Research Application of Laser-induced Shock Wave for Studying Blast-induced Cochlear Injury.

The ear is the organ most susceptible to explosion overpressure, and cochlear injuries frequently occur after blast exposure. Blast exposure can lead to sensorineural hearing loss (SNHL), which is an irreversible hearing loss that negatively affects the quality of life. Detailed blast-induced cochlear pathologies, such as the loss of hair cells, spiral ganglion neurons, cochlear synapses, and disruption of stereocilia, have been previously documented. However, determining cochlear sensorineural deterioration after a blast injury is challenging because animals exposed to blast overpressure usually experience tympanic membrane perforation (TMP), which causes concurrent conductive hearing loss. To evaluate pure sensorineural cochlear dysfunction, we developed an experimental animal model of blast-induced cochlear injury using a laser-induced shock wave. This method avoids TMP and concomitant systemic injuries and reproduces the functional decline in the SNHL component in an energy-dependent manner after LISW exposure. This animal model could be a platform for elucidating the pathological mechanisms and exploring potential treatments for blast-induced cochlear dysfunction.

Evaluation of chronological changes in videofluorographic findings after transoral videolaryngoscopic surgery to reveal mechanism of dysphagia.

OBJECTIVES: Transoral surgery preserves good swallowing function in most cases, however, postoperative dysphagia sometimes leads to fatal complication such as aspiration pneumonia. We investigated the chronological changes in swallowing function have not been revealed relationship with dysphagia. The primary aim of this study was to reveal the mechanism of dysphagia following transoral surgery by analyzing chronological videofluorography (VF) findings. Moreover, the secondary aim of this study was to evaluate the relationship between mechanism of dysphagia and risk factors of patients to clarify the risk for dysphagia lead to prevention of postoperative complications. METHODS: 22 patients who underwent transoral videolaryngoscopic surgery (TOVS) for either supraglottic or hypopharyngeal cancer were evaluated swallowing function. We performed VF during the preoperative, postoperative acute, and stable phases and investigated the chronological changes in the VF findings. The following parameters were evaluated by VF: horizontal distance of laryngeal movement, vertical distance of laryngeal elevation, laryngeal elevation delay time (LEDT), Bolus Residue Scale (BRS) scores, and Penetration Aspiration Scale (PAS) scores. Additionally, we evaluated risk factors for postoperative aspiration by investigating relationships between preoperative VF parameters, age of patients, history of radiation therapy, resection area, tumor (T) stage, postoperative Numeric Rating Scale (NRS), and PAS and BRS scores. RESULTS: The median time at which oral feeding was resumed in this study was 9 (2-200) days. The patients who had postoperative acute PAS scores of 4 and above exhibited delays in resuming oral ingestion after surgery. TOVS did not impair laryngeal elevation and LEDT; however, the BRS and PAS scores temporarily worsened in the acute phase compared to the preoperative scores. These scores almost recovered to their preoperative states in the stable phase, and both the BRS and PAS scores worsened and recovered concurrently. Patients who exhibited poor vertical distance in laryngeal elevation as observed via preoperative VF or who had histories of radiation therapy had worse PAS scores in postoperative acute phase VF. Patients with broad resection areas had worse BRS scores in postoperative acute phase VF. CONCLUSION: TOVS didn't impair the function of laryngeal elevation and elicitation of the swallowing reflex whereas pharyngeal bolus clearance, laryngeal penetration, and aspiration temporarily deteriorated concurrently but eventually almost recovered to their baseline values. Patients with histories of radiotherapy, poor laryngeal elevation, and broad resection areas are at the risk of postoperative dysphagia after TOVS. Patients with these risk factors need appropriate evaluation before resuming postoperative oral intake.

The Effect of the Status of the Ossicular Chain and Choice of Graft Material on Hearing Outcomes in Pediatric Cholesteatoma Surgery.

OBJECTIVE: Compare hearing benefit of incus preservation in primary cholesteatoma surgery versus cartilage-myringostapediopexy. METHODS: Prospective cohort study in a tertiary referral center. Tympanoplasty utilizing cartilage or other grafts, with or without intact incus was performed in 195 ears (187 children) with intact stapes. Outcome measures were pre and post-operative four-tone air conduction (AC) threshold (0.5, 1, 2, 4 kHz) and proportion with normal hearing (AC ≤ 30 dB HL) at 12 months. RESULTS: Ears with intact ossicles had better post-operative AC thresholds than those with incus eroded or removed (median 20 dB HL vs. 30 dB HL, Mann-Whitney P < .001). The normal hearing rate was 81/106 (74%) with intact incus and 46/89 (52%) without (Fisher's exact P = .001). Ears without intact incus and a cartilage-myringostapediopexy had better post-operative thresholds than those with a non-cartilage graft (28.8 dB HL vs. 36.3 dB HL, Mann-Whitney P = .005). Of ears without intact incus, 37/59 (63%) with a cartilage-myringostapediopexy and 9/30 (30%) with a non-cartilage graft had normal hearing post-operatively (Fisher's exact P = .007). By preserving the incus in 12 ears, 1 more ear would have normal hearing than with incus removal plus cartilage-myringostapediopexy (NNT = 12 (CI 3.6-); Fisher's exact = 0.1). CONCLUSION: Preserving an intact ossicular chain conveys a small but significant hearing benefit in cholesteatoma surgery, the magnitude of which should be considered before deciding to remove the intact incus. Cartilage-myringostapediopexy provides a significant gain in hearing when the incus is absent, even without a partial ossicular replacement prosthesis.

Patency of Anterior Epitympanic Space and Surgical Outcomes After Endoscopic Ear Surgery for the Attic Cholesteatoma.

OBJECTIVE: To reveal the patency of the anterior epitympanic space (AES) and the surgical outcomes after transcanal endoscopic ear surgery (TEES) for attic cholesteatoma with a classification of anatomical variation of the AES. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Seventy-four ears (72 patients with early-stage (I or II) attic cholesteatoma) aged between 16 and 85 years (mean: 48.9 yr) who underwent TEES between 2015 and 2017 were analyzed. INTERVENTION: Tympanoplasty with atticoantrotomy was performed with TEES. TEES was performed using a rigid endoscope with an outer diameter of 2.7 mm. MAIN OUTCOME MEASURE: The tensor fold in the AES anatomical classification, the postoperative patency of the AES evaluated by computer tomography images, and hearing outcomes based on the American Academy of Otolaryngology and Head and Neck Surgery criteria were evaluated after TEES for early-stage attic cholesteatoma. RESULTS: There were 14 (18.9%) ears with a vertical tensor fold orientation, 29 (39.2%) ears with an oblique orientation, and 29 (39.2%) ears with a horizontal orientation. The total postoperative patency rate in the AES was 81.0%, without any significant difference in the anatomical variation in the AES, whereas the rate of preoperative complete tensor fold was 90.5%. Cholesteatoma recurrence was observed in three cases (4.1%), and all recurrent cases had obstructed AES. No significant difference was found in the postoperative air-bone gap regardless of the patency of the AES. CONCLUSION: Our findings indicate that TEES is useful in restoring ventilation in the AES, resulting in favorable management of cholesteatoma.

Effect of shock wave power spectrum on the inner ear pathophysiology in blast-induced hearing loss.

Blast exposure can induce various types of hearing impairment, including permanent hearing loss, tinnitus, and hyperacusis. Herein, we conducted a detailed investigation of the cochlear pathophysiology in blast-induced hearing loss in mice using two blasts with different characteristics: a low-frequency dominant blast generated by a shock tube and a high-frequency dominant shock wave generated by laser irradiation (laser-induced shock wave). The pattern of sensorineural hearing loss (SNHL) was low-frequency- and high-frequency-dominant in response to the low- and high-frequency blasts, respectively. Pathological examination revealed that cochlear synaptopathy was the most frequent cochlear pathology after blast exposure, which involved synapse loss in the inner hair cells without hair cell loss, depending on the power spectrum of the blast. This pathological change completely reflected the physiological analysis of wave I amplitude using auditory brainstem responses. Stereociliary bundle disruption in the outer hair cells was also dependent on the blast's power spectrum. Therefore, we demonstrated that the dominant frequency of the blast power spectrum was the principal factor determining the region of cochlear damage. We believe that the presenting models would be valuable both in blast research and the investigation of various types of hearing loss whose pathogenesis involves cochlear synaptopathy.

Scar contracture prevention with local steroid injections in transoral videolaryngoscopic surgery.

OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of local steroid injections to prevent scar contracture after transoral videolaryngoscopic surgery (TOVS) in hypopharyngeal cancer patients. METHODS: Patients were enrolled in this study if they had received a local steroid injection during TOVS and had attended an outpatient clinic after at least three months. All patients were being treated for hypopharyngeal cancer and received a single session of triamcinolone acetonide, injected using a 21-gage needle. Retrospective chart reviews were performed, and the degree of scar contracture, pharyngeal stenosis, vocal fold movements, and adverse events were evaluated. Scar contracture was assessed using a scoring system, which compared the endoscopic findings of treatment and matched pair control groups. RESULTS: A total of 20 patients received local steroid injections during TOVS and were enrolled in the treatment. Scar contracture was seen in 14 patients (70%); however, the degree of scar contracture was significantly decreased when compared to control cases. Vocal fold immobility was observed in five patients, but no pharyngeal stenosis was noted. Adverse effects, such as postoperative laryngeal chondritis or cervical spondylitis, were seen in three patients who had previously been treated with resection to the muscularis propria or definitive irradiation. CONCLUSION: Local steroid injection during TOVS significantly reduced the degree of postoperative scar contracture. However, caution should be used when treating with local steroid injection during TOVS, as this may complicate wound healing in patients who have already received treatment.

Transoral videolaryngoscopic surgery for laryngeal and hypopharyngeal cancer - Technical updates and long-term results.

OBJECTIVE: Transoral videolaryngoscopic surgery (TOVS) was developed as a non-robotic procedure for en bloc laryngo-hypopharyngeal cancer resection. Straight devices had been used for this procedure, however, some cases had difficulty to reach the lesions especially in hypopharyngeal area. To overcome this problem, technical updates to facilitate transoral manipulation were developed and long term oncological and functional results were analyzed. METHODS: Surgical indications were Tis, T1, T2 and selected T3 cases. In advanced T3 or T4 lesions, neoadjuvant chemotherapy was performed before surgery. Radiation failure cases (rT1 and rT2) were also indicated for TOVS. Resectable nodal involvement can be managed by combination of neck dissection. Ninety hypopharyngeal and 25 supraglottic cancer cases were retrospectively reviewed for survival analyses. In fresh hypopharyngeal cancer, 51 Stage 0-II disease and 32 Stage III-IV disease were included. In supraglottic cancer, 11 Stage I-II disease and 9 Stage III-IV disease were included. Twelve radiation failure cases were analyzed separately. As new devices, malleable forceps and malleable suction coagulator were introduced to reach the whole laryngo-hypopharynx. New curved blades for the FKWO retractor were developed and these were applied for difficult hypopharyngeal exposure cases by conventional blades. Swallowing functional outcome and risk factors for postoperative dysphagia were evaluated by univariate analysis. RESULTS: The 5-year overall survival, disease-specific survival and larynx preservation rate of fresh hypopharyngeal cancer cases were 83.2%, 94.3% and 94.6%, respectively. Those of supraglottic cancer cases were 80%, 95% and 94.7%, respectively. Those of salvage cases were 87.5%, 87.5% and 82.5%, respectively. Those of T3 and T4 hypopharyngeal cancer treated by neoadjuvant chemotherapy with TOVS were 75.0%, 82.5% and 100% respectively. Surgical complication included bleeding (2.6%) and emergency tracheostomy (3.4%). Oral intake was maintained in 94.8% cases. By univariate analysis, patient's age (especially 80 years of age or older), larger resected area, arytenoid resection and tracheostomy were regarded as risk factors for postoperative dysphagia. Among 31 recent cases, 5 cases had difficulty in exposing hypopharyngeal lesions by conventional blades. These exposure problems were solved by curved blades. CONCLUSION: Using malleable devices and new curved blades for the FKWO retractor, exposure problems in the hypopharynx could be solved and TOVS could be applied in more cases. Although oncological outcomes and functional outcomes were good, patients with risk factors for dysphagia should be carefully indicated.

Feasibility of transnasal flexible carbon dioxide laser surgery for laryngopharyngeal lesions.

OBJECTIVE: The fiber-guided carbon dioxide (CO2) laser is a useful device for laryngopharyngeal surgery. The flexible CO2 wave-guide laser has been developed and commercially available for several years. However, the transnasal use of CO2 flexible wave-guided laser surgery through the instrument channel of a flexible endoscope (CO2 TNFLS) is not permitted in Japan. This feasibility study aimed to assess the value and the safety of an in-office CO2 TNFLS procedure. METHODS: Patients with small laryngopharyngeal diseases were enrolled from June 2015. Eligible patients had indications with lesions generally localized superficial lesions such as the benign tumor, leukoplakia, and premalignant lesion-like carcinoma in situ (CIS). Patients were locally well anesthetized using xylocaine. After removing as much of the lesion(s) as possible with flexible forceps, the remainder of the lesions were evaporated using CO2 TNFLS through the instrument channel of a flexible endoscope under local anesthesia. RESULTS: Eighteen surgeries involving 13 patients, including 9 papilloma (7 recurrent respiratory papilloma [RRP]), 2 carcinoma in situ, 1 leukoplakia, and 1 large epiglottic cyst), were performed. Four patients with RRP required multiple surgeries. Except for 3 patients with RRP, all patients achieved disease control without additional intervention. All procedures were completed with no severe adverse events. CONCLUSION: Office-based CO2 TNFLS is safe and feasible for patients with laryngopharyngeal pathologies. It is especially valuable for RRP patients with small lesions to avoid surgery under general anesthesia.

Sentinel Lymph Node-Targeted Therapy by Oncolytic Sendai Virus Suppresses Micrometastasis of Head and Neck Squamous Cell Carcinoma in an Orthotopic Nude Mouse Model.

In clinical N0 (cN0) cases with head and neck squamous cell carcinoma (HNSCC), a treatment selection is still controversial: elective neck dissection or watchful waiting. We focused on sentinel lymph node (SLN)-targeted therapy using the urokinase-type plasminogen activator (uPA)-dependent oncolytic Sendai virus "BioKnife." The objectives of this study were to investigate BioKnife migration into SLNs and elucidate its antitumor effect on lymph node metastases (LNM). We established an orthotopic nude mouse model of HNSCC, with LNM being frequently induced. We inoculated HSC-3-M3, human highly metastatic tongue squamous cell carcinoma cells, in the tongue of the nude mice, and after 2 weeks, we injected BioKnife into the primary tumor. We tracked BioKnife migration into the SLNs by immunostaining, RT-PCR, and an in vivo imaging system. We also examined its antitumor effects and mechanisms through serial section analysis of lymph nodes. GFP reporter expression was clearly visible in the lymph nodes of virus groups, which corresponded to SLNs. Relative GFP mRNA was significantly increased in both the tongues and lymph nodes in the virus groups compared with that in the control group (P < 0.05). Serial section analysis showed that BioKnife infected cancer cells and exhibited significant antitumor effect against LNM compared with the control groups (P < 0.05). We detected apoptosis in LNM infected by BioKnife. BioKnife migrated into SLNs after its injection into the primary tumor and effectively suppressed LNM, suggesting that SLN-targeted therapy using BioKnife has great potential to provide a novel and promising alternative to elective neck dissection in cN0 patients with HNSCC.