Faculty Bibliography

Sound-pressure level (SPL) and fundamental frequency (F0) contours were obtained from four postlingually deafened adults who received cochlear implants and from a subject with Neurofibromatosis-2 (NF2) who had her hearing severely reduced following surgery to remove an auditory-nerve tumor and to implant an auditory brainstem implant. SPL and F0 contours for each phrase in passages read before and after changes in hearing were averaged over repeated readings and then normalized with respect to the highest SPL or F0 value in the contour. The regularity of each average contour was measured by calculating differences between successive syllable means and averaging the absolute values of these differences. With auditory feedback made available, the cochlear implant user with the least contour variation preimplant showed no change but all of the remaining speakers produced less variable F0 contours and three also produced less variable SPL contours. In complementary fashion, when the NF2 speaker had her auditory feedback severely reduced, she produced more variable F0 and SPL contours. The results are interpreted as supporting a dual-process theory of the role of auditory feedback in speech production, according to which one role of self-hearing is to monitor transmission conditions, leading the speaker to make changes in speech postures aimed at maintaining intelligibility

BACKGROUND: This study defines the clinical settings in which extended radical neck dissection (ERND) was performed and determines its impact on control of disease in the neck and on survival. METHODS: We reviewed the records of 106 patients undergoing ERND between 1984 and 1993. Most (76) had metastatic squamous cell carcinoma (SCC) that had extended to extranodal structures in the upper neck. RESULTS: Five-year disease-free survival was 39%, and disease was controlled in the neck in 72 patients (68%) with a median follow-up of 5.5 years. A trend toward better survival was seen in patients with SCC (47% at 5 years), compared with those with other histologies (24% at 5 years; P <0.12). Patients with levels I, II, or III involved had better survival (46% at 5 years) than those with level IV, V, or multiple levels involved (14% at 5 years; P <0.0088). Finally, when prior radiation therapy precluded additional irradiation of the neck, survival was only 22% at 5 years, compared with 47% for those who received postoperative radiation (P <0.017). CONCLUSIONS: Although advanced neck disease invading adjacent structures remains an ominous sign, neck control and 5-year survival were achieved in nearly one half of these patients when multimodality therapy was possible

The pathobiology of salivary neoplasms can best be studied in a model system that reflects the native state of the tumor. The present study describes the use of a three-dimensional collagen gel (organoid) system in which pleomorphic adenomas of the parotid gland were propagated in vitro. Five pleomorphic adenoma cultures were established as organoid gels and compared with touch-preparations or cryopreserved specimens of native tumor. The organoid cultures demonstrated normal DNA content, the expression of myoepithelial cell proteins, and the production of sulfated acid mucins; these cellular and secretory features mimicked those found in the archival specimens. Further, organoid cultures of pleomorphic adenoma could be initiated after monolayer culture, demonstrating that culture on a plastic support does not alter the nature of the cells. Development of an in vitro culture system that maintains the native state of pleomorphic adenoma is an important tool for studying the pathobiology of these tumors

Two sisters presented to our medical center with nontraumatic cerebrospinal fluid (CSF) fistulas from left sphenoid sinocranial junction defects. One sister had recurrent meningitis over a 20-year period that prompted a skull base evaluation. Four years later, her younger sister presented with profuse CSF rhinorrhea. Transethmoid sphenoidotomy with sinus obliteration and lumbar-subarachnoid temporary CSF diversion successfully treated one sister, while the other required reoperation and permanent lumbar-peritoneal shunting. In both cases the skull base defect was identically located in the posterolateral left sphenoid sinus. Embryological considerations, evaluation and management are presented

The gamma band response (GBR) is a predominantly exogenous, sinusoidal evoked response that occurs usually between 20 and 130 msec following stimulus onset. This response is believed to represent the synchronization of neuronal assemblies that serve auditory feature integration. The objective of the present investigation was to describe the characteristics of the scalp-recorded auditory evoked gamma band potential (aeGBP) recorded from normal young adult subjects. Results showed the aeGBP to consist of up to four oscillations and were best recorded at the frontal-central midline. The aeGBP was present 80 percent to 100 percent of the time, appeared as onset responses, and was recorded at the shortest latency over the contralateral anterior temporal scalp

Decreased excitatory synaptic activity during development often leads to pre- and postsynaptic atrophy, as assessed anatomically. The present study considers the effect of decreased excitatory transmission on the maturation of synaptic strength. Towards this end, cochlear nucleus neurons, which project to the ipsilateral lateral superior olive (LSO), were denervated in gerbils at postnatal day 7, before the onset of hearing. This manipulation was intended to disrupt spontaneous glutamatergic transmission in the LSO while sparing the glycinergic afferents from the medial nucleus of the trapezoid body (MNTB). Afferent-evoked synaptic activity was assessed 1-6 days after ablation in a brain slice preparation using whole-cell current- and voltage-clamp recordings. In control animals, ipsilaterally evoked excitatory postsynaptic potentials (EPSPs) were present in 91% of neurons tested, but were observed in only 60% of neurons following cochlea removal. The maximum EPSP amplitude was significantly smaller in manipulated neurons compared with controls, and this was accompanied by a higher incidence of ipsilaterally evoked inhibitory postsynaptic potentials (IPSPs). To study the efficacy of excitatory synapses in greater detail, voltage-clamp recordings were made in the presence of strychnine and AP-5 [D(O)-2-amino-5-phosphonopentanoic acid]. The minimum excitatory postsynaptic current (EPSC) amplitude, presumed to reflect the efficacy of a single glutamatergic afferent, was approximately 40% smaller in manipulated neurons. In contrast, MNTB-evoked IPSPs were similar in neurons from control and ablated animals. However, manipulated neurons often exhibited a rebound depolarization after a hyperpolarizing current pulse or an afferent-evoked IPSP. In 70% of manipulated neurons, synaptically evoked rebound depolarizations were reduced, but not eliminated, by glutamate receptor antagonists. The glycine receptor antagonist strychnine did eliminate the IPSP-associated depolarization in these neurons. Collectively, these results suggest that functional denervation of excitatory afferents decreases their synaptic efficacy as result of both cell loss as well as decreased strength of individual surviving synapses

To investigate the etiology of hole formation in the gerbil and rat central auditory system, organotypic cultures were grown in control and veratridine-containing media. The latter condition is known to increase neuronal activity. Tissue was obtained at postnatal day 6 and grown for 6-9 days in vitro, a period prior to the formation of holes in vivo. In both rats and gerbils, veratridine led to the appearance of large numbers of holes, and these were phenotypically similar to those found in vivo. These results support the idea that hole formation is an activity-dependent phenomenon, and suggest that it is not restricted to the mature gerbil auditory system