Analysis of free flap viability based on recipient vein selection.

BACKGROUND: Venous anastomotic failure is the primary reason for microvascular free tissue transfer failure. Donor and recipient veins can be oriented in the same longitudinal axis (end-to-end anastomosis), or the donor vein can be anastomosed to the internal jugular vein in an end-to-side configuration. No consensus on the optimal anastomosis configuration exists. We sought to evaluate whether type of venous anastomosis impacts flap survival rate. METHODS: Data were collected on all patients undergoing microvascular free flap reconstruction of head and neck defects at the University of Washington between August 1993 and April 2007. Flaps with a single venous anastomosis were analyzed. Flaps were stratified into those with end-to-end and end-to-side anastomoses. Survival rates were compared between groups using bivariate and multivariate techniques. RESULTS: Inclusion criteria were met by 786 free flaps; 87% performed in an end-to-end and 13% in an end-to-side configuration. Flap re-exploration and failure rate were 4.3% and 1.1%, respectively. In multivariate analysis, there was no difference in odds of flap re-exploration (OR .70, 95% CI .23-2.18) or flap failure whether or not an end-to-end or end-to-side anastomosis was performed (OR 2.09, 95% CI .38-11.5). CONCLUSIONS: In this large cohort of patients, we found no difference in the odds of flap re-exploration or failure based on venous anastomotic configuration. Reconstructive surgeons should have both anastomotic techniques in their repertoire to optimize the success of every flap.

Recent epidemiology of pediatric cochlear implantation in the United States: disparity among children of different ethnicity and socioeconomic status.

OBJECTIVES/HYPOTHESIS: Congenital severe to profound sensorineural hearing loss (SNHL) is found in higher proportions of children with minority and/or lower socioeconomic status (SES). Cochlear implants were approved by the U.S. Food and Drug Administration for use in children with bilateral severe to profound SNHL in 1990. The objectives of the study were as follows: 1) to study the epidemiology of pediatric cochlear implantation, assessing whether cochlear implant technology is provided to children with severe to profound SNHL in proportion to their racial/ethnic or SES, and 2) to compare data provided by a national health care database with data provided by cochlear implant manufacturers. STUDY DESIGN: Patients aged 0 to 18 years who underwent cochlear implantation in 1997 using a cross-sectional study design. METHODS: Analyses were made of pediatric cochlear implant patients, using data from the 1997 Health Care and Utilization Project/Kids' Inpatient Database. Relative rates of implantation compared with rates of severe to profound SNHL were calculated using national estimates generated from census and Galludet Research Institution data. Logistic regression analysis was carried out to compare implanted children of different racial/ethnic backgrounds. A surrogate measure of socioeconomic status was used based on the median household income of the patient's home ZIP code. Information was also obtained from the two companies producing U.S. Food and Drug Administration-approved cochlear implants in 1997 and used to determine whether the data obtained from the Health Care and Utilization Project/Kids' Inpatient Database were representative of the national cohort of implanted children. RESULTS: The Health Care and Utilization Project/Kids' Inpatient Database identified 124 children who underwent cochlear implant surgery in 1997. White and Asian children were implanted at higher rates than Hispanic and black children. Furthermore, white and Asian children received implants at greater rates than would be expected based on prevalence of severe to profound SNHL. The relative rate (RR) of implantation, defined as the proportion of children who received cochlear implants divided by the proportion of children with severe to profound SNHL (in each race/ethnicity group compared with the same ratio in white children), was similar in white (RR = 1.00) and Asian (RR = 0.93) children but markedly different in Hispanic (RR = 0.28) and black (RR = 0.10) children. Comparison of SES information from the Health Care and Utilization Project/Kids' Inpatient Database population with the manufacturers' database suggested that the Health Care and Utilization Project/Kids' Inpatient Database is representative of all implanted children in the United States. Both sources of information suggested that children receiving cochlear implants in the United States in 1997 resided in above-average SES areas. CONCLUSION: White and Asian children with severe to profound SNHL had higher proportionate rates of cochlear implantation than black and Hispanic children in 1997. Implanted children were more likely to live in areas (represented by ZIP codes) with higher median incomes. Although there was a disparity in rate of cochlear implantation based on race/ethnicity and surrogate measures of SES, these data did not allow the authors to determine the causes for these differences.

Audiologic evidence for further genetic heterogeneity at DFNA2.

A large American family has been mapped to the DFNA2 locus. However, mutation screening of CX31 and KCNQ4, the two genes associated with deafness at this locus, did not identify any mutations. The purpose of this report was to characterize the otologic and audiometric phenotype of this large American family with non-syndromic, autosomal-dominant sensorineural hereditary hearing impairment (HHI). Anamnestic data were obtained, pure-tone audiometry was performed and transient-evoked otoacoustic emissions were recorded. The findings in affected family members were compared to those in unaffected family members and to the respective p50 thresholds of the normal age-matched population. Mutational analysis of the CX26 gene was also performed. The affected members of this family demonstrated progressive symmetric sensorineural hearing impairment. The hearing loss was downward sloping, with mild-to-moderate loss in the low and mid frequencies and severe-to-profound loss in frequencies > 4,000 Hz. The onset of disease was predominantly in the first or early in the second decade. Hearing impairment progressed at approximately 1 dB per year across all frequencies. Transient-evoked otoacoustic emissions revealed a minimal response over all frequencies in affected members but robust responses in all unaffected members. Mutation in the CX26 gene was not present. The affected frequencies observed in this family were similar to those in the original family mapped to DFNA2; however, the age of onset of disease was different and the hearing loss progressed at a slower rate. Therefore, this family provides clinical evidence of genetic heterogeneity at the DFNA2 locus and can serve as a model for age-related hearing loss.

Aquaporin 4 expression in the mammalian inner ear and its role in hearing.

Aquaporin 4 (Aqp4), a member of a family of water transport proteins, is a candidate for playing a critical role in inner ear fluid homeostasis. In this study, we assess cross-species Aqp4 expression in the inner ear, sequence conservation in the 5'-UTR, and hearing in Aqp4 knockout mice. A single Aqp4 isoform was expressed in a highly conserved pattern within the supporting epithelia surrounding the sensory cells of the auditory and vestibular sensory organs and the glial cells surrounding the auditory nerve of the mouse and rat. In the 5'-UTR of mouse and rat Aqp4 gene, sequence conservation was highest in the region spanning the transcription start site. Aqp4 knockout mice demonstrated impaired hearing, but normal neural conduction time. Similar Aqp4 expression pattern and regulatory sequence conservation across species suggest a highly conserved role for Aqp4 in the inner ear. In the Aqp4 deficient mouse, cochlear dysfunction is suggested as the primary cause of hearing impairment in the absence of neural conduction abnormality.