Insular stroke causing unilateral auditory processing disorder: case report.

This case presentation describes a patient with a strategically placed lesion involving the right insula and adjacent white matter. The most remarkable finding associated with this case is the presence of a unilateral auditory processing disorder when presenting speech materials to the left ear. Intervention for this patient is described in addition to a discussion of possible explanations for the unique pattern of auditory dysfunction.

Prediction of auditory nerve survival in humans using the electrical auditory brainstem response.

This investigation studied the electrical auditory brainstem response (EABR) input-output functions in three groups of patients: individuals with normal auditory neural systems; patients with acquired, profound sensorineural hearing loss; and patients with congenital, profound sensorineural hearing loss. Each input-output function was obtained in the operating room under general anesthesia and with the patient paralyzed to eliminate myogenic contamination. In contrast to the acoustically elicited ABR, the EABR waveforms were characterized by a dominant early wave corresponding in latency to wave II. This wave was much larger and often appeared at lower stimulus intensities than wave V. The results, plotted according to rate of growth for waves II and V, showed that normal subjects generally had larger, more robust early waves than either hearing impaired group. Little difference was noted in the amplitudes or rates of growth for wave V among the three groups. Based on these observations, we concluded that the EABR demonstrated differences in the way normal and impaired systems respond to electrical stimulation. In addition, the EABR may be useful in providing a qualitative prediction of neural survival into broad categories of many surviving neurons versus a marked reduction in ganglion/neuronal density.

Myogenic influences on the electrical auditory brainstem response (EABR) in humans.

Two cases demonstrating the effects of myogenic artifact on the electrical auditory brainstem response (EABR) when using a promontory stimulation site are presented. Intensity-response functions were obtained in the unparalyzed condition, then repeated after infusion of a neuromuscular paralyzing agent. In both cases, the myogenic response was observed at lower stimulus intensities than the EABR components. As intensity increased, the myogenic responses grew at extremely rapid rates and made any subsequent identification of auditory responses virtually impossible. To alleviate the adverse influence of myogenic components, general anesthesia and a paralyzing agent must be incorporated into the test protocol when acquiring the EABR using a promontory site of stimulation.

Labyrinthine ossification after meningitis: its implications for cochlear implantation.

Labyrinthine ossification can be found in a high percentage of patients with profound deafness resulting from bacterial meningitis. Radiographic evidence of ossification can be found as early as 2 months after the acute infection, indicating that the intracochlear process probably begins much earlier. If long, intracochlear cochlear implants are to be most successfully used in these patients, an aggressive approach to clinical management following the meningitis should be taken. Illustrative case reports and suggested guidelines for evaluation and treatment are given.

Norms for disproportionate loss in speech intelligibility.

The audiometric records of 324 subjects with sensorineural hearing loss, presumed to be cochlear, were analyzed in order to develop norms for "disproportionate loss" in speech intelligibility. From the scatterplot relating PBmax to PTA2 (average of HTLs at 1,000, 2,000, and 4,000 Hz), and the scatterplot relating SSImax to PTA1 (average of HTLs at 500, 1,000, and 2,000 Hz), linear boundaries were constructed encompassing approximately 98% of observed values. A speech intelligibility score (PB or SSI) may be considered "disproportionately poor" if it falls below this empirically derived boundary.

Clinical applications of the auditory middle latency response.

The auditory middle latency response (AMLR) was first reported 30 years ago. For a variety of reasons, the AMLR was relatively slow to gain clinical acceptance. However, renewed investigational efforts into the nature of the response is leading to a better understanding of the AMLR's characteristics, limitations, and appropriate clinical applications. This paper reviews the current status of the AMLR with regard to clinical utilization and proposes anticipated directions of clinical endeavors.

Customized valve housing.

Numerous remarkable advancements have been made in the area of voice prosthetics. A significant, persistent problem, however, has been the development of air leaks around the tracheostome housing. This problem is particularly apparent with patients having deeply recessed, irregular stomas. This paper describes a customized tracheostome valve housing that is fabricated to minimize or alleviate difficulties associated with maintenance of an airtight seal. Our experience with 12 patients revealed that they maintain adequate seals for 72 hours and enjoy the functional benefits provided by the customized housing.

Evaluation of the minimal auditory capabilities (MAC) test in prelingual and postlingual hearing-impaired adults.

The Minimal Auditory Capabilities (MAC) battery was used to evaluate the auditory performance of nine postlingual and ten prelingual adults with severe to profound hearing loss. Results suggest that degree of hearing loss overrides relative language skills as the primary factor affecting performance. The MAC battery appears promising as a tool for evaluating and monitoring both prelingual and postlingual adults using conventional hearing aids or cochlear implants.

Development of a dichotic sentence identification test for hearing-impaired adults.

Third-order synthetic sentences were aligned to make them suitable for dichotic presentation. These dichotic sentence materials were then administered to 14 normal listeners and 48 hearing-impaired subjects to determine the influence of peripheral hearing loss on test performance. Results suggest that the Dichotic Sentence Identification test is resistant to the influence of peripheral hearing loss until the pure-tone average of 500, 1000, and 2000 Hz exceeds approximately 50 dB. Beyond this level, degree of peripheral hearing loss limits its value for detecting central auditory disorder. Data are also provided on six persons with either confirmed or suspected lesions involving retrocochlear structures.