Microsurgical reconstruction for head and neck in patients with end-stage renal disease undergoing dialysis.

INTRODUCTION: Free flap transfer for head and neck defects has gained worldwide acceptance. Because flap failure is a devastating outcome, studies have attempted to identify risk factors-including renal failure. We sought to determine whether end-stage renal disease (ESRD) patients undergoing dialysis are at increased risk of flap failure following microsurgical head and neck reconstruction. PATIENTS AND METHODS: The study's participants were patients who underwent free flap reconstruction in the head and neck region at Hualien Tzu Chi Hospital between January 2010 and December 2019. We used the National Health Insurance "Specific Diagnosis and Treatment Code" to identify patients undergoing dialysis; these patients comprised the dialysis group, whose members were matched to a non-dialysis group for age and gender. The dependent variables were flap survival rate, take-back rate, and flap failure risk between the dialysis and non-dialysis groups. RESULTS: We included 154 patients in the dialysis (n = 14) and non-dialysis (n = 140) groups. The groups were similar in terms of age and most comorbidities, except diabetes mellitus, hypertension, and coronary artery disease, which were more prevalent in the dialysis group. The dialysis and non-dialysis groups had similar flap survival rates (100% vs. 92.9%; p = .600). Twenty-three patients underwent take-back surgery, most in the non-dialysis group (14.3% vs. 15.0%; p = 1.000). Patients in the dialysis group were more likely to have prolonged intensive care unit stays; however, dialysis alone did not predict flap failure (OR: 0.83; p = .864). CONCLUSION: This study found no significant differences in free flap survival and take-back rates between patients with and without dialysis. Dialysis did not increase the risk of flap failure following microsurgical head and neck reconstruction in this study; however, prospective, randomized controlled trials are needed.

Sound Pressure Distribution in the Ear After Radical Mastoidectomy With Meatoplasty.

OBJECTIVE: We aimed to identify the sound pressure distribution along the external auditory canal after radical mastoidectomy with meatoplasty by combining real ear measurements and measurements obtained using a finite-element model. STUDY DESIGN: Case series with chart review. SETTING: Tertiary care university hospital. PATIENTS: We evaluated 16 patients who had undergone radical mastoidectomy with meatoplasty in one ear and had intact nonoperated contralateral ears, which served as the control group. INTERVENTION DIAGNOSTIC: Real ear measurements testing at specific frequencies were performed postoperatively. MAIN OUTCOME MEASURE: Sound pressure gains were measured at five different depths along the external auditory canal, and a validated finite-element model was used to simulate the sound pressure distributions along the external auditory canals of the operated and nonoperated ears. RESULTS: The average peak resonant frequency near the tympanic membrane in operated ears was significantly lesser than that in nonoperated ears (2434.4 ± 616.4 versus 2935.9 ± 602.2 Hz; Wilcoxon signed-rank test, p < 0.05). The average peak resonant amplitude near the tympanic membrane showed no significant intergroup difference (paired-sample t test, p > 0.05). The peak resonant frequencies at different depths of the external auditory canal varied in the nonoperated ears (Kruskal-Wallis rank-sum test, 2880.9 ± 581.7 Hz, p = 0.02) but did not differ significantly in the operated ears (Kruskal-Wallis rank-sum test, 2464.4 ± 670.3 Hz, p = 0.75). In the finite-element model, the peak resonant frequencies along the depth of the external auditory canal varied in the normal ear and were homogeneous in the operated ear. CONCLUSION: Radical mastoidectomy with meatoplasty altered the sound distribution in the external auditory canal. Our finite-element model successfully simulated the postoperative sound distribution in the external auditory canal and will facilitate development of wearable equipment for these patients.

Optimal N-acetylcysteine concentration for intratympanic injection to prevent cisplatin-induced ototoxicity in guinea pigs.

BACKGROUND: Cisplatin is a chemotherapy drug that can induce sensorineural hearing loss. At present, no otoprotective agent is approved for use. OBJECTIVES: This study investigated the optimal concentration of intratympanic N-acetylcysteine (NAC) to prevent cisplatin-induced ototoxicity in a guinea pig model. MATERIALS AND METHODS: Guinea pigs (n = 64) were treated with a single intratympanic injection containing different NAC concentrations or saline (control) 3 days prior to intraperitoneal injection with cisplatin. The threshold change in the auditory brainstem response was assessed. RESULTS: Four weeks after intraperitoneal cisplatin injection, only the group that received 2% NAC exhibited significant otoprotection (p < .05) compared with the control. Otoprotection was observed at all the frequencies tested (1k, 2k, 4k, and 8k Hz). The 2% NAC group also exhibited significant otoprotection (p < .05) compared with the other NAC groups (at 1k, 2k, 4k, and 8k Hz). The 4% NAC group exhibited significantly reduced hearing capacity (p < .05) in the fourth week compared with controls. CONCLUSIONS AND SIGNIFICANCE: Intratympanic NAC administration is an efficient and safe means of preventing cisplatin-induced ototoxicity. In our animal model, the optimal intratympanic NAC concentration was 2%; concentrations of 4% loss of otoprotection.

Effects of different electrodes used in bone-guided extracochlear implants on electrical stimulation of auditory nerves in guinea pigs.

OBJECTIVE: Conventional cochlear implants provide patients who are deaf with hearing via electrical intracochlear stimulations. Stimulation electrodes are inserted into the cochlea through a cochleostomy or round window membrane (RWM) approach. However, these methods might induce cochlear ossificans and loss of residual hearing by damaging inner ear structures. To avoid an invasive electrode insertion, we developed a novel bone-guided extracochlear implant that stimulated the auditory nerves between the cochlear bones and the RWM to prevent cochlea damage. Power consumption plays an important role in wireless implantable electronic devices. Therefore, we aimed to investigate the effects of different electrodes on the stimulating threshold currents of the auditory nerve and the power consumption of bone-guided extracochlear implants using a commercial stimulator. MATERIALS AND METHODS: Inert aurum (Au) electrodes were compared with biocompatible platinum (Pt) and iridium oxide (IrOx) electrodes in practical implantable applications. IrOx electrodes were used for their high-charge storage capacity, low impedance, and biocompatibility. The electrodes were fabricated via sputtering and were experimentally characterized with cyclic voltammetry and then examined using in vivo tests. RESULTS: Based on electrical auditory brainstem responses, IrOx electrodes yielded lower acoustic nerve-stimulating threshold currents (132 µA) compared with Au electrodes (204 µA). IrOx electrodes also had a lower acoustic nerve stimulating threshold current (132 µA) compared with Pt electrodes (168 µA). CONCLUSION: As expected, IrOx electrodes were beneficial in the development of multielectrode bone-guided extracochlear implants, with the lowest acoustic nerve-stimulating threshold and current consumptions compared with Au and Pt electrodes.

Design and In Vivo Verification of a CMOS Bone-Guided Cochlear Implant Microsystem.

OBJECTIVE: To develop and verify a CMOS bone-guided cochlear implant (BGCI) microsystem with electrodes placed on the bone surface of the cochlea and the outside of round window for treating high-frequency hearing loss. METHODS: The BGCI microsystem consists of an external unit and an implanted unit. The external system-on-chip is designed to process acoustic signals through an acquisition circuit and an acoustic DSP processor to generate stimulation patterns and commands that are transmitted to the implanted unit through a 13.56 MHz wireless power and bidirectional data telemetry. In the wireless power telemetry, a voltage doubler/tripler (2X/3X) active rectifier is used to enhance the power conversion efficiency and generate 2 and 3 V output voltages. In the wireless data telemetry, phase-locked loop based binary phase-shift keying and load-shift keying modulators/demodulators are adopted for the downlink and uplink data through high-Q coils, respectively. The implanted chip with four-channel high-voltage-tolerant stimulator generates biphasic stimulation currents up to 800 µA. RESULTS: Electrical tests on the fabricated BGCI microsystem have been performed to verify the chip functions. The in vivo animal tests in guinea pigs have shown the evoked third wave of electrically evoked auditory brainstem response waveforms. It is verified that auditory nerves can be successfully stimulated and acoustic hearing can be partially preserved. CONCLUSION AND SIGNIFICANCE: Different from traditional cochlear implants, the proposed BGCI microsystem is less invasive, preserves partially acoustic hearing, and provides an effective alternative for treating high-frequency hearing loss.

Prognostic factors of paranasal sinusitis with intracranial invasion: A 14-year review of cases at Hualien Buddhist Tzu Chi Hospital.

Intracranial invasion of paranasal sinusitis is an emergency condition that requires surgical and medical intervention in order to avoid further deterioration. We surveyed patients at the Buddhist Tzu Chi Hospital (Hualien, Taiwan) who had paranasal sinusitis with intracranial invasion. A total of 505 patients with paranasal sinusitis were surveyed at Hualien Buddhist Tzu Chi Hospital over a 14-year period (2000-2013). Data on clinical presentations, microbiology, host factors, postinterventional morbidity, and postinterventional mortality are presented. Of the 505 patients, nine had intracranial invasions (incidence rate, 1.8%). The mortality rate was high among these patients (44.4%, 4/9). Among the various risk factors identified, diabetes had the greatest influence (66.7%, 6/9), which in combination with an immunocompromised condition and cirrhosis is indicative of a poor prognosis.

A novel aerosol-mediated drug delivery system for inner ear therapy: intratympanic aerosol methylprednisolone can attenuate acoustic trauma.

We developed a novel aerosol-mediated drug delivery system for inner ear therapy by using a silicon-based multiple-Fourier horn nozzle. Intratympanic aerosol (ITA) methylprednisolone (MP) delivery can protect hearing after acoustic trauma. The highest concentration of MP (38.9 ± 5.47 ppm) appeared at 2 h and declined rapidly within 10 h. The concentrations of MP remained at a relatively low level for more than 10 h. Compared to the baseline, the auditory brainstem response (ABR) thresholds shifted markedly at 1 h after noise exposure in all groups (p < 0.05). From the cochleograms, it can be noted that the main lesions encompassed the 2-20 kHz frequency range. Significant differences ( ) were observed for the range between 5 and 8 kHz in the cell loss of outer hair cells (OHCs). The losses for IHCs were lower than for OHCs. The MP movement in the middle ear was simulated by a convection diffusion equation with a relaxation time. The relaxation time was 0.5 h, and the concentration threshold of MP on the round window membrane (RWM) in the middle ear (C T) was 8900 ppm. Using the unit hydrograph (UH) method, we obtained a proper boundary concentration on the RWM at the cochlea, which resulted in a well-fit concentration. Finally, a linking mechanism between the middle ear and the cochlea was established by the RWM. The adjustable permeability and concentration threshold provide the flexibility to match the peak times and peak values of the concentration on the RWM in the middle ear and the cochlea.

Modeling sound transmission of human middle ear and its clinical applications using finite element analysis.

We have developed a new finite element (FE) model of human right ear, including the accurate geometry of middle ear ossicles, external ear canal, tympanic cavity, and mastoid cavity. The FE model would be suitable to study the dynamic behaviors of pathological middle ear conditions, including changes of stapedial ligament stiffness, tensor tympani ligament (TTL), and tympanic membrane (TM) stiffness and thickness. Increasing stiffness of stapedial ligament has substantial effect on stapes footplate movement, especially at low frequencies, but less effect on umbo movement. Softer TTL will result in increasing umbo and stapes footplate displacement, especially at low frequencies (f<1000Hz). When the TTL was detached, the vibration amplitude of umbo increased by 6dB at 600Hz and two peaks (300 and 600Hz) were found in the vibration amplitude of stapes footplate. Increasing the stiffness of tensor tympani resulted in a slightly decreased umbo amplitude at very low frequencies (f<500Hz) and significantly decreased displacement up to 12dB at middle frequencies (1000Hz1500Hz. As (TM) thickness was increased, the umbo displacement was reduced, especially at very low frequencies (f<600Hz). Otherwise, the stapes displacement was reduced at all frequencies.

Novel device to measure critical point "Onset" of capillary wave and interpretation of Faraday instability wave by numerical analysis.

A capillary wave was created on a surface by vibrating from the bottom of a container. When the amplitude of the container vibration approached the critical point, called the onset state, the surface broke up and bursted into very small drops on the air. The numerical analysis was used to determine the amplitude of the onset. The onset point was found to be 0.349µm at f=500kHz. The critical amplitude h(cr) was determined by using a multi-Fourier horn nozzle (MFHN) device. The onset point was measured to be 0.37µm using a laser Doppler vibrometer (LDV) with the MFHN at f=486kHz. These drops indicate that particle size distributions of 10.8µm and 7.0µm were produced by the MFHN at f=289kHz and f=486kHz, respectively. These results agreed with those obtained using Kelvin's equation, which predicted D=0.34λ.

Metastatic gallbladder cancer presenting as a gingival tumor and deep neck infection.

Gallbladder cancer has an extremely poor prognosis because it is often diagnosed at an advanced stage. We describe a 63-year-old woman who was treated 4 years previously for gallbladder cancer, with laparoscopic cholecystectomy and secondary hepatectomy after presenting with acute cholecystitis and gallbladder rupture. At her second presentation, she had a left lower gingival tumor and deep neck infection. Incision and drainage and tumor biopsies were performed, and pathology at both sites revealed adenocarcinoma. Positron emission tomography revealed other tumors in the left breast and left lower lung field, which were both proven to be adenocarcinoma by biopsy. The patient's presentation with a metastatic oral tumor was rare. Although the incidence is very low, physicians should consider the possibility of metastatic cancer in a patient with a history of cancer, who presents with new oral tumor or deep neck infection.

Virtual biopsy of rat tympanic membrane using higher harmonic generation microscopy.

Multiharmonic optical microscopy has been widely applied in biomedical research due to its unique capability to perform noninvasive studies of biomaterials. In this study, virtual biopsy based on back-propagating multiple optical harmonics, combining second and third harmonics, is applied in unfixed rat tympanic membrane. We show that third harmonic generation can provide morphologic information on the epithelial layers of rat tympanic membrane as well as radial collagen fibers in middle fibrous layers, and that second harmonic generation can provide information on both radial and circular collagen fibers in middle fibrous layers. Through third harmonic generation, the capillary and red blood cells in the middle fibrous layer are also noted. Additionally, the 3-D relationship to adjacent bony structures and spatial variations in thickness and curvature are obtained. Our study demonstrates the feasibility of using a noninvasive optical imaging system for comprehensive evaluation of the tympanic membrane.

Registration of micro-computed tomography and histological images of the guinea pig cochlea to construct an ear model using an iterative closest point algorithm.

We present a practical and systematic method to reconstruct accurate physical models of the guinea pig ear (n = 1). The method uses a semi-automatic technique to create three-dimensional (3-D) models of the guinea pig cochlea by registration of micro-computed tomography (CT) and histological images. An iterative closest point algorithm was employed to minimize the sum of square errors with respect to the closest histological model and corresponding micro-CT model. This allowed creation of an accurate geometric ear model including external ear canal, tympanic membrane, middle ear cavity, auditory ossicles, and the cochlea. The characteristic cross-sectional areas of scala tympani, scala vestibuli, and scala media were measured. The length, thickness, and apex width of the guinea pig's basilar membrane were compared to the data found in literature. Some shape parameters were also compared among different species. The results confirmed that the geometric model created by this method was accurate. This method provides an effective way to visualize the 3-D structure and the detailed information about ear geometry required for finite element and multibody dynamic analysis.

Surgical anatomy of the spinal accessory nerve: is the great auricular point reliable?

OBJECTIVE: The study was to exam if the great auricular point is a dependable landmark for finding the spinal accessory nerve. DESIGN: A prospective study from January 2004 to August 2006 in a tertiary medical centre. SETTING: A tertiary medical centre, Tzu Chi General Hospital. METHODS: In the modified radical neck dissection, the topographic anatomy of spinal accessory was studied in 50 patients. MAIN OUTCOME: The great auricular point (GAP) was identified and the length of sternocleidomastoid muscle (SCM) below was measured. The distance between the spinal accessory nerve and the greater auricular point was measured. RESULTS: The ratio of the length of the SCM below the nerve exiting point to the total length of the muscle was near 0.66. The mean distance between the GAP and the accessory nerve was 0.92 cm (SD +/- 0.27). CONCLUSIONS: The great auricular point is a reliable landmark for identification of the accessory nerve during the neck dissection.

Income and the incidence of oral cavity cancer: cross-national study.

OBJECTIVE: To examine the relation between income and oral cancer incidence in countries at different stages of economic development. DESIGN: Descriptive study with regression analysis of oral cancer incidence in relation to real gross domestic product (GDP) per capita from 1970 to 2000 performed for 8 different countries. METHODS: GDP per capita was collected from the United States, Hong Kong, Singapore, Italy, Mexico, Philippines, Poland, and Romania. Correlation factor and Pearson values were compared. RESULTS: The association between income and the oral cavity cancer rate was significant in all the countries selected. Using linear regression analysis, the results showed high r2 value. The increase of real GDP correlated negatively with the rate of male oral cavity cancer in the United States, Italy, Hong Kong, and Singapore but not in Mexico, Philippines, Poland, and Romania. CONCLUSIONS: The association between incidence and income appears to depend on per capita GDP, being negative in countries with GDP above US$10,000 and positive in countries with GDP below US$10,000.

A novel opto-electromagnetic actuator coupled to the tympanic membrane.

A new type of electromagnetic vibration transducer designed to be placed onto the tympanic membrane was developed. The actuator consisted of two photodiodes, two permanent magnets, an aluminum ring, two opposing wound coils, a latex membrane and a Provil Novo membrane. An optic probe was designed to allow sound and light signals to enter the ear canal, thereby preventing the acoustic occlusion effect of traditional ear molds. Two light-emitting diodes were used for carrying the input signals. The corresponding photodiodes were used for receiving the light signals and generating currents in the actuator. The opto-electromagnetic vibration actuator was fabricated and tested using a Laser Doppler vibrometer. The actuator showed displacements of vibration between 30 and 1 nm from 300 to 6500Hz and reduced in amplitude at higher frequencies. The average gain of the actuator with 140microA on the umbo displacement was about 20 dB relative to 87 dBA at the distance of 6cm from the tympanic membrane and 0microA in actuator.

Optimal graft thickness for different sizes of tympanic membrane perforation in cartilage myringoplasty: a finite element analysis.

OBJECTIVE: The purpose of this study was to determine, using finite element analysis, the optimal graft thickness for cartilage myringoplasty in patients with different sizes of tympanic membrane (TM) perforations. STUDY DESIGN: We developed a cartilage plate-TM-coupled model using high-resolution computed tomography and finite element analysis. The geometric models of the perforated TM were generated using Patran and ANSYS software. METHOD: Three different sizes of TM perforations (15%, 55%, and 85%, representing small, medium, and large perforations, respectively) were created in the pars tensa. A cartilage plate was used to repair the eardrum perforation, and the new TM-cartilage coupled complex was loaded into our three-dimensional biomechanical model for analysis. The frequency-amplitude responses for different cartilage thicknesses were compared with those for natural TM. RESULTS: Our results show that, first, in cases with 85% perforation, the frequency-amplitude responses that were most similar to natural TM at lower frequencies were for graft thicknesses of 0.2 mm and for 0.1 mm at higher frequencies. Second, in cases with 55% posterior perforation of the TM, assessment of the predicted vibration amplitude of different thicknesses of the cartilage plate showed that a cartilage plate of less than 0.2 mm had a frequency response function similar to that of a natural TM in umbo and stapes footplate displacement. Finally, for a central perforation involving 15% of the TM, a cartilage plate of less than 1.0 mm showed a frequency response function similar to that of TM in umbo and stapes-footplate displacement. CONCLUSIONS: On the basis of our biomechanical analysis, the optimal thickness of a cartilage graft for myringoplasty appears to be 0.1 to 0.2 mm for medium and large TM perforations. For small perforations, a cartilage of less than 1.0 mm is a good compromise between mechanical stability and low acoustic transfer loss.

Biomechanical modeling and design optimization of cartilage myringoplasty using finite element analysis.

The purpose of this study was to determine the acoustic transfer characteristics of cartilage for optimal cartilage myringoplasty. In order to do so, we developed a cartilage plate/tympanic membrane-coupled model using finite element analysis. Cartilage specimens of the tragus were obtained from fresh human cadavers, and the parameters of the tragus were determined by curve fitting and cross-calibration. A cartilage plate was used to repair an eardrum perforation, and the new coupled tympanic membrane-cartilage complex was loaded into our 3-dimensional biomechanical model of the middle ear for analysis. Our results show that first the beta-damping value of the cartilage plate depends on frequency. The value of beta damping was close to 3 x 10(-4) s at lower frequencies and 5 x 10(-6) s at higher frequencies. Secondly, reducing cartilage thickness leads to an improvement of its acoustic transfer qualities. From an acoustics point of view, the 0.1- to 0.2-mm cartilage plate seems to be most preferable with regard to tympanic membrane vibration. Furthermore, thicknesses of 0.2 mm at lower frequencies and 0.1 mm at higher frequencies were regarded as good compromises between sufficient mechanical stability and low acoustic transfer loss.

Three-dimensional reconstruction and modeling of middle ear biomechanics by high-resolution computed tomography and finite element analysis.

OBJECTIVE: To present a systematic and practical approach that uses high-resolution computed tomography to derive models of the middle ear for finite element analysis. STUDY DESIGN: This prospective study included 31 subjects with normal hearing and no previous otologic disorders. Temporal bone images obtained from 15 right ears and 16 left ears were used for evaluation and reconstruction. METHODS: High-resolution computed tomography of temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an Amira visualization system for three-dimensional reconstruction. The created three-dimensional model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. RESULT: The characteristic dimensions of the model were measured and compared with previously published histologic section data. This result confirms that the geometric model created by the proposed method is accurate except that the tympanic membrane is thicker than when measured by the histologic section method. No obvious difference in the geometrical dimension between right and left ossicles was found (P > .05). The three-dimensional model created by finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's, Gan's, and Sun's data across the frequency range of 100 to 8000 Hz. CONCLUSION: The model includes a description of the geometry of the middle ear components and dynamic equations of vibration. The proposed method is quick, practical, low-cost, and, most importantly, noninvasive as compared with histologic section methods.

Sinonasal adenocarcinoma: clinical study of nine cases in Taiwan.

OBJECTIVE: Sinonasal adenocarcinoma is an uncommon disease in Taiwan. This paper presents details of the management and outcome of the disease. MATERIAL AND METHODS: The medical records of patients with sinonasal adenocarcinoma who presented to the Department of Otolaryngology, National Taiwan University Hospital between 1983 and 2002 were retrospectively reviewed. Tumors were staged based on the American Joint Committee of Cancer staging criteria. The series included 5 males and 4 females (mean age 51 years; range 28-75 years). RESULTS: No association between sinonasal adenocarcinoma and occupations such as furniture making, wood working or textile working was found. Epistaxis and nasal obstruction were the most common symptoms. Metastasis to bone or liver was found initially at diagnosis in two cases. Treatment was given according to the tumor stage, the clinical condition of the patient and the patient's wishes: two received combined treatment comprising wide surgical resection and radiotherapy, two received radiotherapy only, one received wide surgical resection only and four received no treatment. At a mean follow-up of 30 months (range 2-68 months), 2 patients were free from the disease and 1 was alive with the disease. Six cases died of the disease. Advanced-stage disease was associated with a poor prognosis. Early-stage disease, a well-differentiated histologic type and surgical resection combined with radiotherapy were associated with a favorable result. CONCLUSION: Sinonasal adenocarcinoma has a low incidence in the general population in Taiwan. However, prognosis is poor owing to delayed diagnosis and the consequent advanced stage of the disease.