Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Hiroki Miyawaki is active.

Publication


Featured researches published by Hiroki Miyawaki.


Cerebrovascular Diseases | 2008

Surgical Outcome following Decompressive Craniectomy for Poor-Grade Aneurysmal Subarachnoid Hemorrhage in Patients with Associated Massive Intracerebral or Sylvian Hematomas

Naoki Otani; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Yoshikazu Yoshino; Hiroshi Yatsushige; Hiroki Miyawaki; Kyoko Sumiyoshi; Aoyagi Chikashi; Satoru Takeuchi; Goh Suzuki

Background: Patients with poor-grade aneurysmal subarachnoid hemorrhage (SAH) presenting with large intracerebral (ICH) or sylvian hematomas (SylH) have poor outcomes due to the mass effect of significant brain stem compression following mass effect. On the other hand, decompressive craniectomy (DC) can reduce morbidity and mortality in critically ill patients with massive ischemic infarction and severe head injury. However, the role of DC in SAH patients is not fully understood. We investigated the outcome of DC in poor-grade SAH presenting with large ICH or SylH. Methods: 110 consecutive patients with poor-grade SAH (Hunt & Kosnik (H&K) grades IV and V, and Fisher group 4) were admitted to our hospital between April 1, 1993, and July 30, 2004. We treated 57 of those who presented with large ICH or SylH using DC. We retrospectively reviewed medical charts, radiological findings, operative notes, and video records. Results: Among the 57 patients (mean age 57.8, male 29, female 28), 25 were classified as H&K grade IV and 32 as grade V. Ruptured aneurysms were located on the internal carotid artery in 11 and the middle cerebral artery in 46 patients. 50 of the aneurysms were small, 5 were medium, and 2 were large. Rerupture was preoperatively confirmed in 13 (22.8%). Hypothermia was applied to 17 (29.8%). The Glasgow Outcome Scale on discharge showed good recovery, moderate recovery, severe disability, vegetative state, and death in 8 (14.0%), 13 (22.8%), 16 (28.1%), 8 (14.0%), and 12 (21.1%), respectively. The outcomes of grade IV patients were favorable and poor in 14 (56.0%) and 10 (40.0%), respectively, and 1 (4.0%) died. Conclusion: Several experimental studies have also indicated that DC significantly improves outcome due to reduced intracranial pressure or increased perfusion pressure. Urgent DC for poor-grade SAH with space-occupying hematoma can lead to survival with good recovery in some patients.


Journal of Clinical Neuroscience | 2009

Clinical and radiological findings and surgical management of ruptured aneurysms at the non-branching sites of the internal carotid artery

Naoki Otani; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Yoshikazu Yoshino; Hiroshi Yatsushige; Kyoko Sumiyoshi; Hiroki Miyawaki; Chikashi Aoyagi; Satoru Takeuchi; Go Suzuki

Ruptured aneurysms located at the non-branching sites of the internal carotid artery, including blister-like aneurysms, possess unique clinical and technical features. This report presents nine consecutively managed patients with these types of aneurysm, detailing the clinical and radiological characteristics and surgical outcomes. The initial angiography identified aneurysmal lesions in six of the nine patients with two of these patients requiring additional three-dimensional (3D) angiography. In three patients the aneurysm was only diagnosed on second or third angiograms. Six patients had blister-like aneurysms, and two had saccular-shaped aneurysms diagnosed on the basis of intraoperative findings. One patient with a saccular aneurysm died without surgery. Eight patients underwent a microsurgical procedure: clipping in five, clipping on wrapping with suturing in two and trapping in one. Three of these eight patients had an intraoperative rupture. A favorable outcome was obtained in seven patients. Advances in microsurgical techniques to prevent premature rupture and 3D radiological diagnosis with careful pre-operative consideration of the surgical strategies will be required for a further improvement of the clinical outcome.


World Neurosurgery | 2011

Clinical characteristics and surgical outcomes of patients with aneurysmal subarachnoid hemorrhage and acute subdural hematoma undergoing decompressive craniectomy.

Naoki Otani; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Yoshikazu Yoshino; Hiroshi Yatsushige; Hiroki Miyawaki; Kyoko Sumiyoshi; Takashi Sugawara; Aoyagi Chikashi; Satoru Takeuchi; Goh Suzuki

OBJECTIVE This report presents 12 consecutively managed patients with aneurysmal subarachnoid hemorrhage (SAH) associated with acute subdural hematoma (ASDH) who underwent decompressive craniectomy (DC) with special attention to their clinical characteristics and surgical outcomes. METHODS We retrospectively reviewed medical charts, radiologic findings, surgical notes, and video records. RESULTS Among these 12 patients (mean age 59.1 years, 4 men, 8 women), the Hunt and Kosnik clinical grade was grade V in 7 patients (58.3%), grade IV in 2 patients (16.7%), grade III in 2 patients (16.7%), and grade II in 1 patient (8.3%). The aneurysms were located on the internal carotid artery in four patients, the middle cerebral artery in six patients, and the anterior communicating artery in two patients. Computed tomography findings on admission revealed ASDH in all patients. In addition, SAH was seen in 11 patients. An intracerebral hematoma was found in eight patients, intraventricular hemorrhaging occurred in four, and an acute hydrocephalus was seen in one patient. All patients underwent a microsurgical clipping procedure and an additional DC. Symptomatic vasospasm was confirmed in six (50%), and eight patients with chronic hydrocephalus received a ventriculoperitoneal shunt (67%). The Glasgow Outcome Scale at discharge showed good recovery in five patients (41.7%), severe disability in four (33.3%), vegetative state in two (16.7%), and death in one patient (8.3%). A favorable outcome was achieved in five patients (41.7%). CONCLUSIONS We suggest that the DC was effective for reducing morbidity and mortality in poor grade patients with SAH presenting with ASDH.


Acta neurochirurgica | 2010

Prognosis for Severe Traumatic Brain Injury Patients Treated with Bilateral Decompressive Craniectomy

Hiroshi Yatsushige; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Naoki Otani; Yoshikazu Yoshino; Kyoko Sumiyoshi; Takashi Sugawara; Hiroki Miyawaki; Chikashi Aoyagi; Satoru Takeuchi; Go Suzuki

PURPOSE Decompressive craniectomy for traumatic brain injury patients has been shown to reduce intracranial hypertension, while it often results in increased brain edema and/or contralateral space-occupied hematoma. The purpose of this study was to determine the prognosis of bilateral decompressive craniectomy in severe head injury patients with the development of either bilateral or contralateral lesions after ipsilateral decompressive craniectomy. METHODS Twelve patients underwent bilateral decompressive craniectomy among 217 individuals who had been treated with decompressive craniectomy with dural expansion from September 1995 to August 2006. The following patient data were retrospectively collected: age, neurological status at admission, time between injury and surgical decompression, time between first and second decompression, laboratory and physiological data collected in the intensive care unit, and outcome according to the Glasgow Outcome Scale. RESULTS Patient outcomes fell into the following categories: good recovery (three patients); mild disability (one patient); severe disability (two patients); persistent vegetative state (one patient); and death (five patients). Patients with good outcomes were younger and had better pupil reactions and neurological statuses on admission. Other factors existing prior to the operation did not directly correlate with outcome. At 24 h post-surgery, the average intercranial pressure (ICP), cerebral perfusion pressure (CPP), glucose level, and lactate level in patients with poor outcomes differed significantly from those of patients with a good prognosis. CONCLUSION Head injury patients with either bilateral or contralateral lesions have poor prognosis. However, bilateral decompressive craniectomy may be a favorable treatment in certain younger patients with reactive pupils, whose ICP and CPP values are stabilized 24 h post-surgery.


Prehospital and Disaster Medicine | 2011

Medical Evacuation of Patients to other Hospitals due to the Fukushima I Nuclear Accidents

Youichi Yanagawa; Hiroki Miyawaki; Jirou Shimada; Kazuma Morino; Ei-ichi Satoh; Yasuhiro Ohtomo; Masayuki Ichihara; Hisayoshi Kondo

doi:10.1017/S1049023X11006418 In the course of responding to the 11 March 2011 Great East Japan Earthquake and tsunami, the Japanese government decided to enforce a 30 km evacuation radius on 17 March 2011 due to the Fukushima I nuclear accidents. The Ministry of Health, Labour and Welfare of Japan found that there were 800 patients in this area. From 19 March to 22 March, these 800 patients were transported to the other 11 nearby prefectures based on results of matching for facilities and available staff. These medical mass evacuations induced confusion because: 1) eight hundred patients were evacuated to other areas within 4 days, 2) some medical staffs within 30 km from the Fukushima I nuclear accidents could not help leaving medical facilities, leaving their patients, and did not provide detailed information concerning their patients, 3) some patients were evacuated twice, initially transferred to a hospital within the 30 km radiation radius that was enforced later during the incident. Medical information on many of these patients was lacking because of the loss of their medical charts, 4) communication lines were broken, including information transmission. Later, the staff of the local government of Fukushima prefecture investigated personal inquiries which were received during evacuation from Fukushima prefecture, however, these investigations were hard to resolve. Medical mass evacuation under complex disasters, especially for a combination of natural disasters and a nuclear accident, made obtaining exact personal information prior to transportation difficult and thus resulted in confusion.


Acta neurochirurgica | 2010

Surgical Outcome Following a Decompressive Craniectomy for Acute Epidural Hematoma Patients Presenting with Associated Massive Brain Swelling

Naoki Otani; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Yoshikazu Yoshino; Hiroshi Yatsushige; Hiroki Miyawaki; Kyoko Sumiyoshi; Takashi Sugawara; Aoyagi Chikashi; Satoru Takeuchi; Go Suzuki

Acute epidural hematomas (AEDH) are generally managed with rapid surgical hematoma evacuation and bleeding control. However, the surgical outcome of patients with serious brain edema is poor. This study reviewed the clinical outcome for AEDH patients and evaluated the efficacy of the DC, especially in patients with associated massive brain swelling. Eighty consecutive patients surgically treated with AEDH were retrospectively assessed. The patients were divided into two groups: (a) hematoma evacuation (HE: 46 cases) and (b) HE+ an external decompression (ED: 34 cases). The medical charts, operative findings, radiological findings, and operative notes were reviewed. In the poor outcome group, there were 18 patients (72%), with a GCS score of less than 8 (severe injury), and 22 patients (88%) who showed pupil abnormalities. Many more patients showed a midline shift, basal cistern effacement, and brain contusion in comparison to the favorable outcome group. In the favorable outcome group, almost all of the patients (98%) showed less than 12 mm of a midline shift. The influential factors may be age, GCS, pupil abnormalities, size, midline shift, basal cistern effacement, coincidence of contusion and swelling. We conclude that an A DC may be effective to manage the AEDH patients with cerebral contusion or massive brain swelling.


Acta neurochirurgica | 2010

Significance of Monitoring the Initial Intracranial Pressure on Hematoma Irrigation with Trephination Therapy for Acute Subdural Hematomas in Critical Conditions

Naoki Otani; Yoshio Takasato; Hiroyuki Masaoka; Takanori Hayakawa; Yoshikazu Yoshino; Hiroshi Yatsushige; Hiroki Miyawaki; Kyoko Sumiyoshi; Takashi Sugawara; Aoyagi Chikashi; Satoru Takeuchi; Go Suzuki

Acute subdural hematoma (ASDH) patients presenting in a severe condition tend to have poor outcomes due to the significant brain edema required to maintain the ICP at less than 20-25 mmHg. This study compared the surgical outcomes of 16 critically ill patients with ASDH who underwent hematoma irrigation with trephination therapy (HITT) based on their initial ICP values. The initial mean GCS score upon admission was four. A unilateral dilated pupil was seen in one and bilateral dilated pupils were seen in seven patients. The co-existence of a brain contusion was seen in seven patients, brain swelling was noted in six patients, and both basal cistern effacement and a midline shift greater than 5 mm were observed in all patients. The mean initial ICP value was 45 mmHg (range: 3 to 85 mmHg). Ten patients (62.5%) underwent a rapid external decompression to evacuate the hematoma. By using the Glasgow Outcome Scale upon discharge a score of good recovery (GR) was assigned to two (12.5 %), moderate disability (MD) to four (25.0 %), vegetative state (VS) to two (12.5 %), and death (D) to eight (50.0 %) patients. All six patients who showed an initial ICP greater than 60 mmHg died despite intensive care. Eight patients who showed an initial ICP less than 40 mmHg had a favorable outcome, but two patients deteriorated due to a traumatic cerebrovascular disorder. It seems that the initial ICP monitoring with HITT for ASDH patients in critical condition may be an important factor for predicting both surgical outcome and clinical course.


Acta neurochirurgica | 2013

Subacute Subdural Hematoma

Satoru Takeuchi; Yoshio Takasato; Naoki Otani; Hiroki Miyawaki; Hiroyuki Masaoka; Takanori Hayakawa; Hiroshi Yatsushige; Keigo Shigeta

Subacute subdural hematoma (SASDH) is a rare entity. We retrospectively reviewed 8 patients with SASDH. Four patients were male and 4 were female, with an age range of 45-87 years (mean, 67.8 years). The minimal level of deterioration ranged from 8 to 14 (mean, 10.5). The deterioration of neurological symptoms was confirmed 4-20 days after injury (mean, 12.9). The hematoma volume was increased in 6 patients. Seven patients underwent surgeries (burr-hole irrigation in 6, craniotomy in 1). The Glasgow Outcome Scale indicated a good recovery in 4 patients and moderate disability in 4 patients. Increased cerebral blood flow was observed just below the SDH in 1 patient. We consider that the hypoperfused tissue in the acute phase might become hyperperfused during the subacute phase owing to impaired autoregulation, and the hyperperfusion may be responsible for the development of the SASDH, leading to deterioration. Further investigations in a larger series are needed to elucidate the mechanism underlying the development of SASDH.


Intensive Care Medicine Experimental | 2014

0919. Effect of catecholamine immediately after blast lung injury caused by laser-induced shock wave in a mouse model

Hiroki Miyawaki; Daizoh Saitoh; Kohsuke Hagisawa; M. Noguchi; S Satoh; Manabu Kinoshita; Hiromi Miyazaki; Yasushi Satoh; Toshihisa Sakamoto

The physical damage inflicted by blast waves is called primary blast injury, and lungs are vulnerable to blast waves [1]. Blast lung injuries (BLI) can be extremely critical during the super-acute phase, and hypotension is supposed to be the main cause of death (1) , but its etiology has not been elucidated. Recent studies have demonstrated that hypotension is mediated by the absence of vasoconstriction [2]. However, research investigated the effectiveness of catecholamine for BLI during the super-acute phase was not identified.


Emergency Medicine Journal | 2012

Usefulness of multiplanar reformation imaging to differentiate minute pneumothorax from perihepatic free air

Youichi Yanagawa; Hiroki Miyawaki

The trunk of a 14-year-old boy was run over by a car. A physical examination revealed right upper abdominal tenderness. A CT scan of …

Collaboration


Dive into the Hiroki Miyawaki's collaboration.

Top Co-Authors

Avatar

Hiroyuki Masaoka

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Naoki Otani

National Defense Medical College

View shared research outputs
Top Co-Authors

Avatar

Satoru Takeuchi

National Defense Medical College

View shared research outputs
Top Co-Authors

Avatar

Yoshio Takasato

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Yoshikazu Yoshino

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Go Suzuki

Nippon Medical School

View shared research outputs
Top Co-Authors

Avatar

Daizoh Saitoh

National Defense Medical College

View shared research outputs
Top Co-Authors

Avatar

Hiromi Miyazaki

National Defense Medical College

View shared research outputs
Top Co-Authors

Avatar

Kohsuke Hagisawa

National Defense Medical College

View shared research outputs
Top Co-Authors

Avatar

Manabu Kinoshita

National Defense Medical College

View shared research outputs
Researchain Logo
Decentralizing Knowledge