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Featured researches published by Hiroyuki Kon.


Neurologia Medico-chirurgica | 2014

Subdural Empyema Due to Lactococcus lactis cremoris: Case Report

Mizuho Inoue; Atsushi Saito; Hiroyuki Kon; Hiroki Uchida; Shinya Koyama; Shinya Haryu; Tatsuya Sasaki; Michiharu Nishijima

Lactococcus lactis cremoris (L. lactis cremoris) infections are very rare in humans. Only three case reports of brain abscess have been reported and the infectious routes and pathological features are still unknown. We experienced a subdural empyema due to L. lactis cremoris in an immunocompetent adult. A 33-year-old man was admitted with fever, right facial pain, left hemiparesis, and left hemianopsia. Computed tomography demonstrated low density fluid collection in the right falcotentorial subdural space. Magnetic resonance (MR) images revealed a high signal lesion on a diffusion-weighted image (DWI) and fluid attenuated inversion recovery (FLAIR) images in the right paratentorial and parafalcine subdural space, right maxillary sinus, and bilateral ethmoidal sinus. He underwent two sequential open surgeries for removal and drainage of empyema and was treated with antibiotics including meropenem and ampicillin. To our knowledge, this is the first report of subdural empyema caused by L. lactis cremoris infection. We report the case and discuss the pathological features with the previous literature.


Clinical Neurology and Neurosurgery | 2005

Thrombosed vertebral artery aneurysm presenting with hemorrhage and bulbar compression: report of two cases

Shin-ichiro Shiraishi; Miki Fujimura; Hiroyuki Kon; Osamu Motohashi; Motonobu Kameyama; Kiyoshi Ishii; Takehide Onuma

Bulbar compression by vertebral artery (VA) aneurysm is extremely rare and only reported in a few cases. We report two cases with thrombosed VA aneurysm compressing medulla oblongata; one presented with bulbar apoplexy hemorrhage and the other with subarachnoid hemorrhage (SAH). A 61-year-old male (case 1) presented with consciousness disturbances, left hemiplegia, and subsequent respiratory arrest. He was subjected to controlled ventilation, and computed tomography (CT) scan showed bulbar hemorrhage. Magnetic resonance imaging (MRI) and digital subtraction angiogram (DSA) revealed fusiform right VA aneurysm with partial thrombosis and bulbar compression. Intra-aneurysmal embolization with Guglielmi detachable coils (GDCs) relieved his clinical symptom including respiratory disturbance. Three months after the onset, he remained moderately disabled. A 76-year-old male (case 2) presented with severe headache and subsequent respiratory disturbance. CT scan on admission showed subarachnoid hemorrhage with acute hydrocephalus. Ventricular drainage rapidly improved consciousness while respiratory disturbance persisted over several days. MRI and DSA suggested spontaneous thrombosis of the right VA dissection with bulbar compression. He showed gradual recovery of his respiration over a week. After ventriculo-peritoneal shunting, he was transferred with moderate disability. These results suggest that the elimination of the pulsatile effect of VA aneurysm adjacent to medulla oblongata can improve symptoms caused by aneurysm-related compression. Early diagnosis and appropriate treatment such as intra-aneurysmal embolization for ameliorating the blood flow inside the aneurysm can relieve mass effect and clinical symptoms.


Case Reports in Neurology | 2013

Endoscopic surgery for traumatic acute subdural hematoma.

Hiroyuki Kon; Atsushi Saito; Hiroki Uchida; Mizuho Inoue; Tatsuya Sasaki; Michiharu Nishijima

Traumatic acute subdural hematoma (ASDH) is generally addressed by craniotomy under general anesthesia. We report a patient whose traumatic ASDH was treated under local anesthesia by one-burr-hole endoscopic surgery. This 87-year-old woman had undergone coil embolization for a ruptured right middle-cerebral artery aneurysm and placement of a ventriculoperitoneal shunt for normal pressure hydrocephalus 5 years earlier. Upon admission, she manifested consciousness disturbance after suffering head trauma and right hemiplegia. Her Glasgow Coma Scale score was 8 (E2V2M4). Computed tomography (CT) demonstrated a thick, left-frontotemporal ASDH. Due to her advanced age and poor condition, we performed endoscopic surgery rather than craniotomy to evacuate the ASDH. Under local anesthesia, we made a burr hole in her left forehead and increased its size to 15 mm in diameter. After introducing a transparent sheath into the hematoma cavity with a rigid endoscope, the clot was evacuated with a suction tube. The arterial bleeding point was electrically coagulated. A postoperative CT scan confirmed the reduction of the hematoma. There was neither brain compression nor brain swelling. Her consciousness disturbance and right hemiplegia improved immediately. Endoscopic surgery may represent a viable method to address traumatic intracranial hematomas in some patients.


Acta neurochirurgica | 2015

Effectiveness of intraarterial administration of fasudil hydrochloride for preventing symptomatic vasospasm after subarachnoid hemorrhage.

Atsushi Saito; Mizuho Inoue; Hiroyuki Kon; Shunji Imaruoka; Kiyoshi Basaki; Hiroshi Midorikawa; Tatsuya Sasaki; Michiharu Nishijima

OBJECTIVE We examined the effect of intraarterial administration of fasudil hydrochloride (IAFC), a Rho kinase inhibitor, for the prevention of symptomatic vasospasm after SAH by evaluating cerebral circulation. METHODS We evaluated IAFC cases of 57 sides of 38 patients (12 men and 26 women, average age 60.2 years old) diagnosed with aneurysmal subarachnoid hemorrhage (SAH) from February 2012 to November 2012. All cases were treated by clipping or coil embolization within 48 h after onset. Indication for IAFC was the existence of a spastic change on follow-up digital subtraction angiography (DSA) compared with that of onset. RESULTS Clipping was performed in 30 cases and coil embolization in 8 cases. IAFC was performed an average of 6.6 days after onset. Color gradient mapping demonstrated reduction of the circulation time after IAFC compared with before IAFC on 39 sides, no change on 15 sides, and extension on 3 sides. Average arterial circulation time before IAFC was 2.25 ± 0.57 s and after IAFC was 1.95 ± 0.55 s. IAFC significantly shortened average arterial circulation (P = 0.005). No case developed symptomatic vasospasm after IAFC. CONCLUSION IAFC significantly reduced the cerebral circulation time after aneurysmal SAH and might be effective for the prevention of symptomatic vasospasm.


World Neurosurgery | 2016

A Dissecting Aneurysm of the Distal Medial Lenticulostriate Artery: Case Report

Atsushi Saito; Hiroyuki Kon; Taigen Nakamura; Tatsuya Sasaki

BACKGROUND Medial lenticulostriate artery (MLSA) aneurysms are rare; to our knowledge, only 2 cases without an association with moyamoya disease have been documented. We treated a ruptured dissecting aneurysm of the distal MLSA surgically using a tube retractor. CASE DESCRIPTION A 66-year-old woman suffered a sudden-onset disturbance in consciousness. Computed tomography showed diffuse subarachnoid hemorrhage and a dense intraventricular hematoma associated with acute hydrocephalus. She underwent emergent ventricular drainage. Angiography revealed a 3-mm distal MLSA aneurysm. On repeat angiographs, the aneurysm had not disappeared. Because the stenotic, narrow structure of the proximal portion of the MLSA disallowed the endovascular approach, we performed direct surgery via the transventricular approach using a tube retractor. The aneurysm on the intraventricular surface of the anterior horn of the lateral ventricle adjacent to the caudate nucleus was exposed. We resected the aneurysm under transcranial motor-evoked potential monitoring because neck clipping would have endangered the patency of the MLSA. Her postoperative course was uneventful. The pathologic diagnosis was ruptured dissecting aneurysm. CONCLUSIONS There is no definitive strategy to treat distal MLSA aneurysms. Our experience illustrates that natural healing of the vessel wall cannot be expected in all cases. Therefore, less-invasive direct surgical as well as endovascular treatment should not be ruled out in patients with ruptured distal MLSA aneurysms.


Journal of Clinical Neuroscience | 2016

Microvascular decompression for intractable singultus.

Atsushi Saito; Toru Hatayama; Hiroyuki Kon; Taigen Nakamura; Tatsuya Sasaki

Intractable singultus due to cerebrovascular disease is very rare. We report a case of intractable singultus that improved after microvascular decompression and present a literature review. The patient was a 58-year-old man with a 30-year history of persistent singultus. Its frequency and duration gradually increased and it was resistant to multiple medical treatments. Microvascular decompression to relieve pressure on the anterolateral surface of the lower medulla oblongata from the vertebral artery resulted in the resolution of singultus. Patients with intractable idiopathic singultus who fail to respond to medical therapy need to be considered for the evaluation of cerebrovascular diseases and microvascular decompression.


Materials Transactions Jim | 1992

Preparation and thermoelectric properties of Mg2Si1-xGex (x=0.0∼0.4) solid solution semiconductors

Yasutoshi Noda; Hiroyuki Kon; Yoshitaka Furukawa; Nobuyuki Otsuka; Isao A. Nishida; Katashi Masumoto


Materials Transactions Jim | 1992

Temperature Dependence of Thermoelectric Properties of Mg2Si0.6Ge0.4

Yasutoshi Noda; Hiroyuki Kon; Yoshitaka Furukawa; Isao A. Nishida; Katashi Masumoto


Childs Nervous System | 2004

Hydrocephalus due to cerebrospinal fluid overproduction by bilateral choroid plexus papillomas

Miki Fujimura; Takehide Onuma; Motonobu Kameyama; Osamu Motohashi; Hiroyuki Kon; Katsuya Yamamoto; Kiyoshi Ishii; Teiji Tominaga


Childs Nervous System | 2004

Cerebral infarction in the caudate nucleus associated with acute epidural hematoma and diffuse brain injury in a child after severe head injury

Miki Fujimura; Motonobu Kameyama; Osamu Motohashi; Hiroyuki Kon; Kiyoshi Ishii; Takehide Onuma

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Tatsuya Sasaki

Fukushima Medical University

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Michiharu Nishijima

Memorial Hospital of South Bend

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Atsushi Saito

University of the Ryukyus

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Katashi Masumoto

Ishinomaki Senshu University

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Isao A. Nishida

National Institute for Materials Science

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