Koji Tokunaga

Kosei Chuo General Hospital, Edo, Tōkyō, Japan

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Publications (108)131.99 Total impact

  • No shinkei geka. Neurological surgery 01/2014; 42(1):59-64. · 0.13 Impact Factor
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    ABSTRACT: We developed the Japanese Registry of Neuroendovascular Therapy 2 (JR-NET2) database and used the information for a retrospective, nation-wide multicenter, observational study to clarify the clinical characteristics, current status of procedures, and outcome of patients treated by neuroendovascular therapy in Japan. In this report, we analyzed the clinical characteristics of dural arteriovenous fistulas (dAVFs) in the JR-NET2 database. All patients with dAVFs treated with endovascular therapy in 150 Japanese hospitals were included. Patient characteristics, clinical presentations, and imaging characteristics were analyzed. A total of 1,075 patients with dAVFs underwent 1,520 endovascular procedures. Of 1,075 patients, 45% were men and 55% were women. The mean age was 65 ± 13 years. The most frequent location of dAVFs was the cavernous sinus (43.6%), followed by the transverse-sigmoid sinus (TSS) (33.4%). Twelve percent of the patients had intracranial hemorrhage, 9% had venous infarction, and 3% had convulsion. The statistically significant independent risk factors of intracranial hemorrhage were TSS, superior sagittal sinus (SSS), tentorium, anterior cranial fossa, cranio-cervical junction, cortical venous reflux (CVR), and varix. Risk factors of venous infarction were age older than 60 years, male sex, TSS, SSS, and CVR. Risk factors of convulsion were male sex, SSS, and CVR. This is the largest nationwide report, to date, of the clinical characteristics of dAVFs treated by neuroendovascular therapy. CVR was a major risk factor of aggressive symptoms.
    Neurologia medico-chirurgica 12/2013; · 0.49 Impact Factor
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    ABSTRACT: Embolization of intracranial tumor is widely performed in Japan, mainly before neurosurgical resection. A retrospective, multicenter, observational study in Japan was conducted to clarify the nature, frequency, and risk factors of complications in intracranial tumor embolization. Patients were derived from the Japanese Registry of NeuroEndovascular Therapy 2 (JR-NET2). A total of 20,854 patients were enrolled in JR-NET2, of which 1,018 patients (4.88 %) with intracranial tumors underwent embolization. The primary end point was the proportion of patients with a modified Rankin scale (mRS) score of 0-2 (independency) at 30 days. The secondary end point was the occurrence of complications related to the procedures. The risk factors of the occurrence of complications were studied. The proportion of patients with mRS scores ≤2 at 30 days after procedure was 91.3 %. Complications occurred in 15 of the 1,012 patients (1.48 %). Multivariate analysis showed that embolization for tumors other than meningioma (OR, 4.626; 95 % CI, 1.347-14.59; p = 0.0105) was significantly associated with the development of complications. The frequency of complications after intracranial tumor embolization was relatively low in this large Japanese cohort. Embolization for tumors other than meningioma was the only significant risk factor for the occurrence of complications.
    Neuroradiology 11/2013; · 2.70 Impact Factor
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    ABSTRACT: Traumatic brain injury (TBI) sustained in a traffic accident or a fall is a major cause of death that affects a broad range of ages. The aim of this study was to investigate the therapeutic effects of intra-arterial transplantation of mesenchymal stem cells (MSCs) combined with hypertonic glycerol (25%) or mannitol (25%) in a TBI model of rats. TBI models were produced with a fluid percussion device. At 24hours after TBI, MSCs (1×10(6) cells/100μl) with glycerol or mannitol were administered via the right internal carotid artery. Rats were evaluated behaviorally and immunohistochemically, and hyperpermeability of the blood-brain barrier (BBB) induced by hypertonic solutions was explored. Compared to PBS or glycerol, the administration of mannitol resulted in increased BBB disruption. The mannitol-treated rats showed significant improvement in motor function. Intra-arterial transplantation of MSCs caused no thromboembolic ischemia. Immunohistochemically, more MSCs were observed in the injured brain tissues of mannitol-treated rats than in glycerol or PBS-treated rats at 24hours after transplantation. Intra-arterial transplantation of MSCs combined with mannitol is an effective treatment in a TBI model of rats. This technique might be used for patients with diseases of the central nervous system including TBI.
    Neuroscience Letters 09/2013; · 2.03 Impact Factor
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    ABSTRACT: Object There is no description of the change in the posterior cerebral artery (PCA) in the diagnostic criteria of moyamoya disease (MMD). However, PCAs are often involved in the clinical setting, and an understanding of the significance of PCA lesions is therefore of great importance when evaluating the disease progression and predicting prognosis. The aim of this study was to assess the difference in posterior circulation involvement in pediatric and adult patients with MMD. Methods The records of 120 consecutive patients with MMD were reviewed. The clinical manifestations at diagnosis were evaluated on the basis of symptoms and CT and MRI findings. The degree of steno-occlusive internal carotid artery (ICA) lesions and the existence of steno-occlusive PCA lesions were evaluated by observing a total of 240 ICAs and PCAs on angiography. Angiographic correlation between anterior and posterior circulation was assessed in pediatric and adult patients with MMD. Results Seventeen (26%) of 66 pediatric patients and 18 (33%) of 54 adult patients exhibited steno-occlusive PCA lesions. There was no significant difference in the prevalence of PCA lesions between pediatric and adult patients with MMD (p = 0.36). The prevalence of infarction in pediatric and adult patients with PCA involvement was significantly higher than that in pediatric and adult patients without PCA involvement (p = 0.0003 and p = 0.003, respectively). There was no significant difference in the distribution of infarction areas between pediatric and adult patients with PCA involvement (p = 0.62). On the basis of the staging system used, steno-occlusive lesions in ICAs ipsilateral to PCAs with lesions were in significantly advanced stages compared with lesions in ICAs ipsilateral to PCAs without lesions in both pediatric and adult cases (p < 0.0001 and p = 0.0008, respectively). Pediatric patients had less advanced steno-occlusive lesions in ICAs ipsilateral to PCAs with lesions compared with adults (p < 0.05). Conclusions The clinical significance of posterior circulation involvement in MMD was similar between pediatric and adult patients. The only significant difference was that less advanced ICA lesions could complicate posterior circulation involvement in pediatric patients.
    Journal of Neurosurgery 08/2013; · 3.15 Impact Factor
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    ABSTRACT: Although self-expanding carotid stents may dilate gradually, the degrees of residual stenosis have been quantified by the NASCET criteria, which is too simple to reflect the configuration of the stented artery. We measured the volumes of the stent lumens chronologically by 3D-CT in patients after carotid artery stenting (CAS), and analyzed the correlations between the volume change and medical factors. Fourteen patients with carotid artery stenosis were treated using self-expanding, open-cell stents. All patients underwent preoperative plaque MRI (magnetization-prepared rapid acquisition gradient-echo, MPRAGE) and chronological 3D-CT examinations of their stents immediately after their placement and 1 day, 1 week, and 1 month after the procedure. The volume of the stent lumen was measured using a 3D workstation. The correlations between stent volume and various factors including the presence of underlying diseases, plaque characteristics, and the results of the CAS procedure were analyzed. Stent volume gradually increased in each case and had increased by 1.04-1.55 (mean, 1.25)-fold at 1 postoperative month. The presence of underlying medical diseases, plaque length, the degree of residual stenosis immediately after CAS, and plaque calcification did not have an impact on the change in stent volume. On the other hand, the stent volume increase was significantly larger in the patients with vulnerable plaques that demonstrated high MPRAGE signal intensity (P < 0.05). A 3D-CT examination is useful for precisely measuring stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period.
    Neuroradiology 07/2013; · 2.70 Impact Factor
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    ABSTRACT: Aneurysms at the vertebrobasilar junction are often found with basilar artery(BA)fenestration. We encountered 10 consecutive cases of aneurysms associated with BA fenestration. The purpose of this study is to describe the frequency, clinical features, and outcome of these aneurysms treated by endovascular procedure. The incidence of these aneurysms in our series was 1.9%. All aneurysms were successfully treated by coil embolization. Half of them were treated by using simple technique, and the other half were treated by using adjunctive techniques such as balloon remodeling technique. 70% of these cases were ruptured, and all except one case showed good recovery at the time of discharge. We found 63 reported cases of this aneurysm in the literature between 2000 and 2012. 57 out of 63 aneurysms were treated by endovascular means with good clinical results. The usefulness of endovascular procedure is reported to be superior to surgical clipping because of their anatomical complexity and the difficulty of surgical exposure for clipping. We conclude that outcome of these aneurysms is favorable and endovascular procedure has become their standard treatment for these aneurysms.
    No shinkei geka. Neurological surgery 07/2013; 41(7):583-592. · 0.13 Impact Factor
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    ABSTRACT: We report here a case of cervical carotid artery aneurysm. This 37-year-old male suffered from acute neck swelling when he was taking lunch after physical work. Ultrasonography demonstrated a cervical pseudoaneurysm and a jet flow, which was blowing into the dome from the carotid artery. Angiogram revealed an aneurysm with a diameter of 3cm at the bifurcation of the common carotid artery. Coil embolization using double-catheter technique was performed and complete occlusion of the aneurysm was obtained without any complications. The patient returned to his normal life. Cervical carotid artery aneurysms are rare and they induce pain by swelling in the neck, hoarseness, swallowing disturbance, hemorrhage, and cerebral ischemia due to embolism. In case of a cervical carotid artery aneurysm, safe and effective treatments are required and endovascular treatment should be considered. Although stent-assisted coil embolization or covered-stent placement were reported as an effective treatment for cervical aneurysms, coil embolization without using a stent was performed in this particular patient who is a young, blue-collar worker because the avoidance of long-term anti-platelet therapy was desirable. Preoperative evaluation is important to select adequate treatment.
    No shinkei geka. Neurological surgery 06/2013; 41(6):515-23. · 0.13 Impact Factor
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    ABSTRACT: We report a rare case of a paraspinal arteriovenous fistula(AVF)treated by combined transarterial and transvenous embolization(TAE/TVE). A 72-year-old woman was admitted after a traffic accident. Abdominal enhanced CT disclosed pre-existing large varices at the L3-L4 level in the right retroperitoneum with multiple feeding arteries and veins draining into the extradural venous plexus in the spinal canal. The lesion was diagnosed as a paraspinal AVF. Four days later, the patient went into a state of shock. Emergency abdominal CT showed retroperitoneal hemorrhage due to rupture of the varix. TAE of the feeders from the right L1-L4 arteries was performed, and rebleeding from the varix was prevented. Three months later, follow-up CTA showed regrowth of the AVF, and TVE was performed. Two microcatheters were navigated transvenously into the varix, and detachable coils were delivered into the small compartment just downstream to the shunts, leading to complete obliteration. We conclude that transarterial flow reduction followed by occlusion of the venous side of the shunts is effective to achieve cure of a complex and high-flow paraspinal AVF.
    No shinkei geka. Neurological surgery 05/2013; 41(5):429-35. · 0.13 Impact Factor
  • Koji Tokunaga, Kenji Sugiu, Isao Date
    No shinkei geka. Neurological surgery 02/2013; 41(2):153-62. · 0.13 Impact Factor
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    ABSTRACT: Aneurysms located on the superior cerebellar artery(SCA)are uncommon and their presentation, natural history, and clinical management are poorly understood. Reports related to the endovascular or surgical management of SCA aneurysms are rare. Herein, we report two cases of SCA aneurysm. The first is that of a 70-year-old woman who presented with subarachnoid hemorrhage(SAH). Surgical treatment(neck clipping)of the ruptured SCA aneurysm was performed, and the flow of the parent artery disappeared. The second is that of a 69-year-old woman with an unruptured SCA aneurysm who underwent endovascular surgery to occlude the parent artery. Neither patients exhibited any additional neurological deficits. SCA aneurysms often have either relatively wide or undefinable necks, so it is difficult to preserve the parent artery. According to several surgical reports, occlusion of the SCA appears well tolerated for a variety of reasons.
    No shinkei geka. Neurological surgery 01/2013; 41(1):45-51. · 0.13 Impact Factor
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    ABSTRACT: Recent advances in endovascular techniques greatly improved the ability to treat complex cerebral aneurysms. However, patients with wide-necked cerebral aneurysms have posed a special challenge to conventional endovascular therapy. We report a novel method of embolizing wide-necked basilar apex aneurysms by employing a Y-configuration, double stent technique. A 40-year-old woman with a partially thrombosed basilar apex aneurysm transferred to our hospital after diagnosis of subarachnoid hemorrhage. Cerebral angiography revealed a wide-necked aneurysm which neck was incorporating the origins of both the posterior cerebral arteries. In treatment procedure, a microcatheter was inserted into the aneurysm followed by coiling of the upper half of the dome. Next, the first stent was deployed in the right P2 segment extending down to the mid basilar artery and the second stent was then deployed with half of the stent in the left P2 and the other half within the lumen of the previously placed stent. Finally, the microcatheter was withdrawn near the neck, and the rest of the aneurysmal dome was packed by additional coils. The result was favorable. Successful coil embolization of a wide-necked bifurcation aneurysm can be achieved by using the double stenting Y-configuration in this case. This result continues to provide highly encouraging support of this novel technique to treat a subset of complex, wide-necked aneurysms that until recently were considered poor candidates for endovascular therapies.
    No shinkei geka. Neurological surgery 11/2012; 40(11):1005-12. · 0.13 Impact Factor
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    ABSTRACT: Magnetic resonance imaging is used with increasing frequency to provide accurate clinical information in cases of acute brain injury, and it is important to ensure that intracranial pressure (ICP) monitoring devices are both safe and accurate inside the MRI suite. A rare case of thermal brain injury during MRI associated with an overheated ICP transducer is reported. This 20-year-old man had sustained a severe contusion of the right temporal and parietal lobes during a motor vehicle accident. An MR-compatible ICP transducer was placed in the left frontal lobe. The patient was treated with therapeutic hypothermia, barbiturate therapy, partial right temporal lobectomy, and decompressive craniectomy. Immediately after MRI examination on hospital Day 6, the ICP monitor was found to have stopped working, and the transducer was subsequently removed. The patient developed meningitis after this event, and repeat MRI revealed additional brain injury deep in the white matter on the left side, at the location of the ICP transducer. It is suspected that this new injury was caused by heating due to the radiofrequency radiation used in MRI because it was ascertained that the tip of the transducer had been melted and scorched. Scanning conditions-including configuration of the transducer, MRI parameters such as the type of radiofrequency coil, and the specific absorption rate limit-deviated from the manufacturer's recommendations. In cooperation with the manufacturer, the authors developed a precautionary tag describing guidelines for safe MR scanning to attach to the display unit of the product. Strict adherence to the manufacturer's guidelines is very important for preventing serious complications in patients with ICP monitors undergoing MRI examinations.
    Journal of Neurosurgery 10/2012; · 3.15 Impact Factor
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    ABSTRACT: The aim of this study was to analyze the effect of endovascular treatment of basilar (BA) tip aneurysms. The authors performed a retrospective analysis of 79 aneurysms of the BA tip that had been treated using endovascular coil embolization for the last 11 years. Fifty-six patients were women, and 23 were men. The average age of the patients was 63.7 years (range, 35-83 year). The average maximum diameter of the aneurysms was 8.0 mm (range, 2-30 mm). Forty-seven patients (60%) presented with acute subarachnoid hemorrhage (SAH), 1 patient (1%) had an unruptured aneurysm with mass effect, and 31 patients (39%) had incidental aneurysms. Immediate anatomic outcomes demonstrated complete occlusion (CO) in 53 aneurysms (67%), residual neck (RN) in 22 aneurysms (28%), and residual aneurysm (RA) in 4 aneurysms (5%). One patient died from rebleeding 6 hours after the embolization. Another patient suffered from rebleeding 6 years after the initial embolization, and was successfully treated with re-embolization. Four patients suffered from asymptomatic P1 occlusion. No symptomatic complication was observed in the unruptured group. Retreatment was performed in 5 patients, including 4 broad-neck large ruptured aneurysms and 1 giant thrombosed aneurysm. Angiographic and clinical results have been improving in recent cases in this study. Technical advances such as highly compliant balloon remodeling microcatheter and 3D-reconstructed digital angiography contributed to this improvement. Our results indicate that endovascular treatment of BA tip aneurysm is safe and effective. The long-term stability after coil embolization is still a matter of concern. Further improvement is expected.
    No shinkei geka. Neurological surgery 09/2012; 40(9):765-74. · 0.13 Impact Factor
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    ABSTRACT: Objectives. Patients with moyamoya disease (MMD) very rarely develop both cerebral ischaemia and haemorrhage. The aim of this study was to clarify the clinical and radiographic features of MMD in patients who presented with both ischaemia and haemorrhage, compared with MMD patients who presented with one or the other. Materials and methods. The records of 92 consecutive patients with MMD were reviewed. These patients were divided into three groups, according to the type of presentation: ischaemic presentation (Group I); haemorrhagic presentation (Group H); and haemorrhagic-ischaemic presentation (Group H-I). The patient characteristics, areas of infarction, and angiographic findings were evaluated. Results. Seventy-six (82%) of the 92 patients were categorised as Group I, 7 (8%) as Group H, and 9 (10%) as Group H-I. Median follow-up periods for Group H-I was 55 months (IQR, 36-116 months). There were eight females in Group H-I, in which the median age was 30 years. Of the nine cases in Group H-I, six presented with cerebral haemorrhage as the precedent event and three had complications during the acute phase. In Group H-I, the prevalence of posterior cerebral artery (PCA) lesions was high (42%) and infarctions were most frequently found in PCA-related areas. Conclusions. The presence of steno-occlusive PCA lesions may be of pathogenic importance in MMD patients who develop both cerebral ischaemia and haemorrhage. The prevalence of this type of stroke in MMD patients is higher than expected, and further investigation in clinical settings is thus warranted.
    British Journal of Neurosurgery 08/2012; · 0.86 Impact Factor
  • Clinical neurology and neurosurgery 05/2012; · 1.30 Impact Factor
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    ABSTRACT: We report here a case of massive nasal bleeding from the sphenopalatine artery three weeks after endonasal transsphenoidal surgery. This 66-year-old male suffered from massive nasal bleeding with the status of hypovolemic shock. Under general anesthesia, an emergent angiography revealed an extravasation from the sphenopalatine artery. Trans-arterial embolization using coil and n-butyl-cyanoacrylate (NBCA) was performed following the diagnostic angiography. Complete occlusion of the injured artery was achieved. The patient showed good recovery from general anesthesia. Delayed nasal bleeding after endonasal transsphenoidal surgery is a rare but important complication. The sphenopalatine artery and its branch are located in the hidden inferior lateral corner of the sphenoid sinus and may be injured during enlargement of the sphenoid opening. When massive delayed nasal bleeding follows transsphenoidal surgery and damage of the internal carotid artery has been ruled out, endovascular treatment of the external carotid artery should be considered.
    No shinkei geka. Neurological surgery 01/2012; 40(1):55-60. · 0.13 Impact Factor
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    ABSTRACT: Patients with dural arteriovenous fistulas (DAVFs) in the transverse-sigmoid sinus suffer from several symptoms: bruit, headache, visual impairment, and so on. But depression is rare in patients with DAVF. The authors reported a rare case presenting the improvement of depression after the treatment of a dural arteriovenous fistula in the left transverse-sigmoid sinus. A 46-year-old male had suffered from depression and was treated with antidepressants at a local hospital for four years. The patient was temporarily laid off due to his depression. Afterwards, he had Gerstmann's syndrome and came to our hospital. A DAVF in the left transverse-sigmoid sinus was demonstrated on the angiogram. The DAVF was successfully treated with endovascular surgery, coil embolization of the isolated diseased sinus through the mastoid emissary vein which was a draining vein from the fistula. After this treatment, his depression as well as Gerstmann's syndrome was improved and the quantity of the antidepressants decreased. The patient returned to work without any antidepressant two years after the treatment. DAVFs might be one of the causes of depression. It may be necessary to evaluate cerebral vessels in patients suffering from depression by using MRA or 3D-CTA even if there are not any abnormal findings on plain CT scans.
    Case reports in psychiatry. 01/2012; 2012:730151.
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    ABSTRACT: INTRODUCTION: Percutaneous transvenous embolization (TVE) using coils is a well-established treatment of cavernous sinus dural arteriovenous fistula (CSdAVF). However, it is sometimes difficult to achieve complete occlusion by coil embolization. In these two cases, we were able to obtain complete angiographic obliteration of the fistulas without complications by means of percutaneous TVE using n-butyl-cyanoacrylate (NBCA) after we failed when TVE using coils. Case 1: An 89-year-old woman presented with double vision. She was diagnosed as Barrow type D right CSdAVF draining only to the cortical vein. We treated the patient by TVE using coils, but the microcatheter was withdrawn before complete occlusion was attained. The repositioning of the microcatheter was difficult, so we used 30% NBCA for TVE, and obtained complete obliteration of the fistula. Case 2: An 87-year-old woman presented with right exophthalmos, and chemosis. She was diagnosed as Barrow type C right CSdAVF draining only to the right superior ophthalmic vein with very slow flow. We planned to treat her, using TVE with coils, but we could place only 3 coils and obtained only partial obliteration of the fistula. So we additionally used 25% NBCA for TVE, and obtained complete obliteration of the fistula. CONCLUSION: Compared to TVE using coils, TVE using NBCA gives rise to many problems, but, we can use NBCA as a second option if TVE using coils results in only partial obliteration as in these cases.
    No shinkei geka. Neurological surgery 12/2011; 39(12):1189-96. · 0.13 Impact Factor
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    ABSTRACT: Posterior reversible encephalopathy syndrome (PRES) is a clinico-neuroradiological entity with typical symptoms and symmetric high-signal intensity lesions in the bilateral parieto-occipital lobes on T2-weighted or fluid-attenuated inversion recovery (FLAIR) MRI. We described three patients with PRES of varied etiologies. Patient 1 was a young man with severe hypertension who presented with headache and visual disturbance. Patient 2 had leukemia and was receiving umbilical cord blood cell transplantation with immunosuppressant, and developed PRES with convulsions. Patient 3 was a pregnant woman with renal failure, who repeatedly developed PRES with convulsions. FLAIR and apparent diffusion coefficient mapping were useful in detecting PRES lesions in our patients, although diffusion-weighted imaging and CT scans had limited use in the diagnosis. Adequate and prompt treatment with antihypertensive medication immediately ameliorated the symptoms, with improvement of abnormal MRI findings. In previous reports, delayed diagnosis might have affected the prognosis. Further work on the clinical manifestations of PRES and its therapy is required.
    Journal of Clinical Neuroscience 03/2011; 18(3):406-9. · 1.25 Impact Factor

Publication Stats

469 Citations
131.99 Total Impact Points


  • 2008–2012
    • Kosei Chuo General Hospital
      Edo, Tōkyō, Japan
    • Japanese Red Cross
      Edo, Tōkyō, Japan
    • National Cerebral and Cardiovascular Center
      Ōsaka, Ōsaka, Japan
  • 1998–2011
    • Okayama University
      • Department of Neurological Surgery
      Okayama, Okayama, Japan
  • 2007
    • University Hospital Medical Information Network
      • Department of Neurosurgery
      Tokyo, Tokyo-to, Japan
    • Numazu City Hospital
      Sizuoka, Shizuoka, Japan
  • 1999–2006
    • Okayama Rosai Hospital
      Okayama, Okayama, Japan
  • 2004
    • Kurume University
      • Department of Radiology
      Kurume, Fukuoka-ken, Japan
  • 2003
    • University of Geneva
      • Division of Neurology
      Genève, GE, Switzerland