Three-dimensional topography of rat trigeminal ganglion neurons using a combination of retrograde labeling and tissue-clearing techniques.

The trigeminal nerve is the sensory afferent of the orofacial regions and divided into three major branches. Cell bodies of the trigeminal nerve lie in the trigeminal ganglion and are surrounded by satellite cells. There is a close interaction between ganglion cells via satellite cells, but the function is not fully understood. In the present study, we clarified the ganglion cells' three-dimensional (3D) localization, which is essential to understand the functions of cell-cell interactions in the trigeminal ganglion. Fast blue was injected into 12 sites of the rat orofacial regions, and ganglion cells were retrogradely labeled. The labeled trigeminal ganglia were cleared by modified 3DISCO, imaged with confocal laser-scanning microscopy, and reconstructed in 3D. Histograms of the major axes of the fast blue-positive somata revealed that the peak major axes of the cells innervating the skin/mucosa were smaller than those of cells innervating the deep structures. Ganglion cells innervating the ophthalmic, maxillary, and mandibular divisions were distributed in the anterodorsal, central, and posterolateral portions of the trigeminal ganglion, respectively, with considerable overlap in the border region. The intermingling in the distribution of ganglion cells within each division was also high, in particular, within the mandibular division. Specifically, intermingling was observed in combinations of tongue and masseter/temporal muscles, maxillary/mandibular molars and masseter/temporal muscles, and tongue and mandibular molars. Double retrograde labeling confirmed that some ganglion cells innervating these combinations were closely apposed. Our data provide essential information for understanding the function of ganglion cell-cell interactions via satellite cells.

Tracheostomy Tube Exchange Failure Under General Anesthesia: A Case Report and Retrospective Analysis.

A 54-year-old man with squamous cell carcinoma of the tongue underwent bilateral cervical lymph node dissection, total tongue resection, forearm flap reconstruction, and tracheostomy. The plan was to replace the oral endotracheal tube (ETT) with a cuffed tracheostomy tube at the end of the surgical case while the patient was still under general anesthesia. No major complications were expected as the tracheal foramen was visible once surgical access was obtained. However, removal of the ETT and subsequent placement of the tracheostomy tube failed twice. Successful ventilation was not observed via capnography, and the patient's peripheral oxygen saturation (SpO2) dropped to 70%. The anesthesiologist concluded that securing the airway through the tracheostomy would be difficult. The patient was immediately reintubated orally at which time his SpO2 was 38%, and he was successfully resuscitated and recovered without any sequelae. This rare situation was one we had not encountered previously, so we retrospectively analyzed all tracheostomy cases performed by our department from the past 3 years. Data from 54 patients who underwent tracheostomy tube exchange after tracheostomy were aggregated from their medical records and compared with our patient. Excluding the conditions during surgery, we surmised that tracheal depth, S/H ratio, and body weight were identified as potentially significant risk factors for failed tracheal tube placement or exchange.

Maintaining Tooth Vitality With Super Minimally Invasive Pulp Therapy.

In aging humans, tooth loss is a predictor of decreased longevity. Tooth loss is mainly caused by dental caries and periodontal disease. Pulpitis refers to inflammation of the dental pulp caused by bacterial infection secondary to dental caries. It is accompanied by severe toothache and has infectious disease-associated pathophysiology. Pulpitis is mainly treated by pulpectomy, which is aimed at removing the infected dental pulp and controlling pain by removing nociceptive nerve fibers. However, teeth without dental pulp have a poor prognosis. In this report, we proposed a novel "super minimally invasive pulp" therapy for treating pulpitis without pulpectomy, which combines antibiotics, steroids, and ultrasound-guided trigeminal nerve block (UGTNB) to protect the dental pulp. UGTNB is used as an analgesic for severe pain, antibiotics for pulp infections, and steroids as antiinflammatory drugs. This novel therapy could improve the longevity of the tooth and thereby oral health.

Fraction of Inspired Oxygen With Low-Flow Versus High-Flow Devices: A Simulation Study.

PURPOSE: The fraction of inspired oxygen while administering oxygen to patients must be measured as it represents the alveolar oxygen concentration, which is important from a respiratory physiology viewpoint. Therefore, the purpose of this study was to compare the fractions of inspired oxygen obtained through different oxygen delivery devices. METHODS: A simulation model of spontaneous respiration was used. The fractions of inspired oxygen obtained through low- and high-flow nasal cannulas and a simple oxygen mask were measured. The fraction of inspired air was measured every second for 30 s after 120 s of oxygen administration. This was measured three times under each condition. RESULTS: With a low-flow nasal cannula, airflow reduced both the intratracheal fraction of inspired oxygen and extraoral oxygen concentration, indicating that exhalatory respiration occurred during rebreathing and may be involved in increasing the intratracheal fraction of inspired oxygen. CONCLUSION: Oxygen administration during expiratory flow may lead to an increased oxygen concentration in the anatomical dead space, which may be involved in the increase in the fraction of inspired oxygen. With a high-flow nasal cannula, a high fraction of inspired oxygen can be achieved even at a flow rate of 10 L/min. When determining the optimum amount of oxygen, it is necessary to set an appropriate flow rate for patients and specific conditions without being bound by the fraction of inspired oxygen values alone. It might be difficult to estimate the fraction of inspired oxygen while using a low-flow nasal cannula and simple oxygen mask in clinical situations.

A Method for Preventing Aerosols During Dental Treatment With an Oroscope.

Dentists have a much higher risk of exposure to coronavirus disease (COVID-19) than other healthcare workers. The virus is transmitted primarily through respiratory droplets and close/direct contact. Aerosol propagation is also possible in the case of prolonged exposure to high concentrations in a relatively closed environment. In this report, we describe the use of an aerosol box model to prevent aerosol generation during dental procedures. This report serves to inform clinicians on the potential effectiveness of this stopgap measure in cases where aerosol-generating procedures are unavoidable and medical supplies and personal protective equipment are in short supply.

A Novel Pain Relief Approach for the Treatment of Multiple Dental Caries and Pulpitis.

Anxiety and stress toward treatment can hamper treatment completion in patients with dental caries and pulpitis. Therefore, effective management of post-treatment pain is important because poor pain management can lead to patient dissatisfaction. Ultrasound-guided nerve blocks provide good postoperative analgesia in maxillofacial surgeries. These surgeries can be performed under general or local anesthesia without complications. Here, we present the case of a patient with dental phobia who was successfully treated with these techniques. The patient was a 22-year-old woman with a history of manic-depressive illness who presented with 23 decayed teeth. She had previously undergone vital pulp therapy; however, post-treatment pain led to treatment-related stress, and the patient discontinued the dental treatment. She preferred the dental treatment to be completed with as little pain as possible and wanted to avoid a pulpectomy. The patient's history of heavy use of non-steroidal anti-inflammatory drugs (NSAIDs) made her resistant to NSAIDs. As a result, the analgesic effect of NSAIDs could not be expected. After intravenous midazolam and propofol sedation, an ultrasound-guided inferior alveolar nerve block was performed bilaterally, and 0.375% ropivacaine was used as a local anesthetic. The patient did not complain of post-operative pain, and no post-operative analgesics were required.

Jaw Manipulation Using Ultrasound-Guided Inferior Alveolar Nerve Block for Trismus in Temporomandibular Disorders.

Temporomandibular disorders are a group of disorders with symptoms that include pain and clicking sounds in the temporomandibular joint and restricted mouth opening. For the treatment of temporomandibular disorders with trismus, herein, we suggest a new approach: "jaw manipulation using the ultrasound-guided inferior alveolar nerve block technique." A woman in her 60s developed temporomandibular disorders and presented with severe trismus owing to pain in the temporomandibular joint. Ultrasound-guided inferior alveolar nerve block was performed with ropivacaine, which relieved the pain in the patient. Furthermore, we performed jaw manipulation for trismus. Since the analgesic effect lasts for 3 days, self-training can be performed while the pain is relieved. After five sessions of "jaw manipulation using the ultrasound-guided inferior alveolar nerve block technique," trismus significantly improved in this patient. Ultrasound-guided inferior alveolar nerve block can be effective in relieving temporomandibular disorder-related pain and trismus.

Ultrasound-guided inferior alveolar nerve block for trismus during dental treatment: a case report.

BACKGROUND: Temporomandibular disorder (TMD) is a broad term that encompasses pain and/or dysfunction of the masticatory musculature and TM joints (TMJs). When TMD becomes a chronic condition, the symptoms are extremely difficult to manage and require multiple interventions. CASE PRESENTATION: A woman in her 50s developed TMD after a traffic accident 30 years ago. The patient presented with severe trismus due to TMJ pain and a maximum mouth opening of 20 mm. Ultrasound-guided inferior alveolar nerve block (IANB) was performed with ropivacaine. After IANB, the pain during mouth opening subsided and the maximum mouth opening improved to 40 mm. Dental treatment could be performed without difficulty and the patient could keep her mouth open throughout the treatment. CONCLUSIONS: Treatments for chronic TMD are limited and it is necessary to identify the precise etiology before choosing a treatment option. In this patient, ultrasound-guided IANB proved to be effective in relieving TMD-related trismus.

Anesthetic Management of a Patient With a Vagal Nerve Stimulator.

Vagal nerve stimulation (VNS) is an established adjunctive treatment for patients with refractory epilepsy. VNS is effective in many cases, but few patients achieve complete elimination of seizures. Furthermore, VNS can cause respiratory complications, such as obstructive sleep apnea. This report describes the successful anesthetic management of a 28-year-old woman with a VNS device who underwent dental treatment under general anesthesia. She was morbidly obese and had undergone placement of a VNS device secondary to drug-resistant epilepsy 2 years prior but continued to experience daily epileptic seizures. Because of concerns about the risk of perioperative epileptic seizures and apneic events, use of the dedicated VNS device magnet was planned if such complications occurred. Total intravenous anesthesia was induced with propofol and remifentanil and a bispectral index sensor was used to help monitor brain wave activity for evidence of seizures along with the depth of anesthesia. Postoperatively, the patient received positional therapy and supplemental oxygen while being closely monitored in recovery. The anesthetic course was completed uneventfully without need of the VNS magnet. A thorough understanding of the mechanics of a VNS device, including proper use of the VNS magnet, is critical for an anesthesiologist during the perioperative period.