K Nagata

Showa University, Shinagawa, Tōkyō, Japan

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Publications (23)27.8 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The head-shaking method combined with cisternal irrigation has been proposed to be effective in preventing cerebral vasospasm after subarachnoid hemorrhage (SAH) by facilitating rapid washout of the clot from the subarachnoid space. This study was conducted to evaluate the effectiveness of this method. The inclusion criteria included the following: 1) Fisher Grade 3 SAH on admission computerized tomography (CT) scans; 2) aneurysm secured within 48 hours of SAH onset; and 3) no focal deficit and ability to obey commands within 24 hours postsurgery. Two hundred thirty patients treated between 1994 and 2002 fulfilled the criteria. Because only one machine was available and it required I month of maintenance every other month, 114 patients underwent irrigation combined with the head-shaking method (head-shaking group), whereas the remaining 116 patients received cisternal irrigation alone (control group). There were no significant differences in sex, age, site of aneurysm, or preoperative grade between the two groups. The incidence of symptomatic vasospasm with or without infarction, cerebral infarction on CT scans, and permanent ischemic neurological deficit was 25.7, 17.7, and 8.8%, respectively, in the control group and 15.2, 4.5, and 2.7% in the head-shaking group. The difference was statistically significant for symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit (p < 0.05). In a multivariate backward stepwise logistic regression analysis, absence of head shaking was the only variable that was predictive of permanent ischemic neurological deficit (p = 0.061). The outcomes evaluated using the modified Rankin Scale were better in the head-shaking group (p = 0.051). The head-shaking method significantly reduced the incidence of symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit and improved the clinical outcomes in patients who underwent cisternal irrigation therapy after aneurysmal SAH.
    Journal of Neurosurgery 03/2004; 100(2):236-43. · 3.15 Impact Factor
  • Surgery for Cerebral Stroke 01/2004; 32(5):362-369.
  • Journal of Neurosurgery 06/2003; 98(5):1134. · 3.15 Impact Factor
  • Surgery for Cerebral Stroke 01/2003; 31(4):285-289.
  • Surgery for Cerebral Stroke 01/2003; 31(3):170-177.
  • Surgery for Cerebral Stroke 01/2003; 31(2):111-116.
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    ABSTRACT: We report a case of a bilateral vertebral dissecting aneurysm associated with subarachnoid hemorrhage. Proximal ligation of the vertebral artery on the ruptured side combined with wrapping of the contralateral dissection failed to prevent fatal rebleeding. Since enlargement of the contralateral dissection was observed by postoperative angiography, rupture of the growing contralateral dissecting aneurysm may have caused rebleeding. Hemodynamic changes following the occlusion of one vertebral artery might have led to enlargement and subsequent rupture of the contralateral dissection. Direct wrapping was unable to prevent enlargement of the dissection, so radical surgery including bilateral vertebral artery occlusion combined with vascular reconstruction may be the treatment of choice for this type of lesion.
    No shinkei geka. Neurological surgery 04/2002; 30(3):321-5. · 0.13 Impact Factor
  • Surgery for Cerebral Stroke 01/2002; 30(2):113-119.
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    ABSTRACT: In this study we compared the outcome of patients with primary pontine hemorrhage (PPH) in those who underwent stereotaxic aspiration and those treated non-surgically. Out of 75 PPHs, 37 patients were selected. Their consciousness on admission was somnolent to semicoma (alert and deeply comatose cases were excluded). Patients admitted between 1988 and 1990, and between 1995 and 1996 underwent CT guided stereotaxic aspiration (18 cases: Surgical Group), and those admitted between 1991 and 1994 were treated conservatively (19 cases: Conservative Group). The outcome was analyzed three months after the onset from the viewpoint of level of consciousness and severity of paresis, according to the location of the hemorrhage. With regard to consciousness, 13 of 18 cases in the Surgical Group showed remarkable improvement, while only 8 of 19 cases in the Conservative Group did. The severity of paresis was evaluated only among the patients who could obey commands three months after the onset. Paresis improved in 7 of 13 patients in the Surgical Group, vs. in 3 of 8 patients in the Conservative Group (p < 0.05). According to the location of hemorrhage (CT classification), in the Unilateral tegmental type and the Massive type, the Surgical Group and the Conservative Group showed no difference. On the other hand, in the Bilateral tegmental type and the Basal tegmental type, surgery seemed to be more effective than conservative treatment. In conclusion, CT guided stereotaxic aspiration may improve not only the consciousness level but also the functional outcome.
    No shinkei geka. Neurological surgery 09/2001; 29(9):823-9. · 0.13 Impact Factor
  • Surgery for Cerebral Stroke 01/2001; 29(4):245-248.
  • The Journal of trauma 01/2001; 49(6):1138-40. · 2.35 Impact Factor
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    ABSTRACT: Intracranial fusiform aneurysms can be divided into 2 clinically different subtypes: acute dissecting aneurysms and chronic fusiform or dolichoectatic aneurysms. Of these 2, the natural history and growth mechanism of chronic fusiform aneurysms remains unknown. A consecutive series of 16 patients with chronic fusiform aneurysms was studied retrospectively to clarify patient clinical and neuroradiological features. Aneurysm tissues were obtained from 8 cases and were examined to identify histological features that could correspond to the radiological findings. Four histological features were found: (1) fragmentation of internal elastic lamina (IEL), (2) neoangiogenesis within the thickened intima, (3) intramural hemorrhage (IMH) and thrombus formation, and (4) repetitive intramural hemorrhages from the newly formed vessels within thrombus. IEL fragmentation was found in all cases, which suggests that this change may be one of the earliest processes of aneurysm formation. MRI or CT detected IMH, and marked contrast enhancement of the inside of the aneurysm wall (CEI) on MRI corresponded well with intimal thickening. Eight of 9 symptomatic cases but none of 7 asymptomatic cases presented with both radiological features. Data suggest that chronic fusiform aneurysms are progressive lesions that start with IEL fragmentation. Formation of IMH seems to be a critical event necessary for lesions to become symptomatic and progress, and this can be monitored on MRI. Knowledge of this possible mechanism of progression and corresponding MRI characteristics could help determine timing of surgical intervention.
    Stroke 05/2000; 31(4):896-900. · 6.16 Impact Factor
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    ABSTRACT: Neuropsychological disturbances following surgery for anterior communicating artery aneurysms were analyzed in 26 patients (11 males, 15 females) using the Hasegawa dementia scale-revised (HDS-R) over a 3-year period. The patients were aged from 34 to 76 years (mean 54.1 years). Lesions in the frontal lobe were evaluated using computed tomography (CT). Twenty-three patients had symptoms over the course. Four patients had basal forebrain lesion, five had ventral frontal lesion, and 12 had no lesion. Patients with basal forebrain lesion and no lesion tended to show disorientation. The mean HDS-R score was 10.2 points in the patients with ventral frontal lesion, and 13.5 points in the patients with no lesion. These scores are within the range for dementia. The mean HDS-R score in patients with basal forebrain and striate lesions was over 25 points and beyond the range for dementia. Significant differences were observed in the HDS-R score between patients with ventral frontal lesion and basal forebrain lesion, and between patients with no lesion and basal forebrain lesion (p < 0.05). Recovery from neuropsychological disturbances was poorer in patients with ventral frontal lesion and no lesion compared to those with basal forebrain and striate lesions, and their symptoms tended to persist.
    Neurologia medico-chirurgica 03/2000; 40(2):83-6; discussion 86-7. · 0.49 Impact Factor
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    ABSTRACT: The present report describes the successful treatment of cerebral symptomatic vasospasm (SVS) after subarachnoid hemorrhage (SAH) with super-selective intra-arterial infusion of fasudil hydrochloride (ERIL((R))). We treated seventeen vascular territories in 12 patients with selective intra-arterial infusion of fasudil hydrochloride (FSD). FSD was infused through a catheter (a microcatheter in nine patients) at a rate of 1.0 to 1.5 mg/minute (total dose=30 to 60mg/1 vessel) for each vascular territory. Nineteen vascular territories (100%) were angiographically dilated and seven patients (58%) showed early improvement in neurological function after the procedure.
    Interventional Neuroradiology 11/1999; 5 Suppl 1:133-6. · 0.77 Impact Factor
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    ABSTRACT: Expanded polytetrafluoroethylene (ePTFE) can be used as a dura substitute but is associated with leakage of cerebrospinal fluid (CSF) through the suture line. Fibrin glue alone may not prevent this problem. This new method for sealing the suture line in ePTFE membrane uses an absorbable polyglycoic acid mesh soaked with fibrinogen fluid placed on the suture line. Thrombin fluid is then slowly applied to the wet mesh, forming a large fibrin membrane reinforced by the mesh over the suture line. Only one of 33 patients in whom this technique was used had CSF leakage, whereas 12 of 59 patients in whom a dural defect was closed with ePTFE alone showed postoperative subcutaneous CSF collection (p < 0.05). Our clinical experiences clearly show the efficacy of the mesh-and-glue technique to prevent CSF leakage after artificial dural substitution. Mesh and glue can provide an adequate repair for small dural defect. The mesh-and-glue technique may also be used for arachnoid sealing in spinal surgery.
    Neurologia medico-chirurgica 04/1999; 39(4):316-8; discussion 318-9. · 0.49 Impact Factor
  • H Nakatomi, K Nagata, S Kawamoto
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    ABSTRACT: In the majority of cases of ruptured vertebral artery dissecting aneurysm after proximal clipping, the dissected pseudolumen persists for a very short time, probably because re-entry from the pseudolumen is minimal. Recent reports have indicated a high risk of rebleeding of dissecting aneurysms involving the posterior inferior cerebellar artery (PICA) after proximal clipping, probably due to excessive retrograde flow from the distal vertebral artery into both the PICA and the pseudolumen. We describe an extremely rare case of ruptured dissecting aneurysm involving the PICA with persistent patent pseudolumen after proximal clipping. The present case was assumed to have developed a moderate retrograde flow just sufficient to maintain the patent pseudolumen in the chronic stage. Neointimal formation is suggested to be a possible mechanism by which the pseudolumen is stabilized for a very long period.
    Acta Neurochirurgica 02/1999; 141(5):533-6. · 1.55 Impact Factor
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    ABSTRACT: Basilar artery occlusion (BAO) causing brainstem infarction occurred in a 7-year-old boy without any basic disorders. A diagnosis of BAO due to basilar artery dissection (BAD) was suspected at angiography, and this was confirmed by gadolinium-enhanced magnetic resonance imaging (MRI). These investigations clearly showed all the typical diagnostic signs such as a pseudolumen, double lumen and intimal flap, and a pseudolumen in resolution. The spontaneous healing of the dissection was clearly demonstrated during 10 months of follow-up. We stress that BAD can occur in young children and that combined diagnosis with gadolinium-enhanced MRI and angiography is conclusive for diagnosis of dissecting aneurysms. Wider use of these combined diagnostic methods will allow the detection of less severe basilar artery dissection, thus extending the spectrum of presentation and prognosis.
    Acta Neurochirurgica 02/1999; 141(1):99-104. · 1.55 Impact Factor
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    ABSTRACT: A 63-year-old male with a preexisting chronic subdural hematoma presented with progressive confusion and left hemiparesis as well as high fever. Subdural empyema was strongly suspected. At surgery, the empyema was encapsulated by definite inner and outer membranes. Cultures isolated from the subdural fluid and from an abscess of his left thigh yielded methicillin-resistant Staphylococcus aureus. A pulsed-field gel electrophoresis showed these two strains were genetically identical. Hematogenous infection of a preexisting subdural hematoma is an extremely rare cause of subdural empyema.
    Neurologia medico-chirurgica 12/1998; 38(11):743-5. · 0.49 Impact Factor
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    ABSTRACT: A case of intraaxial clear cell ependymoma is reported. A 46-year-old man complained of right hemiparesis. CT scan showed a mass lesion on the median plane with a huge cyst in the left frontal lobe. MRI showed an iso-low intensity mass by T1-weighted image. The tumor was heterogeneously enhanced by Gd-DTPA and the wall was enhanced as well. Angiogram revealed a tumor stain from the right internal carotid artery. The main mass of the tumor was totally removed but the cystic wall was left removed. Histopathological examination revealed clear cell ependymoma. Immunohistochemical examination revealed that, although vimentin and NSE were positive, GFAP, synaptophysin and S-100 were negative. Ultrastructual examination revealed cilia, microvilli and desmosomal junctions. The patient fully recovered after operation and showed no sign of recurrence after an year of follow-up. Clear cell ependymoma is a rare variant of ependymoma. Ultrastructual examination was more useful than immunohistochemical examination for diagnosis.
    Nō to shinkei = Brain and nerve 06/1998; 50(5):431-6.
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    ABSTRACT: The clinical features of "aneurysmal" subarachnoid hemorrhage (SAH) of angiographically unverified etiology were reviewed to clarify the incidence and natural history of dissecting aneurysms as the hemorrhagic source of SAH. We reviewed 30 patients with SAH of unverified etiology in whom initial CT scan showed a diffuse or anteriorly distributed subarachnoid blood clot. Ten of the patients had stenotic or occlusive lesions (SOCL) on initial angiography, and these were the main focus of this study. Among the 10 patients with SOCL on initial angiography, the lesions were located on the anterior circulation in 6 and on the posterior circulation in 4. Ruptured dissecting aneurysms were confirmed by exploratory surgery or autopsy in 6 patients. Subsequent rupture occurred in 6 of the 10 patients (60%), and all 6 of these patients died as a result. The incidence (6/30) of dissecting aneurysms as the cause of SAH of unverified etiology was unexpectedly high, especially when initial angiography disclosed SOCL (6/10). The moribund patients with SOCL showed a high rate of rebleeding, and the untreated recurrent hemorrhages were fatal. Further MRI study is indicated for these patients to demonstrate the intramural hematoma. Compared with the devastating mortality caused by the subsequent ruptures, the extent of surgical morbidity was minor. Surgical intervention could therefore be justified when the following neuroradiological findings are present: (1) SOCL evident on angiography, (2) distribution of SAH on CT compatible with the location of the SOCL, and (3) intramural hematoma on MRI in the same region as the SOCL.
    Stroke 07/1997; 28(6):1278-82. · 6.16 Impact Factor