Tracheal Deviation and Airway Management: Clinical Considerations From a Cadaver.

Severe tracheal deviation detected on preoperative chest radiographs is one of the risk factors for difficult tracheal intubation and difficulty in ventilation using an endotracheal tube after tracheal intubation when managing the airway through tracheal intubation under general anesthesia. In this report, we describe the cadaver of an 81-year-old woman with marked tracheal deviation due to meandering multiple aortas. This report details the importance of anatomical knowledge in developing a detailed airway management plan. The deviated trachea was removed from the cadaver and the tracheal tube was inserted at the glottis to the proximal end of the glottal marker. The tube tip was in contact with the tracheal wall, suggesting ventilation difficulty during intubation. The tortuous brachiocephalic artery passed in front of the trachea, which posed a risk of massive aortic hemorrhage and postoperative trachea-brachiocephalic artery fistula during percutaneous tracheostomy for emergency airway management. The anatomical location of the trachea and carotid artery must be confirmed before surgery/anesthesia to ensure safe airway management.

Expert consensus on difficult airway assessment.

Background: Identifying a potentially difficult airway is crucial both in anaesthesia in the operating room (OR) and non-operation room sites. There are no guidelines or expert consensus focused on the assessment of the difficult airway before, so this expert consensus is developed to provide guidance for airway assessment, making this process more standardized and accurate to reduce airway-related complications and improve safety. Methods: Seven members from the Airway Management Group of the Chinese Society of Anaesthesiology (CSA) met to discuss the first draft and then this was sent to 15 international experts for review, comment, and approval. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) is used to determine the level of evidence and grade the strength of recommendations. The recommendations were revised through a three-round Delphi survey from experts. Results: This expert consensus provides a comprehensive approach to airway assessment based on the medical history, physical examination, comprehensive scores, imaging, and new developments including transnasal endoscopy, virtual laryngoscopy, and 3D printing. In addition, this consensus also reviews some new technologies currently under development such as prediction from facial images and voice information with the aim of proposing new research directions for the assessment of difficult airway. Conclusions: This consensus applies to anesthesiologists, critical care, and emergency physicians refining the preoperative airway assessment and preparing an appropriate intubation strategy for patients with a potentially difficult airway.

Progress in Understanding Radiofrequency Heating and Burn Injuries for Safer MR Imaging.

RF electromagnetic wave exposure during MRI scans induces heat and occasionally causes burn injuries to patients. Among all the types of physical injuries that have occurred during MRI examinations, RF burn injuries are the most common ones. The number of RF burn injuries increases as the static magnetic field of MRI systems increases because higher RFs lead to higher heating. The commonly believed mechanisms of RF burn injuries are the formation of a conductive loop by the patient's posture or cables, such as an electrocardiogram lead; however, the mechanisms of RF burn injuries that occur at the contact points, such as the bore wall and the elbow, remain unclear. A comprehensive understanding of RF heating is needed to address effective countermeasures against all RF burn injuries for safe MRI examinations. In this review, we summarize the occurrence of RF burn injury cases by categorizing RF burn injuries reported worldwide in recent decades. Safety standards and regulations governing RF heating that occurs during MRI examinations are presented, along with their theoretical and physiological backgrounds. The experimental assessment techniques for RF heating are then reviewed, and the development of numerical simulation techniques is explained. In addition, a comprehensive theoretical interpretation of RF burn injuries is presented. By including the results of recent experimental and numerical simulation studies on RF heating, this review describes the progress achieved in understanding RF heating from the standpoint of MRI burn injury prevention.

SARS-CoV-2 recombinant spike protein induces cell apoptosis in rat taste buds.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause loss or alteration of taste and smell as early symptoms or sequelae, but the detailed mechanism behind this phenomenon remains unclear. Here, we investigated whether the SARS-CoV-2 spike protein induces taste cell apoptosis and expression of the apoptosis-related cytokine TNF-α in male Sprague-Dawley rats. Terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-fluorescein nick end labeling (TUNEL) assay results revealed a significantly higher apoptosis index for taste cells in the SARS-CoV-2 group than for those in the control group. An immunohistochemistry analysis indicated significantly more TNF-α-positive cells in the SARS-CoV-2 group compared with the control group. These data suggest that the SARS-CoV-2 spike protein promotes taste cell apoptosis and the release of apoptosis-related cytokine TNF-α, implicating its contribution to the taste malfunction caused by coronavirus disease 2019 (COVID-19).

Tracheal Bronchus Detected During General Anesthesia: A Case Report.

A tracheal bronchus is a congenital abnormality of the tracheobronchial tree in which a displaced or accessory bronchus arises from the trachea superior to its bifurcation. We herein report a case in which a tracheal bronchus was incidentally found after induction of general anesthesia, and we discuss the potential airway management problems that may have ensued. An 80-year-old man was scheduled for buccal mucosa resection and abdominal skin grafting for treatment of squamous cell carcinoma of the left buccal mucosa. Because of trismus and anticipated airway difficulty, an awake intubation was performed under sedation. A 3-branched structure was incidentally observed at the first branching site that was supposed to be the carina. The tip of the endotracheal tube was repositioned 3 cm above the tracheal trifurcation, and the rest of the procedure proceeded uneventfully. A flexible fiberoptic scope is not used in many anesthesia cases, making the identification of such tracheal or bronchial abnormalities more difficult. Therefore, it is important to carefully check the bronchial morphology on any available chest radiographs before surgery, listen to lung sounds after intubation, and assess thoracic lung compliance without neglecting routine safety checks.

SARS-CoV-2 recombinant proteins-induced degeneration of taste buds in rat circumvallate papillae.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections cause loss or alteration of taste and smell as early symptoms and sequelae, but the detailed mechanism remains unclear. This study investigated whether coronavirus disease 2019-induced taste disorders are caused by direct effects on taste bud cells. SARS-CoV-2 recombinant spike and nucleocapsid proteins were applied to circumvallate papillae of male Sprague-Dawley rats. Immunohistochemistry and image analysis were used to compare the number of taste buds, and taste bud cells and area, together with confirmation of angiotensin-converting enzyme 2 (ACE2) expression. Immunohistochemical analysis revealed ACE2 expression in the taste buds of rat circumvallate papillae. Decreases in the number of taste buds, taste bud cells, and their area were observed at 12 days after application of SARS-CoV-2 recombinant spike and nucleocapsid proteins. These data suggest that SARS-CoV-2 proteins induce degeneration of taste buds.

Changes in Magnetic Resonance Signal Fluctuation in Superior Sagittal Sinus: Deterioration of Arteriolar Vasomotor Function of Young Smokers.

(1) Cerebral arteriolar vasomotor function is vital for brain health and has been examined through CO2 inhalation or breath-holding, which are both challenging for patients. We have developed a non-invasive method to evaluate this function with magnetic resonance imaging (MRI) by utilizing respiration-induced natural changes in partial pressure of arterial CO2 (PaCO2). In this study, we applied this method for 20s to evaluate the chronic effect of a few years smoking on the cerebral arteriolar vasomotor function. (2) A single slice (five slice thicknesses: 15 mm to 7 mm) perpendicular to the superior sagittal sinus of was imaged successively for 45 s using spin-echo echo-planar imaging by 3T MRI for ten smokers (24.5 ± 1.6 years) and ten non-smokers (24.3 ± 1.4 years), respectively. The venous oxygenation fluctuation (ΔYr) caused by the respiration-induced changes of PaCO2, which reflects the arteriolar vasomotor function, was calculated from the time series MR signal changes of superior sagittal sinus. (3) The ΔYr values of the smokers (0.7 ± 0.6) were significantly lower than those of the non-smokers (1.3 ± 0.8) (p = 0.04). (4) Degeneration of the cerebral arteriolar vasomotor function due to chronic smoking (even after 20s) was demonstrated by our non-invasive MRI-based method.

Role of voltage-gated sodium channels in axonal signal propagation of trigeminal ganglion neurons after infraorbital nerve entrapment.

Chronic pain arising from peripheral nerve injuries represents a significant clinical challenge because even the most efficacious anticonvulsant drug treatments are limited by their side effects profile. We investigated pain behavior, changes in axonal signal conduction and excitability of trigeminal neurons, and expression of voltage-gated sodium channels (NaVs) in the infraorbital nerve and trigeminal ganglion (TG) after infraorbital nerve entrapment (IoNE). Compared to Sham, IoNE rats had increased A- and C-fiber compound action potentials (CAPs) and Aδ component of A-CAP area from fibers innervating the vibrissal pad. After IoNE, A- and C-fiber CAPs were more sensitive to blockade by tetrodotoxin (TTX), and those fibers that were TTX-resistant were more sensitive to blockade by the NaV1.8 selective blocker, A-803467. Although NaV1.7 blocker, ICA-121431 alone, did not affect Aδ-fiber signal propagation, cumulative application with A-803467 and 4,9-anhydro-TTX significantly reduced the Aδ-fiber CAP in IoNE rats. In patch clamp recordings from small- and medium-sized TG neurons, IoNE resulted in reduced action potential (AP) depolarizing current threshold, hyperpolarized AP voltage threshold, increased AP duration, and a more depolarized membrane potential. While the transcripts of most NaVs were reduced in the ipsilateral TG after IoNE, NaV1.3, NaV1.7, and NaV1.8 mRNAs, and NaV1.8 protein, were significantly increased in the nerve. Altogether, our data suggest that axonal redistribution of NaV1.8, and to a lesser extent NaV1.3, and NaV1.7 contributes to enhanced nociceptive signal propagation in peripheral nerve after IoNE.

Subcapsular hepatic hematoma as a complicating cardiac surgery.

An 80-year-old woman was hospitalized for aortic valve insufficiency, paroxysmal atrial fibrillation, and ascending aortic aneurysm. She underwent aortic valve replacement, pulmonary vein isolation, left atrium appendectomy, and ascending aorta replacement. She developed a subcapsular hepatic hematoma during the surgery. The patient was managed conservatively and discharged successfully.

An autopsy case of adult-onset neuronal intranuclear inclusion disease with perivascular preservation in cerebral white matter.

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by appearance of eosinophilic hyaline intranuclear inclusions. While the main symptoms of adult-onset NIID are dementia or limb weakness, some patients present with encephalitic episodes and transient neurological symptoms. The pathophysiology of these acute, transient symptoms, however, remains unknown. Here, we describe an autopsy case of adult-onset NIID with progressive dementia and transient hemiparesis. The patient was a 70-year-old man without a relevant family history, and initially presented with progressive dementia. He then exhibited transient left hemiparesis at 75 years of age and died of ureteral cancer at 77 years of age. Neuropathological examination revealed the presence of multiple areas of focal spongiosis in the subcortical white matter and patchy myelin pallor of the white matter, as in previous reports. However, perivascular areas were preserved even in the damaged white matter. In addition, dense glial fibrillary acidic protein (GFAP)-immunoreactive astrocytic processes were observed in these areas. [Correction added on 23 January 2022, after first online publication: the preceding sentence has been corrected to improve readability.] GFAP immunohistochemistry revealed decreased density and morphological abnormalities of astrocytes in the affected white matter. These pathological findings might reflect blood-brain barrier impairment and dysregulation of blood flow, which may be related to the pathophysiology of the acute, transient symptoms observed in NIID.

Punctate Enhancement of Bilateral Basal Ganglia in a Case of Epstein-Barr Virus Encephalitis.

Epstein-Barr virus (EBV) encephalitis is caused by initial infection or reactivation of EBV. In adults, the risk factors of EBV encephalitis include human immunodeficiency virus infection, immunosuppressant drugs, congenital immune deficiencies, post-stem cell transplantation, and post-solid organ transplantation. However, a few cases of adult-onset EBV encephalitis without these risk factors were also reported. The efficacy of steroid or intravenous immunoglobulin remains unclear in the treatment of EBV encephalitis. Herein, we report a case of an 82-year-old man with fever and disturbance of consciousness who was diagnosed as having EBV encephalitis. Gadolinium-enhanced magnetic resonance imaging showed punctate enhancement in the bilateral basal ganglia, which resembled chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS). Symptoms and enhanced lesions improved after immunotherapy. Immunotherapy may be effective in the treatment of EBV encephalitis with CLIPPERS-like lesions.

[An adult case of neurocutaneous melanosis with acute exacerbation after a long asymptomatic period following excision of a melanocytic nevus].

Neurocutaneous melanosis is caused by postzygotic NRAS mutations in neural crest cells, resulting in large or multiple nevi in the skin and proliferation of leptomeningeal melanocytes in the central nervous system. The onset of neurological symptoms is usually before the age of 2 years, but it can also occur in adults. A 35-year-old male had been asymptomatic for a long time after excision of a large congenital melanocytic nevus, but he developed headache, disturbance of consciousness, and seizure. Methotrexate was ineffective, cerebral pressure was decreased by spinal drainage, and steroid pulse therapy was temporarily effective. Seizures and disturbance of consciousness worsened and the patient died on the 92nd day. Cerebrospinal fluid human melanin black-45 immunostaining and serum 5-S-cysteinyldopa (5-S-CD) were useful in diagnosing melanocytic proliferation, and serum 5-S-CD may be useful in predicting prognosis.

Thoracic endovascular aortic repair of a ruptured acute type B aortic dissection presenting with right hemothorax: a case report and review of the literature.

Ruptured acute type B aortic dissection is a life-threatening condition with a high mortality rate. Right hemothorax secondary to this condition is extremely rare. Herein, we report a successful treatment of a ruptured acute type B aortic dissection via thoracic endovascular aortic repair in a 45-year-old man who initially presented with right hemothorax. Contrast-enhanced computed tomography confirmed massive right hemothorax and acute type B aortic dissection in which the primary entry was located just below the left subclavian artery. Moreover, a possible rupture site in the descending aorta at the level of Th6 was identified. We then performed an endovascular aortic repair with left subclavian artery open surgical debranching. His postoperative course was uneventful. The patient did not have any complications at a 6-month follow-up.

Electromagnetic simulation of RF burn injuries occurring at skin-skin and skin-bore wall contact points in an MRI scanner with a birdcage coil.

PURPOSE: To simulate radiofrequency (RF) burns that frequently occur at skin-skin and skin-bore wall contact points. METHODS: RF burn injuries (thumb-thigh and elbow-bore wall contacts) that typically occur on the lateral side of the body during 1.5 T magnetic resonance imaging (MRI) scans were simulated using a computational human model. The model was shifted to investigate the influence of the position of the patient in an MRI scanner. The specific absorption rate (SAR), electric field, and temperature were mapped. RESULTS: Regarding the contact points located near the edge of the birdcage transmission coil, under the allowable maximum RF power exposure i.e., the average whole-body SAR at the safety limit value (2 W/kg), the 10-g-tissue-averaged SAR (SAR10g) at those points significantly increased for both the thumb-thigh (180 W/kg) and elbow-bore wall (48 W/kg) cases. Both values significantly exceeded the highest safety limit of the partial-body SAR (10 W/kg). The electric field, the square of which is proportional to SAR, was remarkably high near the edge of the birdcage transmission coil. The peak SAR10g for each injury case was associated with contact-point peak temperatures that reached 52 °C at approximately 1 min following RF exposure onset; a 1-min period of exposure to this temperature causes a first-degree burn. CONCLUSIONS: We demonstrated high heat generation in RF burn injury cases in silico. The RF heating occurring on the lateral side of the body was strongly dependent on the electric field distribution, which is dominantly determined by an RF transmission coil.

Selective targeting of peripheral cannabinoid receptors prevents behavioral symptoms and sensitization of trigeminal neurons in mouse models of migraine and medication overuse headache.

ABSTRACT: Migraine affects ∼15% of the world's population greatly diminishing their quality of life. Current preventative treatments are effective in only a subset of migraine patients, and although cannabinoids seem beneficial in alleviating migraine symptoms, central nervous system side effects limit their widespread use. We developed peripherally restricted cannabinoids (PRCBs) that relieve chronic pain symptoms of cancer and neuropathies, without appreciable central nervous system side effects or tolerance development. Here, we determined PRCB effectiveness in alleviating hypersensitivity symptoms in mouse models of migraine and medication overuse headache. Long-term glyceryl trinitrate (GTN, 10 mg/kg) administration led to increased sensitivity to mechanical stimuli and increased expression of phosphorylated protein kinase A, neuronal nitric oxide synthase, and transient receptor potential ankyrin 1 proteins in trigeminal ganglia. Peripherally restricted cannabinoid pretreatment, but not posttreatment, prevented behavioral and biochemical correlates of GTN-induced sensitization. Low pH-activated and allyl isothiocyanate-activated currents in acutely isolated trigeminal neurons were reversibly attenuated by PRCB application. Long-term GTN treatment significantly enhanced these currents. Long-term sumatriptan treatment also led to the development of allodynia to mechanical and cold stimuli that was slowly reversible after sumatriptan discontinuation. Subsequent challenge with a previously ineffective low-dose GTN (0.1-0.3 mg/kg) revealed latent behavioral sensitization and increased expression of phosphorylated protein kinase A, neuronal nitric oxide synthase, and transient receptor potential ankyrin 1 proteins in trigeminal ganglia. Peripherally restricted cannabinoid pretreatment prevented all behavioral and biochemical correlates of allodynia and latent sensitization. Importantly, long-term PRCB treatment alone did not produce any behavioral or biochemical signs of sensitization. These data validate peripheral cannabinoid receptors as potential therapeutic targets in migraine and medication overuse headache.

Torque property of titanium alloy cerebral aneurysm clips in a magnetic resonance scanner.

Titanium (Ti) alloys have been introduced in magnetic resonance (MR) safe implantable medical devices because the susceptibility of Ti is approximately 1/10 that of the Co-Cr-Ni alloy (Elgiloy), which was the previously preferred MR-safe material. The torque applied to metallic materials in an MR imaging (MRI) scanner is commonly believed to increase with the susceptibility of the material. However, a visual inspection showed that the torque applied to Ti alloy cerebral aneurysm clips is comparable with that in the case of those of Elgiloy. In this study, we measured the torque applied to the small test pieces of rods and aneurysm clips quantitatively in a 3-T MRI using an accurate self-developed torque measurement apparatus. The maximum torques of Ti alloy and Elgiloy rod test pieces were comparable as 1.1 and 1.2 µN·m, respectively. The values for Ti alloy aneurysm clips were distinctly higher than the values for those of Elgiloy. These contradictory results of a larger torque for smaller-susceptibility products could be explained by our new theory, which takes into account the crystal susceptibility anisotropy in addition to the conventional torque due to the shape anisotropy.

Circuit-Specific Early Impairment of Proprioceptive Sensory Neurons in the SOD1G93A Mouse Model for ALS.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which motor neurons degenerate, resulting in muscle atrophy, paralysis, and fatality. Studies using mouse models of ALS indicate a protracted period of disease development with progressive motor neuron pathology, evident as early as embryonic and postnatal stages. Key missing information includes concomitant alterations in the sensorimotor circuit essential for normal development and function of the neuromuscular system. Leveraging unique brainstem circuitry, we show in vitro evidence for reflex circuit-specific postnatal abnormalities in the jaw proprioceptive sensory neurons in the well-studied SOD1G93A mouse. These include impaired and arrhythmic action potential burst discharge associated with a deficit in Nav1.6 Na+ channels. However, the mechanoreceptive and nociceptive trigeminal ganglion neurons and the visual sensory retinal ganglion neurons were resistant to excitability changes in age-matched SOD1G93A mice. Computational modeling of the observed disruption in sensory patterns predicted asynchronous self-sustained motor neuron discharge suggestive of imminent reflexive defects, such as muscle fasciculations in ALS. These results demonstrate a novel reflex circuit-specific proprioceptive sensory abnormality in ALS.SIGNIFICANCE STATEMENT Neurodegenerative diseases have prolonged periods of disease development and progression. Identifying early markers of vulnerability can therefore help devise better diagnostic and treatment strategies. In this study, we examined postnatal abnormalities in the electrical excitability of muscle spindle afferent proprioceptive neurons in the well-studied SOD1G93A mouse model for neurodegenerative motor neuron disease, amyotrophic lateral sclerosis. Our findings suggest that these proprioceptive sensory neurons are exclusively afflicted early in the disease process relative to sensory neurons of other modalities. Moreover, they presented Nav1.6 Na+ channel deficiency, which contributed to arrhythmic burst discharge. Such sensory arrhythmia could initiate reflexive defects, such as muscle fasciculations in amyotrophic lateral sclerosis, as suggested by our computational model.

Three-dimensional quantification of magnetic resonance imaging artifacts associated with shape factors.

Differences in the volumes of artifacts caused by variously shaped titanium objects on magnetic resonance imaging (MRI) were evaluated. Spherical-, square cubic-, and regular tetrahedron-shaped isotropic, and elongated spherical-, elongated cubic-, and elongated tetrahedron-shaped anisotropic objects, with identical volumes, were prepared. Samples were placed on a nickel-doped agarose gel phantom and covered with nickel-nitrate hexahydrate solution. Three-Tesla MR images were obtained using turbo spin echo and gradient echo sequences. Areas with ±30% of the signal intensity of the standard background value were considered artifacts. Sample volumes were deducted from these volumes to calculate the total artifact volumes. Isotropic samples had similar artifact volumes. For anisotropic samples, the artifact volume increased in proportion with the normalized projection area. MRI artifact size can be reduced by high anisotropic designs, and by positioning the long axis of the metal device as parallel as possible to the magnetic field axis.

Heating sensation in patients with and without spinal fixation devices during MRI examination at different magnetic field strengths.

BACKGROUND: Radiofrequency (RF) heating during MRI theoretically increases with magnetic field strength. In addition, implanted metallic devices are reported to further increase RF heating. However, a detailed evaluation of this type of heating remains scarce in clinical practice. PURPOSE: To assess possible risks and discomfort related to RF heating during MRI examinations of patients with and without metallic implantable devices. STUDY TYPE: A retrospective study of previous questionnaire results on the heating sensation during MRI examinations of the lumbar spine. SUBJECTS: In all, 715 patients, of whom 101 had implanted lumbar spine fixation devices. FIELD STRENGTH/SEQUENCE: 1T and 3T/T1 - and T2 -weighted imaging. ASSESSMENT: The number of patients who perceived heating around the lumbar spine or other regions during the MRI examination. STATISTICAL TESTS: A chi-square test with respect to static field strength B0 , presence of lumbar spine fixation devices, and duration of the MRI examination. RESULTS: The number of patients who perceived heating around the lumbar spine during the MRI examination significantly increased from 5.0% at 1T to 47.5% at 3T (P < 0.001), without a significant difference between patients with and without lumbar spine fixation devices (P = 0.23 at 1T, P = 0.48 at 3T), and regardless of the duration of the MRI examination (P = 0.88 at 1T, P = 0.15 at 3T). DATA CONCLUSION: Sensation of RF heating increased by around 10 times from 1T to 3T MRI examination, but the influence of implanted lumbar spine fixation devices on the RF heating sensation has not been observed. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:525-533.