No abstract

The cochlear summating potential (SP) to a tone is a baseline shift that persists for the duration of the burst. It is often considered the most enigmatic of cochlear potentials because its magnitude and polarity vary across frequency and level and its origins are uncertain. In this study, we used pharmacology to isolate sources of the SP originating from the gerbil cochlea. Animals either had the full complement of outer and inner hair cells (OHCs and IHCs) and an intact auditory nerve or had systemic treatment with furosemide and kanamycin (FK) to remove the outer hair cells. Responses to tone bursts were recorded from the round window before and after the neurotoxin kainic acid (KA) was applied. IHC responses were then isolated from the post-KA responses in FK animals, neural responses were isolated from the subtraction of post-KA from pre-KA responses in NH animals, and OHC responses were isolated by subtraction of post-KA responses in FK animals from post-KA responses in normal hearing (NH) animals. All three sources contributed to the SP; OHCs with a negative polarity and IHCs and the auditory nerve with positive polarity. Thus the recorded SP in NH animals is a sum of contributions from different sources, contributing to the variety of magnitudes and polarities seen across frequency and intensity. When this information was applied to observations of the SP recorded from the round window in human cochlear implant subjects, a strong neural contribution to the SP was confirmed in humans as well as gerbils. NEW & NOTEWORTHY Of the various potentials produced by the cochlea, the summating potential (SP) is typically described as the most enigmatic. Using combinations of ototoxins and neurotoxins, we show contributions to the SP from the auditory nerve and from inner and outer hair cells, which differ in polarity and vary in size across frequency and level. This complexity of sources helps to explain the enigmatic nature of the SP.

Objective: There is considerable variation in the travel required for a patient with head and neck squamous cell carcinoma (HNSCC) to receive a diagnosis. The impact of this travel on the late diagnosis of cancer remains unexamined, even though presenting stage is the strongest predictor of mortality. Our aim is to determine whether travel time affects HNSCC stage at diagnosis independently of other risk factors, and whether this association is affected by socioeconomic status. Materials and Methods: Cases were obtained from the CHANCE database, a population-based case-control study in North Carolina (n=808). The mean age was 59.6 and 72% were male. Stage at diagnosis was categorized as early (T1-T2) or advanced (T3-T4) T stage and the presence or absence of nodal metastasis. Multivariate logistic regression models were used to estimate odds ratios for stage-at-diagnosis based on travel time, after adjustment for variables including demographics, income, insurance status, alcohol, and tobacco use.

The Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 1 (MCAHS1) has been described in two families to date. We describe a 2-year-old Mexican American boy with the syndrome and additional manifestations not yet reported as part of the phenotype. The patient presented with severe hypotonia, microphallus and left cryptorchidism, and was later diagnosed with epilepsy and severe cortical visual impairment. He also had supernumerary nipples, pectus excavatum, a short upturned nose, fleshy ear lobes and a right auricular pit. Massively parallel exome sequencing and analysis revealed two novel compound heterozygous missense (Trp136Gly and Ser859Thr) variants in the PIGN gene. This report extends and further defines the phenotype of this syndrome.

These results underscore that caution is warranted in revision flap surgery, patients with prior neck operations, and patients aged ≥60 years.