Masakazu Okawa
Fukuoka University
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Featured researches published by Masakazu Okawa.
Journal of Stroke & Cerebrovascular Diseases | 2014
Satoshi Kimura; Toshiyasu Ogata; Jiro Fukae; Masakazu Okawa; Toshio Higashi; Mitsutoshi Iwaasa; Tooru Inoue; Yoshio Tsuboi
BACKGROUND The safety of recombinant tissue plasminogen activator (rt-PA) and/or endovascular therapy for patients using the novel oral anticoagulant (NOAC) for atrial fibrillation remains unclear. METHODS We report a patient who was treated by both rt-PA and endovascular thrombectomy who suffered from acute ischemic stroke under treatment with NOAC. RESULTS An 83-year-old woman had a medical history with ischemic stroke due to paroxysmal atrial fibrillation and was then administered 10 mg of rivaroxaban daily. Although she took rivaroxaban in the morning, ischemic stroke recurred at midnight of that day. Soon after transferring to our hospital, we confirmed right middle cerebral artery (MCA) occlusion in the patient and then initiated treatment with intravenous rt-PA. Although no hemorrhagic complication occurred, recovery of her symptoms was not seen, and endovascular thrombectomy was performed. Although the inferior branch of the MCA was recanalized, an infarct was seen in her left frontal lobe. Hemorrhagic transformation was not observed during or after these combined treatments. CONCLUSIONS Thrombolysis and/or endovascular thrombectomy might be safe for patients treated with the new anticoagulant rivaroxaban.
Journal of Neurosurgery | 2013
Tetsuya Ueba; Masakazu Okawa; Hiroshi Abe; Masani Nonaka; Mitsutoshi Iwaasa; Toshio Higashi; Tooru Inoue; Koichi Takano
OBJECT Indocyanine green (ICG) videography is commonly used in the neurosurgical field for minimally invasive neurosurgery. The aim of this study was to evaluate a new intraoperative imaging modality by performing transdural ICG videography during surgery for meningiomas. METHODS Between March 2011 and April 2012, 10 patients with meningiomas received intravenous injection of 12.5 mg ICG just prior to dural opening. The cases comprised 8 convexity meningiomas and 2 foramen magnum meningiomas. Efficacy of the transdural ICG videography was assessed in terms of the tumor volume, the circulation time from the first appearance of the vessel to the appearance of the venous sinus, the tendency to bleed, and the discrimination of the venous sinus. RESULTS The mean tumor volume was 71.6 ± 87.9 ml (the mean is expressed ± SD throughout). The cortical arteries, veins, and the venous sinus were identified by the ICG videography transdurally. The projection of the meningiomas was identified by a shadow (which the authors call the eclipse sign). Total eclipse signs were obtained in 8 cases and partial eclipse signs were obtained in 2 cases; tumor volume in the latter was more than 200 ml. In 5 of 10 cases the adjacent venous sinuses were exposed and were successfully visualized by ICG videography in 5.92 ± 1.05 seconds from the first appearance of the vessel. In 5 of 10 cases the total and the partial eclipse signs were diminished in 3.46 ± 1.31 seconds. The diminishment of the total and the partial eclipse sign was earlier than the visualization of the venous sinus (p = 0.011, t-test), revealing bleeding from the tumor that was observed until coagulation of the feeding arteries from the intracranial arteries. CONCLUSIONS Prior to opening of the dura mater, transdural ICG videography was used successfully to visualize the dural attachment of meningiomas and the venous sinus, resulting in safe and appropriate dural opening. The diminishment of the total and partial eclipse signs may represent significant feeding from the intracranial arteries and a tendency to bleed during resection.
Journal of Neurosurgery | 2010
Koji Iihara; Masakazu Okawa; Tomohito Hishikawa; Naoaki Yamada; Kazuhito Fukushima; Hidehiro Iida; Susumu Miyamoto
The authors report a rare case of slowly progressive neuronal death associated with postischemic hyperperfusion in cortical laminar necrosis after radial artery/external carotid artery-middle cerebral artery bypass graft surgery for an intracavernous carotid artery aneurysm. Under barbiturate protection, a 69-year-old man underwent high-flow bypass surgery combined with carotid artery sacrifice for a symptomatic intracavernous aneurysm. The patient became restless postoperatively, and this restlessness peaked on postoperative Day (POD) 7. Diffusion-weighted and FLAIR MR images obtained on PODs 1 and 7 revealed subtle cortical hyperintensity in the temporal cortex subjected to temporary occlusion. On POD 13, (123)I-iomazenil ((123)I-IMZ) SPECT clearly showed increased distribution on the early image and mildly decreased binding on the delayed image with count ratios of the affected-unaffected corresponding regions of interest of 1.23 and 0.84, respectively, suggesting postischemic hyperperfusion. This was consistent with the finding on (123)I-iodoamphetamine SPECT. Of note, neuronal density in the affected cortex on the delayed (123)I-IMZ image further decreased to the affected/unaffected ratio of 0.44 on POD 55 during the subacute stage when characteristic cortical hyperintensity on T1-weighted MR imaging, typical of cortical laminar necrosis, was emerging. The affected cortex showed marked atrophy 8 months after the operation despite complete neurological recovery. This report illustrates, for the first time, dynamic neuroradiological correlations between slowly progressive neuronal death shown by (123)I-IMZ SPECT and cortical laminar necrosis on MR imaging in human stroke.
Journal of Stroke & Cerebrovascular Diseases | 2014
Masakazu Okawa; Tetsuya Ueba; Toshiyasu Ogata; Hiroshi Abe; Toshio Higashi; Tooru Inoue
BACKGROUND AND PURPOSE Renal insufficiency is a known risk factor for stroke. However, the impact of carotid endarterectomy (CEA) on stroke incidence in patients requiring dialysis remains controversial. We hypothesized that patients undergoing dialysis have no greater risk for periprocedural adverse events. METHODS We performed a retrospective chart review of 12 CEA patients who were on dialysis at the time of CEA. The charts were reviewed for patient demographics, systemic vascular disease, perioperative morbidity and mortality rates, and long-term outcome. Outcomes were recorded in terms of modified Rankin Scale (mRS). RESULTS The mean patient age at the time of CEA was 66.9 ± 7.3 years, with 1 patient having received carotid artery stenting for restenosis. Of the 12 patients undergoing 15 CEAs while being dialysis dependent, none exhibited periprocedural complications including stroke and myocardial infarction. During the follow-up period (mean, 56.1 ± 38.8 months), 3 patients had strokes unrelated to the target vessels for CEA, and 3 patients died from acute myocardial infarction, congestive heart failure, and sepsis. The calculated 5-year survival rate in our series was 58.3% in all cases, 40.0% in symptomatic patients, and 71.4% in asymptomatic patients. Eight patients (66.6%) had a good outcome. CONCLUSIONS These data suggest that patients undergoing dialysis were at no greater risk for periprocedural complications when undergoing CEA. Thus, CEA may be effective for stroke prevention in hemodialysis patients.
Neuropathology | 2013
Tetsuya Ueba; Masakazu Okawa; Hiroshi Abe; Tooru Inoue; Koichi Takano; Hiroyuki Hayashi; Kazuki Nabeshima; Koichi Oshima
We present a case of a 53‐year‐old HIV negative man with a 2‐month history of progressive recent memory disturbance, gait disturbance and urinary incontinence. On MRI, an infiltrative tumor in the brain and spinal cord was noted. Subsequent positron emission tomography studies along with bone marrow biopsy and serum protein electrophoresis showed no evidence of systemic disease. Open brain biopsy results revealed a small lymphocytic infiltrate with scattered plasma cells in a predominantly perivascular growth pattern. The morphology was consistent with involvement by a low‐grade B‐cell lymphoma. Immunohistochemical findings showed CD20+, CD10–, CD5–, TdT–, EBV–encoded RNA in situ– and IgM–. The above findings were consistent with involvement by a non‐dural extranodal marginal zone B‐cell lymphoma (MZBCL) primary to the brain and spinal cord. This is a case report of a CNS MZBCL of mucosa‐associated lymphoid tissue type involving the brain and spinal cord parenchyma.
Journal of Clinical Neuroscience | 2013
Mitsutoshi Iwaasa; Tetsuya Ueba; Masani Nonaka; Masakazu Okawa; Hiroshi Abe; Toshio Higashi; Tooru Inoue
Subarachnoid hemorrhage (SAH) with intraventricular hemorrhage (IVH) is associated with poor outcomes. The aim of this study was to evaluate the safety and feasibility of combined coiling and neuroendoscopy for treating severe SAH with massive IVH. Between April 2008 and June 2011, 49 patients with a severe SAH were treated at the Department of Neurosurgery, Fukuoka University, Japan; 10 of these patients had a massive IVH with a ruptured aneurysm. All 10 patients (three men and seven women; mean age, 63.1±8.5 years) were treated with coiling and neuroendoscopic removal of the IVH within 2 days of onset. Coiling was successfully performed at a mean volume embolization ratio of 21.8±5.5%. Neuroendoscopic removal of the IVH reduced the mean Graeb score from 10.5±2.0 to 4.8±2.5 (p=0.005). All external drains were removed on day 3. No rebleeding or acute hydrocephalus was noted. The Glasgow Outcome Scale scores at discharge indicated two patients with good recovery, three with moderate disability, four in a vegetative state, and one dead. A good modified Rankin Scale (mRS) score (0-2) at least 6 months later (mean follow-up period, 15.4±9.2 months) was observed for five patients (50%), and a poor mRS score (3-6) was observed for the remaining four patients. Neuroendoscopically removing the IVH from all of the ventricles between the lateral and the fourth ventricle and coiling the ruptured aneurysm is a safe, feasible approach for treating severe SAH with massive IVH.
World Neurosurgery | 2016
Kenji Fukuda; Toshio Higashi; Masakazu Okawa; Mitsutoshi Iwaasa; Hiroshi Abe; Tooru Inoue
OBJECTIVE The authors introduce a new fusion technique using 2 three-dimensional digital subtraction angiography images acquired by a flat-panel detector angiographic system to understand the detailed angioarchitecture of complex cerebral and spinal vascular malformations. METHODS Eleven consecutive cases of arteriovenous fistula or arteriovenous malformation with lesions that involved 2 major vessels (i.e., internal carotid arteries, external carotid arteries, vertebral arteries, or spinal arteries) were included. Three-dimensional rotational angiography was performed in each affected vessel after conventional cerebral or spinal angiography. Subsequently, the 2 three-dimensional digital subtraction angiography images were fused. RESULTS The fused images provided the accurate three-dimensional angioarchitecture of complex vascular malformations clearly with high spatial resolution. In particular, the relationship between the nidus/fistulous point, the feeding arteries from each major vessel, and the draining veins could be easily delineated from different directions and multiple angles. Surgical or endovascular treatment was performed in all cases based on the information from these fused three-dimensional images. CONCLUSIONS A fusion technique using two three-dimensional digital subtraction angiography is beneficial for preoperative planning and successful treatment in cases of complex cerebral and spinal vascular malformations.
Journal of Neurosurgery | 2015
Masakazu Okawa; Takaaki Amamoto; Hiroshi Abe; Sohei Yoshimura; Toshio Higashi; Tooru Inoue
Wake-up stroke is most likely to be caused by small-vessel disease, and is related to snoring. The authors present a rare case of far-lateral cervical disc herniation with neck rotation, resulting in wake-up stroke in a young woman. The patient, a 31-year-old woman, was admitted to the hospital because of dysarthria and confusion when she awoke in the morning. Brain MRI showed acute infarction in the posterior fossa. Cerebral angiography showed thrombus in the distal top of the basilar artery and the bilateral posterior cerebral arteries. During angiography, the thrombus size decreased with heparinization. There was severe stenosis of the right vertebral artery (VA) at C5-6, and head rotation to the right resulted in complete occlusion of the right VA. Neck MRI showed far-lateral intervertebral disc herniation. Surgical decompression of the VA was performed via the anterior cervical approach. Histological examination showed a degenerative intervertebral disc. Postoperative angiography confirmed successful decompression of the VA.
Journal of Stroke & Cerebrovascular Diseases | 2015
Masakazu Okawa; Toshiyasu Ogata; Hiroshi Abe; Kenji Fukuda; Toshio Higashi; Tooru Inoue
BACKGROUND The aim of this study was to evaluate the safety and feasibility of carotid endarterectomy (CEA) in Japanese octogenarians. METHODS This study prospectively included 157 consecutive CEA procedures in 145 patients treated at Fukuoka University Hospital between May 2008 and April 2013. Clinical and radiologic findings were obtained from the medical records and by telephone interview. Major events and outcomes were compared between patients 80 years of age or older (octogenarians) and those less than 79 years of age (nonoctogenarians). RESULTS The rate of major adverse events (major stroke, myocardial infarction, or death) in the perioperative period was 1.2%. Follow-up data were available for 142 patients (97.9%). Only 1 case (.7%) of ipsilateral stroke occurred during the follow-up period. Thirteen patients died of causes other than stroke. The estimated 1-, 3-, and 5-year overall survival rates were 98.5%, 96.9%, and 93.1%, respectively. Nineteen (13.4%) of the patients were octogenarians. There were no significant differences in baseline characteristics between octogenarians and nonoctogenarians, except for age. In octogenarians, there were no major adverse events during the perioperative period and no cases of stroke or stroke-related death during the follow-up period. The estimated 1-, 3-, and 5-year overall survival rates in octogenarians were 92.9%, 92.9%, and 61.9%, respectively. There was no significant difference in overall survival between octogenarians and nonoctogenarians (P = .371). CONCLUSIONS The results of this study suggest that CEA can be safely performed in Japanese octogenarians. Midterm outcomes were relatively good, but long-term outcomes require further study.
Interventional Neuroradiology | 2015
Masakazu Okawa; Toshio Higashi; Masaki Komiyama; Kenji Fukuda; Hiroshi Abe; Tooru Inoue
We present a case of unilateral internal carotid artery (ICA) agenesis with trans-sellar anastomosis associated with a right aortic arch, and discuss the embryonic development and clinical implications of this condition. A 26-year-old woman without significant medical history was referred to our hospital complaining of tinnitus. She denied any other symptoms, and examination did not reveal any other neurological deficits. Radiological examinations showed agenesis of the right ICA with trans-sellar anastomosis, and a right aortic arch. This vascular configuration reflects the anatomical homology with avian vascular structure. Recognition of this anomaly has important implications for clinical situations, such as the planning of carotid or transsphenoidal surgery, the management of thromboembolic disease, and the surveillance and detection of associated cerebral aneurysms.