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Biomedical subjects

T Kitajima

Publications and source records attributed to T Kitajima.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

A generalized Hebbian rule for activity-dependent synaptic modifications.

In this paper our previous model of activity-dependent synaptic modification is extended and applied to a model neuron with active dendrites and is used in computer simulations to examine in detail the dependence of synaptic modifications on the interval between the onset of excitatory postsynaptic potentials (EPSPs) and postsynaptic action potentials (APs). The EPSP amplitude is increased when the action potentials occur within 20 ms after EPSPs and is reduced when the action potentials occur within 20 ms before EPSPs. Furthermore, the absolute value of changes in the EPSP amplitude tends to increase as the interval between APs and EPSPs decreases. A learning rule for synaptic modifications described in this paper may, hence, further generalize the Hebbian rule which requires conjunctive presynaptic and postsynaptic activity for synaptic modification to occur. Functional roles for such a generalized Hebbian rule are also considered.

Action Potentials↗
PubMedDate not supplied

Delayed severe airway obstruction due to hematoma following stellate ganglion block.

BACKGROUND AND OBJECTIVES: Delayed onset of airway obstruction following stellate ganglion block (SGB) may be life threatening. We treated a patient who developed a severe airway obstruction caused by a large hematoma several hours after an SGB. METHODS: A 62-year-old woman suffering from sudden deafness developed dyspnea 2 hours after undergoing her fourth SGB, and evidenced swelling and tenderness in her anterior neck and chest. Her pharyngolaryngeal tissues were edematous, and the glottis was markedly narrowed. Computed tomograms and magnetic resonance images revealed a large soft tissue mass extending from the first cervical vertebra to the diaphragm. RESULTS: Surgical tracheotomy was performed to maintain her airway. Swelling of the vocal cord disappeared on the eleventh day after the operation. CONCLUSIONS: We believe that the SGB needle injured the vertebral artery and caused massive hemorrhage anterior to the cervical vertebra, subsequently inducing pharyngolaryngeal edema by obstructing the venous and lymphatic drainage of the cervical region.

Airway Obstruction↗
PubMedDate not supplied

Excision of spinal tumor in a patient with severe pulmonary dysfunction using combined spinal and epidural anesthesia with two epidural catheters.

BACKGROUND AND OBJECTIVES: Combined spinal and epidural anesthesia (CSEA) has become common practice. We performed CSEA using two epidural catheters in a 69-year-old female with severe pulmonary dysfunction caused by a diaphragmatic hernia, who underwent surgical excision of a lumbar spinal tumor. METHODS: Combined spinal and epidural anesthesia was performed using two epidural catheters to minimize postoperative pulmonary complications. One epidural catheter was inserted above the surgical region, at the T11-12 interspace, and another one below the surgical region, via the sacral hiatus. Spinal anesthesia was produced using the L5-S1 interspace and 3 mL 0.5% bupivacaine. Oxygen, 3 L/min, was administered through a face mask during surgery. RESULTS: Fifteen minutes after spinal anesthesia, analgesic level was confirmed below T7 using the pinprick method. The patient complained of pain in the surgical region 10 minutes after the dura mater was opened. We injected 5 mL 2% mepivacaine through the upper epidural catheter to relieve the pain. We also injected 10 mL 2% mepivacaine through the lower catheter when she felt pain in the right leg. The perioperative course was uneventful. Oxygen saturation was maintained above 95%. CONCLUSIONS: Combined spinal and epidural anesthesia using two epidural catheters was used successfully to excise a spinal tumor in a patient with severe pulmonary dysfunction.

Anesthesia, Epidural↗
PubMedDate not supplied

Use of computed tomography for maxillary nerve block in the treatment of trigeminal neuralgia.

BACKGROUND AND OBJECTIVES: Maxillary nerve block has traditionally been performed by using external anatomic landmarks. However, the classic approach to the nerve may be confounded because of anatomic variability. We describe a technique for the block using the suprazygomatic route guided by computed tomography (CT). CASE REPORT: A 90-year-old woman had a 30-year history of episodic pain in her right maxillary region. We attempted to block the maxillary nerve with classic technique, but we could not identify the nerve by eliciting paresthesia. In addition, bleeding was noted after repeated attempts. To minimize complications and confirm the correct position of the needle tip, we planned the block with a suprazygomatic approach using CT guidance. The needle was inserted without paresthesia. The CT scan showed the needle tip was placed at the entrance of the pterygopalatine fossa and the distribution of contrast medium spread appropriately around the pterygopalatine fossa. After confirming the clinical effect and lack of complications of the block using the local anesthetic, 0.5 mL of 7% phenol was injected. This technique resulted in complete sensory loss in the area innervated by the maxillary nerve, and did so without complications. CONCLUSIONS: A maxillary nerve block guided by a CT imaging is an alternative to classic techniques.

Aged↗
PubMedDate not supplied

Acute cigarette smoking reduces vasodilative effect induced by sympathetic block in dogs.

BACKGROUND AND OBJECTIVES: The aim of this study is to clarify the influence of acute cigarette smoking on vasodilation induced by sympathetic block. METHODS: We measured mean arterial pressure, heart rate, left brachial artery blood flow (BABF), right femoral artery blood flow (FABF), and plasma catecholamines in dogs to examine the effect of acute cigarette smoking after stellate ganglion block (SGB). The experimental protocol was: (1) Left SGB using 1.0 mL 0.5% mepivacaine without smoking (sham smoking); and (2) left SGB using 1.0 mL 0.5% mepivacaine followed by a single cigarette smoking (nicotine 1 mg) 15 minutes after the block. RESULTS: SGB induced a significant increase of BABF during the study (baseline, 100%; peak at 10 minutes after SGB, 176% +/- 9%; P <.05) in sham smoking and a significant decrease of FABF from 10 minutes after the block to 20 minutes after sham smoking (baseline, 100%; bottom at 5 minutes after sham smoking, 82% +/- 8%; P <.05). Smoking after SGB induced a significant decrease of BABF 60 minutes after smoking (baseline, 100%; 69% +/- 11%; P <.05) and a significant decrease of FABF during the study (baseline, 100%; bottom at 20 minutes after smoking, 74% +/- 20%; P <.05). Smoking significantly increased plasma norepinephrine and epinephrine through the study. CONCLUSIONS: Sympathetic block induces a significant increase of peripheral blood flow, but smoking produces a significant decrease in the blood flow in the SGB-induced dilated vessels.

Anesthetics, Local↗