Endoscopic screening for synchronous esophageal neoplasia among patients with incident head and neck cancer: Prevalence, risk factors, and outcomes.

Esophageal squamous-cell neoplasia (ESCN) is a common second primary neoplasia found in patients with head-and-neck squamous-cell carcinoma (HNSCC). This study sought to identify the risk factors for synchronous ESCN and how they influence survival in HNSCC patient. Eight hundred and fifteen incident HNSCC patients were prospectively recruited for endoscopy screening for ESCN using white-light imaging, narrow-band imaging, Lugol chromoendoscopy, and pathological confirmation. Associated lifestyle and clinicopathological data were collected. The interquartile follow-up period cutoffs were 11.3, 20.5 and 34.9 months. 124 patients (15.2%) were diagnosed as having synchronous ESCN (66 low-grade dysplasia, 29 high-grade dysplasia, and 29 esophageal squamous-cell carcinoma). Consumption of alcohol, but not betel nut or cigarette, was significantly associated with the presence of synchronous ESCN (adjusted odds ratio [aOR] = 7.1 and 10.9 for former and current drinkers, respectively). There was an interaction between cumulative dose of alcohol consumption and alcohol flushing response on the development of ESCN. High-dose drinkers with flush response were 16.9 times more likely to have esophageal high-grade dysplasia/SCC than non-drinkers. Compared with oral cavity cancer patients, those with hypopharyngeal, laryngeal and oropharyngeal cancer were 6.8, 4.6 and 2.8 times more likely to have esophageal high-grade dysplasia/SCC. HNSCC patients with synchronous ESCN had lower overall survival than those without (p < 0.0001). In conclusion, surveillance of ESCN is strongly recommended for the high-risk subpopulation of HNSCC patients, especially drinkers who have a flush response to alcohol, and those with distant metastasis of index cancer and cancers in hypopharynx, oropharynx and larynx.

Head and neck extranodal lymphoma in a single institute: a 17-year retrospective analysis.

The study's purposes are to identify patient characteristics, treatment response and survival rate, and to describe the important prognostic factors for our patients with extranodal head and neck lymphoma. Furthermore, no study has systemically discussed the overall figure of this disease in Taiwan and we analyzed our data on this topic. A retrospective review was performed for 86 patients with extranodal head and neck lymphoma, diagnosed in Kaohsiung Medical University Hospital, between 1990 and 2007. We evaluated the medical records and analyzed the possible factors affecting treatment outcomes, survival rate, and free-from-disease (FFD) survival rate. Forty-nine male and 37 female patients were included with a male:female ratio of 1.32:1. The most frequent histologic type was diffuse large B cell lymphoma, accounting for 41.9% of the total. The most common primary site involved with extranodal head and neck non-Hodgkin's lymphoma was a tonsil with 27 cases (31.4%). Stage, international prognostic index (IPI) score, B symptoms, lactate dehydrogenase (LDH) level, and lymph node status significantly affected treatment response. The overall 5- and 10-year survival rates were 68.0% and 57.8%, respectively. The FFD survival rate was 53.6% and 49.3% at 5 and 10 years, respectively. Factors including stage, lymph node status, LDH level, and IPI score produced significant differences in both overall survival and FFD survival. Our analyzed information is similar to other previously presented studies. Stage, IPI score, B symptoms, LDH level, and neck nodal status can be used to evaluate the treatment outcomes. Neck nodal status and stage are the two significant prognostic factors for overall survival.

Surgical treatment for thyrotoxic hypokalemic periodic paralysis: case report.

Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare, potentially life-threatening endocrine emergency. It is characterized by recurrent muscle weakness and hypokalemia. Because many THPP patients do not have obvious symptoms and signs of hyperthyroidism, misdiagnosis may occur. The published studies revealed that definitive therapy for THPP is control of hyperthyroidism by medical therapy, radioactive iodine or surgery, but the long-term post-operative follow-up result was not observed. We reported two cases of medically refractory THPP with recurrent paralysis of extremities and hypokalemia, and both were combined with thyroid nodules. Both patients were treated with total thyroidectomy; the pathology revealed that one is Graves' disease with thyroid papillary carcinoma, and the other is adenomatous goiter with papillary hyperplasia. No episode of periodic paralysis was noted and laboratory evaluation revealed normal potassium level during the post-operative follow up. Our experience suggests that total thyroidectomy by experienced surgeon is an appropriate and definite treatment for medically refractory THPP, especially in cases combined with thyroid nodules.

Noninfectious painful neck mass mimicking malignancy in a child.

BACKGROUND: A large painful mass on the posterior neck of a child of a relatively short duration is uncommon. Barring infectious origin, differential diagnosis can be difficult without a definitive biopsy. METHODS AND RESULTS: A 12-year-old girl had a markedly painful posterior neck mass and limitation of neck motion without fever for 1 month. The rapid clinical course and poorly defined marginal zone of the CT images led to suspicion of malignancy. Although the initial frozen section suggested low-grade fibrosarcoma, a successful wide excision and paraffin pathology confirmed the diagnosis of myositis ossificans circumscripta (MOC) from the semispinalis capitis muscle. CONCLUSION: The occurrence of MOC in children is rare and may easily be misdiagnosed as soft tissue sarcoma. Both knowledge of the disease and guidelines for taking an aggressive biopsy sample are essential for correct diagnosis and appropriate treatment.

Features of parotid gland diseases and surgical results in southern Taiwan.

Various parotid gland diseases are seen clinically, including inflammation, sialolithiasis, and benign and malignant tumors. It is important to differentiate between these to make a correct diagnosis and for proper management. Here, we investigated the relationship between tumor characteristics and pathology, and considered whether the former could be used to differentiate malignant from benign parotid gland diseases. We retrospectively reviewed the charts and data of 316 patients who underwent surgery in Kaohsiung Medical University Chung-Ho Memorial Hospital from January 1, 1998 to December 31, 2008. Two hundred and eighty-one patients (88.9%) had benign disease, and 35 (11.1%) had malignant disease. The most common benign disease was pleomorphic adenoma (115 cases, 36.4%), but the most common disease in male patients was Warthin's tumor, a finding which, as far as we aware, has not been previously been reported in the literature. The incidence of Warthin's tumor seems to be increasing. In malignant disease, the most common was acinic cell carcinoma (8 cases, 22.9%). Compared with benign disease, malignant parotid gland disease more often presents as a hard, painful, fixed and large mass (> 3 cm), and more often involves the deep lobe of the parotid gland. Partial parotidectomy was adequate for most tumors, including pleomorphic adenoma. The most common postoperative complication was temporary facial palsy, followed by permanent facial palsy. However, there was no difference in transient facial palsy rate between benign and malignant parotid gland disease, although parotid gland cancer had a higher incidence of permanent facial palsy postoperatively.

Predisposing factors of complicated deep neck infections: 12-year experience at a single institution.

OBJECTIVES: To review our experience with deep neck infections and identify the risk factors for developing complications and prolonged hospitalization. SUBJECTS AND METHODS: We analyzed the prospectively collected database of 439 patients with deep neck infections between January 1996 and July 2007 at a single institution. Their demographic data, duration of hospitalization, etiology, underlying systemic disease, bacteriologic and radiologic studies, complications, and treatment outcome were reviewed and analyzed. Patients with superficial abscess or cellulitis, necrotizing fasciitis, and peritonsillar abscess were excluded. RESULTS: Dental infection and upper airway infection remained the two most common etiologies. Coexisting head and neck malignancy was found in eight cases. Patients with systemic diseases and a C-reactive protein value of more than 100 microg/mL tend to develop complications, resulting in prolonged hospitalization. CONCLUSION: We should pay more attention to those patients with systemic diseases or C-reactive protein values more than 100 microg/mL. The current study represents the largest and longest analysis of deep neck infection in the available literature.

Influence of nondepolarizing muscle relaxants on intraoperative neuromonitoring during thyroid surgery.

OBJECTIVE: The objective of this study was to find a nondepolarizing muscle relaxant to replace succinylcholine during thyroid surgery with intraoperative neuromonitoring (IONM) because succinylcholine can cause severe adverse effects. DESIGN: Prospective study of 232 patients undergoing thyroidectomies. SETTING: A tertiary medical centre. METHODS: One hundred thirty-one patients received 0.5 mg/kg rocuronium (group R) and 101 patients received 0.5 mg/kg atracurium (group A) to facilitate electromyographic (EMG) endotracheal tube insertion. EMG signals were obtained from the vagus nerve before and after dissection of the recurrent laryngeal nerve and were defined as the V1 and the V2 signal, respectively. Accelerometry (twitch [% TW]) was used to monitor the quantitative degree of neuromuscular transmission at the adductor pollicis muscle. MAIN OUTCOME MEASURES: The amplitude (muV) of the V1 and V2 signals and the correlated degree of neuromuscular transmission (% TW). RESULTS: V1 and V2 signals were obtained from all patients successfully. The % TW at the V1 signal was significantly lower than that at the V2 signal in group R and group A. The mean recovery time from complete neuromuscular blockade to the initial twitch was 43.9 +/- 11 minutes. Only in the subgroup in which the correlated TW was 0% while eliciting the V1 signal were the amplitudes of the V1 signals significantly lower than those of the V2 signal in both groups. CONCLUSIONS: A single dose (0.5 mg/kg) of rocuronium and atracurium was feasible for IONM during thyroid surgery. This study showed that 44 minutes after administration of these two muscle relaxants is adequate for eliciting an EMG signal from the vagus nerve.

Matrix metalloproteinase-9 gene polymorphisms in nasal polyposis.

BACKGROUND: Matrix metalloproteinase (MMP) is involved in the upper airway remodeling process. We hypothesized that genetic variants of the MMP-9 gene are associated with cases of chronic rhinosinusitis with nasal polyposis. METHODS: We conducted a case-control study where 203 cases of chronic rhinosinusitis with nasal polyposis and 730 controls were enrolled. Three tagging single nucleotide polymorphisms (SNPs) and one promoter functional SNP rs3918242 were selected. Hardy-Weinberg equilibrium (HWE) was tested for each SNP, and genetic effects were evaluated according to three inheritance modes. Haplotype analysis was also performed. Permutation was used to adjust for multiple testing. RESULTS: All four SNPs were in HWE. The T allele of promoter SNP rs3918242 was associated with chronic rhinosinusitis with nasal polyposis under the dominant (nominal p = 0.023, empirical p = 0.022, OR = 1.62) and additive models (nominal p= 0.012, empirical p = 0.011, OR = 1.60). The A allele of rs2274756 has a nominal p value of 0.034 under the dominant model and 0.020 under the additive model. Haplotype analysis including the four SNPs showed a global p value of 0.015 and the most significant haplotype had a p value of 0.0045. We did not see any SNP that was more significant in the recurrent cases. CONCLUSIONS: We concluded that MMP-9 gene polymorphisms may influence susceptibility to the development of chronic rhinosinusitis with nasal polyposis in Chinese population.

Investigation of optimal intensity and safety of electrical nerve stimulation during intraoperative neuromonitoring of the recurrent laryngeal nerve: a prospective porcine model.

BACKGROUND: Intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) has recently been more frequently applied in thyroid surgery. However, concerns have been raised regarding the safety and optimal intensity of electrical nerve stimulation. METHODS: Eight piglets were enrolled, and electrically evoked electromyography (EMG) was recorded from the vocalis muscles via endotracheal surface electrodes. The baseline EMG was measured and continuous pulsatile stimulations were performed on the vagus nerve and RLN for 10 minutes. Changes of EMG waveform and cardiopulmonary status were analyzed. RESULTS: A dose-response curve existed with increasing EMG amplitude as stimulating current was increased, with maximum amplitude elicited on vagal and RLN stimulation at <1 mA. No obvious EMG changes and untoward cardiopulmonary effects were observed after the stimulation. CONCLUSIONS: Electrical stimulation is safe during IONM in this porcine model. Minimal current that required generating the maximal evoked EMG, approximately 1 mA in this study, can be selected to minimize the risk of nerve damage and cardiopulmonary effects.

Standardization of intraoperative neuromonitoring of recurrent laryngeal nerve in thyroid operation.

BACKGROUND: The lack of standardized procedures of intraoperative neuromonitoring (IONM) during thyroid operations may lead to highly variable results, and many of these results can cause misleading information and, conversely, increase the risk of recurrent laryngeal nerve (RLN) injury. Therefore, standardization of IONM procedures is necessary. METHODS: A total of 289 patients (435 nerves at risk) who underwent thyroidectomy by the same surgeon were enrolled in this study. Each patient was intubated with EMG endotracheal tube by the same anesthesiologist. Standardized IONM procedures were applied in each patient. The procedures include preoperative and postoperative video-recording of vocal cord movement, ensuring the correct position of electrodes after the neck was placed at full extension, vagal stimulation and registration of EMG signals before and after RLN dissection, and photographic documentation of the exposed RLN. RESULTS: Five patients encountered dysfunction of IONM, which was caused by malposition of electrodes and the problem was detected at once. One patient with non-RLN was detected at the earlier stage of operation. Eighteen nerves experienced loss of EMG signals during thyroid dissection, and the causes of nerve injuries were well elucidated with the application of our standardized IONM procedures. CONCLUSIONS: The standardized IONM procedures are useful and helpful not only to eliminate false IONM results, but also to elucidate the mechanism of RLN injury. After ascertaining the surgical pitfalls and improving the surgical techniques, the palsy rate was significantly reduced in this study.

The role of neck ultrasonography in thyroid cancer.

PURPOSE: The aim of this study was to assess the diagnosis accuracy rate of neck ultrasonography (US) characteristics in thyroid cancer. MATERIALS AND METHODS: A retrospective study of patients who underwent thyroid surgery for palpable thyroid nodules at the department of Otolaryngology Head and Neck surgery, Kaohsiung Medical University Hospital, Taiwan. RESULTS: Between January 1993 and December 2006, 378 patients with palpable thyroid nodules underwent thyroid total lobectomy or total thyroidectomy. Preoperation evaluations included neck US, ultrasound-guided fine-needle aspiration cytology (USGFNA) and technetium-99m scintigraphy. Postoperative histopathology revealed 297 are benign and 81 are malignant. Comparing preoperative surveys with postoperative histopathology, the outcome analyses included the sensitivity, specificity, accuracy rate, positive predictive value and negative predictive value. The sensitivity of US, USGFNA, and technetium-99m scintigraphy were, respectively, 51.9%, 75.0%, and 73.8%; the specificity were, respectively, 93.9%, 94.6%, and 25.3%; the accuracy rate were, respectively, 86.8%, 90.8%, and 35.0%; positive predictive value were, respectively, 63.6%, 76.9%, and 19.8%; negative predictive value were, respectively, 90.5%, 94.1%, and 79.5%. CONCLUSIONS: The neck US is a useful method in the evaluation of thyroid nodules, and the US characteristics can be used to distinguish the risk of malignant thyroid nodules. We recommend neck US in all patients with thyroid nodules, and if any malignant characteristics were noted, USGFNA can be arranged.

Feasibility of intraoperative neuromonitoring during thyroid surgery after administration of nondepolarizing neuromuscular blocking agents.

BACKGROUND: A short-acting depolarizing neuromuscular blocking agent (NMBA), succinylcholine, has been utilized for thyroid operations with intraoperative neuromonitoring (IONM). Because of its potential to cause serious side effects, this prospective study tried to determine the feasibility of IONM after administration of a nondepolarizing NMBA during thyroid operations. METHODS: Complete IONM data for 179 patients who had normal cord mobility were investigated: 90 patients received an induction dose of rocuronium (group R) and 89 received atracurium (group A). Electromyography signals were obtained from the vagus nerve before and after resection of the thyroid lobe and were defined as V(1) and V(2) signals, respectively. Accelerometry (percent twitch) was used to monitor the quantitative degree of neuromuscular blockade. RESULTS: V(1) and V(2) signals were obtained successfully in all patients. The percent twitch at the V(1) signal was significantly lower than that at the V(2) signal in both groups (39% +/- 20% vs. 69% +/- 26% in group R; 35% +/- 28% vs. 56% +/- 35 % in group A; both p < 0.01). However, the magnitude of the V(1) and V(2) signals did not differ significantly in either in group (473.8 +/- 290.8 microV vs. 528 +/- 316.2 microV in group R; 584.8 +/- 394.3 microV vs. 637.8 +/- 458.2 microV in group A; both p > 0.05). CONCLUSIONS: A single dose of either rocuronium or atracurium was feasible for IONM during thyroid surgery and provided adequate muscle relaxation for tracheal intubation.

Glutathione peroxidase 3 gene polymorphisms and risk of differentiated thyroid cancer.

BACKGROUND: The antioxidant enzyme glutathione peroxidase 3 (GPX3) can lessen the oxidative stress in the thyroid gland. We tested for the association between tagging single nucleotide polymorphisms (tSNPs) of the GPX3 gene and the risk of differentiated thyroid cancer (DTC). METHODS: A total of 6 tSNPs (rs3763013, rs8177412, rs3805435, rs3828599, rs3792796, and rs2070593) of GPX3 were genotyped in Chinese DTC cases (n = 268) and controls (n = 378). Multivariate logistic regression was performed to estimate the genetic effect with adjustment for age and sex. RESULTS: There was no significant finding of genotype analysis in each tSNP associated with DTC, papillary thyroid carcinoma, or patients with regional lymph node metastasis. In the older group (age > or =45 years), subjects who carried at least 1 G allele of rs3805435 had a decreased risk of DTC compared with patients of AA homozygote (sex- and age-adjusted odds ratio [OR] = 0.50, P = .009). An individual with at least 1 T allele of rs3828599 had a decreased risk of DTC compared with an individual of the CC homozygote (sex- and age-adjusted OR = 0.53, P = .018). An individual carrying the TC genotype of rs8177412 in the older group had an increased risk of DTC than controls (sex- and age-adjusted OR = 1.73, P = .037). CONCLUSION: We found that the G allele of rs3805435 or the T allele of rs3828599 may exert a protective effect for DTC in the older population, whereas the C allele of rs8177412 confers an increased risk effect for DTC.

Huge sphenoid sinus olfactory neuroblastoma: a case report.

Intranasal or paranasal sinus olfactory neuroblastoma is a rare malignant neoplasm of olfactory neuroepithelial origin, accounting for approximately 5% of paranasal sinus cancers. Most of the presenting symptoms include nasal obstruction, nasal bleeding, anosmia, rhinorrhea, and headache. In this present report, we describe a 79-year-old man who presented with bilateral nasal congestion for more than 1 year. Nasoendoscopy showed a huge, smooth, mucosal tumor in the nasopharynx with extension to the posterior nasal septum. The tumor was completely resected under endonasal endoscopy and the pathology revealed olfactory neuroblastoma. Olfactory neuroblastomas usually arise in the cribriform plate and superior turbinate. However, the origin and isolation of olfactory neuroblastomas to the sphenoid sinus is exceedingly rare. Only four cases of olfactory neuroblastoma isolated in the sphenoid sinus have been described in English literature and the frequency of presenting symptoms with cranial neuropathies and headache. We report a case of primary sphenoid sinus olfactory neuroblastoma with the greatest enlargement reported to date.

Association between polymorphisms in DNA base excision repair genes XRCC1, APE1, and ADPRT and differentiated thyroid carcinoma.

PURPOSE: DNA BER pathway is related with carcinogenesis. We hypothesized that functional polymorphisms of three BER genes, XRCC1, apurinic/apyrimidinic endonuclease (APE1), and ADPRT, confer risks for DTC and its progression. EXPERIMENTAL DESIGN: Five common nonsynonymous single nucleotide polymorphisms (Arg194Trp, Arg280His, and Arg399Gln for XRCC1; Asp148Glu for APE1; and Val762Ala for ADPRT) were genotyped in Chinese DTC cases and controls. RESULTS: The XRCC1-194Trp/Trp genotype showed a significantly increased risk for DTC (odds ratio, 1.85; 95% confidence interval, 1.11-3.07; P = 0.018). Subset analysis based on regional LN metastasis showed that the genetic effect came primarily from the subjects with LN metastasis (odds ratio, 4.54; 95% confidence interval, 2.11-9.79; P = 0.0001), but no significant association for subjects without LN metastasis. The other four single nucleotide polymorphisms did not show significant results. Haplotype analysis of XRCC1 polymorphisms yielded a significant result (P = 0.004), especially in the subjects with LN metastasis (P = 0.0002). Moreover, we found that XRCC1-194Trp and ADPRT-762Ala variants collectively contributed to an increased risk of the disease and LN metastasis, with the combined variant homozygotes exhibiting the highest 3.18-fold risk for DTC (P = 0.046) and 9.25-fold risk for DTC with LN metastasis (P = 0.004). CONCLUSIONS: The XRCC1 polymorphisms, especially the 194Trp allele, may have an effect on DTC development and progression. This variant can interact with ADPRT-762Ala variant to further substantially increase susceptibility to the disease and regional LN metastasis. Identifying these risk genetic markers could provide more insight into the DTC pathogenesis and may also provide information to develop better prevention and therapeutic strategies.

Matrix metalloproteinase-2 gene polymorphisms in nasal polyps.

OBJECTIVE: To systematically investigate the role of matrix metalloproteinase-2 (MMP2) tagging single nucleotide polymorphisms (SNPs) and promoter functional polymorphism in the development of nasal polyps in a Chinese population in Taiwan. DESIGN: We conducted a case-control study in 136 cases of chronic rhinosinusitis with bilateral nasal polyps and 136 controls. Seventeen SNPs were selected, including 16 tagging SNPs and 1 promoter functional SNP. The genotypes were determined by TaqMan technology. Hardy-Weinberg equilibrium was tested for each SNP, and genetic effects were evaluated according to 3 modes of inheritance. Subset analysis based on the recurrence of nasal polyps was also performed. SETTING: Medical university center hospital. RESULTS: All 17 SNPs were in Hardy-Weinberg equilibrium. When comparing the patients with recurrent nasal polyps and controls, none of the SNPs reached the significant level of P < .05 except rs857403. The AT genotype of rs857403 had an adjusted odds ratio of 2.07 (95% confidence interval, 1.09-3.95) (P = .03). However, the result became nonsignificant after including an additional 691 controls. Therefore, we considered that the initial significance was a false-positive finding. Neither haplotype analysis nor subset analysis yielded any significant result. CONCLUSION: The MMP2 gene does not play a crucial role in conferring risk for nasal polyps in a Taiwanese population.

Arecoline, a major alkaloid of areca nut, inhibits p53, represses DNA repair, and triggers DNA damage response in human epithelial cells.

The International Agency for Research on Cancer declared that areca nut was carcinogenic to human. Areca nut is the main component of betel quid (BQ), which is commonly consumed in Asia. Epidemiological studies have shown that BQ chewing is a predominant risk factor for oral and pharyngeal cancers. It has been known that areca nut is genotoxic to human epithelial cells. However, the molecular and cellular mechanisms underlying areca nut-associated genotoxicity are not fully understood. Here we showed that arecoline, a major alkaloid of areca nut, might contribute to oral carcinogenesis through inhibiting p53 and DNA repair. We found, on the biological aspect, that arecoline could induce gamma-H2AX phosphorylation, a sensitive DNA damage marker, in KB, HEp-2, and 293 cells, suggesting that DNA damages were elicited by arecoline. This phenomenon was supported by the observations of arecoline-induced hyperphosphorylation of ATM, Nbs1, Chk1/2, p53, and Cdc25C, as well as G2/M cell cycle arrest, indicating that a cellular DNA damage response was activated. To explore the possible mechanism accounting for arecoline-elicited DNA damages, we found that arecoline could inhibit p53 by its expression and transactivation function. As a result, the expression of p53-regulated p21(WAF1) and the p53-activated DNA repair were repressed by arecoline. Finally, we showed that p53 mRNA transcripts were frequently down-regulated in BQ-associated oral cancer, suggesting that arecoline-mediated p53 inhibition might play a role in BQ-associated tumorigenesis.

Expression of hypoxia-inducible factor 1alpha in the nasal polyps by real-time RT-PCR and immunohistochemistry.

OBJECTIVE: Hypoxia may result in increased recruitment of inflammatory cells and release of various inflammatory cytokines. Local hypoxia within the sinus is believed to aggravate sinus inflammation. In this study, we tried to investigate the correlation of hypoxia-inducible factor, which is upregulated under hypoxic condition, and nasal polyposis. SUBJECTS AND METHODS: Forty-four polyps from patients undergoing endoscopic sinus surgery and 38 inferior turbinate mucosa were obtained for immunohistochemical staining. Twenty-three polyps and 22 turbinate mucosa also underwent real-time reverse transcription-polymerase chain reaction for quantification of messenger RNA (mRNA). The severity of the disease was judged by the Lund-Mackay CT scoring. RESULTS: Expression of hypoxia-inducible factor protein, but not mRNA, was significantly increased in nasal polyps compared with that in the turbinate mucosa, but it did not correlate with the disease severity. CONCLUSION: We suggest that hypoxia may have a role in the initiation of nasal polyposis.

The mechanism of recurrent laryngeal nerve injury during thyroid surgery--the application of intraoperative neuromonitoring.

BACKGROUND: Identification of recurrent laryngeal nerve (RLN) has decreased the rates of permanent RLN palsy during thyroid operations; however, unexpected RLN palsy still occurs, even though the visual integrity was assured and most nerve injuries were not recognized intraoperatively. The aim of this study is to determine the causes of RLN palsy and to identify potentially reversible causes of RLN injury during the operation with the application of intraoperative neuromonitoring (IONM). METHODS: One hundred and thirteen patients with 173 nerves at risk were enrolled in this study. All operations were performed by the same surgeon. The 4-step procedure of IONM was designed to obtain electromagnetic (EMG) signals from the vagus nerve and RLN before and after resection of thyroid lobe. RESULTS: Sixteen nerves had loss of EMG signals after thyroid dissection, and the causes of nerve injuries were well elucidated with the application of IONM. One nerve injury was caused by inadvertent transection, which led to permanent RLN palsy. Among the remaining 15 nerves, 1 injury was caused by a constricting band of connective tissue, which was detected precisely and released intraoperatively, 2 by inadvertent clamping of the nerve, and 12 by apparent overstretching at the region of Berry's ligament. (Five nerves regained signals before closing the wound, but 1 showed impaired cord movement. Another 7 nerves did not regain signals before closing the wound, and all developed temporary RLN palsy.) CONCLUSIONS: Our 4-step procedure of IONM is useful and helpful in elucidating the potential operative pitfalls during dissection near the RLN. Although the rates of RLN palsy were not decreased in this study, the use of neuromonitoring provided instructive information for future operations by ascertaining where and how the RLN has been injured.