Biomedical subjects

W Taki

Publications and source records attributed to W Taki.

At least 73 records · Page 4Linked to original sources

PubMed1997

Human second somatosensory area: subdural and magnetoencephalographic recording of somatosensory evoked responses.

OBJECTIVE: To investigate somesthetic functions of the perisylvian cortex. METHODS: Somatosensory evoked magnetic fields (SEFs) and somatosensory evoked potentials (SEPs) of the perisylvian cortex were recorded directly from subdural electrodes in a patient with a left frontal brain tumour. RESULTS: The most prominent SEP components after electrical stimulation of the right and left hands and the right foot were double peaked negativity recorded just above the sylvian fissure (latency 80 to 150 ms), respectively (N1a and N1b). Generator sources for the magnetoencephalographic counterparts of those peaks (N1a(m) and N1b(m)) were both localised at the upper bank of the sylvian fissure, and those of N1a(m) were more anteromedially located than those of N1b(m). CONCLUSIONS: These findings suggest the existence of at least two separate somatosensory areas within the human perisylvian cortex.

Adult↗

PubMed1997

Endovascular treatment of a partially thrombosed giant basilar tip aneurysm using interlocking detachable coils--case report.

A 65-year-old female presented with visual acuity loss. Magnetic resonance imaging confirmed the presence of a partially thrombosed giant aneurysm on the basilar tip. Cerebral angiography showed the opacified lumen of the aneurysm was 25 x 15 mm with a broad-based neck. Using a transfemoral approach, a microcatheter was guided through the vertebral artery and placed directly into the aneurysm under local anesthesia. Interlocking detachable coils were deposited into the patent portion of the aneurysm, resulting in 95% obliteration of the aneurysm and preservation of the parent artery. No complication was observed during or after surgery. Follow-up angiography 2 months later demonstrated the aneurysm was 95% occluded. No coil compaction was observed. Endovascular coil embolization therapy provides a therapeutic option for management of basilar tip aneurysms.

Aged↗

PubMed1997

[A case of cavernous dural arteriovenous fistula resulting in intracerebral extravasation during transvenous embolization].

Cortical venous drainage has been described as one of the major risk factors for dural arteriovenous fistula, which may induce venous hypertension leading to venous ischemia or intracerebral hemorrhage. However, it is rather rare to observe cortical venous drainage manifesting in this way in the cavernous sinus region. We report a case of a 55-year-old gentleman with a right cavernous dural arteriovenous fistula, presenting with conjunctival chemosis, exophthalmus and ocular hypertension on the affected side. Magnetic resonance imaging showed a small intracerebral hemorrhage in the right frontal lobe. Cerebral angiography revealed a dural arteriovenous fistula in the right cavernous sinus draining into the right olfactory vein via the uncal vein, as well as into the superior and inferior ophthalmic veins. This unusual cortical venous reflux was thought to be consistent with the intracerebral hemorrhage found on the magnetic resonance imaging. The patient underwent transvenous embolization for the dural arteriovenous fistula using an inferior petrosal catheterization into the uncal vein was difficult, and the cortical venous reflux through the vein seemed to be slight. However, extravasation of the contrast material occurred in the right frontal lobe after obliteration of the ophthalmic veins during the procedure. The cause of the extravasation was suspected to be the same olfactory vein that had been involved in the previous intracerebral hemorrhage. The obliteration of the dural fistula was continued rapidly, and the fistula disappeared after the embolization. Neurologically, the patient had no noticeable troubles, except for a mild headache. The pretreatment symptoms were alleviated within several days, and the patient was discharged in a week. We emphasize the following points from this rare case in order to facilitate a safer procedure during transvenous embolization for cavernous dural arteriovenous fistula. It is important to obliterate the cortical venous drainage as early as possible, even if the reflux is small or the catheterization is difficult. Repeated, careful sinography is useful for the evaluation of the drainage pattern at certain stages during the transvenous embolization procedure.

Arteriovenous Fistula↗

PubMed1997

[Use of jerk-locked back averaging for detecting the epileptiform discharge in a patient with supplementary motor seizure].

A 23-year-old, right handed women has suffered from supplementary motor seizures manifesting tonic followed by clonic contractions of the left foot, occasionally spreading to the left hand and trunk, since the age of 7 years. The mean frequency of seizures on admission was about 10 times per day. A brain MRI showed an abnormal intensity area about 3 cm in diameter in the right mesial frontal lobe involving the superior frontal and cingulate gyri. Six habitual seizures were recorded during long-term monitoring with digital EEG segments time-locked to the clonic contractions of the left foot, a negative spike was detected about 50 ms before the EMG onset at the midline fronto-central area slightly lateralized to the left. In the focal motor seizure arising from the mesial frontal lobe like in the present case, jerk-locked back averaging helps detecting the epileptiform activity which is otherwise undetectable.

Adult↗

PubMed1996

Embolization of cerebral aneurysms with a liquid embolus, EVAL mixture: report of three cases.

Embolization of three surgically difficult cerebral aneurysms was performed using our newly developed non-adhesive embolic material, EVAL mixture (ethylene vinyl alcohol copolymer). Conventional embolic materials such as detachable balloons or microcoils were not used because of a large or irregular aneurysmal neck. After temporary occlusion of the parent artery with a superselective balloon catheter, the EVAL mixture was slowly injected through a microcatheter placed in the aneurysm or parent artery. The locations of the aneurysms were anterior communicating artery, basilar artery-posterior cerebral artery and basilar artery-anterior inferior cerebellar artery (BA-AICA). One aneurysmal occlusion and 2 parent artery occlusions were performed. Patients had no persistent deficits. The patient with the BA-AICA aneurysm associated with an arteriovenous malformation died of rupture of the residual AVM due to haemodynamic change 2 weeks after embolization. In selected and limited cases, embolization of surgically difficult cerebral aneurysms using EVAL mixture was more effective and safer than embolization using conventional embolic materials such as balloons and microcoils.

Adult↗

PubMed1996

A cationic polymer, Eudragit-E, as a new liquid embolic material for arteriovenous malformations.

We have developed a new liquid material for embolisation of arteriovenous malformations: a mixture of methyl and butyl methacrylate, plus dimethylaminoethyl methacrylate copolymer (Eudragit-E) in a solvent consisting of ethanol and iopamidol. Upon contact with aqueous substances, Eudragit-E precipitates rapidly and forms a soft elastic sponge within 3 s, as the ethanol diffuses. In blood, the positively charged Eudragit-E aggregates the negatively charged blood elements. Transcatheter embolisation of 4 canine and 52 rat renal arteries was feasible. Histological studies revealed no acute inflammatory reaction within 1 week, but mild to moderate reactions in the subacute and chronic stages. No recanalisation was seen. Because of its unique properties and excellent thrombogenicity the Eudragit-E, mixture seems a promising embolic material.

Analysis of Variance↗

PubMed1996

Subdural recording of ictal DC shifts in neocortical seizures in humans.

PURPOSE: Invasive ictal EEG recording is often necessary to delineate epileptogenic areas in patients with intractable partial epilepsy, but even intracranial ictal recordings often reveal ill-defined onset zones in neocortical epilepsy. We studied the physiologic significance of ictal direct current (DC) potentials recorded intracranially in human epilepsy. METHODS: We made intracranial ictal EEG recordings in three patients with intractable partial seizures arising from frontal, lateral temporal, and parietal neocortical areas by using closely spaced subdural electrodes (platinum in two patients and stainless steel in one patient) with both standard (1.5 Hz) and open (0.016 Hz) low-frequency filter (LFF) settings. RESULTS: The initial ictal pattern was localized to two to nine subdural electrodes and characterized by very low voltage and high-frequency rhythmic activity ("electrodecremental pattern"). A slow-rising negative potential (DC potential) was seen in a slightly more restricted area (two to six electrodes) and occurred 1-10 s before the initial ictal EEG discharges in two patients. CONCLUSIONS: These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.

Adolescent↗

PubMed1996

[A case of intractable temporal lobe epilepsy: discrepancy between epileptogenic area and structural lesion demonstrated by subdural recording].

We reported a 25-year-old man with intractable right temporal lobe epilepsy in whom subdural recording successfully delineated the epileptogenic area in the right anterior mesial to basal temporal region in spite of the presence of a postoperative lesion in the right posterior temporal region. The patient underwent right posterior temporal resection due to ependymoma at the age of 8 years. Since age 19, he had suffered from medically intractable psychomotor seizures. Ictal scalp-recorded EEG suggested an epileptogenic area at the right temporal area, but it could not specifically demarcate the site because of bone deficits from the previous surgery. Ictal SPECT showed a hyperactive area in the right anterior temporal area, which was inconsistent with the MRI finding. In case of partial epilepsy associated with structural lesion like in the present case, if results of various non-invasive studies are discrepant as to the epileptogenic area, invasive studies using, for example, subdural EEG monitoring is necessary to determine the responsible area.

Adult↗

PubMed1995

Changes in cerebral blood flow induced by balloon test occlusion of the internal carotid artery under hypotension.

Balloon test occlusion (BTO) of the internal carotid artery (ICA) combined with cerebral blood flow (CBF) study has proved to be a sensitive test for prediction of the outcome of permanent vessel occlusion. In this study, we evaluated the acute changes in regional CBF during BTO under hypotension in order to examine the possible risk of cerebral ischaemia after surgical treatment. Eleven patients in whom surgical carotid sacrifice was planned underwent BTO combined with CBF studies using technetium-99m hexamethyl-propylene amine oxime single-photon emission tomography under hypotension by decreasing the systemic blood pressure by about 50 mm Hg using a ganglion blocking agent. All patients showed a mild to severe decrease in CBF in the ipsilateral ICA territory relative to the contralateral side. A decrease in CBF of greater than 20% was observed in nine patients (82%), and two of them showed a decrease exceeding 40%. However, no ischaemic symptoms were demonstrated during scanning with hypotensive BTO. Our results suggest that in many patients with negative normotensive BTO, a considerable reduction in CBF would occur during hypotension. This procedure may predict a possible risk of hypotensive accident during and/or after surgery.

Adult↗

PubMed1995

Dolichoectasia of the middle cerebral artery--Case report.

A 59-year-old female with a previous history of head injury presented with mild occipitalgia due to dolichoectasia of the middle cerebral artery (MCA). Initial examination by computed tomography and angiography using the usual projections suggested a terminal internal carotid artery saccular aneurysm. However, angiography by the reverse Waters view excluded a saccular aneurysm. Superselective angiography using a microcatheter revealed the complex tortuous course of the MCA due to dolichoectasia. She was discharged and has remained asymptomatic. Superselective angiography is extremely useful for the diagnosis of dolichoectasia localized in the MCA.

Carotid Artery, Internal↗

PubMed1995

Immediately detachable coil for aneurysm treatment.

We developed an endovascular coil that is instantly detached by high-frequency electrical current. By applying the electrical current, a polyvinyl alcohol junction between the coil and the delivery wire is disrupted by heat within a second. This detachment system was shown to be reliable in the treatment of experimental aneurysms.

Animals↗

PubMed1995

[A case of arteriovenous malformation successfully treated with functional mapping of the language area by PET activation study].

The authors report a case of temporal AVM safely treated by mapping the language area with PET activation study. The patient was a 50-year-old woman with temporal epilepsy as her chief complaint. MRI and angiography revealed a right temporal AVM. Before surgical treatment, we assessed the dominant hemisphere with PET activation study. We performed PET scanning while the patient was playing "capping" (called "Shiritori" in Japanese), from which we subtracted PET images performed when she was in a resting state, and then we superimposed those images upon MRIs. The blood flow increased in the left frontal operculum (Broca's area), the left caudal head, the left putamen and the right cerebellar hemisphere. We were thus able to determine that her left hemisphere was dominant, and that it was safe to undertake embolization and operation for the AVM. Postoperative course was uneventful and higher cortical functions were preserved perfectly. In cases of cerebral AVMs, unusual dominancy of cerebral hemispheres is often encountered, and so, preoperative evaluation of the relation of AVM to the eloquent cortex is essential. In our study, blood flow increased in some areas other than the language area, but they were considered to be areas related to phonation, and we think that we were able to map the language area. Though this method is still in its preliminary stage, we think it gives us useful information for surgical treatment of cerebral AVMs.

Brain↗

PubMed1994

[Perioperative management of coagulation and fibrinolytic activity in endosaccular embolization of cerebral aneurysms].

Endosaccular embolization is an innovative and effective treatment for surgically formidable cerebral aneurysms. Platinum microcoils are soft, easily fit to complex configuration of aneurysms, highly thrombogenic, so that suitable for this purpose. Recently developed Guglielmi detachable coils have more advantages in terms of retrievability and electrothrombotic effect. However, distal migration of intraaneurysmal thrombus produces thromboembolism in normal cerebral arteries, leading to neurological deficits. Three cases are presented in which thromboembolic complications occurred during or after embolization of cerebral aneurysms with platinum microcoils. Emergent fibrinolytic treatment resolved neurological deficits in each case without any other complications. From these lessons, a protocol of intra- and postoperative anticoagulation and antiplatelet therapy is presented. In conclusion, perioperative management of fibrinolytic and coagulation activity is extremely important in preventing thromboembolic complication and obtaining successful result.

Adult↗

PubMed1994

Experimental study and clinical use of poly(vinyl acetate) emulsion as liquid embolisation material.

A new material, an emulsion of poly(vinyl acetate) was experimentally developed and clinically used to overcome several disadvantages in currently used liquid embolisation materials. The emulsion microparticles, 0.3-0.7 microns in size, possessed cationic charge on the surface and hence aggregated immediately on contact with fluids containing anions. This inert polymer has the advantage that it does not induce a deleterious reaction in living tissue. Moreover, its medium is water and it is not adhesive, like the cyanoacrylates. Several concentrations of emulsion were injected into the renal arteries of dogs. For the investigation of tissue reactions and the possibility of recanalisation, the emulsion was injected into rats both subcutaneously and into the renal arteries. The renal artery injections in dogs showed adequate radiopacity and consistent complete occlusion. The lower the concentration of the emulsion, the smaller the arteries which could be occluded. Even at very low concentrations, however, venous occlusion did not occur. Histological study of the embolised rat kidney revealed no detectable damage in the vessel wall and no recanalisation for up to 6 months. The subcutaneously injected PVAc emulsion elicited mononuclear cell infiltration and gradual centripetal fibrosis, without any deleterious effect on the surrounding tissue. A cerebral arteriovenous malformation (AVM) was embolised using the material. Histology of the resected nidus showed findings similar to those in the animal experiments.

Adult↗

PubMed1994

Pathogenetic and therapeutic considerations of carotid-cavernous sinus fistulas.

Carotid-cavernous sinus fistula (CCF) is a syndrome in which arteriovenous shunts exist between the carotid artery and the cavernous sinus. These shunts vary widely in pathogenesis, angiogram, haemodynamics and treatment. Several systems of classification in terms of either haemodynamics, aetiology and/or pathogenesis have been reported, but they are not comprehensive. A more comprehensive and simpler nomenclature of classification is now required. Fifty seven cases of CCFs were analyzed and were classified according to their pathogenesis, angiography and treatment modalities. There were 11 traumatic CCFs with direct shunts (T-D group), and 2 traumatic CCFs with indirect shunts (T-I group). Spontaneous CCFs were divided into three groups. There were 37 spontaneous CCFs caused by dural arteriovenous shunts that were naturally classified as being indirect shunts (SD-I group). There were 5 spontaneous CCFs caused by suspected connective tissue disorders, such as fibromuscular dysplasia, Ehlers-Danlos syndrome etc.; these had direct shunts. Care was needed to avoid dissection of the artery or complications due to the fragility of connective tissue (SC-D group). There were 2 spontaneous CCFs caused by the rupture of an inflaclinoid aneurysm without any background of connective tissue disorder; these had direct shunts (SA-D group). By this system of grouping and use of abbreviations, each case of CCF can be clearly delineated in terms of its pathogenesis and selection for appropriate treatment.

Adult↗

PubMed1994

Improved provocative test for the embolization of arteriovenous malformations--technical note.

A modified provocative test to assess the safety of embolization of cerebral and spinal arteriovenous malformations is described. The modified test uses successive amobarbital and lidocaine injections to elicit any possible neurological deficit, both mixed with radiopaque material to visualize the distribution of the anesthetic in the vessels. The modified provocative test caused no false negative results in 11 patients tested, compared to six of 27 patients with the unmodified method.

Amobarbital↗

PubMed1994

[Percutaneous transluminal angioplasty (PTA) for stenosis at the subclavian artery and at the origin of the vertebral artery: therapeutic indication and some adjunctive safe methods during PTA].

Percutaneous transluminal angioplasty (PTA) for brachiocephalic occlusive lesions has progressed. In this paper our experiences and results of PTA in dealing with those lesions are described with emphasis on adjunctive procedures during PTA. Recently, twenty-four patients with stenosis of the subclavian artery (SA) and/or stenosis at the origin of the vertebral artery (VA) were included in this study. Among the 24, there were 16 cases with SA stenosis, 6 cases with stenosis at the origin of VA and 3 cases with both SA and stenosis at the origin of VA. The stenosis was due to atherosclerosis in 21 cases and aortitis in 3 cases. Most of the patients presented ischemic symptoms of vertebrobasilar circulation and affected upper extremities. In PTA of brachiocephalic lesions, one of the most formidable complications is an embolism distal to the central nervous system. To prevent this complication, a vascular endoscope was used for visualization of the luminal surface of the stenotic lesions in 7 cases, and a protective balloon was used in 4 recent cases. The protective balloon was used for transient occlusion of the artery to alter the flow direction so that the possible emboli might be forced to flow away to a less critical distal artery. In the distal protective balloon technique, the protective balloon was set so as to occlude the stenotic artery distally. Debris caused by PTA was aspirated and/or washed out to an extracranial artery with heparinized saline. In the proximal protective balloon technique, the protective balloon was set so as to occlude the stenotic artery proximally. Debris was washed out with blood flow caused by the induced steal phenomenon to an extracranial artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Characteristics of ethylene vinyl alcohol copolymer (EVAL) mixtures.

PURPOSE: To determine physical characteristics of mixtures of ethylene vinyl alcohol copolymer (EVAL) and metrizamide dissolved in dimethyl sulfoxide, liquid materials developed for embolization of arteriovenous malformations. METHODS: EVAL and dimethyl sulfoxide were mixed in various proportions and sterilized. The viscosity and density of each mixture was measured. Precipitation times were determined by dropping the mixtures into saline or human blood. The mixtures were filtered and the filtrates weighed. RESULTS: Densities and viscosities of the various mixtures differed significantly, proportionally to the concentration of EVAL. Precipitation times also differed significantly, in inverse proportion to the concentration of EVAL. Temperature and aqueous solution did not affect precipitation times significantly. The weight of the filtrate significantly increased with time but was constant for each precipitation time. Temperature significantly affected filtrate weight; aqueous solution did not. CONCLUSIONS: Because of their different physical properties, the various EVAL mixtures are suited to embolizing different types of arteriovenous malformations.

Arteriovenous Malformations↗