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Biomedical subjects

T Iwabuchi

Publications and source records attributed to T Iwabuchi.

At least 19 recordsLinked to original sources
PubMed1992

A ring electrode to record extraocular muscle activities during skull base surgery.

A ring-shaped electrode was developed and used in 20 patients to record evoked electromyographic responses directly from the extraocular muscles during skull base surgery. Intra-operative monitoring with this electrode helps the surgeon to localize the nerves that innervate the extraocular muscles precisely and to refrain from disturbing important neural structures during operations. Such monitoring also provides some insight into the pathophysiology of the dysfunction of these nerves resulting from skull base lesions.

Abducens Nerve↗
PubMed1992

[The dura mater adjacent to the attachment of meningiomas: its enhanced MR imaging and histological findings].

The dura mater adjacent to the attachment of meningiomas was enhanced on MR imaging with intravenous Gd-DTPA infusion. It was examined histologically in four patients with intracranial globoid meningiomas. Histological examination revealed that there was no tumor cell invasion within the dura mater enhanced on MR imaging, except at the point of their attachment. A layer of tumor cells was occasionally observed on the surface of the dura mater, but this was limited to within 5 mm of the tumor margin. Our electronmicroscopic observation indicated that enhancement of the dura mater adjacent to the attachment of meningiomas was caused by increased vascular permeability of the dural vessels and extended extravascular space.

Aged↗
PubMed1992

[Electrophysiological identification of the cochlear and vestibular nerves in the cerebellopontine angle: experimental study and clinical implication].

Electrical stimulation was applied on the surface of the eighth cranial nerve in the cerebellopontine angle of dogs and the evoked potentials were recorded with surface electrodes on the scalp. The shape of the evoked potentials recorded was different according to the portion of the nerve stimulated electrically. It was, therefore, possible to precisely identify the nerve stimulated from the surface recorded evoked potentials. This electrophysiological method may be helpful for the surgeon to precisely locate the cochlear and vestibular nerves in various operations in the cerebellopontine angle in human. Our preliminary experience of this monitoring method in acoustic neuroma excision was presented.

Animals↗
PubMed1992

[Hallucinose pédonculaire with left MLF syndrome caused by midbrain infarction--a case report].

A 65-year-old male suffering from left MLF syndrome accompanied by transient hallucinose pédonculaire caused by the midbrain infarction is reported. In the first night of his admission with MLF syndrome, he complained of sleeplessness followed by transient visual hallucination. The hallucination was vivid and colored scene in which many strangers were seen around the patient, and he was well oriented without dreadfulness at that time. A small infarction in the left tegmentum was revealed by MR imaging, which was supposed to cause the hallucination.

Aged↗
PubMed1992

[Five cases of intracranial lipoma; CT and magnetic resonance images].

We encountered five cases of intracranial lipoma after introduction of MRI. They were located in the quadrigeminal plate, interpeduncular fossa, pineal region and two of them were found in the cerebellopontine angle, (although intracranial lipoma in this location has been reported to be extremely rare). MRI can precisely locate a small lesion that would be overlooked by CT scans. Operative treatment was performed in two symptomatic cases (CP angle and pineal lesions) and the tumors were subtotally resected. The symptoms of the patients disappeared postoperatively. This indicated that even subtotal removal can alleviate the symptoms of intracranial lipomas and that favorable results can be obtained.

Adult↗
PubMed1992

[A case report of a massive pulmonary tumor embolism occurring during surgery for renal cell carcinoma].

A 59-year-old man, who suffered a massive pulmonary tumor embolism during surgery for renal cell carcinoma with vena caval invasion, was treated by emergency pulmonary embolectomy using cardiopulmonary bypass. Renal cell carcinoma occasionally extends into the inferior vena cava (IVC) as a tumor thrombus. In such patients, removal of the tumor thrombus from the IVC has to be performed in addition to radical nephrectomy. However, the massive pulmonary tumor embolism is a major potential hazard during radical surgical resection. To prevent intraoperative pulmonary embolisms from occurring, scheduled use of cardiopulmonary bypass with the cooperation of cardiovascular surgeons is recommended.

Carcinoma, Renal Cell↗
PubMed1991

Changes of plasma thromboxane level in subarachnoid haemorrhage. A study with 11-dehydro-TXB2 as measuring index.

Changes of plasma thromboxane level in subarachnoid haemorrhage (SAH) were studied clinically and experimentally using 11-dehydro-thromboxane B2 (11 DTX) as a measuring index. 11 DTX is a major long-lived metabolite formed from thromboxane (TX) B2, and is said to be a more reliable parameter for detecting TXA2 production in biological systems. In this clinical study, blood was sampled from the cubital vein of 10 SAH patients on the earliest possible day (day 0 or 1), during the vasospasm predilection period (day 7 approximately 11) and in the chronic stage (day 16 approximately 32). Plasma concentrations of 11 DTX and 6-keto-PGF 1 alpha were measured in clinical cases. A canine SAH model was produced by the two haemorrhage methods and blood was sampled from the superior sagittal sinus before and on day 4 of the first cisternal blood injection. 11 DTX, TXB2 and platelet function were examined in each sample. In the clinical studies, plasma 11 DTX levels tended to be higher in the early stage of SAH but decreased thereafter to the normal or lower level. Plasma concentrations of 6-keto-PGF1 alpha tended to decrease mildly during the vasospasm predilection period. In the experimental study, neither definite change of plasma 11 DTX level nor neurological deficit could be induced by the mimic SAH, while an increase in platelet aggregability and narrowing of the basilar artery were observed. 11 DTX was inferred to be a more reliable parameter of TX biosynthesis than TXB2.

Adult↗
PubMed1991

Progressive deterioration of auditory evoked potentials after excision of an acoustic neurinoma: case report.

The authors report the case of a 17-year-old girl who underwent excision of bilateral neurinomas of the cerebellopontine angle. Although her auditory evoked potentials were well maintained during the operation, they deteriorated gradually and progressively for the following 2 months. This seemed to reflect degeneration of the cochlear nerve fibers initiated by operative manipulation in the cerebellopontine angle in a patient who had no hearing when she awoke from surgery.

Adolescent↗
PubMed1991

Vestibular nerve injury as a complication of microvascular decompression.

We report a case of hemifacial spasm in which hearing was well preserved after microvascular decompression, but the vestibular nerve was injured selectively. We review the pathophysiological mechanisms relevant to this complication in the light of results of animal experimental studies we have conducted. In addition, we discuss the clinical significance of this particular type of cranial nerve injury.

Arteries↗
PubMed1991

Rotatostereoradiography: a new radiodiagnostic method--development of a new three-dimensional radiodiagnostic device and evaluation in neurosurgical clinics.

The rotatostereoradiographic device uses an x-ray tube coupled with an image intensifier rotating through a 180 degree arc in 2.25 seconds. The rapidly rotating x-ray tube allows 180 degree-arc angiograms to be obtained with a single injection of contrast medium. Subtracted fluoroscopic angiograms can be viewed immediately after injection of the contrast medium with digital recording. These three-dimensional images are displayed on side-by-side monitors stereoscopically. The mortality and morbidity of subarachnoid hemorrhage can only be greatly reduced by surgical treatment of unruptured aneurysms and arteriovenous malformations detected by a wide survey of subarachnoid hemorrhage. Such a wide survey would be possible utilizing intra-arterial digital subtraction angiography via the ascending aorta and this new three-dimensional radiodiagnostic method. A fluoroscopic device must be used to allow easier manipulation of the catheter from the axillary or brachial artery.

Adult↗
PubMed1991

[Effects of perfluorochemicals on the depressed rCBF and brain metabolism shortly after the hypertensive ICH].

The effect of perfluorodecalin and perfluorotripropylamine, Fluosol DA-20% (FDA-20%), on the ischemic brain after hypertensive intracerebral hemorrhage (ICH) was evaluated and the mechanism investigated. Regional cerebral blood flow (rCBF), and cerebral metabolic ratios of oxygen (CMRO2) and glucose (CMRGlu) were measured before and after infusion of FDA-20%. The rCBF was estimated by single photon emission computed tomography using the 133Xe inhalation method, and CMRO2 and CMRGlu were determined by calculating arteriovenous difference between the femoral artery and the jugular bulb. The results showed: 1) The mean cerebral blood flow (mCBF) in both affected and non-affected hemispheres significantly increased by 10-20% over the control during 3 hours and 6-12 hours after infusion of 500 ml and 1000 ml FDA-20%, respectively. 2) Administration of 500 ml FDA-20% caused a maximal increase of 15% in CMRO2 and 24% in CMRGlu, and 1000 ml FDA-20% administration caused a maximal increase of 30% in CMRO2 and 75% in CMRGlu. 3) There was no significant change in mean blood pressure, arterial partial pressure of carbon dioxide and oxygen, or hematocrit before and after FDA-20% infusion. The results indicate that FDA-20% improved rCBF and brain metabolism in the ischemic brain of hypertensive ICH. FDA-20% may operate as an excellent oxygen carrier, and stimulate the brain metabolism directly.

Adult↗
PubMed1991

[Preoperative treatment of esophageal cancer with oral peplomycin jelly].

Pepleo-jelly, peplomycin (PEP) compounded with sodium polyacrylate (PANa), was used as a local preoperative chemotherapy for esophageal cancer. Thirty milligrams of PEP emulsified in 10 ml of jelly was orally administered for 17 patients on consecutive bed time, and the average total dose was 470 mg. Concentrations of PEP in blood and tissue were measured with a bioassay. PEP was not detected in the blood but was detected in esophageal tissue and regional lymphnodes. A significant difference (p less than 0.05) of tissue concentrations between normal esophageal mucosa (0.11 microgram/g) and malignant region (0.34 microgram/g) was noted. Furthermore, PEP was detected in many regional lymphnodes. Histological antitumor effect (Ef2) was noted in three of the eight metastatic lymphnodes. A side effect of this treatment was not recognized. It is believed that this treatment is safe and useful in combination with other adjuvant cancer therapy.

Acrylic Resins↗
PubMed1991

[P3 portion aneurysm of the posterior cerebral artery; a case report].

A case was reported of surgically treated saccular aneurysm located at the right posterior temporoparietooccipital artery junction (P3 portion of PCA). An aneurysm of this portion is said to be rare, and only 7 cases have been described so far. A 74-year-old female was transferred to our clinic, after 3, 5 months of sustaining aneurysmal rupture, for surgical treatment. The patient had been treated conservatively because of her severe condition in the early stage. She was in nearly apallic state with left hemiparesis at the time of admission to our clinic. During the acute stage of her illness, moderate hematoma in the right ambient cistern without hydrocephalus, and an aneurysm at P3 portion of the right posterior cerebral artery with marked arteriosclerosis were delineated by CT, and by right vertebral angiography respectively. However, in the CT taken 3, 5 months after the onset, moderate hydrocephalus and a low density area in the right internal capsule were detected. Aneurysmal neck clipping was performed using the right posterior subtemporal approach, without any deformity of the parent arteries. Occlusion of the right parietooccipital artery occurred, however, probably on the 2nd postoperative day. Despite the newly developed left homonymous hemianopsia, general condition, including consciousness level, improved postoperatively particularly after the ventriculo-peritoneal shunt was carried out.

Aged↗
PubMed1991

[Intracranial administration of tissue plasminogen activator and its important factors involved concerning the pH and osmotic pressure].

Tissue plasminogen activator (t-PA) is expected to be used for cisternal drainage in subarachnoidal hemorrhage, for dissolving of the residual hematoma after stereotactic evacuation of a cerebral hematoma, and for regional intraarterial injection therapy for occlusion of the primary cerebral artery. This is because the drug exerts a very potent and immediate dissolving-effect on a hematoma when it is locally administered. However, the solubility of t-PA is rapidly decreased at pH 5 or more. At pH 7 or more, precipitation of crystals is observed when the concentration of t-PA exceeds 20 x 10(4) IU/ml. The pH of the t-PA general-purpose solution (for intravenous injection) is adjusted at 4.6 to 4.8 because of its solubility and stability, and the osmotic pressure is also increased with an increase in concentration of t-PA. When the concentration of t-PA is 750 x 10(4) IU/ml, the osmotic ratio is 30 and the pH is 4.82. These features suggest that a locally administered t-PA solution at high concentration may induce meningeal irritation leading to headache and vomiting, and exacerbation of symptomatic cerebral vasospasm when it is used for cisternal drainage. Furthermore, the t-PA solution administered intraarterially at high concentration may induce adverse effects such as dessiocyte and echinocyte deformation of erythrocytes and the sludging phenomenon of leukocytes in the cerebral microcirculation, and a sensation of fever and pain upon injection. Therefore, the dose and method of administration of the t-PA for local intracranial use should be determined by taking into consideration its pH and osmotic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Occurrence of vestibular and facial nerve injury following cerebellopontine angle operations.

To elucidate how surgery in the cerebellopontine (CP) angle may cause vestibular and facial nerve injury, the 7th and 8th cranial nerves of dogs were manipulated as in human surgery along with monitoring of auditory evoked brain stem responses. Postoperatively, histological examinations were performed to investigate the effect of the surgical manipulations. We found that the occurrence of vestibular, facial and cochlear nerve injury was dependent on the direction of the excessive movement of the nerves in the cerebellopontine (CP) angle. Caudal-to-rostral shift of the nerve trunk most effectively avulsed the vestibular nerve. Haemorrhages were revealed between the vestibular ganglion and the fundus of the internal auditory canal. This caudal-to-rostral retraction could also damage the facial nerve in its intrapetrous labyrinthine portion. This was likely to be one of the pathophysiological mechanisms responsible for postoperative facial nerve palsy occasionally observed in human cases. Rostral-to-caudal retraction of the cerebellum damaged the cochlear nerve selectively. Although caudal-to-rostral retraction, instead of lateral-to-medial one, has been recommended to protect the cochlear nerve, this retraction was shown to be dangerous to the vestibular nerve if excessive. The clinical significance of the fragility of the vestibular nerve was discussed and the importance of preserving the vestibular nerve function is stressed.

Animals↗
PubMed1990

Clinico-statistical study on morphological risk factors of middle cerebral artery aneurysms.

Influences of various factors on postoperative outcome of 122 well-documented cases, out of a total of 151 cases of middle cerebral artery aneurysm, are discussed in this paper. The shape of the aneurysm, major axis, major axis/neck and major/minor axis ratio were correlated with the presence or absence of a bleb (p less than 0.0000001), and indicated a correlation not only between aneurysmal shape and the outcome (p less than 0.05) but also between preoperative seriousness and the outcome (p less than 0.05). The preoperative seriousness and the grade of subarachnoid haemorrhage indicated a close correlation between each of these two parameters and the outcome (p less than 0.000001 for each). Both the quantity and the colour of CSF outflow from the chiasmal cistern showed close correlation with vasospasm (p less than 0.01), onset of hydrocephalus (p less than 0.01) and the outcome (p less than 0.001). Moreover, vasospasm and hydrocephalus grade itself also showed close correlation with the outcome (p less than 0.001 and p less than 0.00001). All parameters: blood pressure grade, BPmax, BPmin, BP fluctuation showed correlations not only with preoperative seriousness (p less than 0.001) and the outcome (p less than 0.0001) but also with subarachnoid haemorrhage frequency, number of aneurysms, and major axis/neck ratio.

Activities of Daily Living↗