Wen-Rei Kuo

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 Berrys 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.

Standardization of Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve in Thyroid Operation

BackgroundThe 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.MethodsA 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.ResultsFive 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.ConclusionsThe 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.

Different impact from betel quid, alcohol and cigarette: risk factors for pharyngeal and laryngeal cancer.

The risks of betel quid chewing with or without tobacco, alcohol drinking and cigarette smoking have been well explored in the oral cavity but not in the pharynx and larynx. We conducted a case‐control study to investigate the association of these three risk factors to cancers of the pharynx and larynx in Taiwan. A total cases of 148 pharyngeal cancer, 128 laryngeal cancer and 255 hospital controls, all men, were recruited. Betel quid chewing was a significant independent risk factor (adjusted odds ratio [aOR] = 7.7; 95% confidence interval [CI] = 4.1–15.0) similar to that of alcohol drinking (aOR = 6.6; 95% CI = 3.5–13.0) for pharyngeal cancer, but not for laryngeal cancer (aOR = 1.3; 95% CI = 0.7–2.5) on which cigarette smoking (aOR = 7.1) exerts a stronger significant independent risk than alcohol drinking (aOR = 3.8). For pharyngeal cancers, chewers who consumed >20 quid/day, chewed with inflorescence in the quid or swallowed the betel quid juice were at higher risks; significant dose‐response effects were found in daily quantity of drinking and chewing, and cumulative quantity of drinking. Synergistic effects from the 3 risk factors existed both on the pharynx (aOR = 96.9) and the larynx (aOR = 40.3), and attributed for 93.1% and 92.9% respectively. Our study is the first evidence to show that betel quid chewing without tobacco has different impact on the pharynx (digestive tract) and the larynx (airway), and supports the concept that exposure quantity and direct mucosal contact with the betel quid juice may contribute to carcinogenesis. Our results show an important insight into the impact of betel quid chewing on other sites of the digestive tract other than the oral cavity.

Interaction between cigarette, alcohol and betel nut use on esophageal cancer risk in Taiwan

Objective  In 2003 esophageal cancer was the sixth leading cause of death among men in Taiwan, but it is the fastest increasing (70%) alimentary tract cancer. The aim of this study was to investigate the impact of different habits of betel nut chewing on esophageal squamous cell carcinoma (SCC) and its interaction with cigarette use and alcohol consumption.

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.

The Efficacy of Intraoperative Corticosteroids in Recurrent Laryngeal Nerve Palsy after Thyroid Surgery

BackgroundRecurrent laryngeal nerve palsy (RLNP) is one of the most common complications after thyroidectomy. We aim to evaluate the role of intraoperative corticosteroids in preventing or treating postoperative RLNP.Materials and MethodsWe conducted a prospective study of 295 patients who underwent either total lobectomy or total thyroidectomy with or without using intraoperative corticosteroids. All cases were operated on by the same surgeon. Measurement of the RLNP rate was based on the number of nerves at risk. Data were analyzed for differences in postoperative temporary or permanent RLNP rate and recovery days.ResultThe rate of temporary/permanent RLNP was 5.7% (11 out of 194)/0.52% (1 out of 194) and 6.9% (12 out of 173)/0.58% (1 out of 173) according to groups with and without corticosteroids. This difference did not reach statistical significance. Among those 23 patients who recovered from RLNP, the mean time to recovery was significantly shorter for patients receiving intraoperative steroids (28.6 vs. 40.5 days, P = 0.045).ConclusionA single dose of intraoperative corticosteroids did not produce any benefit in terms of reducing the postoperative temporary/permanent RLNP rate, but it did shorten the recovery time for patients suffering from temporary RLNP.

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

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.

Audiometric Patterns and Prognosis in Sudden Sensorineural Hearing Loss in Southern Taiwan

OBJECTIVES: To investigate factors affecting the prognosis of sudden sensorineural hearing loss (SSNHL). STUDY DESIGN AND SETTING: This is a retrospective study of patients with SSNHL hospitalized at an academic medical center. All patients in this study were treated with prednisolone and dextran. We compared a new 7-pattern classification for audiometric pattern and prognosis analysis with Sheehy classification. RESULTS: We analyzed 148 affected ears in 146 patients. Occurrence of SSNHL was associated with changes in season. The best prognosis was with the midtone pattern of the 7-pattern classification and with the low-tone pattern of Sheehy classification. The older patients, those with vertigo, or those treated after 6 days had a poor prognosis. There was no significant association between ESR level and prognosis. CONCLUSIONS: SSNHL patients with midtone loss have the best prognosis. This study of the audiometric patterns and prognostic factors of SSNHL allow us to better predict its outcome. EBM RATING: B-2

A long-term study on hearing status in patients with nasopharyngeal carcinoma after radiotherapy.

Objective: To study the long-term sensorineural hearing status after radiotherapy in patients suffering from nasopharyngeal carcinoma. Study Design: A prospective study of 220 patients (395 ears) with a median follow-up of 36 months. Setting: A university hospital. Patients: Four criteria were needed. The patient had to have had at least 12 months of audiologic follow-up, no concurrent chronic ear disease, no direct tumor invasion of ear, and no significant sensorineural hearing loss before radiotherapy. Intervention: Pure-tone audiography and impedance audiometry—which were performed before and at the third month after completion of radiotherapy and at a yearly interval thereafter—formed the basis of the study. Main Outcome Measures: The significance level in this study was defined as a bone conduction threshold increase of more than 10 dB between the initial audiogram and those obtained after the completion of radiotherapy. An increase of more than 30 dB was defined as severe loss. Results: Paired t test indicated that the mean bone conduction threshold before and after radiotherapy were significantly different (paired t test, p < 0.05). Logistic regression showed that patient age was related to the significant loss at speech frequency but not to the loss at 4 kHz. The presence of postradiation otitis media with effusion, preirradiation hearing status, and addition of chemotherapy were found to be not influential on hearing change. Conclusion: Hearing deterioration may begin as early as 3 months after the completion of radiotherapy. Early change may be transient, but the effect of radiation on hearing tended to be chronic and progressive.

Matrix metalloproteinase-9 gene polymorphisms in nasal polyposis.

BackgroundMatrix 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.MethodsWe 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.ResultsAll 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.ConclusionsWe concluded that MMP-9 gene polymorphisms may influence susceptibility to the development of chronic rhinosinusitis with nasal polyposis in Chinese population.