Predictors of plate extrusion in oromandibular free flap reconstruction.

OBJECTIVES: Plate extrusions after free tissue transfer for mandibular reconstruction can be problematic and generally require revision surgery. Our objective was to assess the predictors of plate extrusion and compare outcomes between fibular free flaps (FFF), lateral border scapular flaps (LBSF), and scapular tip free flaps (STFF). METHODS: Retrospective review of consecutive patients who underwent osseous free tissue reconstruction of the mandible (2008-2014) at Victoria Hospital, London, Ontario. Patient demographics and treatment-related information were collected. RESULTS: We identified 134 procedures and 27 (20.2%) plate extrusions (21/61 FFF, 3/49 STFF, and 3/24 LBSF). Freedom from extrusion after 2 years was significantly associated with the use of FFF (P = .003, HR 6.09 1.82-20.44), performing 1 osteotomy (P = .03, HR 2.61 1.08-6.31), and anterior mandibular defects (P = .01, HR 2.66 1.25-5.66) in the univariate model. FFF's were employed more frequently in younger patients, with 2.4 mm plates, more anterior defects, and with a greater number of osteotomies (P < .001). However, after controlling for these variables in multivariate analyses the use of a FFF was the only significant predictor of extrusion at 2 years (P = .006, HR 3.68 1.46-9.28). CONCLUSIONS: At our institution, use of the STFF predicts mandibular defects that are less prone to developing plate extrusion and FFF tended to be used more frequently in anterior defects with osteotomies. However, after controlling for these factors use of the FFF appeared to have higher rates of extrusion than scapular flaps. Further prospective studies controlling for defect variables are needed to elucidate the risk factors for plate extrusion.

microRNAs in sudden hearing loss.

OBJECTIVES: To compare the circulating microRNA (miRNA) expression profiles between sudden sensory neural hearing loss (SSNHL) patients and age-matched normal hearing controls. STUDY DESIGN: Prospective cohort multi-center study. METHODS: Patients presenting within 28 days of onset of SSNHL were prospectively recruited along with contemporaneous age-matched controls. Pooled sera of four patient (n = 09, mean age = 53.0 years; 07, 55.0; 10, 52.9; 10, 51.6) and two control (09, 51.2 and 03, 50.0) groups were assessed using a TaqMan Low Density Array. The patients' sera were also divided into two pools, untreated (04, 57.7) and treated (32, 52.6) for additional analysis. miRNA expression level was derived from cycle threshold (Ct) values normalized to a global mean. Inter-group mean Ct differences with fold changes ≥2.0 and ≤0.5 at P < .05 were considered significant. Bioinformatic databases were used to identify putative target mRNAs or validated genes and their functional annotations. RESULTS: Thirty-six SSNHL patients (mean age 53.0 ± standard deviation (SD) 15.2 years) and 12 controls (50.9 ± 11.9) were studied. Eight miRNAs hsa-miR-590-5p/ -186-5p/ -195-5p/ -140-3p/ -128-3p/ -132-3p/ -375-3p, and -30a-3p were identified as significantly differentially expressed in SSNHL patients. Most of these miRNAs were abundantly identified in the nervous system and the putative target messenger RNAs (mRNAs) were enriched in signaling pathways such as phosphatidyl inositol 3 kinase/protein Kinase B (PI3K/Akt), Ras and mitogen-activated protein kinase (MAPK). CONCLUSION: These findings suggest the possible cellular signaling pathways that underlie the disruption of auditory signal transmission in SSNHL. LEVEL OF EVIDENCE: 2 Laryngoscope, 130:E416-E422, 2020.

The Notch ligands Jagged2, Delta1, and Delta4 induce differentiation and expansion of functional human NK cells from CD34+ cord blood hematopoietic progenitor cells.

Notch receptor signaling is required for T cell development, but its role in natural killer (NK) cell development is poorly understood. We compared the ability of the 5 mammalian Notch ligands (Jagged1, Jagged2, Delta1, Delta3, or Delta4) to induce NK cell development from human hematopoietic progenitor cells (HPCs). CD34(+) HPCs were cultured with OP9 stromal cell lines transduced with 1 of the Notch ligands or with OP9 stromal cells alone, in the presence of IL-7, Flt3L, and IL-15. Differentiation and expansion of CD56(+)CD3(-) cells were greatly accelerated in the presence of Jagged2, Delta-1, or Delta-4, versus culture in the absence of ligand or in the presence of Jagged1 or Delta3. At 4 weeks, cultures containing Jagged2, Delta1, or Delta4 contained 80% to 90% NK cells, with the remaining cells being CD33(+) myelogenous cells. Notch-induced NK (N-NK) cells resembled CD56(bright) NK cells in that they were CD16(-), CD94(-), CD117(+), and killer immunoglobulin-like receptors (KIR(-)). They also expressed NKp30, NKp44, NKp46, 2B4, and DNAM-1, with partial expression of NKG2D. The N-NK cells displayed cytotoxic activity against the K562 and RPMI-8226 cell lines, at levels similar to activated peripheral blood (PB) NK cells, although killing of Daudi cells was not present. N-NK cells were also capable of interferon (IFN)-gamma secretion. Thus, Notch ligands have differential ability to induce and expand immature, but functional, NK cells from CD34(+) HPCs. The use of Notch ligands to generate functional NK cells in vitro may be significant for cellular therapy purposes.

Shouldering the load of mandible reconstruction: 81 cases of oromandibular reconstruction with the scapular tip free flap.

BACKGROUND: The scapular tip free flap (STFF) is becoming more popular for oromandibular reconstruction. This article reviewed the early and late outcomes in a larger series over 9 years. METHODS: We conducted a retrospective review of all consecutive patients who underwent oromandibular reconstruction using the STFF at London Health Sciences Centre. Demographic information, surgical data, and complications were collected and analyzed. RESULTS: From April 2008 to March 2017, 81 STFFs were performed in 80 patients. The average bony reconstruction measured 5.4 cm. Bone-only flaps were utilized in 24 cases (29.6%). Five cases (6.2%) required a single osteotomy. There were 3 (3.7%) flap failures. There were 7 plate extrusions and 11 cases of radiographic nonunion. CONCLUSION: The STFF is a reliable option with acceptable early and long-term results. The STFF may be considered as a first line option especially for shorter bone defects or in conjunction with complex soft tissue requirements.

Outcomes of Cutaneous Squamous Cell Carcinoma in the Head and Neck Region With Regional Lymph Node Metastasis: A Systematic Review and Meta-analysis.

IMPORTANCE: There is a need to summarize the available evidence and provide quantitative data of the most important prognostic factors for patients with metastatic cutaneous squamous cell carcinoma of the head and neck region with regional lymph node metastasis (McSCCHN). OBJECTIVE: To undertake a PRISMA-compliant systematic review and meta-analysis of all published studies on the risk factors for overall survival (OS), locoregional control (LRC), locoregional recurrence (LRR), and disease-specific survival (DSS) for patients with McSCCHN. DATA SOURCES: PubMed, CINAHL, and Embase were searched from 1946 to August 2018 for English-language articles. STUDY SELECTION: Inclusion criteria were randomized clinical trials or observational studies reporting on at least 10 patients with McSCCHN; studies analyzing 1 defined risk factor; reporting OS, LRC, LRR, or DSS; and clinical follow-up of 1 year of more. For the final analysis we included risk factors that were analyzed for the same outcome in at least 3 studies. Of the 2923 articles screened, 21 articles met the inclusion criteria. DATA EXTRACTION AND SYNTHESIS: PRISMA guidelines were used for abstracting the data. Two reviewers independently abstracted the data. Risk of bias was estimated with the Newcastle-Ottawa Scale. Meta-analysis was performed using the random-effects model. All analysis took place between January and October 2018. MAIN OUTCOMES AND MEASURES: The primary end point was OS. Secondary end points included LRC, LRR, and DSS. RESULTS: A total of 20 observational studies and 1 randomized clinical trial were identified, representing 3534 patients (some reviewed articles reported no demographic characteristics), and were included in the analysis. Significant risk factors associated with OS were immunosuppression (hazard ratio [HR] of death, 2.66; 95% CI, 2.26-3.13), extracapsular spread (HR, 1.90; 95% CI, 1.12-3.23), adjuvant radiotherapy (HR, 0.45; 95% CI, 0.27-0.78), lymph node ratio (HR, 1.91; 95% CI, 1.09-3.35), and advanced age (HR, 1.03; 95% CI, 1.00-1.07). Immunosuppression (HR, 3.82; 95% CI, 2.47-5.92) and adjuvant radiotherapy (HR, 0.52; 95% CI, 0.33-0.84) were also significant risk factors for DSS. CONCLUSIONS AND RELEVANCE: Immunosuppressed patients and those with extracapsular extension have poor prognosis. Adjuvant radiotherapy is associated with an improvement in OS. These risk factors will assist with better risk stratification and may also help to inform future clinical trials.

Integration of 2D CMUT arrays with front-end electronics for volumetric ultrasound imaging.

For three-dimensional (3D) ultrasound imaging, connecting elements of a two-dimensional (2D) transducer array to the imaging system's front-end electronics is a challenge because of the large number of array elements and the small element size. To compactly connect the transducer array with electronics, we flip-chip bond a 2D 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array to a custom-designed integrated circuit (IC). Through-wafer interconnects are used to connect the CMUT elements on the top side of the array with flip-chip bond pads on the back side. The IC provides a 25-V pulser and a transimpedance preamplifier to each element of the array. For each of three characterized devices, the element yield is excellent (99 to 100% of the elements are functional). Center frequencies range from 2.6 MHz to 5.1 MHz. For pulse echo operation, the average - 6-dB fractional bandwidth is as high as 125%. Transmit pressures normalized to the face of the transducer are as high as 339 kPa and input-referred receiver noise is typically 1.2 to 2.1 mPa/pHz. The flip-chip bonded devices were used to acquire 3D synthetic aperture images of a wire-target phantom. Combining the transducer array and IC, as shown in this paper, allows for better utilization of large arrays, improves receive sensitivity, and may lead to new imaging techniques that depend on transducer arrays that are closely coupled to IC electronics.

Cellular stress and apoptosis contribute to the pathogenesis of autism spectrum disorder.

The molecular pathogenesis of autism spectrum disorder, a neurodevelopmental disorder, is still elusive. In this study, we investigated the possible roles of endoplasmic reticulum (ER) stress, oxidative stress, and apoptosis as molecular mechanisms underlying autism. This study compared the activation of ER stress signals (protein kinase R-like endoplasmic reticulum kinase [PERK], activating transcription factor 6 [ATF6], inositol-requiring enzyme 1 alpha [IRE1α]) in different brain regions (prefrontal cortex, hippocampus, cerebellum) in subjects with autism and in age-matched controls. Our data showed that the activation of three signals of ER stress varies in different regions of the autistic brain. IRE1α was activated in cerebellum and prefrontal cortex but ATF6 was activated in hippocampus. PERK was not activated in the three regions. Furthermore, the activation of ER stress was confirmed because the expression of C/EBP-homologous protein (CHOP), which is the common downstream indicators of ER stress signals, and most of ER chaperones were upregulated in the three regions. Consistent with the induction of ER stress, apoptosis was found in the three regions by detecting the cleavage of caspase 8 and poly(ADP-ribose) polymerase as well as using the transferase dUTP nick end labeling assay. Moreover, our data showed that oxidative stress was responsible for ER stress and apoptosis because the levels of 4-Hydroxynonenal and nitrotyrosine-modified proteins were significantly increased in the three regions. In conclusion, these data indicate that cellular stress and apoptosis may play important roles in the pathogenesis of autism. Autism Res 2018, 11: 1076-1090. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Autism results in significant morbidity and mortality in children. The functional and molecular changes in the autistic brains are unclear. The present study utilized autistic brain tissues from the National Institute of Child Health and Human Development's Brain Tissue Bank for the analysis of cellular and molecular changes in autistic brains. Three key brain regions, the hippocampus, the cerebellum, and the frontal cortex, in six cases of autistic brains and six cases of non-autistic brains from 6 to 16 years old deceased children, were analyzed. The current study investigated the possible roles of endoplasmic reticulum (ER) stress, oxidative stress, and apoptosis as molecular mechanisms underlying autism. The activation of three signals of ER stress (protein kinase R-like endoplasmic reticulum kinase, activating transcription factor 6, inositol-requiring enzyme 1 alpha) varies in different regions. The occurrence of ER stress leads to apoptosis in autistic brains. ER stress may result from oxidative stress because of elevated levels of the oxidative stress markers: 4-Hydroxynonenal and nitrotyrosine-modified proteins in autistic brains. These findings suggest that cellular stress and apoptosis may contribute to the autistic phenotype. Pharmaceuticals and/or dietary supplements, which can alleviate ER stress, oxidative stress and apoptosis, may be effective in ameliorating adverse phenotypes associated with autism.

Fitting behaviors of Fourier transform and Zernike polynomials.

PURPOSE: To evaluate the residual fit errors for wavefront measurements and corneal surfaces in virgin and post-surgery eyes using the Fourier transform and Zernike 6th- and 10th-order expansions. METHODS: Using MatLab (The MathWorks, Inc.) and VOLCT program (Sarver and Associates, Inc.), wavefront gradient fields derived from the Hartmann-Shack lenslet array of the CustomVue System (Visx, Inc.) and the corneal surface obtained from the Humphrey Atlas topographer (Carl Zeiss, Inc.) were fitted with the Fourier transform and Zernike 6th- and 10th-order expansions. The wavefront gradient fields and corneal surfaces reconstructed by the 3 methods were compared with original ones, and the residual fit errors were analyzed (6.0 mm pupil). Ten eyes in each of the 4 groups (virgin eyes, post-laser in situ keratomileusis (LASIK) for myopia, post-LASIK for hyperopia, and post-radial keratotomy) were included. RESULTS: Wavefront gradient fields reconstructed with Fourier transform produced significantly smaller residual fit errors than Zernike 6th-order in all groups and Zernike 10th-order in all eyes except post-myopic-LASIK eyes. In all groups, wavefront gradient fields reconstructed with Zernike 10th order yielded significantly smaller residual errors than Zernike 6th order (all P<.05). Higher residual errors were produced by these 3 methods in more highly aberrated eyes. When corneal surfaces for all groups were reconstructed, the Fourier transform produced significantly lower residual fit errors than Zernike 6th order and 10th order and the Zernike 10th order yielded significantly lower residual errors than Zernike 6th order (all P<.05). As corneal higher-order aberrations increased, higher residual surface fit errors were produced by Zernike 6th-order and 10th-order expansions but not by Fourier transform. CONCLUSIONS: Fourier transform reconstructed ocular wavefront and corneal topographic maps more accurately than Zernike polynomials up to the 10th order. Clinical implications require further study.

Boot Camps: Preparing for Residency.

Simulation-based boot camps are growing in popularity and are effective in onboarding novice residents with new knowledge, skills, and behaviors. These intensive and immersive courses may be used to train residents and allied health professionals in specific procedures, teamwork, and management of rare clinical scenarios. A needs assessment of learners determines the course curriculum. Boot camps are designed to encourage active and hands-on participation with deliberate practice and immediate feedback. As surgical education shifts toward competency-based medical education, there may be an even greater role for simulation-based boot camps as a training and assessment tool.

Reconstruction after salvage laryngectomy.

Both early and advanced stage laryngeal cancers are treated with organ-preserving strategies including radiation alone or concurrent chemoradiotherapy. While organ-preserving modalities have proven effective in eradicating cancer while also preserving laryngeal function, there remains a proportion of cases where residual or recurrent cancer prevails, or conversely, where radiotherapy renders a larynx dysfunctional. In these circumstances, salvage total laryngectomy is often the surgical treatment. The effects of radiotherapy to the neck, amplified by chemotherapy, can create an inhospitable surgical environment, making the salvage laryngectomy an operation fraught with the potential for major complications such as the dreaded pharyngocutaneous fistula. The introduction of vascularized tissue from outside the irradiated field decreases the risk of major wound complications. Free tissue transfer, with a variety of donor sites available, is commonly employed to reconstruct either a patch or a circumferential segment of the pharynx. When there is enough pharyngeal mucosa for primary closure, a vascularized onlay graft or a pharyngeal interposition graft can be used to reinforce the closure. This has been demonstrated to both reduce the severity of pharyngocutaneous fistula and decrease the risk of developing a pharyngocutaneous fistula compared to primary closure alone. Beyond mitigating the risk for perioperative complications, flap selection may have implications on the long-term outcomes after salvage total laryngectomy and these must be considered preoperatively. The purpose of this review is to examine the various options for reconstruction after salvage total laryngectomy and to examine some of their advantages and disadvantages in the short and long-term.

Primary facial reanimation in head and neck cancer.

Facial Paralysis (FP) profoundly impairs the life of individuals, both functionally and psychosocially. Surgical approaches to treat this condition are myriad, but the ultimate goal is to restore symmetry and movement. Ablative surgery for tumors of the head and neck region are amongst the most common etiologies causing FP and this group of patients represents unique challenges. Surgical defects may have multiple competing reconstructive requirements and addressing the FP must be considered in this context. Furthermore, extent of disease, patient age, duration of preceding paralysis, adjuvant treatment, as well as the various different type of facial nerve defects are factors that may influence the type of reconstructive technique selected to address the FP. The complexity of FP especially following head and neck ablation can lead to results that are inconsistent and humbling. FP defects can be broadly described as having the potential for facial muscle recovery versus irreversible paralysis. Literature that specifically focuses on primary facial reanimation procedures in the oncological setting is scarce. We present a comprehensive review of primary facial reanimation after ablative surgery including the descriptions of a wide array of surgical techniques such as reinnervation, dynamic muscle transposition, static suspension, and free tissue transfer. Understanding the advantages and limitations of the different options will enable the surgeon to offer treatment for the paralyzed face for most clinical scenarios.

Evaluating organ preservation outcome as treatment endpoint for T1aN0 glottic cancer.

OBJECTIVES/HYPOTHESIS: Common endpoints in reporting the outcomes for early glottic cancer do not highlight the importance of organ preservation. We evaluated the treatment outcomes among patients with T1aN0 laryngeal cancer with laryngectomy-free disease-specific survival (LFS-DSS), which is defined as time to total laryngectomy or time to death from cancer cause, against all other endpoints. STUDY DESIGN: Outcome research on an institutional database. METHODS: A retrospective review covered all consecutive patients from 2003 to 2013. Patients with T1a laryngeal squamous cell carcinoma (SCC) were offered the options of either radiation treatment (RT) or transoral laser microsurgery (TLM). Tumor control, survival outcomes, standard definition laryngectomy-free survival (LFS), and LFS-DSS were calculated. RESULTS: There were 105 patients, of whom 53 were treated with TLM and 52 were treated with RT. There were 11 recurrences within the TLM group, of which four were successfully salvaged with repeated TLM and two were salvaged with RT. Among the four recurrences within the RT group, all four patients had salvage total laryngectomies. The 5-year overall survival for patients treated with TLM versus RT was 86% versus 85% (P = .887), disease-free survival was 69% versus 78% (P = .151), LFS was 65% versus 77% (P = .198), LFS-DSS was 100% versus 88% (P = .030), and ultimate locoregional control was 100% in both groups. CONCLUSIONS: Patients with T1aN0 glottic SCC treated with RT or TLM have similar survival outcomes. Patients with T1a tumor treated with TLM have better organ preservation compared to RT, when measured with LFS-DSS. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1322-1327, 2017.

Analysis of bacterial cultures in infectious keratitis, 1997 to 2004.

PURPOSE: To review bacterial culture results in infectious keratitis at a tertiary referral center. DESIGN: Retrospective case series. METHODS: Analysis of Gram stain, bacterial culture, and targeted antibiotic sensitivities of all cases of presumed infectious keratitis at Duke University Eye Center from 1997 to 2004 (n = 453). RESULTS: Cultures were positive in 307 cases (68%); 21% demonstrated polymicrobial growth. Among 388 isolates, 81% were Gram-positive. Gram stain results were available in 334 cases, demonstrating 18% sensitivity and 94% specificity. Antibiotic sensitivities revealed 24% resistance of tested S. aureus isolates to cefazolin, and <5% resistance of tested gram-negative isolates to various antibiotics, with no statistically significant increase from 1997 to 2004. CONCLUSIONS: In this study, the microbial profile has remained stable from 1997 to 2004. Gram stain studies were of poor sensitivity, while culture yields were significantly higher and demonstrated a relatively high polymicrobial infection rate. Increasing antibiotic resistance was not clearly demonstrated.

Treatment of traumatic LASIK flap dislocation and epithelial ingrowth with fibrin glue.

PURPOSE: To describe a case of a traumatic late dislocation of a laser-assisted in situ keratomileusis (LASIK) flap complicated by epithelial ingrowth. DESIGN: Interventional case report. METHODS: A 50-year-old woman presented 21 months after uncomplicated LASIK with painful vision loss in the right eye after minor trauma. RESULTS: A dislocation of the LASIK flap was noted at examination and was repositioned. One week later, epithelial ingrowth was detected in the flap interface. The ingrowth was treated with flap lifting, debridement, and sealing of the flap with fibrin glue. Visual acuity returned to baseline, and there was no recurrence after 20 months of follow-up. CONCLUSIONS: Traumatic dislocations of LASIK flaps may occur many months after uncomplicated surgery and may be associated with epithelial ingrowth after successful repositioning. The additional use of fibrin glue in conjunction with thorough debridement may be helpful in preventing the recurrence of epithelial ingrowth.

Intraoperative ultrasonography used to determine the extent of surgery necessary during posterior fossa decompression in children with Chiari malformation type I.

OBJECT: In this retrospective analysis, the authors report a prospective study in which intraoperative ultrasonography was used to determine the extent of surgery necessary during posterior fossa decompression surgery for Chiari malformation Type I (CM-I) in children. METHODS: Between 1995 and 2003, posterior fossa decompression was performed in 149 patients (mean 5.9 years of age, range 9 months-18 years of age) with CM-I. Of these, 130 underwent intraoperative ultrasonographic evaluation of the craniocervical junction (CCJ) and 15 did not. Four patients with craniosynostosis were excluded from the study. Duraplasty and tonsillar shrinkage were performed when ultrasonographic evidence showed significant decreases in cerebrospinal fluid (CSF) or abnormal tonsillar piston action. Surgical success was determined on the basis of clinical outcome and need for reoperation. One hundred and twenty-four (95.5%) of the children had successful outcomes following surgery and six (4.5%) experienced continued or worsening symptoms requiring reoperation. Forty patients did not undergo duraplasty because the ultrasonography evidence showed adequate decompression with bone removal alone. Of 90 patients with significant compression, decreased CSF dynamics, and/or abnormal tonsillar piston-like action at the CCJ, 85 underwent duraplasty and tonsillar shrinkage and five did not for various reasons. One patient in whom the dura mater was violated accidentally during bone decompression subsequently underwent duraplasty. Hospital stays lasted 6.4 +/- 3.9 days (mean +/- standard deviation) when duraplasty was performed compared with 4.3 +/- 1.1 days when it was not (p < 0.0003). After bone decompression alone, no patient experienced complications. After duraplasty, 12 patients experienced complications and had headaches, nausea, and pain more often than patients who underwent bone decompression alone. Mean tonsillar descent was 11 +/- 4 mm after bone decompression only and 13.9 +/- 4.9 mm after duraplasty, with tonsillar shrinkage (p < 0.0003) seen on magnetic resonance imaging. CONCLUSIONS: In patients who undergo decompressive surgery for CM-I, intraoperative ultrasonography may be a useful tool to aid the surgeon in deciding whether to opt for bone removal only or bone removal plus duraplasty and tonsillar shrinkage.

3-D ultrasound imaging using a forward-looking CMUT ring array for intravascular/intracardiac applications.

Forward-viewing ring arrays can enable new applications in intravascular and intracardiac ultrasound. This work presents compelling, full-synthetic, phased-array volumetric images from a forward-viewing capacitive micromachined ultrasonic transducer (CMUT) ring array wire bonded to a custom integrated circuit front end. The CMUT ring array has a diameter of 2 mm and 64 elements each 100 microm x 100 microm in size. In conventional mode, echo signals received from a plane reflector at 5 mm had 70% fractional bandwidth around a center frequency of 8.3 MHz. In collapse mode, 69% fractional bandwidth is measured around 19 MHz. Measured signal-to-noise ratio (SNR) of the echo averaged 16 times was 29 dB for conventional operation and 35 dB for collapse mode. B-scans were generated of a target consisting of steel wires 0.3 mm in diameter to determine resolution performance. The 6 dB axial and lateral resolutions for the B-scan of the wire target are 189 microm and 0.112 radians for 8 MHz, and 78 microm and 0.051 radians for 19 MHz. A reduced firing set suitable for real-time, intravascular applications was generated and shown to produce acceptable images. Rendered three-dimensional (3-D) images of a Palmaz-Schatz stent also are shown, demonstrating that the imaging quality is sufficient for practical applications.

Experimental characterization of collapse-mode CMUT operation.

This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane. In collapse-mode operation, the DC bias voltage is first increased beyond the collapse voltage, then reduced without releasing the collapsed membrane. In collapse-mode operation, the center of the membrane is always in contact with the substrate. In the case of a circular membrane, the maximum AC displacement occurs along the ring formed between the center and the edge of the membrane. The experimental characterization presented in this paper includes impedance measurements in air, pulse-echo experiments in immersion, and one-way optical displacement measurements in immersion for both conventional and collapse-mode operations. A 205-microm x 205-microm 2-D CMUT array element composed of circular silicon nitride membranes is used in the experiments. In pulse-echo experiments, a custom integrated circuit (IC) comprising a pulse driver, a transmit/receive switch, a wideband low-noise preamplifier, and a line driver is used. By reducing the parasitic capacitance, the use of a custom IC enables pulse-echo measurements at high frequencies with a very small transducer. By comparing frequency response and efficiency of the transducer in conventional and collapse regimes, experimental results show that a collapsed membrane can be used to generate and detect ultrasound more efficiently than a membrane operated in the conventional mode. Furthermore, the center frequency of the collapsed membrane can be changed by varying the applied DC voltage. In this study, the center frequency of a collapsed transducer in immersion is shown to vary from 20 MHz to 28 MHz with applied DC bias; the same transducer operates at 10 MHz in the conventional mode. In conventional mode, the maximum peak-to-peak pressure is 370 kPa on the transducer surface for a 40-ns, 25-V unipolar pulse excitation. In collapse mode, a 25-ns, 25-V unipolar pulse generates 590 kPa pressure at the surface of the transducer.

Metastatic mammary carcinoma to the orbit masquerading as maxillary sinusitis.

INTRODUCTION: We report on a case of isolated metastatic breast cancer to the medial rectus muscle. This entity is exceedingly rare. CASE: A 44-year-old female with a history of breast cancer presented with unilateral maxillary symptoms and was treated for sinusitis. Over time, she developed ocular pain, diplopia, blurred vision and eventually complete adduction deficit. RESULTS: T1-weighted magnetic resonance imaging revealed a medial rectus lesion. Biopsy via transnasal transorbital endoscopic approach revealed metastatic mammary carcinoma. DISCUSSION: Metastatic disease to the orbit should be considered in the differential diagnosis of refractory maxillary sinus pain in patients with a known underlying malignancy.

Golf-associated head injury in the pediatric population: a common sports injury.

OBJECT: Golf-related injuries constitute a common type of sports injury in the pediatric population. The increase in the frequency of these injuries is largely attributed to the increase in the popularity of golf and greater use of golf carts by children. METHODS: The purpose of this study was to investigate the mechanisms and complications associated with golf-related injuries in the pediatric population and, by doing so, assist in the prevention of such injuries. We reviewed the charts of 2546 pediatric patients evaluated by the neurosurgery service at the authors' institution over a 6-year period. There were 64 cases of sports-related injuries. Of these, 15 (23%) were golf-related, making these injuries the second-largest group of sports-related injuries. Depressed skull fracture was the most common injury observed. Neurosurgical intervention was required in 33% of the cases. With rare exceptions, patients made good recoveries during a mean follow-up period of 22.2 months. One death occurred due to uncontrollable cerebral edema following a golf cart accident. One child required shunt placement and several revisions following an injury sustained from a golf ball. CONCLUSIONS: Children should be advised on the proper use of golf equipment as a preventive measure to avoid these injuries. Precautionary guidelines and safety training guidelines should be established. The institution of a legal minimum age required to operate a golf cart should be considered.