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Dive into the research topics where Kenta Yamakawa is active.

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Featured researches published by Kenta Yamakawa.


Neurosurgery | 1982

Spontaneous intracranial hemorrhage caused by brain tumor: its incidence and clinical significance.

Susumu Wakai; Kenta Yamakawa; Shinya Manaka; Kintomo Takakura

Hemorrhage from brain tumor was confirmed clinically, surgically, or on autopsy in 94 of 1861 cases (5.1%) treated during the past 18 years: 49 of 311 pituitary adenomas (15.8%) and 45 of 1550 other brain tumors (2.9%). The higher incidence of hemorrhage from pituitary adenoma was statistically significant (p less than 0.001). In brain tumors other than pituitary adenoma, the incidence of hemorrhage was significantly higher in the patients under 14 years old (17 of the 322 cases, 5.3%) than in the patients over 15 years old (28 of the 1228 cases; 2.3%) (p less than 0.001). Nineteen patients showed no evidence of clinical symptoms related to bleeding. Twenty-six patients had a definite history of an acute episode that suggested sudden bleeding. In 11 of these, the apoplectic syndrome was the initial presenting symptoms. The incidence of hemorrhage was not statistically correlated with sex. The hemorrhage was intratumoral in 30 cases, intracerebral in 7, subarachnoid in 7, and subdural in 1. The tumors were supratentorial in 36 cases, pineal in 1, and infratentorial in 8. Primary and metastatic choriocarcinoma and primary embryonal carcinoma seemed to cause hemorrhage most frequently. The following precipitating factors were found in 7 of the 17 patients aged under 14: ventricular drainage in 2, ventriculoperitoneal shunt in 2, carotid angiography in 1, head injury in 1, and leukemia in 1. Seven of the 17 patients under 14 years old died of massive bleeding from the tumor. Unless there is evidence of vascular disease such as cerebral aneurysm, vascular malformation, or hypertensive cerebrovascular disease, intracranial hemorrhage should be suspected of being due to a brain tumor.


Neurosurgery | 1989

Clinical Course and Surgical Prognosis of 33 Cases of Intracranial Epidermoid Tumors

Kenta Yamakawa; Nobuyuki Shitara; Shigeru Genka; Shinya Manaka; Kintomo Takakura

Thirty-three cases of intracranial epidermoid tumors treated during the past 25 years were analyzed with regard to clinical manifestations, recurrence rates related to the extent of surgery, and long-term survival rates. Epidermoid tumors caused various symptoms, especially in the cerebellopontine angle (15 cases), of which a transient remission of symptoms was observed in 4 cases (23.5%). The average time from initial symptoms to surgery was much shorter in suprasellar region and third ventricular locations (average of 11 months) than in other locations (average of 7 years). In 28 patients (84.9%), the tumor was removed totally or subtotally. Most of the patients could lead an independent and useful life after operation (93.1%). Among the 29 patients in a long-term follow-up survey, seven tumors recurred after an average interval of 8 years and 10 months (from the first to second operation) and 12 years and 6 months (from the second to third operation). Patients with recurrent tumors were successfully treated, and excellent functional prognosis was observed even after the second or third operation. The 20-year survival rate was 92.8% (Kaplan-Meier method).


Neurological Research | 1989

The role of endothelin in the pathogenesis of vasospasm following subarachnoid haemorrhage

Katsuhisa Ide; Kenta Yamakawa; Tadayoshi Nakagomi; Tomio Sasaki; Isamu Saito; Hiroki Kurihara; Masao Yosizumi; Yoshio Yazaki; Kintomo Takakura

The purpose of the present study was to evaluate the vasocontractile activity of endothelin, a newly isolated endothelium-derived constrictor peptide, in canine basilar arteries in vitro and in vivo. Endothelin at concentrations of 10(-12) M approximately 3 X 10(-8) M elicited dose-dependent contractions of canine basilar arteries in vitro. The maximum tension was larger than that induced by 40 mM KCl. The EC50 value was 1.9 +/- 0.6 X 10(-9) M (mean +/- SEM). The endothelin-induced contraction was reversed by 10(-8) M nicardipine or 10(-5) M approximately 10(-4) M papaverine. An intracisternal injection of 0.6 approximately 1.2 X 10(-12) mol/kg of endothelin caused biphasic contraction of the basilar artery lasting for more than 24 h. The initial phase of the contraction accompanied remarkable changes in vital signs such as an acute rise of blood pressure, bradycardia and respiratory arrest. An intracisternal injection of 2.0 X 10(-12) mol/kg of endothelin also induced acute contraction of the basilar artery. However, all of the dogs which received an intracisternal injection of 2.0 X 10(-12) mol/kg of endothelin died from sustained respiratory insufficiency. The present results demonstrate that endothelin induces strong and long-lasting contractions of cerebral arteries. Therefore, endothelin may play an important role in the pathogenesis of vasospasm.


Neurosurgery | 1989

Intramedullary cavernous angioma with trigeminal neuralgia: a case report and review of the literature.

Nobuhito Saito; Kenta Yamakawa; Tomio Sasaki; Isamu Saito; Kintomo Takakura

A case of intramedullary cavernous angioma of the upper cervical spinal cord, initially associated with trigeminal neuralgia, is reported. Magnetic resonance imaging precisely depicted the entire extent of the lesion. The angioma was totally removed and the operation was successful in relieving the patient of neuralgia. The previously reported 23 cases of intramedullary cavernous angiomas are reviewed, and the clinical symptoms, diagnosis, and treatment of this rare condition are discussed.


Surgical Neurology | 1983

Neurogenic hypoventilation caused by an enlarged fourth ventricle

Kenta Yamakawa; Susumu Wakai; Shinya Manaka; Kintomo Takakura

Abstract A case of neurogenic hypoventilation, which seems likely to have been caused by compression to the respiratory center in the dorsal medulla oblongata by an enlarged fourth ventricle, is presented. The patient developed obstruction of the outlets of the fourth ventricle seven years after an operation for a choroid plexus papilloma.


Neurologia Medico-chirurgica | 1991

Effect of High-dose Methylprednisolone on Vasospasm After Subarachnoid Hemorrhage

Kenta Yamakawa; Tomio Sasaki; Shinichi Tsubaki; Tadayoshi Nakagomi; Isamu Saito; Kintomo Takakura


Journal of Stroke & Cerebrovascular Diseases | 2003

Effect of edaravone on cerebral vasospasm following experimental subarachnoid hemorrhage

Tadayoshi Nakagomi; Kenta Yamakawa; Tomio Sasaki; Isamu Saito; Kintomo Takakura


Neurologia Medico-chirurgica | 1989

Pharmacological Effect of Endothelin, an Endothelium-derived Vasoconstrictive Peptide, on Canine Basilar Arteries

Tadayoshi Nakagomi; Katsuhisa Ide; Kenta Yamakawa; Tomio Sasaki; Hiroki Kurihara; Isamu Saito; Kintomo Takakura


Neurologia Medico-chirurgica | 1995

Instrumentational Posterior Fusion for Atlanto-axial Subluxation in a Young Child with Down's Syndrome : Case Report

Michihiro Kohno; Hiroshi Takahashi; Kenta Yamakawa; Buichi Ishijima; Hiroshi Mitsui


Surgery for Cerebral Stroke | 1991

Effect of Single Intracisternal Bolus Injection of Tissue Plasminogen Activator on Experimental Vasospasm after Subarachnoid Hemorrhage

Kenta Yamakawa; Tadayoshi Nakagomi; Tomio Sasaki; Isamu Saitoh; Kintomo Takakura

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