Biomedical subjects

S Kadoyama

Publications and source records attributed to S Kadoyama.

5 recordsLinked to original sources

PubMed1996

Congenital absence and aberrant course of the internal carotid artery.

We retrospectively reviewed the imaging features of an aberrant course of the internal carotid artery (ICA) in one patient and its unilateral absence in four. Absence of the ICA was initially detected by MRI and MR angiography in both patients who underwent these examinations. CT revealed an abnormal or absent carotid canal in all cases. Radiological diagnosis by MRI and MR angiography could play an important role in the diagnosis.

Adult↗

PubMed1991

[Spontaneous disappearance of a middle fossa arachnoid cyst--a case report].

A case of a middle fossa arachnoid cyst which spontaneously disappeared is reported. A 16 year old boy visited our out-patient clinic complaining of headache after a blunt head trauma by a motorcycle accident. The neurological examination was negative except for mild neck pain on the flexion and extension of neck. Plain x-ray of skull and neck were negative. CT scan demonstrated an arachnoid cyst in the left Sylvian fissure. It was planned to follow up the patient by CT scan. After 10 months, he was examined by CT scan, which revealed the spontaneous disappearance of the arachnoid cyst and some dilatation of the anterior horn of the lateral ventricle. The patient did not have any additional trauma or infection during the interval between two examinations. Spontaneous disappearance of arachnoid cyst was extremely rare as only 4 cases were reported previously. The basic mechanism of this natural cure was considered to be rupture of outer or inner membrane of arachnoid cyst which would facilitate absorption of its content.

Adolescent↗

PubMed1988

Structural mechanics of the blowout fracture: numerical computer simulation of orbital deformation by the finite element method.

Blowout fractures most frequently involve the orbital floor. The contour of the orbit has been postulated as one of the factors responsible for this phenomenon, but only a few studies have been carried out. The present study was planned to determine the effect of the contour of the orbit when intraorbital pressure is raised to simulate the hydraulic mechanism of blowout fracture. The profile of the orbit was estimated from five dry human skulls, and the measurements were approximated to frame models. The deformation of these models by raised intraorbital pressure was calculated by computer simulation using the finite element method. In all of the orbital models, the deformation of the orbital floor was significantly greater than that of the roof. These findings verified that the orbital roof has a higher resistance than the floor against raised intraorbital pressure. We suspect that this resistance is due to the arched shape of the orbital roof, whereas the floor is rather flat.

Computer Simulation↗

PubMed1987

Parasellar chondroma: a case report.

A case of a 19-year-old man with a right parasellar chondroma examined with computed tomography (CT) and nuclear magnetic resonance (NMR) scan is reported. The literature about CT and NMR scan findings of intracranial chondroma is reviewed. Typical CT findings are a round, high density mass with calcification, that is only slightly enhanced by contrast medium.

Adult↗

PubMed1987

[Stress distribution in the brain--numerical simulation by the finite element method].

The analysis of the deformation of brain and distribution of stress caused by the compression from outside would be interesting and also useful for the better understanding of the pathophysiology in the cases of intracranial hematoma and other space occupying lesions. The computerized numerical simulation using the finite element method was carried out to analyze these problems. A simple brain model of two dimensions, that was composed of the inner surface of skull, brain and lateral ventricles, was utilized and it was divided into 101 triangular elements for the calculation of finite element method by a 16-bit personal computer. The model of brain was compressed in two different ways; one was a subdural hematoma type where the force of compression was distributed over relatively wide area and the other was a epidural hematoma type where compression was localized to smaller area. In both types, the brain was compressed on the left fronto-temporal region. The deformation of brain in the subdural hematoma type model was that corresponding to the hematoma of crescent shape just as seen on the CT scan of actual case. The lateral ventricle of affected side was deformed more markedly than that of contralateral side. The midline structure of the brain was shifted to normal side and shift was larger in the portion anterior to the lateral ventricles. The stress was distributed from the area beneath the hematoma to remote location in the affected hemisphere but the propagation of stress was blocked by the falx and it was very small in the contralateral hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗