Prolonged blockade of the cervical sympathetic nerve by stellate ganglion block accelerates therapeutic efficacy in trigeminal neuropathy.

PURPOSE: Stellate ganglion block (SGB) is effective in treating head and neck pain and neuropathic diseases by increasing tissue blood flow through its sympatholytic effect. This study aimed to investigate the relationship between duration of cervical sympathetic nerve block by SGB and its therapeutic efficacy against trigeminal neuropathy after orthognathic surgery. METHODS: Twenty-eight patients with trigeminal neuropathy were randomly assigned to two groups (mepivacaine and levobupivacaine) according to the drug used for SGB. Increased blood flow, which is a symptom of sympathetic blockade, was recorded for 180 min after SGB. Current perception threshold, warm or cool detection threshold, and tactile detection threshold were measured preoperatively, postoperatively, on day 10 after initiation of SGB, and 3 months postoperatively to compare therapeutic efficacy between the groups. RESULTS: The levobupivacaine group had a significantly longer duration of increased blood flow compared with the mepivacaine group. Values of current perception threshold, warm and cool detection threshold, and tactile detection threshold significantly improved in the levobupivacaine group on day 10 after initiation of SGB and 3 months postoperatively. CONCLUSION: A prolonged increase in blood flow due to long-term sympatholytic effects accelerates the therapeutic efficacy of SGB in trigeminal neuropathy.

A Nasal High-Flow System Prevents Upper Airway Obstruction and Hypoxia in Pediatric Dental Patients Under Intravenous Sedation.

PURPOSE: Upper airway obstruction (UAO) and oxygen desaturation are risk factors for major complications of intravenous sedation (IVS) in pediatric dental patients. This study aimed to investigate the use of a nasal high-flow (NHF) system for the prevention of UAO and oxygen desaturation in pediatric dental patients under IVS. METHODS: The authors implemented a prospective randomized design. Thirty pediatric patients (aged 3 to 12), scheduled for dental treatment under IVS, were enrolled in this study. The subjects were randomly assigned to 1 of 2 groups: patients who received oxygen at 5 L/minute through a nasal cannula (NC group) and patients who received oxygen at 2 kg/L/minute, up to a maximum of 30 L/minute, through the NHF system (NHF group). The predictor variable was flow rate. The primary outcome variable was the need for intervention during treatment, and the secondary outcome variable was the lowest peripheral capillary oxygen saturation values during the procedure. Additional study variables measured included patient age, gender, weight, height, and surgical duration. The Mann-Whitney U test and Fisher exact test were used for statistical analysis, with P < .05 considered as significant. RESULTS: Both the NC (n = 15; mean age, 6.2 ± 2.3) and NHF (n = 15; mean age, 5.9 ± 2.5) groups had a male:female ratio of 2:1. The use of the NHF system significantly improved the lowest peripheral capillary oxygen saturation values during treatment (P < .05). Jaw lifting, to relieve UAO and facilitate spontaneous breathing, was required in both the NC (n = 10) and NHF (n = 3) groups (P < .05). The need for interventions during treatment was significantly lower in the NHF group (P < .05). CONCLUSIONS: The results of this study suggest that the use of the NHF system can prevent UAO and improve the respiratory condition of pediatric dental patients under IVS.

Effects of stellate ganglion block on postoperative trigeminal neuropathy after dental surgery: a propensity score matching analysis.

This study aimed to evaluate the effects of stellate ganglion block (SGB) on postoperative trigeminal neuropathy (TNP) after dental surgery. This was a retrospective study based on the medical records of all patients with postoperative TNP at Kyushu Dental University Hospital from 2014 to 2019. Patients were divided into the SGB group (received SGB) and non-SGB group (did not receive SGB). We evaluated the severity of TNP at 3 months after surgery and the incidence rate of abnormal sensations. Abnormal sensations were counted using patients' reports of uncomfortable symptoms during the treatment, including dysaesthesia, allodynia, and hyperalgesia. A propensity score (PS) matching analysis was performed to evaluate these data. After PS matching, amongst others, the force equivalent values of the Semmes-Weinstein test at 3-months post-treatment were significantly lower in the SGB group than in the non-SGB group (2.00 ± 0.44 vs 2.30 ± 0.48; p < 0.05). In addition, after PS matching, the incidence rate of abnormal sensations during the treatment was significantly lower in the SGB group than in the non-SGB group (10 cases [4.7%] vs 22 cases [10.3%]; p < 0.05). Collectively, the findings support that SGB may improve the recovery from postoperative TNP and reduce the incidence rate of abnormal sensations after dental surgery.

Real-time evaluation of swallowing in patients with oral cancers by using cine-magnetic resonance imaging based on T2-weighted sequences.

OBJECTIVE: The aim of this study was to evaluate whether a new cine-magnetic resonance imaging (CMRI) technique might be useful for evaluating swallowing function in patients with different types of oral cancers by assessing 12 CMRI-related parameters. STUDY DESIGN: In total, 111 patients with oral cancers were evaluated. We examined whether visualization of fluid flow and determination of flow direction to the trachea or the esophagus were possible with CMRI. We evaluated the correlations between CMRI-related parameters and self-reported dysphagia scores as the status of dysphagia, T classification groups as tumor staging for preoperative patients, alterations in CMRI-related parameters between pre- and postoperative patients, and the degree of invasiveness of oral cancer surgery. RESULTS: We could judge the flow direction to the esophagus on CMRI in all 111 patients. Six CMRI-related parameters showed significant correlations with dysphagia status. Increases in CMRI-related parameters were significantly related to deterioration of swallowing status, as shown by a decrease in self-reported dysphagia scores, advances in the T classification, and degree of invasiveness of oral cancer surgery. CONCLUSIONS: The results of the present study suggest that CMRI can be used to directly visualize swallowing dynamics and objectively evaluate the swallowing complaints of patients with oral cancer.

Characteristics of diffusion-weighted images and apparent diffusion coefficients of ranulas and other masses in and around the floor of the mouth.

OBJECTIVE: The aim of this study was to evaluate the characteristics of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values of ranulas. In addition, to elucidate DWI findings and ADC values of other representative masses in and around the floor of the mouth. STUDY DESIGN: DWI findings and ADC values in 35 patients with ranulas and 33 patients with other masses were retrospectively reviewed with a central focus on cystic masses or lesions that may have cyst-like components in and around the floor of the mouth based on the diagnosis of each respective disease. RESULTS: Ranulas were all well-defined, homogeneous masses with high signal intensity on DWI. The mean ± standard deviation ADC value of the 35 ranulas was 2.59 ± 0.31 × 10-3 mm2/s. There was a significant difference in ADC values between simple and plunging ranulas. On DWI, most other masses were heterogeneous, and most ADC values, except those for thyroglossal duct cysts, hemangiomas, and pleomorphic adenomas, were significantly lower than those for ranulas. CONCLUSIONS: The characteristic DWI and ADC findings of ranulas can be determined accurately, and these data can be significantly useful in the differential diagnosis of many kinds of diseases in and around the oral floor.

Sedation With a Combination of Dexmedetomidine and Midazolam for Pediatric Dental Surgery.

Intravenous sedation (IVS) is commonly used to complete dental treatment for uncooperative pediatric patients. Propofol (PRO) is widely used for IVS because of its short context sensitive half-time and amnestic effect. However, administering PRO to patients who have a history of egg anaphylaxis is still somewhat controversial. The evidence that supports the potential risks for allergic reactions following PRO use in patients with egg allergies is limited with some anesthesiologists recommending against its use in these patients. Alternative drug regimens for procedural sedation in this population are therefore desirable. Dexmedetomidine (DEX), a selective α-2 agonist, has antianxiety and sedative properties and has been widely used not only for procedural sedation with mild inhibitory effects on respiration but also during minor surgeries for its analgesic effect. In this paper, we describe the successful administration of a combination of DEX and low-dose midazolam (MDZ) for sedation in an uncooperative pediatric patient. Both DEX and MDZ have been reported as safe and useful sedatives for dental treatment, and their combination may provide a helpful option for IVS of pediatric patients for whom PRO is not preferred.

Prostanoid-dependent spontaneous pain and PAR2-dependent mechanical allodynia following oral mucosal trauma: involvement of TRPV1, TRPA1 and TRPV4.

Abstract: During dental treatments, intraoral appliances frequently induce traumatic ulcers in the oral mucosa. Such mucosal injury-induced mucositis leads to severe pain, resulting in poor quality of life and decreased cooperation in the therapy. To elucidate mucosal pain mechanisms, we developed a new rat model of intraoral wire-induced mucositis and investigated pain mechanisms using our proprietary assay system for conscious rats. A thick metal wire was installed in the rats between the inferior incisors for one day. In the mucosa of the mandibular labial fornix region, which was touched with a free end of the wire, traumatic ulcer and submucosal abscess were induced on day 1. The ulcer was quickly cured until next day and abscess formation was gradually disappeared until five days. Spontaneous nociceptive behavior was induced on day 1 only, and mechanical allodynia persisted over day 3. Antibiotic pretreatment did not affect pain induction. Spontaneous nociceptive behavior was sensitive to indomethacin (cyclooxygenase inhibitor), ONO-8711 (prostanoid receptor EP1 antagonist), SB-366791, and HC-030031 (TRPV1 and TRPA1 antagonists, respectively). Prostaglandin E2 and 15-deoxyΔ12,14-prostaglandin J2 were upregulated only on day 1. In contrast, mechanical allodynia was sensitive to FSLLRY-NH2 (protease-activated receptor PAR2 antagonist) and RN-1734 (TRPV4 antagonist). Neutrophil elastase, which is known as a biased agonist for PAR2, was upregulated on days 1 to 2. These results suggest that prostanoids and PAR2 activation elicit TRPV1- and TRPA1-mediated spontaneous pain and TRPV4-mediated mechanical allodynia, respectively, independently of bacterial infection, following oral mucosal trauma. The pathophysiological pain mechanism suggests effective analgesic approaches for dental patients suffering from mucosal trauma-induced pain.

Comparison of pain tolerance thresholds of upper limb to identify the most appropriate venipuncture site.

PURPOSE: Venipuncture is often accompanied by pain, which can compromise dental care and foment distrust toward dental care providers. The aim of the present study was to identify sites on the forearm and hand that have the greatest pain tolerance threshold (PTT) during venipuncture. MATERIALS AND METHODS: The PTT was estimated in 20 healthy volunteers using a noninvasive nerve conduction threshold device. The subjects self-stimulated 5 sites (median cubital vein, cephalic vein at the cubitus, basilic vein, cephalic vein at the carpus, and superficial dorsal vein) at 2 kHz, 250 Hz, and 5 Hz. We measured the stimulation intensity before the subject deactivated the device. Differences in the average PTT values at each site were compared using the Kruskal-Wallis and Scheffé tests. P <.05 was considered to indicate statistical significance. RESULTS: The PTT was significantly greater at the superficial dorsal vein than at the basilic vein for all 3 noninvasive nerve conduction threshold frequencies (P < .05). The estimated PTT was significantly greater at the superficial dorsal vein than at the median cubital vein and cephalic vein at the carpus in response to 250-Hz stimulation (P < .05). CONCLUSIONS: The greater PTT of the superficial dorsal vein suggests that venipuncture at this site should result in the lowest pain intensity among all upper limb sites.

A nasal high-flow system prevents hypoxia in dental patients under intravenous sedation.

PURPOSE: Hypoxia is a major complication in dental patients under intravenous sedation (IVS). A nasal high-flow (NHF) system has been reported to achieve effective oxygenation in patients with sleep apnea syndrome. This study investigated the ability of the NHF system to prevent hypoxia in dental patients under IVS. MATERIALS AND METHODS: Thirty patients scheduled for dental treatment under IVS were enrolled. Patients were randomly divided into 3 groups: patients spontaneously breathing oxygen at 5 L/minute through a nasal cannula (NC5 group), patients administered oxygen at 30 L/minute through the NHF system, and patients administered oxygen at 50 L/minute through the NHF system. Hypnosis was induced by bolus administration of midazolam (0.05 mg/kg) followed by continuous administration of propofol (target blood concentration, 1.2 to 2 µg/mL). Noninvasive blood pressure, peripheral capillary oxygen saturation (SpO2), heart rate, and bispectral index values were recorded every 2.5 minutes before the induction of anesthesia. Interventions, such as jaw lifting, were recorded during IVS and arterial blood gas analysis was performed at the end of sedation. Patient and surgeon satisfaction with IVS was evaluated by interview. RESULTS: Minimum SpO2 was lowest in and surgeons were least satisfied with the NC5 group. In addition, interventions were required most frequently in the NC5 group (P < .05). Compared with the NC5 group, use of the NHF system improved partial pressures of oxygen and carbon dioxide in dental patients under IVS (P < .05). CONCLUSIONS: These results suggest that use of the NHF system can prevent hypoxia in dental patients under IVS. Further studies are necessary to determine the appropriate flow rate and indications for NHF in obese patients.

Distinct time courses of microglial and astrocytic hyperactivation and the glial contribution to pain hypersensitivity in a facial cancer model.

Although recent evidence suggests that central glial hyperactivation is involved in cancer-induced persistent pain, the time course of this hyperactivation and the glial contribution to pain hypersensitivity remain unclear. The present study investigated the time-dependent spatial changes of microglial and astrocytic hyperactivation in the trigeminocervical complex, which consists of the medullary (MDH) and upper cervical (UCDH) dorsal horns, and pain-related behaviors in a rat facial cancer model in which Walker 256B-cells are inoculated into the vibrissal pad. In this model, the tumors grew within the vibrissal pad, from which sensory nerve fibers project into the MDH, but did not expand into the infraorbital region, from which fibers project into the UCDH. Nevertheless, mechanical allodynia and thermal hyperalgesia were observed not only in the vibrissal pad but also in the infraorbital region. Western blotting and immunofluorescence studies indicated that microglia were widely activated in the trigeminocervical complex on day 4 and gradually inactivated by day 11. In contrast, astrocytes were only activated in the MDH on day 4; the hyperactivation later expanded into the UCDH. Daily administration of the glial hyperactivation inhibitor propentofylline beginning on day 4 suppressed the glial hyperactivation on later days. Propentofylline treatment largely prevented allodynia/hyperalgesia in the infraorbital region beginning on day 5, although established allodynia/hyperalgesia in the vibrissal pad was less sensitive to the treatment. These results suggest that central glial hyperactivation, transient microglial hyperactivation and persistent astrocytic hyperactivation, contributes to the development of pain hypersensitivity but not to the maintenance of pain in this model.