Faculty Bibliography

Three postlingually deafened adults who received cochlear implants read passages before and after their prostheses were activated while their lung volumes were measured with an inductive plethysmograph that transduced the cross-sectional areas of the speaker's chest and abdomen. Lung volumes at the initiation and termination of the speakers' expiratory limbs, their average air flow, and the volume of air they expended per syllable were derived from tracings of calibrated lung volume displayed by computer. The activation of the speakers' cochlear prostheses was followed in every case by a significant change in average airflow, which rose for two subjects with initially low flow rates and fell for one subject who had a much higher average preimplant flow rate. These changes in average flow rate were accompanied by corresponding changes in volume of air expended per syllable, statistically reliable in two of the three cases. There were no significant changes in the levels at which speakers initiated their expiratory limbs, but one speaker, after his prosthesis was activated, reliably increased the level of air in his lungs at the end of expiratory limbs to an average value that no longer required him to draw on expiratory reserve volume

This study examined the morphological development of single inhibitory arborizations in the gerbil central auditory brain stem. Using a brain slice preparation, neurons of the medial nucleus of the trapezoid body (MNTB) were filled with horseradish peroxidase (HRP), and their complete arborizations were analyzed along the tonotopic axis of the lateral superior olive (LSO). The projections in neonatal animals displayed well-defined arbors that were ordered appropriately within the LSO. It was evident from the axonal pathways that the MNTB afferents could correct for projection errors after reaching the postsynaptic population. As development progressed, a number of arbors established diffuse or inappropriate projections within the LSO. These immature arborizations were no longer apparent by 18-25 days postnatal. The anatomical specificity of arbors at 12-13 and 18-25 days was quantified by measuring the distance that terminal boutons spread across the frequency axis. There was a significant reduction of this distance in older animals. In addition, there was a significant reduction in the mean number of boutons per arbor between 12-13 days and 18-25 days. The maximum nucleus cross-sectional area continued to increase through 15-16 days, indicating that the refined arbors occupied an even smaller fraction of the postsynaptic structure. Taken together, these observations suggest that central inhibitory arbors form exuberant contacts that must be eliminated during development

The course of the facial nerve may place it within the current field generated by an activated cochlear implant to produce incidental facial movement. We investigated the presence of facial nerve stimulation associated with cochlear implants in the VA Cooperative Study of Advanced Cochlear implants. Twelve of 82 patients enrolled in this study demonstrated facial nerve stimulation within 2 years of implant activation. Facial nerve stimulation in six patients with multiple channel implants (Nucleus or ineraid devices) either resolved spontaneously (n = 2), or was eliminated by deactivating basal (n = 2) or apical (n = 2) electrodes. Two of six patients with single-channel electrodes (3-M/Vienna devices) demonstrated facial nerve stimulation that resolved spontaneously (n = 2), resolved with lowering current output (n = 2), or was refractory to processor adjustment (n = 2). Intraoperative assessment in one of the refractory cases indicated that facial nerve stimulation resulted from current spread through the modiolus to activate the facial nerve. A variety of factors, including implant design, stimulus parameters, and local tissue impedances, may interact to produce incidental facial stimulation. Low-impedance pathways between the scala tympani and the modiolus may deserve increased recognition as an interactive factor in cochlear implant performance

Cystic enlargement of the parotid gland is a newly described manifestation of infection with human immunodeficiency virus (HIV). A review of 15 such patients with respect to clinical presentation, natural history, and management is presented. Follow-up ranges from 1 to 27 months, averaging 10 months. In 47% of the patients, parotid swelling was the chief complaint leading to the diagnosis of HIV infection. T-cell analysis revealed the tendency for this lesion to occur in the early stages of immunodeficiency when T-cell counts are high. Histologic examination revealed findings resembling benign lymphoepithelial lesion. It is felt that these lesions are a local manifestation of a systemic disease and treatment should be tailored with this in mind. Surgical excision may not be necessary. Fine-needle aspiration (FNA) was found to be useful diagnostically and therapeutically. Recognition of this entity is essential for the head and neck specialist in providing an early diagnosis of HIV infection.

Cystic parotid enlargement is a newly recognized manifestation of HIV infection. It commonly occurs early in the spectrum of HIV-related illnesses and may be part of LAS. Serologic confirmation of HIV infection and CT imaging usually establishes the diagnosis. Cytologic or histopathologic evaluation may be required for diagnostic confirmation and for management.