47 research outputs found
Long-range order and low-energy magnetic excitations in CeRu2Al10
The nature of the unconventional ordered phase occurring in CeRu2Al10 below
T0 = 27 K was investigated by neutron scattering. Powder diffraction patterns
show clear superstructure peaks corresponding to forbidden (h + k)-odd
reflections of the Cmcm space group. Inelastic neutron scattering experiments
further reveal a pronounced magnetic excitation developing in the ordered phase
at an energy of 8 meV.Comment: 5 pages; 4 figure
Neutron scattering study of the long-range ordered state in CeRu2Al10
Elastic and inelastic neutron scattering measurements have been performed on
powder and single-crystal samples of orthorhombic CeRu2Al10. The order forming
below T0 = 27 K was identified as a long-range antiferromagnetic state with the
wave vector k = (1,0,0). The magnetic spectral response in the ordered phase,
measured on powder, is characterized by a spin gap and a pronounced peak at 8
meV, whose Q dependence suggests a magnetic origin. Both features are
suppressed when temperature is raised to T0, and a conventional relaxational
behavior is observed at 40 K. This peculiar spin dynamics is discussed in
connection with recent magnetization results for the same compound.Comment: 5 pages, 5 figures, International Conference on Heavy Electrons 2010
(Tokyo Metropolitan University, September 17 - 20, 2010), to be published in
Journal of the Physical Society of Japan. Typo corrected p. 3: "sites denoted
1 and 3" => "1 and 4
Persistent frequent subclinical seizures and memory impairment after clinical remission in smoldering limbic encephalitis.
Aim. To delineate a possible correlation between clinical course and EEG abnormalities in non-infectious “smoldering” limbic encephalitis. Methods. Long-term clinical data, including video-EEG monitoring records, were analysed in two patients. Results. The two patients were positive for anti-voltage-gated potassium channel complex antibody and unspecified antineuronal antibody, respectively. The latter patient had small cell lung carcinoma. Both patients had memory impairment and clinical seizures. EEG showed frequent subclinical seizure patterns in the bilateral temporal regions. Subclinical seizure patterns and memory impairment persisted over one to two years after clinical seizure remission. Therapy (prednisolone and chemoradiation in the two patients, respectively) resulted in decreased occurrence of subclinical seizure patterns and memory improvement. Conclusions. EEG seizure patterns may persist years after clinical seizure remission in “smoldering” limbic encephalitis and lead to memory impairment
Study of predisposing risk factors and etiology of chronic subdural hematoma in clipped patients of unruptured intracranial aneurysms: An institutional experience
Introduction: Chronic subdural hematoma in clipped patients of unruptured intracranial aneurysms might lead to sudden neurological deterioration and may need emergency evacuation. We studied the effects of various factors in its etiology. Materials and methods: A retrospective study of 91operated clipped patients of unruptured aneurysms in the year 2014-2015 was taken. Various predisposing factors were studied. Results: Goreisan use was not associated with any reduction in post operative CSDH formation. Arachnoidoplasty and reduced post operative dead space contributed in a reduced formation of CSDH. Conclusion: Older male patients with aneurysms who had been treated with anticoagulant drugs should be considered candidates for additive ARP to prevent the development of postoperative CSDH
Computational Fluid Dynamics in Unruptured Intracranial Aneurysms
Introduction and Objective: Intracranial aneurysm, also known as brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery causes a localized dilation or ballooning of the blood vessel. There is no objective way, device or tools, of predicting rupture of aneurysm so far. Computational fluid dynamics (CFDs) was proposed as a tool to identify the rupture risk. Purpose of study: To reveal the correlation of CFD findings with intraoperative microscopic findings and prove the relevance of CFDin the prediction of rupture risk and in the management of unruptured intracranial aneurysms. Subjects and Methods: A prospective cohort study was conducted inNeurosurgery department of Fujita Health University Banbuntane Hotokukai Hospital, Nagoya, Japanduring a 3?month period in 2018,from January to March, Ten patientswere diagnosed unruptured intracranial aneurysms (UIA). In diagnosis computed tomography (CT) angiogram, CFD and digital subtraction angiogram were included. Intraoperatively microscopic examination of the aneurysm wall was carried out and images recorded. The correlation between microscopic dome morphology and CFD information was performed. Results: Nine cases were found intraoperatively to have a higher risk of rupture based on the thinning of the wall. One cases had an atherosclerotic wall. All cases had low wall shear stress (WSS). In 90 % of cases Low WSS was able to predict the potency rupture risk in the near future. Conclusions: This study of CFD and its correlation with intraoperativefindings of the aneurysm suggested that low WSS of the aneurysm wall is associated with thin wall aneurysm and hence increased risk of aneurysm rupture. Thus CFD can be used to predict the risk of rupture of unruptured aneurysm and for planning of its treatment
Long term prognosis of ventriculoatrial shunt for idiopathic normal pressure hydrocephalus in the elderly
Objective: A retrospective study was conducted to access the long-term prognosis of inserting the Ventriculoatrial (VA) shunt in the elderly for the idiopathic normal pressure hydrocephalus (iNPH). Material and Methods: Retrospective data is collected from April 2004 to August 2015, and 1065 patients were selected. Patients who underwent surgical examination or surgery in suspected iNPH were included. Tap test is done in all cases and found to be effective for 968 cases and 656 VA shunts for 614 cases. Out of 614 cases there are 440 cases in which patient age were over 75 years. Of these 440 cases only 141 cases were able to observe 03 years or more after the surgery, 37 deaths and 05 cases with survival and unknown prognosis were found among them. So we analyzed this group mainly in 99 cases that the prognosis after 03 years was known. We access the outcome of VA shunt by the modified Rankin scale (mRS), iNPH grading scale (iNPHGS) and complications in the operative 656 cases and in 03 years follow up of 141 patients. Results: Of 141, there are 78 males and 63 females. Age at the time of VA shunt insertion was 81.5±4.1 years and age at final follow-up was 85.2±4.4 years. The proportion of patients who achieved a favorable outcome by complications was 97.9% in 03 years follow-up period and 87.7% in which follow-up is less than 03 years. At the time of VA shunt insertion out of 141, 57 patients lies between 75-79 years, 57 between 80-84, 24 between 85 to 89, and only 03 were found to be 90 years or more. At the time of final follow-up at 03 years, 15 patients lies between 75 to 79 years, 56 between 80 to 84 years, 57 between 85 to 89 years and 23 patents were found to be 90 years or greater. 70 cases or almost 50% exceeded 85 years. At the time of VA shunt 1, 11, 39, 51, 36, 3, 0 patients were in 0 to 6 modified Rankin Scale Score respectively and at 03 years follow-up 8, 19, 32, 29, 9, 2, 37 were in 0 to 6 mRS respectively. Comparison of the study is done with SIPHONI study on VP shunt and LP shunt. Conclusion: Patients suspected of having idiopathic normal pressure hydrocephalus were treated by VA shunt and found no significant difference in serious adverse effects. This study shows that VA shunt is an effective choice for iNPH in the late elderly population, but it needs more randomized control trial to establish its efficacy
High Flow Bypass for Cavernous Carotid Aneurysms
Introduction and objective: High flow extracranial to intracranial (HF EC–IC) cerebral revascularisation may be necessary in the management of complex skull base tumours and intracranial aneurysms. Bypass grafting can be considered high flow when a radial artery or the saphenous vein is interposed between the extracranial carotids arteries and intracranial vessels. The decision as to whether to use a low flow or high flow bypass is determined by the anticipated cerebral blood flow needed and the availability of a supply source. In this study, we have used this method to bypass for two cases of giant aneurysms of the cavernous sinus part of the ICA. Methods: Two cases of giant ICE aneurysm not amenable to clipping or coiling were taken since 2016. Patients were treated in Neurosurgery department of Fujita Health University Banbuntane Hotokukai Hospital, Nagoya, Japan. During bypass surgery, intraoperative methods were used to determine the patency of the graft artery: Doppler sonography and indocyanine green (ICG) Dual-Image Videoangiography (DIVA). Results: Two patients with symptomatic large and giant cavernous carotid aneurysms were evaluated as not amenable for clipping or endovascular treatment due to location and size of the aneurysm and associated high morbidity risk with these treatment options. In both cases radial artery graft was used for high-flow EC-MCA bypass and proximal internal carotid artery was ligated. Additionally, for high-flow bypass was performed superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. DIVA, ICG and Doppler sonography were used multiple times to assess the patency of graft artery. In one case there was not complete ligation of the IC after postop DSA, the next day was performed reintervention to completely ligate IC. Postoperative course was uneventful, there were no mortality or morbidity. Follow-up showed good recovery and postoperative CT and DSA showed complete occlusion of ligated IC and patent functioning arterial graft. Conclusions: Cavernous carotid aneurysms (CCA) are rare and pose considerable challenges in management. A bypass procedure before parent artery occlusion, preferable to reduce the risks of postocclusion stroke. Intraoperative Doppler sonography and DIVA makes it easy to check the patency of the graft. DIVA is superior over Doppler or ICG in terms of better visualization of related anatomical structures
Real-time patency verification during clipping aneurysm and STA-MCA by-pass with dual-image videoangiography
The dual-image videoangiography (DIVA) is a new tool which helps identify ves-sels and surrounding structure. This method is based on use of indocyanine green video angiography (ICG-VA) technology on real time microscopic operative image. In this two case, we report of using DIVA in STA-MCA bypass surgery of 46 years old, female patient of stenosis of right MCA. And using DIVA during clipping ICA paraclinod aneurysm of 35 years old, female. During surgery, it helped in identifying temporal and frontal branches of the STA and there careful selection. After anastomosis, DIVA was used to refine vessel patency and functioning of the anastomosis. DIVA has the potential to replace ICG-VA as a tool for checking the patency of graft during bypass procedures and obliteration of aneurysm along with surgical procedures for AVM and d-AVF. DIVA allows visualization of vessels against a background of normal brain and has better visualization at greater depth and high magnification. This is particularly important during bypass surgery, which very often is performed in deep surgical fields and high magnification