[Cryptogenic stroke--vascular malformation-clinical features].
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Diffusion Magnetic Resonance Imaging↗
Biomedical subjects
Hiroki Kurita
Publications and source records attributed to Hiroki Kurita.
The risk of hemorrhage after radiosurgery for cerebral arteriovenous malformations.
BACKGROUND: Angiography shows that stereotactic radiosurgery obliterates most cerebral arteriovenous malformations after a latency period of a few years. However, the effect of this procedure on the risk of hemorrhage is poorly understood. METHODS: We performed a retrospective observational study of 500 patients with malformations who were treated with radiosurgery with use of a gamma knife. The rates of hemorrhage were assessed during three periods: before radiosurgery, between radiosurgery and the angiographic documentation of obliteration of the malformation (latency period), and after angiographic obliteration. RESULTS: Forty-two hemorrhages were documented before radiosurgery (median follow-up, 0.4 year), 23 during the latency period (median follow-up, 2.0 years), and 6 after obliteration (median follow-up, 5.4 years). As compared with the period between diagnosis and radiosurgery, the risk of hemorrhage decreased by 54 percent during the latency period (hazard ratio, 0.46; 95 percent confidence interval, 0.26 to 0.80; P=0.006) and by 88 percent after obliteration (hazard ratio, 0.12; 95 percent confidence interval, 0.05 to 0.29; P<0.001). The risk was significantly reduced during the period after obliteration, as compared with the latency period (hazard ratio, 0.26; 95 percent confidence interval, 0.10 to 0.68; P=0.006). The reduction was greater among patients who presented with hemorrhage than among those without hemorrhage at presentation and similar in analyses that took into account the delay in confirming obliteration by means of angiography and analyses that excluded data obtained during the first year after diagnosis. CONCLUSIONS: Radiosurgery significantly decreases the risk of hemorrhage in patients with cerebral arteriovenous malformations, even before there is angiographic evidence of obliteration. The risk of hemorrhage is further reduced, although not eliminated, after obliteration.
Adult↗
Radiation-induced apoptosis of oligodendrocytes in the adult rat optic chiasm.
OBJECTIVES: The present study characterized glial cell injury provoked in adult rat chiasm within 24 hours after a single, high-dose irradiation of 20 Gy. METHODS: All chiasmal glial cells in a section were counted, and the percentage of TUNEL-positive glial cells exhibiting apoptotic morphology was defined as the apoptotic rate. RESULTS: Numbers of apoptotic cells increased significantly (p<0.0001) from 3 to 8 hours after exposure, but returned to baseline levels by 24 hours. Little evidence of apoptosis was observed in non-irradiated chiasms. Similar patterns of increase in apoptotic rate were observed in the genu of the corpus callosum, but the extent was significantly lower (p=0.047) in the optic chiasm, with a maximal rate of 1.9%. Immunohistochemically, apoptotic cells were positive for CNP, a marker for oligodendrocytes. DISCUSSION: These data indicate that chiasmal irradiation induces limited, but significant apoptotic depletion of the oligodendroglial population, and may participate in the development of radiation-induced optic neuropathy.
Analysis of Variance↗
Gamma knife surgery for arteriovenous malformations involving the corpus callosum.
OBJECT: The purpose of this study was to evaluate the safety and efficacy of gamma knife surgery (GKS) for the treatment of arteriovenous malformations (AVMs) involving the corpus callosum. METHODS: Thirty-two patients aged from 7 to 65 years (median 25 years) with AVMs of the corpus callosum underwent GKS between 1990 and 2002. The maximum AVM diameter was more than 3 cm in 11 patients (34%). The AVM volume ranged from 0.1 to 19.1 cm3 (median 1.6 cm3). The median dose to the AVM margin was 20 Gy (range 17-28 Gy). Patients were followed for 1 to 12 years (median 9 years). The angiographically confirmed actuarial obliteration rate was 64% and 74% at 4 and 6 years, respectively. Younger patient age (p < 0.05) and lower radiosurgery-based grading score (calculated from the patient age and AVM volume; p < 0.01) were the significant factors affecting successful AVM obliteration. No patient suffered a hemorrhage after GKS, although 28 patients (88%) had a history of hemorrhage from their AVMs. Radiation-induced neurological deficit was observed only in one patient (3%) who had undergone previous radiotherapy (50 Gy). No patient experienced complications of occlusion or stenosis of the normal vascular structures adjacent to the AVM. CONCLUSIONS: Gamma knife surgery is a safe and effective treatment for selected patients with AVMs involving the corpus callosum, and it carries a low risk of damaging adjacent critical vascular structures. Even ruptured AVMs with relatively large diameter can be successfully treated, especially in younger patients, with minimal morbidity and a low risk of repeated hemorrhage.
Adolescent↗
Gamma knife surgery for hemangioblastomas.
OBJECT: The authors reviewed their 14-year experience using stereotactic radiosurgery for the treatment of hemangioblastomas and define the role and the proper strategy for radiosurgery of this condition. METHODS: This is a retrospective study of 38 hemangioblastomas in 13 patients. Seven patients had von Hippel-Lindau disease. All patients have undergone at least one follow-up visit. The median and mean tumor volumes were 0.23 cm3 and 0.72 cm3 respectively (range 0.004::4.84 cm3). Twenty-eight tumors received 20 Gy to the margin, and the remainder received 18 Gy. The median clinical follow-up period was 36 months (range 3-159 months). No patient died. The survival rate was 84.6% (11 of 13 patients). The actuarial 5- and 10-year survival rates were both 80.8%. The median radiological follow-up period was 35 months (range 7-147 months). Only one tumor increased in volume 24 months after treatment in association with an intratumoral hemorrhage. The tumor control rate was 97.4% (37 of 38 tumors). Actuarial 5- and 10-year control rates were both 96.2%. New lesions and/or those increasing in size outside the irradiated area were discovered in five patients (38.5%). Nine tumors revealed peritumoral contrast enhancement which was seen more frequently in larger tumors with a volume greater than 0.5 cm3 (p = 0.0034). CONCLUSIONS: Gamma knife surgery is a safe and effective method to control hemangioblastomas for as many as 10 years. Higher doses and smaller tumors probably contribute to good outcomes. Recurrence outside the original irradiated area is common. Peritumoral contrast enhancement may be seen in larger tumors. The authors recommend regular imaging follow up and early repeated treatment in the face of new or growing tumors.
Adult↗
[Targeted small craniotomy and evacuation for subscute subdural hematomas: technical report of two cases].
The etiology and proper treatment of symptomatic subacute subdural hematomas remains to be elucidated. We describe two cases of this entity successfully treated with small craniotomy and evacuation. Both patients initially treated conservatively for traumatic thin subdural hematomas because of poor medical condition and mild neurological symptoms, but suffered abrupt neurological deterioration between 2 and 3 weeks after the admission. CT scan showed decreased density of hematomas with minimal increase in volume, and significant swelling of ipsilateral cerebral hemisphere. Urgent two-burr-hole small craniotomy was effective for evacuation of partially organized hematoma. During surgery, definite hematoma membrane was not confirmed. Postoperatively, brain swelling rapidly disappeared and both patients discharged ambulatory without neurological deficit. The present cases are a reminder of this peculiar type of hematoma in patients with delayed neurological deterioration after nonsurgical management of acute subdural hematoma. The rationale for use of small craniotomy is discussed in terms of current understanding of pathogenetic mechanism for this unusual condition.
Aged↗
[Our current technique for basic pterional craniotomy].
Pterional cnaniotomy is frequently used in neurosurgical practice, but still poses significant cosmetic and functional drawbacks. Here, we describe our modified technique to overcome such problems as the sterilization of the scalp without brush and razor, preemptive analgesia, preservation of the periostium for reconstruction, retrograde dissection of the temporal muscle, and complete sphenoidotomy using chisel or drills. The tips of our pterional craniotomy offer suitable size and depth of working field around the paraclinoidal regions, maintaining cosmetic satisfaction of the patients.
Anesthesia↗
Morphologic changes in neo-intimal proliferation in an experimental aneurysm after coil embolization: effect of factor XIII administration.
We investigated histological changes in aneurysmal orifices after embolization with Guglielmi detachable coils (GDCs) and determined the effects of the wound-healing factor, factor XIII, on promoting intimal proliferation by scanning electron microscopy (SEM). GDC embolization was performed in an experimental model of aneurysm in swine. In the control group (17 aneurysms), the aneurysms were resected immediately after surgery, at 1 and 3 weeks after the procedure. In the factor XIII-administered group (13 aneurysms), the swine received factor XIII postoperatively, and the aneurysms were excised at 1 and 3 weeks. The endothelial cell proliferation changes in the aneurysm orifices in both groups were evaluated by SEM. The histological changes at the orifices began immediately after the procedure, and endothelialization was observed at 1 week. One week after the procedure, the rate of endothelial cell proliferation was significantly higher in the factor XIII group (P<0.05). But no difference was observed at 3 weeks, when endothelialization of the orifices was essentially completed. The process of intimal proliferation after coil embolization was similar to the wound-healing process after vascular intimal injury. Administration of the wound-healing factor, factor XIII, would contribute rapid intimal proliferation and may be effective to facilitate complete obliteration of aneurysms after coil embolization.
Animals↗
Defecation-induced vertigo.
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Arachnoid Cysts↗
Meningiomatosis in a survivor of Hiroshima.
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Aged↗
High plasma concentration of brain natriuretic peptide in patients with ruptured anterior communicating artery aneurysm.
The purpose of this study is to investigate the mechanism of increased atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with subarachnoid hemorrhage due to ruptured aneurysms. ANP and BNP plasma concentrations were measured by immunoradiometoric assay in 53 patients at the day of onset of ruptured aneurysm, the correlation between values of increased ANP or BNP, and sex, age, location of ruptured aneurysm, degree of SAH, and severity of WFNS were statistically studied. The concentration of BNP in ruptured anterior communicating artery aneurysm (A-com) shows a significant elevation compared with other site aneurysms (p = 0.0007). The patients classified as WFNS Grade V, show a significantly higher concentration of BNP, compared with the patients classified as Grade I-IV (p =0.01). It is concluded that the hypersecretion of BNP, but not ANP, is caused by direct mechanical damage at the anterior hypothalamus by ruptured A-com aneurysm and a higher increase of BNP is also observed in cases suffering from severe neurological deficit.
Adult↗
Proposed treatment strategy for cavernous sinus meningiomas: a prospective study.
OBJECTIVE: To establish a safe and effective treatment strategy for cavernous sinus (CS) meningiomas, we prospectively analyzed the outcome of a treatment protocol combining surgery and radiosurgery during the past 7 years. METHODS: Tumors confined to the CS and distant from the optic apparatus and the brainstem were treated with radiosurgery alone. Tumors attached to or compressing the optic apparatus and brainstem and that were larger than 3 cm in mean diameter, extended into the multiple cranial fossae, and were suspected of being malignant were treated with combined nonradical microsurgery and radiosurgery. RESULTS: In accordance with this treatment protocol, 40 patients aged 26 to 72 years (median, 51 yr) with primary (n = 27) or recurrent (n = 13) CS meningiomas (volume range, 0.9-39.3 cm(3); median volume, 5.4 cm(3)) were treated with combined surgery and radiosurgery (n = 23) or radiosurgery alone (n = 17). During radiosurgery, 12 to 18 Gy (median, 16 Gy) was delivered to the tumor margin. The follow-up period ranged from 14 to 79 months (median, 47 mo). The actuarial tumor control rate was 94.1% at 5 years. The improvement of cranial nerve function was significantly frequent in patients with primary CS meningiomas (P < 0.05). Permanent cranial nerve dysfunction was significantly frequent in patients with tumors compressing the brainstem or smaller than 10 cm(3) (P < 0.05). All 36 patients with a pretreatment Karnofsky Performance Scale score of 90 or more maintained the same range after treatment. CONCLUSION: Proper combination of microsurgery and radiosurgery for CS meningiomas provides excellent growth control with favorable functional state. Outcomes were better when this protocol was adopted at the initial diagnosis for patients with smaller tumors that did not compress the brainstem.
Adult↗
Analysis of nidus obliteration rates after gamma knife surgery for arteriovenous malformations based on long-term follow-up data: the University of Tokyo experience.
OBJECT: A large number of clinical studies have been made on treatment outcomes of radiosurgery for arteriovenous malformations (AVMs), but the reported obliteration rates following this treatment vary significantly, perhaps reflecting the different methods and timings of the imaging studies used. METHODS: The authors retrospectively analyzed their experience with gamma knife surgery in 400 patients with AVMs (follow-up period 1-135 months, median 65 months), with special reference to the imaging modality used in each case. The calculated obliteration rates varied from 68.2 to 92%, depending on imaging modality and timing of evaluation. When only unquestionable imaging data such as demonstrations of a residual nidus on computerized tomography (CT) or magnetic resonance (MR) images or findings on angiograms were used in the calculation, the obliteration rates were 72% at 3 years and 87.3% at 5 years. Factors leading to a better obliteration rate were previous hemorrhage (p = 0.0084), smaller nidus (p = 0.0023), and higher radiation dose to the lesion's margin (p = 0.0495), as determined in a multivariate analysis. Factors leading to an earlier obliteration of the nidus were male sex (p = 0.0001), previous hemorrhage (p = 0.0039), smaller nidus diameter (p = 0.0006), and dose planning using angiography alone (p = 0.0201). CONCLUSIONS: After the introduction of CT and MR images into dose planning, the conformity and selectivity of dosimetry improved remarkably, although the latency intervals until obliteration were prolonged. Imaging outcomes for AVMs should be evaluated using data provided by longer follow-up periods. The timing of additional treatments for residual AVMs should be decided cautiously, considering the size of the AVM, the patient age and sex, and the history of hemorrhage before radiosurgery.
Adolescent↗
white-eyed shunt.
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Cerebral Angiography↗
[Clinical significance of natriuretic peptides in patients with aneurysmal subarachnoid hemorrhage].
Hyponatremia and hypovolemia following aneurysmal subarachnoid hemorrhage (SAH) might be speculated by exaggerated secretion of natriuretic peptides and resulted ischemic sequela caused by cerebral vasospasm. We measured serum concentration of natriuretic peptides and investigated their influence on post-SAH hyponatremia. Among 49 patients of SAH, their plasma concentration of the natriuretic peptides (atrial natriuretic peptide: ANP and brain natriuretic peptide: BNP) were measured at the day of ictus and 7th day of SAH. The correlation between concentration of natriuretic peptides and location of aneurysm, severity of SAH, incidence of hyponatremia and symptomatic vasospasm were elucidated. The plasma concentration of ANP did not alter on admission and 7th day post SAH, whereas that of BNP increased in the patients with moribund SAH and those with ruptured A-com aneurysm. The initial increase of BNP following SAH could be attributed to direct damage of SAH on the hypothalamus. Hyponatremia and symptomatic vasospasm tended to occur in the patients who had persistent increase of plasma BNP concentration during one week post SAH. Therapeutic intervention to maintain normonatremia by fluid-management decreased occurrence of symptomatic vasospasm, even though patients with increased plasma BNP concentration. It might be concluded that increased secretion of BNP following SAH is caused by direct effect to the hypothalamus and prolonged hyper secretion of BNP resulted hyponatremia, hypovolemia and exaggerated symptomatic vasospasm.
Aneurysm, Ruptured↗
Malignant transformation of a vestibular schwannoma after gamma knife radiosurgery.
Stereotactic radiosurgery is used to treat benign tumours, but its long-term effects are not fully understood. Here we describe a vestibular schwannoma that underwent malignant transformation 6 years after gamma knife radiosurgery applied to the tumour remnant after a primary resection. Histological specimens of the original specimen did not show any atypical features. Genotyping showed a TP53 mutation in the recurrent tumour, which did not exist in the original tumour. Our results suggest that radiosurgery induced the malignant transformation, and we propose a cautious application of this treatment for benign tumours.
Adult↗
De novo dissecting aneurysm in a patient with a ruptured saccular lesion. Case report.
Formation of a new saccular aneurysm after successful treatment of ruptured aneurysm has recently raised significant clinical concerns; however, de novo formation and rupture of a dissecting aneurysm has not been discussed. The authors report on a 42-year-old man who initially sought treatment for a ruptured saccular aneurysm of the right middle cerebral artery, which was successfully eliminated by surgical clipping of the aneurysm neck. Two years later, the patient presented with another subarachnoid hemorrhage and was found to have a dissecting aneurysm of the right vertebral artery, which arose from a previously angiographically documented normal artery. This rare association sheds light on the causes and growth of two distinct types of aneurysms, both clinically and pathologically.
Adult↗
Retrospective analysis of a 10-year experience of stereotactic radio surgery for arteriovenous malformations in children and adolescents.
OBJECT: To obtain information essential to the decision to perform radiosurgery for arteriovenous malformations (AVMs) in children and adolescents, the authors retrospectively analyzed their experience with gamma knife surgery for AVMs in 100 patients ranging in age from 4 to 19 years. METHODS: Follow-up periods ranged from 6 to 124 months (median 71 months), and the actuarial obliteration rates demonstrated by angiography were 84.1, 89.4, and 94.7% at 3, 4, and 5 years, respectively. Factors associated with better obliteration rates in univariate analysis included the following: a patient age of 12 years or younger; a mean nidus diameter of 2 cm or less; a nidus volume of 3.8 cm3 or less; a maximum diameter of the nidus less than 3 cm; and a Spetzler-Martin grade of III or less. Radiation-induced neuropathy was seen in four patients, and the risk factors were considered to be a nidus in the brainstem and a maximum radiation dose greater than 40 Gy. Hemorrhage developed during the latency interval in four patients, and one patient with a cerebellar AVM died of the hemorrhage. The annual bleeding rate was 1.5%. Feeding arteries located in the posterior cranial fossa and an AVM nidus located in the cerebellum were significantly associated with the risk of hemorrhage. After angiographically verified obliteration of the nidus, 51 patients continued to be observed from 1 to 110 months (median 67 months); hemorrhage developed in one patient 38 months after nidus obliteration. CONCLUSIONS: Radiosurgery is an acceptable treatment for small AVMs in children and adolescents in whom a higher obliteration rate can be achieved with lower risks of interval hemorrhage compared with the reported results in the general population. Careful follow-up observation seems to be required, however, even after angiographically verified obliteration.
Adolescent↗