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T Iwabuchi

Publications and source records attributed to T Iwabuchi.

At least 91 records · Page 5Linked to original sources
PubMed1989

[Relationship between directions of cerebellar retractions and cochlear and vestibular nerve injuries].

It is said that lateral-to-medial retraction of the cerebellar hemisphere is hazardous because, by this retraction, avulsion injury of the cochlear nerve and internal auditory artery may be caused. Caudal-to-rostral retraction of the cerebellar hemisphere is, therefore, recommended in operations in the CP angle such as microvascular decompression procedures. From the results of our present study, however, it can be said caudal-to-rostral retraction can easily cause vestibular nerve damage. However, rostral-to-caudal retraction may damage the cochlear nerve just as lateral-to-medial retraction does. These differences of the eighth nerve injuries according to directions of cerebellar retractions are explicable from the fact that the vestibule and vestibular nerve are located posterior to the cochlea and cochlear nerve. Most of dysequilibrium appearing after manipulations in the CP angle may be due to vestibular nerve damage-avulsion of the vestibular nerve and its accompanying vessels from the vestibular apparatus.

Action Potentials↗
PubMed1988

Damage of the peripheral auditory system after operations in the cerebellopontine angle. A scanning electron-microscopic observation in dogs.

Cochlear nerve injuries caused by manipulations in the cerebellopontine angle were electrophysiologically and morphologically investigated in dogs. Operative procedures similar to those performed in the cerebellopontine angle of humans were applied in dogs. Auditory-evoked potentials were recorded throughout the experiments. Postoperatively, the temporal bones were studied with a scanning electron microscope. The portions of the cochlear nerve fibers and branches of the internal auditory artery that exit from the bony cochlea into the internal auditory canal were susceptible to traction force derived from manipulations in the cerebellopontine angle. The cochlear nerve fibers from the basal turn of the cochlea were most easily pulled out from the fundus of the internal auditory canal. In some cases, massive hemorrhages and exudation of plasma were observed in the entire modiolus; these compressed the cochlear nerve trunk. The Schwann-glial junctions of the cochlear nerves were separated in some dogs, indicating this junction was one of the most vulnerable sites to operative manipulations in the cerebellopontine angle.

Animals↗
PubMed1986

An angiographic study of incidence and morphology of infundibular dilation of the posterior communicating artery.

In the last 9 years, infundibular dilatation (ID) has been sought in 260 aneurysm (An) cases and 398 carotid angiogram's (CAG) to reveal its incidence and morphology. Findings were as follows: The incidence was about double that so far published. Small ID, usually triangular in shape, tended to become round as it grew larger (P less than 0.01). Large ID favored young age (P less than 0.05). In internal carotid-posterior communicating aneurysm (IC-P com An) cases, a high incidence of ID was noted as compared to other An cases (P less than 0.05), and intermediate or large, round ID accounted for high ratios. Cases with a history of hypertension showed a high large ID ratio (P less than 0.05). Cases with well developed P com A had a high ratio of large, round ID (P less than 0.01). In cases with a large divergent angle of ICA and P com A, intermediate or large, round ID was found in high ratio (P less than 0.05). Aggressive follow-up or treatment was thought necessary in cases which possess the factors mentioned.

Adolescent↗
PubMed1986

Dural sinus pressure: various aspects in human brain surgery in children and adults.

To prevent air embolism and minimize neurosurgical venous hemorrhage, the dural sinus pressure (confluens sinuum pressure, CSP) was examined under various conditions in 47 cases, 11 of whom were children. Either the extracranial (group A) or catheter type (group B) pressure transducer was used. The latter gave approximately 30% higher values than the former. In any surgical position, children showed a tendency toward higher pressure than did adults. This was particularly the case in the sitting position; adults showed negative pressure [-8.6 +/- 2.3 (SD) mmHg, group A], whereas all eight children less than 9 yr of age (group A, 5 cases; group B, 3 cases) showed positive pressure. The youngest with negative CSP in a sitting position was a 9-yr-old boy. When the upper half of the body was raised, the CSP decreased linearly and became zero at approximately 25 degrees. In anteflexion of the neck, the CSP decreased significantly, and even with inclination of the upper half of the body of only 15-20 degrees or more upward, negative pressure was observed in adults. In children, right and left rotation of the neck showed remarkable increase of the CSP. In both supine and sitting positions, CSP was elevated sufficiently by bilateral jugular compression to prevent air embolism. Positive-pressure respiration did not raise the CSP, contrary to widely accepted knowledge. This study was originally performed in relation to brain surgery, but the results also seemed to be valuable in physiology.

Adolescent↗
PubMed1986

[Posterior fossa subdural hematoma in neonates: report of two cases and review of the literature].

Posterior fossa subdural hematoma in neonates caused by birth trauma is rare; only 30 clinical cases can be found in the literature so far. Here we experience two similar cases and review that literature. Case #1 is that of a full-term female born in the pelvic position. At 21 hours after birth she developed convulsions and a CT scan revealed a high-density area, mainly in the right posterior fossa. On the fourth day, a right suboccipital craniectomy was performed and about 15 ml of hematoma was removed. At present her mental and somatic development is appropriate for her age (5 months), despite the fact that moderate brain atrophy was seen in the CT scan taken at 4 months. Case #2 is that of a full-term female also born in the pelvic position. At 38 hours she became convulsive and opisthotonic; a CT scan revealed a high-density area in the posterior fossa. No neurological abnormality was seen thereafter, however, and she was treated conservatively. On the 18th day, the high-density area in the CT scan had almost disappeared. In the CT scan taken at 6 months moderate brain atrophy was seen, but at the present age of two she evidences quite normal development both mentally and somatically. These cases lead us to emphasize the importance of prompt diagnosis followed by removal of hematoma, and the usefulness of CT scan as a diagnostic method in clinical manifestations of this sort.

Birth Injuries↗
PubMed1985

Gangliocytoma of the pineal body. A case report and review of the literature.

Ganglion cell tumours are mostly seen in children and young people, but they are extremely rare, accounting for 0.1-0.5% of all brain tumours. It usually occurs in the floor of the third ventricle and the temporal lobe. Recently we have experienced a pineal gangliocytoma, probably the first ever seen in Japan and the fourth case in the world, and have succeeded in a total removal of it. The case concerns a 51-year-old man who suffered from intermittent blurred vision and headache of 3 years' duration. CT showed, together with severe hydrocephalus, positive contrast medium enhancement and a somewhat irregular but sharply circumscribed high density lesion suggestive of a meningioma. But the brain scintiscan revealed a badly and irregularly demarcated region of warm activity and having little change with time mainly in the pineal region, which was strongly suspicious of gliomas. Hence this scan was thought to be important in diagnosing this tumour. As an operative procedure, biparieto-occipital craniotomy was successfully performed in the "sea lion" position to remove the tumour totally. Pathological findings indicated a mixture of dispersion and concentration of giant cells possessing prominent nucleoli, abundant chromatin and a prominent nucleus or several nuclei of varying sizes and process-like cell bodies polygonal or irregular in shape. GFAP stain showing no glial fibres and the tumour was thought to be a gangliocytoma.

Brain Neoplasms↗
PubMed1985

Prevention of cerebral vasospasm with OKY-046 an imidazole derivative and a thromboxane synthetase inhibitor. A preliminary co-operative clinical study.

The prevention of cerebral vasospasm with OKY-046, an imidazole derivative and a thromboxane synthetase inhibitor, was studied co-operatively at ten neurosurgical services. Intravenous administrations of 2, 5 or 10 mu/kg/minute of OKY-046 were given continuously from the earliest possible day to the 14th SAH-day to 82 patients with ruptured cerebral aneurysm. Sixty-eight patients (83%) showed moderate to high high-density (SAH) in their initial CTs. Angiographic vasospasms were seen in 58 patients, representing 71% of all cases or 81% of the 72 cases for which angiograms were available: the vasospasms of 45 patients (55 or 63%) were moderate to severe. Symptomatic vasospasm occurred, however, only in 27 patients (33%): in 18 of those cases, moreover, the symptoms were mild or transient. The conditions of the patients at one month after the SAH were classified into 9 grades from 0 (normal) to 8 (deceased). Fifty-two patients (63%) were classified as 0 or 1, and 64 (78%) as better than 3 (possible daily life unaided). The administration of OKY-046 was proven to decrease TXB2 in the blood. This paper emphasizes the effectiveness of the drug for symptomatic vasospasm, and supports our previous contention that cerebral microthrombosis may play an important role in the pathogenesis of cerebral vasospasm.

Acrylates↗
PubMed1985

Deterioration of auditory evoked potentials during cerebellopontine angle manipulations. An interpretation based on an experimental model in dogs.

Evoked action potentials from the internal auditory meatus portion of the cochlear nerve (IAM-EAP's) and brain-stem auditory evoked potentials (BAEP's) from the vertex were simultaneously recorded during cerebellopontine angle (CPA) manipulations (retractions of the cerebellar hemisphere and the cochlear nerve) in dogs. The BAEP changes noted in these dogs were the same as those seen in patients. The IAM-EAP's showed graded deterioration related to BAEP changes. The results are as follows: Prolongation of the I-V interpeak latency of BAEP's, the most common finding during CPA manipulations, is the reflection of prolongation of the I-II interpeak latency, which is caused by conduction impairment or block of the nerve impulses between the extracranial portion of the cochlear nerve and the brain stem. The operative manipulations representing stretch or compression injury to the cochlear nerve in the CPA leads to an acute traumatic cranial nerve root lesion--a retrocochlear lesion. The obliteration of all BAEP components including wave I cannot be caused by conduction block. This is caused by occlusion of the internal auditory artery. Wave I of the BAEP's and the P1-N1 complex of the IAM-EAP's are important indicators of cochlear blood flow during surgical intervention. As possible causes of internal auditory artery obstruction, mechanical distortion of the relationship between the anterior inferior cerebellar artery (AICA) and the internal auditory artery at the junctional portion, mechanical vasospasm of the AICA-internal auditory artery complex, and ensuing no-reflow phenomena are discussed. Evoked action potentials are expected to be a useful intraoperative real-time monitor during CPA surgery that can detect rapid changes derived from cochlear artery insufficency. The real-time aspects can overcome some of the disadvantages of BAEP monitoring.

Animals↗
PubMed1984

Non-ionic water soluble contrast medium 3-deoxy-3-iodo-D-glucose (DIG) for use in the CSF space. An experimental study with mongrel and beagle dogs.

A non-ionic water soluble contrast medium, 3-Deoxy-3-Iodo-D-Glucose (DIG), was experimentally evaluated for use in the cerebrospinal fluid (CSF) space, and compared with other contrast media. Two ml (180 mgI/ml) of DIG were injected either intraventricularly or intracisternally in 15 adult mongrel dogs (average weight: 6.4 kg), and X-ray photographic, CSF, EEG, and histological studies were then performed. Additional tests were made on four beagle dogs (average weight: 9.8 kg), focussing particularly on changes in cell count and protein in the CSF following alternate intracisternal injections of 2 ml (170 mgI/ml) of DIG and metrizamide (Amipaque), and on epileptogenicity following intracisternal injection of 3 ml (300 mgI/ml) of DIG. That DIG provides adequate definition was demonstrated both by the ventriculograms and cisternograms, and by comparison with metrizamide. Neither epileptic discharges in the EEG nor epileptic symptoms were seen in any of the dogs used in the studies. In the CSF drawn 24 hours after the injection, protein tended to increase moderately with DIG, but pleocytosis was mild with both media. Histological studies of the central nervous system structures around the cisterna magna revealed no definite abnormal findings. Neither fibrosis nor arachnoid adhesions were seen in scanning electron microscopic observations of the basal subarachnoid spaces.

Animals↗
PubMed1984

A clinico-experimental study on various wrapping materials of cerebral aneurysms.

In this paper, we discuss the results of a systemic study of various materials so far used for wrapping, using the intracranial arteries of 43 mongrel dogs. The findings obtained are: Muscle, fascia and dura observed began to show necrotic and absorbable change within 1 to 2 months after operation, suggesting their unreliability. Bemsheet was superior in this study in adhesiveness to the vascular wall, highly contributory to constructing a firm reinforced wall by proliferating collagen fibres in the space of stereo-reticular structure of cotton fibre. No change occurred in the cotton fibre itself with the passage of time. Lyodura had a poor adhesiveness to the vascular wall with detectable gap; in addition, it showed necrosis and absorption in the bending site. Coating with Aron alpha A had a relatively poor adhesiveness to the vascular wall and seemed to crack and disappear with time.

Animals↗
PubMed1984

Total removal of a falcotentorial junction meningioma by biparietooccipital craniotomy in the sea lion position: a case report.

The successful total removal of a huge falcotentorial junction meningioma in a 59-year-old woman by biparietooccipital craniotomy with the patient in the sea lion position (prone with a hyperextended neck and with 20 degrees elevation of the upper and lower halves of the body) is reported, with some comments on the advantages of this approach and position. Taking advantage of the exposure of the dural sinus, the confluens sinuum pressure was measured by direct catheterization with the patient in various positions. The pressure was 3.6 cm H2O in the sea lion position, 2.4 cm H2O in the reverse jackknife position (supine with 20 degrees elevation of the upper and lower halves of the body), and -12 cm H2O in the sitting position.

Adult↗