicians to the most appropriate device for each patient. This paper outlines audiological guidelines for the latest devices, as well as research from the most up-to-date clinical trials. We also outline the evidence base for some potentially contentious issues in the field of bone conduction, including bilateral fitting of BCHIs in those with bilateral conductive hearing loss as well as the use of BCHIs in single-sided deafness (SSD). Bilateral fitting of BCHIs have been found to significantly increase the hearing thresholds in quiet and improve sound localization, but to give limited benefits in background noise. Studies conducted via multiple assessment questionnaires have found strong evidence of subjective benefits for the use of BCHIs in SSD. However, there is little objective evidence of benefit for SSD patients from sound localization and speech in noise tests.

Middle ear hearing reconstruction is unpredictable. Difficulties arise because of host factors, such as ventilation or scarring, surgical technique factors, such as prosthesis placement and stabilization, and design and mechanical factors influencing the properties of the prosthesis. Often there is a balancing act between choosing optimal stability, and maximizing the mechanical vibrations of the prosthesis. We review our and other investigators' work, in design and ideal placement of middle ear prostheses. Middle ear prostheses need to be rigid enough to deliver acoustic forces without bending. Prosthesis mass has a modest effect at higher frequencies. A key point is that rotational movements of the prosthesis have to be constrained. Prosthesis head size and cartilage interposition, within reason, have little effect on vibration transmission. Reconstruction to the malleus may have some small mechanical advantage; however this is not clearly proven. Similarly, there is no proven advantage in reconstructing to the stapes head instead of the footplate. The most important factor for good long term results is probably the stability of the prosthesis, both to acute inertial forces such as trauma, and to slower term changes such as tympanic membrane position and scarring contractures.

The functional changes that occur in the brain due to deafness may affect the way the auditory system processes sound after cochlear implantation. Brain plasticity plays a crucial role in the success of cochlear implantation to facilitate or develop spoken language in profoundly deaf individuals. The functional plasticity that occurs in postlingually deaf adults during periods of deafness can both support and hinder speech understanding with a cochlear implant, depending on the nature and degree of functional changes. Evidence so far suggests that the strategies people use to communicate while deaf may influence whether the functional changes are adaptive or maladaptive. In the case of children with congenital deafness, evidence is very strong for a sensitive period in which auditory input must be restored if subsequent oral language is to be developed successfully. Successful oral language use and speech understanding in individuals implanted after 7 years of age depends strongly on the pre-implant use of hearing aids and auditory-verbal communication. Future research should focus on how to harness our growing knowledge of brain plasticity to optimize the outcomes of cochlear implantation in each individual.

Surgery aimed at hearing rehabilitation risks damaging residual inner ear function, especially cochlear implant surgery. Pharmacological intervention to reduce this risk has shown great promise in animal models. The challenge is to deliver medication to the appropriate part of the inner ear in appropriate concentrations for long enough to be effective. Barriers to achieving these goals include: the blood/labyrinth barrier, limiting systemic drug delivery to the inner ear, slow rates of diffusion from the base of the cochlea to the apex, limiting intratympanic delivery from the middle ear to the cochlear apex, delayed intracochlear fibrosis, requiring extended medication delivery postoperatively. Intracochlear drug delivery via a drug-eluting cochlear implantation (CI) electrode may solve many of these pharmacologic issues. It is likely that more than one medication will be necessary to maximize inner ear protection and this may include steroids and appropriate growth factors. Such protection may also be helpful for otologic surgical procedures other than CI that have lower risks to hearing.