A Case of Anterior Arytenoid Cartilage Dislocation During Nasal Tracheal Intubation Using an Indirect Video Laryngoscope

Arytenoid cartilage dislocation can occur as a complication of tracheal intubation and laryngeal trauma, but its occurrence with indirect video laryngoscopy has not been reported. This paper reports anterior arytenoid dislocation occurring after nasotracheal intubation performed under indirect laryngoscopy using a video laryngoscope (McGRATH MAC; Medtronic). The dislocation is presumed to have resulted from the laryngoscope blade being initially inserted too deeply and applying pressure to the posterior aspect of the left cricoarytenoid joint. This patient's anterior arytenoid dislocation was treated conservatively using speech therapy with resolution occurring approximately 40 days postoperatively. On the 74th day after surgery, fibroscopic examination confirmed recovery and healing of the dislocation. However, other types of arytenoid dislocations and laryngeal injuries may require alternative treatment. Early consultation with an otolaryngologist is recommended if arytenoid dislocation is suspected.

Severe Bradycardia Occurring After Assisted Mouth Opening: A Case Report

We report a case of severe bradycardia during general anesthesia due to reduced atrioventricular conduction capacity believed to have been caused by the trigeminocardiac reflex (TCR). A 46-year-old woman was scheduled for intraoral scar revision under general anesthesia. When the surgeon opened her mouth intraoperatively, the patient's blood pressure immediately increased, and she developed significant bradycardia and a transient Mobitz type II second-degree atrioventricular block. It was assumed that the mandibular division of the trigeminal nerve (V-3) was stimulated by the surgeon stretching the patient's mouth open while remifentanil simultaneously provided sympatholytic effects, resulting in activation of the TCR. The patient quickly responded well to atropine and had no additional complications.

Combined Effect of Midazolam and Bone Morphogenetic Protein-2 for Differentiation Induction from C2C12 Myoblast Cells to Osteoblasts

In drug repositioning research, a new concept in drug discovery and new therapeutic opportunities have been identified for existing drugs. Midazolam (MDZ) is an anesthetic inducer used for general anesthesia. Here, we demonstrate the combined effects of bone morphogenetic protein-2 (BMP-2) and MDZ on osteogenic differentiation. An immortalized mouse myoblast cell line (C2C12 cell) was cultured in the combination of BMP-2 and MDZ (BMP-2+MDZ). The differentiation and signal transduction of C2C12 cells into osteoblasts were investigated at biological, immunohistochemical, and genetic cell levels. Mineralized nodules formed in C2C12 cells were characterized at the crystal engineering level. BMP-2+MDZ treatment decreased the myotube cell formation of C2C12 cells, and enhanced alkaline phosphatase activity and expression levels of osteoblastic differentiation marker genes. The precipitated nodules consisted of randomly oriented hydroxyapatite nanorods and nanoparticles. BMP-2+MDZ treatment reduced the immunostaining for both α1 and γ2 subunits antigens on the gamma-aminobutyric acid type A (GABAA) receptor in C2C12 cells, but enhanced that for BMP signal transducers. Our investigation showed that BMP-2+MDZ has a strong ability to induce the differentiation of C2C12 cells into osteoblasts and has the potential for drug repositioning in bone regeneration.

The Effect of Adding Midazolam to Propofol Intravenous Sedation to Suppress Gag Reflex During Dental Treatment

We retrospectively investigated the efficacy and safety of propofol administration alone and in combination with midazolam for gag reflex suppression during dental treatment under intravenous sedation. We included 56 patients with an overactive gag reflex who were to undergo dental treatment under intravenous sedation. They were divided into propofol (P group, n = 22) and midazolam with propofol (MP group, n = 34) groups. The P group received propofol alone, while the MP group received midazolam (0.04 mg/kg) prior to target-controlled infusion (TCI) of propofol (titrated for adequate sedation). The patients' anesthetic records were evaluated for vital sign changes, adverse cardiovascular or respiratory event frequency, the number of forced treatment interruptions, and the TCI-predicted cerebral propofol concentration at gag reflex suppression (posterior tongue stimulation with a dental mirror). No significant differences were observed between the 2 groups preoperatively. There were no cases of forced interruptions or significant respiratory compromise in either group. Cardiovascular adverse event frequency was lower in the MP group than in the P group (all p < .05). Our results suggest that propofol, when combined with midazolam, minimized cardiovascular effects compared with propofol alone when used to suppress the gag reflex in patients during dental treatment under intravenous sedation.

New method for postoperative pain relief using a combination of noxious and non-noxious stimuli after impacted wisdom tooth extraction

Although in clinical dentistry the major method used for pain relief is oral administration of analgesics, alternative methods are available, such as transcutaneous electrical nerve stimulation (TENS), acupuncture, vibration and conditioned pain modulation (CPM), formerly termed diffuse noxious inhibitory control. The aim of the present study was to investigate the combined effects of non-noxious (TENS) and noxious (CPM) stimuli on postoperative pain after extraction of an impacted wisdom tooth. The study involved 44 patients who were scheduled to undergo impacted wisdom tooth extraction. The patients were randomly allocated into four groups: noxious stimuli, non-noxious stimuli, combined noxious and non-noxious stimuli, and a sham group. On the day after tooth extraction, stimulation procedures for pain relief were performed and changes in the level of perceived pain were scored using a visual analog scale (VAS). The combination of non-noxious and noxious stimuli decreased the VAS scores by 63.7%, indicating a more potent analgesic effect than that in the non-noxious, noxious, and sham groups. This method of analgesia using a combination of non-noxious and noxious stimuli can be applied to patients who are unable to tolerate analgesics, such as those with allergy, hypersensitivity or digestive disorders, and those who are pregnant.

Hypoesthesia associated with mandibular movement after sagittal split ramus osteotomy

PURPOSE

This retrospective study investigated the relationship between the degree of neurosensory disturbance (NSD) and mandibular movement distance after sagittal split ramus osteotomy (SSRO) and assessed sensory recovery.

METHODS

Lower lip hypoesthesia was evaluated at 1 week, 1 month, and 2 months after SSRO in 38 patients categorized according to the distance of mandibular movement: S group (0-7 mm; n = 17, 4 males and 13 females) and L group (7-14 mm; n = 21, 7 males, 14 females). Symptoms were evaluated by visual analog scale (VAS), tactile-threshold (SW) test, static 2-point discrimination (s-2PD) test, and current perception threshold (CPT) test.

RESULTS

The two groups did not differ significantly in gender and age. The Aβ fiber results of the CPT test differed significantly between the groups at 1 week and 1 month postsurgery (P < 0.05). There were no significant differences between the groups throughout the period in terms of VAS, SW, s-2PD, Aδ fiber, and C fiber of CPT.

CONCLUSIONS

Post-SSRO, the incidence of NSD in terms of tactile sensation may be greater in the L group early postoperatively. This may assist surgeons in explaining postoperative hypoesthesia to patients preoperatively.

An analysis of green discoloration of urine caused by propofol infusion

BACKGROUND

Propofol is a short-acting, intravenous sedative-hypnotic agent that is widely used for the induction and maintenance of general anesthesia and sedation. An uncommon adverse effect of propofol is green discoloration of the urine, which has been reported not only under general anesthesia but also with sedation. Although it is assumed that the phenolic derivatives of propofol can cause green discoloration of the urine, the actual origin remains unknown. The aim of this report was to identify the origin of the green discoloration of the urine using liquid chromatography-mass spectrometry (LC-MS).

CLINICAL FEATURES

The patient, a 51-year-old man, was scheduled for his oral surgery under general anesthesia using propofol. Postoperatively, the color of his urine was observed to be green. We compared and analyzed both the green urine and the normal urine using LC-MS.

CONCLUSION

We experienced a case of a patient with green discoloration of the urine after general anesthesia using propofol. Although LC-MS analysis showed 2 unique peaks in the green urine at 490 and 590 nm, obvious causes were not revealed.

Case of Vasovagal Syncope With Asystole Associated With Propofol Sedation

Few cases of bradycardic complications occurring under intravenous sedation have been reported. Here, we report a case of vasovagal syncope with asystole (7.2 seconds) associated with propofol sedation.

Enhancement of Analgesic Effect by Combination of Non-Noxious Stimulation and Noxious Stimulation in Humans

The aim of the this study was to investigate the combined effects of heterosegmental non-noxious and noxious stimulation on electrically induced tooth pain. The late component of somatosensory-evoked potentials (SEP), induced by electrical tooth stimulation and pain intensity, were examined under electrical stimulation to forearms. Noxious, non-noxious, and combined non-noxious and noxious electrical stimulation were applied to median nerves on the forearms. Four experimental sessions (ie, control session, combined non-noxious and noxious stimulation session, non-noxious stimulation session, and noxious stimulation session were performed for each subject at each 10-minute interval for 30 minutes. The amplitudes of the SEP and VAS scores in the combined stimulation session decreased significantly compared with those in the control session and the reduction rates were 51.1% (13.4 μV) and 41.0% (23.5 mm), respectively. These results show that the combined stimulation has a more potent analgesic effect than that of either the non-noxious or the noxious stimulation. It is suggested that a potent analgesia was produced by an activated central mechanism, including endogenous opioid and descending pain inhibitory systems due to combined non-noxious and noxious stimulation.

Effects of dexmedetomidine on conditioned pain modulation in humans

BACKGROUND

Systemic administration of dexmedetomidine (DEX; selective α(2) -adrenoceptor agonist) is found to inhibit diffuse noxious inhibitory control in rats, now referred to as conditioned pain modulation (CPM) in humans. The present study was designed to investigate the effect of intravenous administration of DEX on CPM in humans.

METHODS

There were two sequential sessions in this double blind, randomized study. The first session was the control with normal saline infusion (N(1st), L(1st), H(1st)). During the second session, three types of agents were infused: normal saline (N(2nd)); a low plasma concentration of DEX (0.04 ng/mL; L(2nd)); and a high plasma concentration of DEX (0.08 ng/mL; H(2nd)). The amplitude of somatosensory evoked potentials (ampSEP)s and the visual analogue scale of tooth pain (VASt) induced by electrical tooth stimulation were evaluated with and without conditioning CO(2) laser stimulation of the hand. The inhibition rate (% inhibition) was calculated [= (1-[ampSEP or VASt with conditioning stimuli]/[ampSEP or VASt without conditioning stimuli]) × 100] to compare the magnitude of the DEX effects on CPM.

RESULTS

The inhibition rates of ampSEPs and VASt in Types N, L and H varied significantly, demonstrating a dose-dependent reduction of CPM effects of ampSEP and VASt during randomized DEX administration, consistent with results from animal studies.

CONCLUSIONS

The present study shows that systemic administration of an α(2) -adrenoceptor agonist (DEX), less than the clinical dose, inhibited CPM in humans. These results may provide some mechanistic insight into why many chronic pain patients show impaired CPM.

General anesthesia for a patient with deletion 6q syndrome in addition to laryngomalacia undergoing dental treatment

Chromosome 6 deletions are very rare (1,2), and deletion 6q syndrome is clinically characterized by mental and/or neuromotor retardation and microcephaly (3). Other alterations frequently observed are decreased biparietal diameter, hypertelorism, hypotelorism, absent eyebrows, prominent eyes with ptosis, receding chin, dysmorphic ears, large extremities, prominent nasal bridge, long philtrum, epicthus, strabismus, and micrognathia (3-5). Laryngomalacia is the most common congenital laryngeal anomaly and the most frequent cause of stridor in infants (6-11). We report the case of a 14-year-old male patient with both deletion 6q syndrome and laryngomalacia, who we treated for multiple dental caries. He had a medical history of tracheotomy at age 11 years for laryngomalacia, and has suffered from epileptic attacks and aspiration pneumonia over the last 2 and 6 years, respectively. Since he was mentally retarded and in a poor respiratory state, dental treatment under general anesthesia was scheduled in our hospital. General anesthesia was induced and maintained using 30% nitrous oxide and 1-3% sevoflurane in oxygen through the tracheotomy tube. Pre- and intraoperative endotracheal suction improved the condition of both lungs markedly and the procedures were uneventful and completed in 2 h and 58 min.