Faculty Bibliography

OBJECTIVES/HYPOTHESIS: Head and neck squamous cell carcinoma (HNSCCA) has declined in the United States since the late 1970s. During this time, substantial immigration from other countries has occurred, and the average lifespan has increased. We tested the hypothesis that these trends have altered the HNSCCA patient population. STUDY DESIGN: Retrospective analysis was made of population-based data from the SEER database, a national registry capturing roughly 10% of all U.S. cancer diagnoses. METHODS: We examined all unique diagnoses of HNSCCA in the database from 1976 to 1999 and determined the breakdown of cases by age, sex, and race. RESULTS: The absolute number of new HNSCCA diagnoses per year declined overall by 5% during the time period of the study, whereas new diagnoses in patients older than 74 years of age increased by more than 20%. The rate of HNSCCA per 100,000 person-years in elderly women did not change, and the rate in elderly men decreased, indicating that the observed increase in cases is explained by a growing population of elderly persons at risk. An increase in the absolute number of cases, but not the incidence rate, was also seen among persons younger than 50 years of age. Although both the absolute number of new cases and the incidence rates of HNSCCA in white male patients declined substantially, the percentage of HNSCCA patients classified as minorities increased from 14.5% to more than 20% of all cases. During the time period of the study, the overall number of HNSCCA cases in nonwhite and Hispanic patients increased by 36%. CONCLUSION: Increasing numbers of elderly and minority patients with HNSCCA are likely to alter patterns of disease and utilization of health care resources

This paper discusses the modern neurosurgeon's use of advanced magnetic resonance imaging in pre-operative and perioperative planning. The effect of advanced imaging on the risk and benefit analysis of surgery is discussed in particular

Pathologic processes involving the urachus are usually related to inflammatory or sinofistular conditions. Neoplasms rarely arise within this structure, and when they do occur, they are typically epithelial, with mucinous adenocarcinoma being the most common. Mesenchymal lesions, both benign and malignant, have rarely been described in this location. We report the case of a 66-year-old white man who presented with a primary urachal malignant fibrous histiocytoma and died of metastatic disease 20 months after the initial diagnosis. This is an unusual case of malignant fibrous histiocytoma arising in a urachal remnant

Voltage-dependent membrane conductances support specific neurophysiological properties. To investigate the mechanisms of coincidence detection, we activated gerbil medial superior olivary (MSO) neurons with dynamic current-clamp stimuli in vitro. Spike-triggered reverse-correlation analysis for injected current was used to evaluate the integration of subthreshold noisy signals. Consistent with previous reports, the partial blockade of low-threshold potassium channels (I(KLT)) reduced coincidence detection by slowing the rise of current needed on average to evoke a spike. However, two factors point toward the involvement of a second mechanism. First, the reverse correlation currents revealed that spike generation was associated with a preceding hyperpolarization. Second, rebound action potentials are 45% larger compared to depolarization-evoked spikes in the presence of an I(KLT) antagonist. These observations suggest that the sodium current (I(Na)) was substantially inactivated at rest. To test this idea, I(Na) was enhanced by increasing extracellular sodium concentration. This manipulation reduced coincidence detection, as reflected by slower spike-triggering current, and diminished the hyperpolarization phase in the reverse-correlation currents. As expected, a small outward bias current decreased the pre-spike hyperpolarization phase, and TTX blockade of I(Na) nearly eliminated the hyperpolarization phase in the reverse correlation current. A computer model including Hodgkin-Huxley type conductances for spike generation and for I(KLT) showed reduction in coincidence detection when I(KLT) was reduced or when I(Na) was increased. We hypothesize that desirable synaptic signals first remove some inactivation of I(Na) and reduce activation of I(KLT) to create a brief temporal window for coincidence detection of subthreshold noisy signals