Near-IR Charge-Transfer Emission at 77 K and Density Functional Theory Modeling of Ruthenium(II)-Dipyrrinato Chromophores: High Phosphorescence Efficiency of the Emitting State Related to Spin-Orbit Coupling Mediation of Intensity from Numerous Low-Energy Singlet Excited States.

Efficient charge-transfer (CT) phosphorescence in the near-IR (NIR) spectral region is reported for four substituted Ru-(R-dipyrrinato) complexes, [Ru(bpy)2(R-dipy)](PF6), where bpy is 2,2'-bipyridine and the substituent R is phenyl (ph), 2,4,6-trimethylphenyl, 4-carboxyphenyl (HOOC-ph), or 4-pyridinyl. The experimentally determined phosphorescence efficiency, ιem(p) = kRAD(p)/(νem(p))3 (where kRAD(p) and νem(p) are the phosphorescence rate constant and the phosphorescence frequency, respectively), of the [Ru(bpy)2(R-dipy)]+ complexes was approximately double that of [Ru(bpy)(Am)4]2+ complexes (Am = ammine ligand) in the NIR region. Density functional theory (DFT) modeling indicated two strikingly different electronic configurations of the triplet emitting state (Te) in the two types of complexes. The Te of [Ru(bpy)2(R-dipy)]+ complexes shows a CT-type corresponding to the metal-to-ligand charge transfer (MLCT)-(Ru-(R-dipy)) and the ππ*-(R-dipy) moiety configurations, and the Te state in the [Ru(bpy)(Am)4]2+ complexes corresponds to an approximately MLCT excited state consisting of mostly MLCT-(Ru-bpy) with a minimal ππ*(bpy) contribution. DFT modeling also indicated that the low-energy singlet excited states in the Te geometry (Sn(T)) of the [Ru(bpy)2(ph-dipy)]+ complex consist of numerous CT-Sn(T)-type states of the Ru-dipy and Ru-bpy moieties, whereas the [Ru(bpy)(Am)4]2+ ions show quite simple MLCT-Sn(T)-type states of the Ru-bpy moiety. Based on experimental observations, DFT modeling, and the plain spin-orbit coupling (SOC) principle, we conclude that the remarkably high ιem(p) amplitudes of the [Ru(bpy)2(R-dipy)]+ complexes relative to those of [Ru(bpy)(Am)4]2+ complexes can be attributed to the relatively substantial contribution of intrinsic SOC-mediated intensity stealing from the numerous low-energy CT-type Sn(T) states.

Cascade In Situ Phosphorylation and One-Pot Glycosylation for Rapid Synthesis of Heptose-Containing Oligosaccharides.

We report a one-pot glycosylation strategy for achieving rapid syntheses of heptose (Hep)-containing oligosaccharides. The reported procedure was designed to incorporate an in situ phosphorylation step into an orthogonal one-pot glycosylation. Hep-containing oligosaccharides were assembled directly from building blocks with minimal effort expended on manipulation of protecting and aglycone leaving groups. The utility of our one-pot procedure was illustrated by synthesizing partial core oligosaccharide structure present in the lipopolysaccharide of Ralstonia solanacearum.

The anti-angiogenic and anti-vasculogenic mimicry effects of GN25 in endothelial and glioma cells.

BACKGROUND AND PURPOSE: Scientists have been exploring anti-angiogenic strategies to inhibit angiogenesis and prevent tumor growth. Vasculogenic mimicry (VM) in glioblastoma multiforme (GBM) poses a challenge, complicating anti-angiogenesis therapy. A novel drug, GN25 (3-[{1,4-dihydro-5,8-dimethoxy-1,4-dioxo-2-naphthalenyl}thio]-propanoic acid), can inhibit tumor formation. This study aims to investigate the microenvironmental effects and molecular mechanisms of GN25 in anti-angiogenesis and anti-VM. EXPERIMENTAL APPROACH: MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay was used to evaluate the cell viability of different concentrations of GN25 in human umbilical vein endothelial cells (HUVEC) and Uppsala 87 malignant glioma (U87MG) cells. Functional assays were used to investigate the effects of GN25 on angiogenesis-related processes, whereas gelatin zymography, enzyme-linked immunosorbent assays, and Western blotting were utilized to assess the influence on matrix metalloproteinase (MMP)-2 and vascular endothelial growth factor (VEGF) secretion and related signaling pathways. KEY RESULTS: GN25 suppressed migration, wound healing, and tube formation in HUVECs and disrupted angiogenesis in a rat aorta ring and zebrafish embryo model. GN25 dose-dependently reduced phosphatidylinositol 3-kinase/AKT and inhibited MMP-2/VEGF secretion in HUVECs. In U87MG cells, GN25 inhibited migration, wound healing, and VM, accompanied by a decrease in MMP-2 and VEGF secretion. The results indicate that GN25 effectively inhibits angiogenesis and VM formation in HUVECs and U87MG cells without affecting preexisting vascular structures. CONCLUSION AND IMPLICATIONS: This study elaborated GN25's potential as an anti-angiogenic agent by elucidating its inhibitory effects on classical angiogenesis. VM provides valuable insights for developing novel therapeutic strategies against tumor progression and angiogenesis-related diseases. These results indicate the potential of GN25 as a promising candidate for angiogenesis-related diseases.

Orthogonal Glycosylation with Phosphate Acceptors for Expeditious Synthesis of Bacterial Inner Core Oligosaccharides.

We report a practical one-pot glycosylation strategy for synthesis of bacterial inner core oligosaccharides that composed of unavailable L-glycero-D-manno and D-glycero-D-manno-heptopyranose components. The glycosylation method features a new orthogonal glycosylation procedure; whereby a phosphate acceptor is coupled with a thioglycosyl donor producing a disaccharide phosphate, which can be engaged in another orthogonal glycosylation procedure to couple with a thioglycosyl acceptor. The phosphate acceptors used in above one-pot procedure are directly prepared from thioglycosyl acceptors via the in-situ phosphorylation. Such phosphate acceptor preparation protocol eliminates the traditional protection and deprotection procedures. Based on the new one-pot glycosylation strategy, two partial inner core structures of Yersinia pestis lipopolysaccharide and Haemophilus ducreyi lipooligosaccharide were acquired.

Management of tracheal deformity during intubation: a case report.

Failure or difficulty in intubating the trachea can be either due to inability to visualize the glottis or some pathology at the level of or below the cords. This report describes a case of difficult intubation suspected of being related to neck scarring from previous surgery. Computed tomography (CT) was used to evaluate the patient's airway and revealed upper tracheal angulation. We describe a method to secure the airway in this patient with a two-person technique by rotating an oral endotracheal tube 180 degrees counterclockwise to adjust to the curvature of the trachea. Problems with intubation should be anticipated in patients with scarring of the neck, and equipment for aiding intubation should be on hand. Furthermore, we found that CT contributed to the assessment of the difficulty of intubation in this kind of patient.

Lateral rotation of the lower extremity increases the distance between the femoral nerve and femoral artery: an ultrasonographic study.

Femoral nerve block (FNB) is by far the most useful lower extremity regional anesthetic technique for the anesthesiologist, and high-resolution ultrasonography is a useful tool with which to guide the performance of FNB. However, the relationships between the femoral nerve and the femoral artery in different lower extremity positions have rarely been discussed. The purpose of this study was to evaluate the relative positions of the femoral nerve and artery at different lateral rotational angles of the lower extremities using ultrasonographic imaging. We enrolled 41 healthy volunteers in this study. Two-dimensional ultrasonographic images of the femoral nerve were obtained using an ultrasound unit, in the inguinal crease, for four positions of the bilateral lower extremities: 0 degrees , 15 degrees , 30 degrees and 45 degrees lateral rotation of each extremity. The following assessments were made in each position: minimal skin-to-nerve distance (SN) and deviation of nerve-to-landmark (femoral artery pulsation) horizontal distance (NF). A trend towards lateral rotation of both lower extremities was identified. The Pearson correlation values between rotational degree to SN and rotational degree to NF were -0.216 and 0.430, with p values of 0.001 and less than 0.001, respectively. Body mass index had a good correlation ( r = 0.76-0.78) with SN. The results of our ultrasound study revealed that the more lateral the rotation of both lower extremities, the closer the femoral nerve was to the skin and the farther away it was from the femoral artery. In order to increase the success rate and decrease the rate of complications, a suggested lateral 45 rotation of both lower extremities is strongly recommended when performing FNB using the peripheral nerve stimulator technique or the field block technique. In any situation, individual ultrasound guidance is recommended for FNB whenever possible.

Seizure after local anesthesia for nasopharyngeal angiofibroma.

We report a young male patient who experienced seizure after local injection of 3 mL 2% lidocaine with epinephrine 1:200,000 around a recurrent nasal angiofibroma. After receiving 100% oxygen via mask and thiamylal sodium, the patient had no residual neurologic sequelae. Seizure immediately following the injection of local anesthetics in the nasal cavity is probably due to injection into venous or arterial circulation with retrograde flow to the brain circulation. Further imaging study or angiography should be done before head and neck surgeries, especially in such highly vascular neoplasm.

Tracheostomy tube ignition during microlaryngeal surgery using diode laser: a case report.

Ignition of the tracheal tube during laser microlaryngeal surgery under general anesthesia is an uncommon complication with potentially serious consequences. We present here a case of a patient with glottic stenosis following endotracheal intubation, who experienced this potentially catastrophic combustion during endoscopic arytenoidectomy, using a diode laser under general anesthesia via 60% FiO2, with an airway fire occurring at the tracheostomy tube and causing tubal damage and obstruction. The anesthetic connecting tube was immediately disconnected and the tracheostomy tube replaced. No adverse consequences to this patient's upper airway were noted during follow-up visits. Higher oxygen concentrations, the presence of combustibles, and the narrowness of the surgical field during endolaryngeal diode laser surgery are risk factors for airway fires.

Well-defined palladium(0) complexes bearing N-heterocyclic carbene and phosphine moieties: efficient catalytic applications in the Mizoroki-Heck reaction and direct C-H functionalization.

Two series of well-defined palladium(0) complexes with phosphine-functionalized N-heterocyclic carbene ligands were prepared. These complexes featured six- and seven-membered chelate rings in the two series. Among the seven-membered chelate complexes, those featuring the PCy2 moiety exhibited observable fluxional behavior on the NMR time scale, corresponding to the interchange between two sets of conformations. Most of these novel complexes were successfully structurally characterized by single-crystal X-ray diffraction studies. These two series of palladium(0) complexes were tested for their potential catalytic applications in two mechanistically distinct reactions, namely, Mizoroki-Heck coupling and direct C-H functionalization reactions. One of the six-membered chelate complexes was found to be an efficient pre-catalyst for mediating the coupling reactions between aryl chlorides and alkenes. The palladium(0) complex could also be effectively applied in the direct C-H functionalization reactions of aryl bromides with 1,2-dimethylimidazole.

A survey of parental consent process for newborn screening in Taiwan.

Recent technological developments in newborn screening (NBS) allow many genetic/metabolic disorders to be detected pre-symptomatically even though they may be untreatable. Thus, current NBS faces ethical, legal, and social challenges. Obtaining parental consent for NBS demonstrates respect for and educates parents. The purpose of this study was to explore current practices in obtaining parental consent to conduct NBS in Taiwan. A self-administered questionnaire was mailed to obstetric clinicslhospitals (N=339) and 204 questionnaires were returned for a response rate of 60.2%. Parental consent processes for NBS were divided into three categories-informed consent, informed refusal, and no informedlconsent. Between 66.7-67.6% clinics/hospitals used an "informed consent" model for all NBS items. Although most clinics/hospitals frequently informed parents before screening was conducted, the information given was often incomplete. Moreover, a "no informedl consent" model was used for congenital adrenal hyperplasia (CAH) and rare geneticlmetabolic disorders in between 22.5% and 25.1% of the clinics/hospitals, respectively. A total of 23.1% of clinics/hospitals chose an "informed refusal" model for the five traditional genetic/metabolic disorders. Using logistic regression analysis, the parental consent process for the five traditional disorders was found to have significant associations with the classification of the hospitals and the contracted NBS center (p < 0.01). Regional hospitals less frequently used the "informed consent" model than local clinics, and the clinics/hospitals that contracted with National Taiwan University Hospital were more likely to follow an "informed consent" model rather than those contracted with Taipei Institute Pathology. Establishing specific guidelines to regulate the parental consent process and educate medical personnel is crucial.

Energy Dependence of the Ruthenium(II)-Bipyridine Metal-to-Ligand-Charge-Transfer Excited State Radiative Lifetimes: Effects of ππ*(bipyridine) Mixing.

The variations in band shape with excited state energy found for the triplet metal to ligand charge transfer ((3)MLCT) emission spectra of ruthenium-bipyridine (Ru-bpy) chromophores at 77 K have been postulated to arise from excited state/excited state configurational mixing. This issue is more critically examined through the determination of the excited state energy dependence of the radiative rate constants (kRAD) for these emissions. Experimental values for kRAD were determined relative to known literature references for Ru-bpy complexes. When the lowest energy excited states are metal centered, kRAD can be anomalously small and such complexes have been identified using density functional theory (DFT) modeling. When such complexes are removed from the energy correlation, there is a strong (3)MLCT energy-dependent contribution to kRAD in addition to the expected classical energy cubed factor for complexes with excited state energies greater than 10 000 cm(-1). This correlates with the DFT calculations which show significant excited state electronic delocalization between a π(bpy-orbital) and a half-filled dπ*-(Ru(III)-orbital) for Ru-bpy complexes with (3)MLCT excited state energies greater than about 16 000 cm(-1). Overall, this work implicates the "stealing" of emission bandshapes as well as intensity from the higher energy, strongly allowed bpy-centered singlet ππ* excited state.

Spinal process landmark as a predicting factor for difficult epidural block: a prospective study in Taiwanese patients.

Although epidural anesthesia is a common practice in neuraxial blockade, difficult access to the epidural space is a frequent problem in operating theaters. We designed this study of epidural blocks to determine if the spinal landmark grading system is valuable in predicting a difficult epidural block. Before the epidural block, we collected the following data: demographics, body habitus (normal, thin, obese, pregnant), spinal anatomy (normal, deformed), spinal level (lumbar, thoracic), and spinal landmark grade (grade 1: spinous processes visible; grade 2: spinous processes not seen but easily palpated; grade 3: spinous processes not seen and not palpated but the interval between them is palpated as a low landmark under the thumb; grade 4: other). We performed all 848 epidural blocks initially using a midline approach and an 18-gauge Touhy needle. We evaluated the technical difficulty of the epidural block using three methods: whether the epidural block was accomplished at the spinal level (first-level success); the total number of attempts at skin puncture (attempts-S); and total number of attempts to change ligament puncture direction (attempts-L) required to complete the epidural block. Of all examined factors, spinal landmark grade correlated best with technical difficulty as measured by all three methods. Deformed spinal anatomy and body habitus both correlated with difficulty, merely from the total numbers of attempts (attempts-S and attempts-L). Thoracic epidurals were more difficult than lumbar epidurals by all three measures of difficulty. We concluded that this spinal landmark grading system is valuable in predicting a difficult epidural block and advocate its use as a predictor by anesthesiologists.

Aggravated DNA damage as a basis for enhanced glioma cell killing by MJ-66 in combination with minocycline.

Despite recent advances in the treatment of malignant glomas, the prognosis of patients remains very poor and more efficient therapeutic approaches are urgently needed. In the present study, we investigated whether 2-(naphthalene-1-yl)-6-pyrrolidinyl-4-quinazolinone (MJ-66), a synthetic quinazolinone analog, induces glioma cell death through DNA damage. Treatment of C6 glioma cells with MJ-66 resulted in a time-dependent increase in γ-H2AX and increased the appearance of nuclear γ-H2AX foci. MJ-66 interfered with G2/M DNA damage checkpoint through increasing phosphorylated levels of Chk1 and Cdc25C. UCN-01, a Chk1 inhibitor, reversed MJ-66-induced activation of Cdc25C and caspase 3. MJ-66 inhibited tumor growth and prolonged survival time in intracranial glioma xenograft model. The combination of MJ-66 and Mino enhanced DNA damage and synergistically inhibited tumor growth and prolonged survival time in intracranial glioma xenograft model. These results suggest that the combination of MJ-66 and Mino may be developed as a new therapeutic strategy against malignant gliomas.

MJ-66 induces malignant glioma cells G2/M phase arrest and mitotic catastrophe through regulation of cyclin B1/Cdk1 complex.

Malignant gliomas are among the most devastating cancers as they are resistant to many kinds of treatment. Despite recent advances in the diagnosis and treatment, the prognosis of patients remains very poor and the development of new drug is urgently needed. Here, we report that a synthetic quinazolinone analog 2-(naphthalene-1-yl)-6-pyrrolidinyl-4-quinazolinone (MJ-66) induced glioma cell death. Immunofluorescence staining showed that MJ-66-induced cell death was associated with multinucleated phenotype and multipolar spindles that were typical characteristics of mitotic catastrophe. Flow cytometry analysis revealed that MJ-66 caused glioma cell cycle arrest at G2/M phase and increased the proportion of polyploidy cells. Western blotting indicated that the expression of cyclin B1, Cdk1 pY15 and Cdk1 increased after treatment with MJ-66. MJ-66 effectively inhibited tumor growth and induced apoptosis in the xenograft animal model of U87 human glioma cells. Together, these results suggest that MJ-66 inhibited malignant gliomas growth through inducing mitotic catastrophe by interference with G2/M cell cycle checkpoint which may open a new avenue for the treatment of malignant gliomas.

Inhibition of glioma growth by minocycline is mediated through endoplasmic reticulum stress-induced apoptosis and autophagic cell death.

BACKGROUND: We have reported that minocycline (Mino) induced autophagic death in glioma cells. In the present study, we characterize the upstream regulators that control autophagy and switch cell death from autophagic to apoptotic. METHODS: Western blotting and immunofluorescence were used to detect the expressions of eukaryotic translation initiation factor 2α (eIF2α), transcription factor GADD153 (CHOP), and glucose-regulated protein 78 (GRP78). Short hairpin (sh)RNA was used to knock down eIF2α or CHOP expression. Autophagy was assessed by the conversion of light chain (LC)3-I to LC3-II and green fluorescent protein puncta formation. An intracranial mouse model and bioluminescent imaging were used to assess the effect of Mino on tumor growth and survival time of mice. RESULTS: The expression of GRP78 in glioma was high, whereas in normal glia it was low. Mino treatment increased GRP78 expression and reduced binding of GRP78 with protein kinase-like endoplasmic reticulum kinase. Subsequently, Mino increased eIF2α phosphorylation and CHOP expression. Knockdown of eIF2α or CHOP reduced Mino-induced LC3-II conversion and glioma cell death. When autophagy was inhibited, Mino induced cell death in a caspase-dependent manner. Rapamycin in combination with Mino produced synergistic effects on LC3 conversion, reduction of the Akt/mTOR/p70S6K pathway, and glioma cell death. Bioluminescent imaging showed that Mino inhibited the growth of glioma and prolonged survival time and that these effects were blocked by shCHOP. CONCLUSIONS: Mino induced autophagy by eliciting endoplasmic reticulum stress response and switched cell death from autophagy to apoptosis when autophagy was blocked. These results coupled with clinical availability and a safe track record make Mino a promising agent for the treatment of malignant gliomas.

Application of a double-lumen tube for one-lung ventilation in patients with anticipated difficult airway.

One-lung ventilation (OLV) is essential in some surgical situations. The use of double- lumen tubes (DLTs) can achieve OLV more quickly and more easily than bronchial blockers. The management of a difficult airway is a challenge for anesthesiologists when, at the same time, OLV is needed for a surgical procedure. This report describes the successful application of DLTs in two patients with difficult airways, and who were scheduled for pulmonary decortication. Case 1 already had a permanent tracheostomy, while Case 2 had oral cancer with an extremely limited mouth opening and needed elective tracheostomy for anesthesia. Nasal intubation of Case 2 was done with fiberoptic-guided intubation with the patient awake. OLV was achieved uneventfully after inserting the DLT directly through the tracheostomy in both cases. We also describe the appropriate use of airway devices for OLV, focusing on patients with an anticipated difficult airway.

Accuracy of the central landmark for catheterization of the right internal jugular vein after placement of the ProSeal laryngeal mask airway.

OBJECTIVE: Catheterization of the internal jugular vein (IJV) after placement of a laryngeal mask airway (LMA) has been reported to be difficult. The purpose of this study was to evaluate the accuracy of the central landmark for catheterization of the right IJV after placement of a ProSeal LMA. METHODS: We enrolled 80 patients (30 men and 50 women) who were scheduled to undergo surgery under general anesthesia conveyed by a size 3 ProSeal LMA. A needle pathway based on the central landmark for right IJV catheterization was simulated. Ultrasound images were obtained, which we contrasted with the simulated pathway to evaluate whether the landmark accuracy remained unchanged after placement of the ProSeal LMA. Both frequency of simulated right carotid artery (CA) puncture and overlap between the right IJV and right CA were also investigated. RESULTS: The simulated needle pathway ran along the course of the right IJV in 60% (48/80) of subjects, and transected the CA in 31.3% (25/80) of subjects. Both events together occurred in 20% (16/80) of subjects. The central landmark had a medial bias of 6.8 mm (95% confidence interval, 5.3-8.4). In 83.8% (67/80) of subjects, the center of the right IJV was lateral to the central landmark. The possibility of overlap of the right IJV and CA was high after ProSeal LMA placement. CONCLUSION: After placement of the ProSeal LMA, the central landmark could not offer a good success rate at the first puncture attempt. When using the central landmark to catheterize the IJV after a ProSeal LMA placement, medial deviation of the central landmark should be considered. Ultrasound guidance may be helpful in difficult cases.

Haloperidol plus ondansetron prevents postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

BACKGROUND: A combination of antiemetic drugs could be an effective method to prevent severe postoperative nausea and vomiting (PONV). Therefore, we examined the prophylactic effect of haloperidol plus ondansetron on PONV. METHODS: We enrolled 210 patients (n = 70 in each of 3 groups) undergoing elective laparoscopic cholecystectomy for this randomized double-blind study. Patients were randomized to intravenous saline 2 mL and intramuscular haloperidol 2 mg (Group H), intravenous ondansetron 4 mg and intramuscular saline 2 mL (Group O), or intravenous ondansetron 4 mg and intramuscular haloperidol 2 mg (Group H+O), administered after induction of general anesthesia and 30 minutes before the conclusion of surgery. We compared the complete response rates, incidence of PONV, nausea scores, the need for rescue medication, patient satisfaction scores, and adverse events during the 24-hour study. RESULTS: The H+O group had the highest complete response rate to treatment (79%) compared with group H (61%) and group O (62%) (p < 0.05 for both). Patient satisfaction scores were significantly higher in the H+O group (8.3 +/- 1.8) than in the H (7.0 +/- 2.4) and O (7.2 +/- 2.5) groups (p < 0.05 for both). In addition, nausea scores were significantly lower in the H+O group (1.2 +/- 2.6) than in the H (2.5 +/- 3.3) and O (2.2 +/- 3.1) groups (p < 0.05 for both). CONCLUSION: We conclude that the combination of prophylactic haloperidol (2 mg) plus ondansetron (4 mg) provides a higher complete response rate and greater patient satisfaction after laparoscopic cholecystectomy than either drug used alone.

Perioperative airway management in a child with Treacher Collins syndrome.

We report the perioperative airway management in a 12-year-old boy suffering from Treacher Collins syndrome (TCS) and severe mental retardation who was scheduled for elective dental treatment under general anesthesia. TSC is also known as mandibulofacial dysostosis or Franceschetti syndrome, usually with a potentially difficult airway presentation. It is a major challenge for the anesthesiologist to manage an uncooperative child with such a congenital airway anomaly. A difficult airway was encountered during induction of general anesthesia, and both oral intubation by direct laryngoscopy and classic laryngeal mask airway (LMA) insertion were unsuccessful. In an expedient critical trial, with the cooperation of two anesthesiologists, one performing nasal fiberoptic intubation and the other maintaining oral mask ventilation, a nasal endotracheal tube was successfully placed at the first attempt, although at the expense of prolonged respiratory depression in the patient. Therefore, fiberoptic nasal intubation simultaneously with mask ventilation for placement of the endotracheal tube is a practical substitute for a difficult airway usually managed by LMA with inadequate ventilation. After extubation, tracheostomy may be indicated if the TCS patient suffers from persistent difficult upper airway in consequence of a traumatic intubation.

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.