Naohiro Ohshita

Characteristics of the trigeminal depressor response in cats

We studied the effects of electrical stimulation of the inferior alveolar nerve (IAN) on cardiovascular responses in cats. There was statistical correlation between cardiovascular response and prestimulus mean arterial blood pressure (MABP) and heart rate (HR). A trigeminal depressor response (TDR) was induced when the prestimulus MABP and HR were above 95 mm Hg and 140 beats/min, respectively. We investigated further to identify the vasomotor regulating center and neural transmitters involved in TDR. In the medulla, electrical stimulation of the dorsomedial medulla, the infratrigeminal nucleus (IFT), and the rostral ventrolateral medulla (RVLM) induced a vasopressor response. We confirmed that neurons in the RVLM were retrogradely labeled by wheat germ agglutinin‐conjugated horseradish peroxidase injection into the nucleus intermediolateralis of the spinal cord. The vasopressor response induced by IFT stimulation was similar to that induced by IAN stimulation. Vasodepressor responses were induced when the caudal ventrolateral medulla, the nucleus tractus solitarius, the lateral tegmental field, the trigeminal nucleus interpolaris, the trigeminal spinal tract, and the paramedian reticular nucleus were stimulated. These responses, however, were not similar to the vasodepressor response induced by IAN stimulation but were similar to the cardiovascular response induced by vagal afferent stimulation. After spinalization or lesion of the RVLM, MABP and HR decreased and TDR completely disappeared. Inhibitory synaptic ligands and receptors were localized using immunohistochemical techniques. Neurons immunopositive for adrenaline, noradrenaline, and γ‐aminobutyric acid (GABA), and adrenaline α2A, GABAA, GABAB, and glycine receptors were distributed along the sympatho‐reflexive route including the RVLM and IFT. These results suggest that TDR could be induced as negative feedback to sympathetic hyperactivity whenever MABP and HR are high, because of the inhibitory control of the RVLM.

Propofol is not effective for hyperventilation syndrome.

H yperventilation syndrome (HVS) occurs in approximately 6%–11% of the general patient population (1). Death (2,3) and hypoxemia (4) are associated with HVS. In addition, HVS is a complication sometimes encountered in dentistry (5–7). Some patients with severe HVS may require drug treatment. Benzodiazepines are generally prescribed for HVS, although little is known about whether propofol is effective for its prevention or treatment. We describe a patient with HVS, which could not be prevented and treated with IV sedation by a continuous infusion of propofol but in which the administration of midazolam was effective.

Anesthetic Management of a Patient With Multiple Sclerosis

A 54-year-old woman diagnosed with multiple sclerosis (MS) at the age of 19 years was scheduled to undergo temporomandibular joint mobilization. She was currently in a remission phase from her MS but with persistent sequelae, including impaired eyesight and muscle weakness of the limbs. In addition, the blood vessels in her upper limbs were compromised by the formation of internal shunts secondary to vascular prosthesis replacements for plasma exchange therapy in MS. After a previous joint mobilization surgery, her temporomandibular joint developed adhesions with resultant trismus. One of the adverse effects of general anesthesia can be exacerbations of MS symptoms. Minimizing mental and physical stress caused by surgical and anesthetic procedures and maintenance of stable body temperature are important considerations. Awake intubation was performed under sedation with midazolam and fentanyl. After intubation, anesthesia was induced with propofol, remifentanil, and rocuronium. Maintenance of anesthesia was achieved with oxygen-N2O-sevoflurane, remifentanil, fentanyl, and rocuronium. In this case, no adverse events occurred intraoperatively. However, the patient experienced lingering weakness of the limbs in the postoperative period, and activities of daily living of the patient were affected.

Anesthetic Management of a Patient With Ehlers-Danlos Syndrome

We describe the case of a 37-year-old woman who had been diagnosed with Ehlers-Danlos syndrome (EDS) 4 years earlier and was scheduled to undergo removal of synovial chondromatosis in the temporomandibular joint. EDS is a heritable connective tissue disorder and has 6 types. In this case, the patient was classified into EDS hypermobility type. The major clinical feature of this type is joint hypermobility. The patient had sprain or subluxation of the elbows and ankles and dislocation of the knees. Anticipated problems during general anesthesia would be affected by the disease type. For this patient, extra attention was directed to positional injury-induced neuropathy and articular luxation, cutaneous injuries, injuries related to intubation and ventilation, and postoperative pain. Anesthesia was induced with propofol, remifentanil, and rocuronium and maintained with oxygen-air-desflurane, propofol, remifentanil, fentanyl, and rocuronium. In this case, the patient was safely managed without adverse events.

Anesthetic Management of a Patient With Charcot-Marie-Tooth Disease

Charcot-Marie-Tooth disease (CMTD) is a hereditary peripheral neuropathy and is characterized by progressive muscle atrophy and motor-sensory disorders in all 4 limbs. Most reports have indicated that major challenges with general anesthetic administration in CMTD patients are the appropriate use of nondepolarizing muscle relaxants and preparation for malignant hyperthermia in neuromuscular disease. Moderate sedation may be associated with the same complications as those of general anesthesia, as well as dysfunction of the autonomic nervous system, reduced perioperative respiratory function, difficulty in positioning, and sensitivity to intravenous anesthetic agents. We decided to use intravenous sedation in a CMTD patient and administered midazolam initially and propofol continuously, with total doses of 1.5 mg and 300 mg, respectively. Anesthesia was completed in 3 hours and 30 minutes without adverse events. We suggest that dental anesthetic treatment with propofol and midazolam may be effective for patients with CMTD.