Particle-size dependent structural transformation of skyrmion lattice.

Magnetic skyrmion is a topologically protected particle-like object in magnetic materials, appearing as a nanometric swirling spin texture. The size and shape of skyrmion particles can be flexibly controlled by external stimuli, which suggests unique features of their crystallization and lattice transformation process. Here, we investigated the detailed mechanism of structural transition of skyrmion lattice (SkL) in a prototype chiral cubic magnet Cu2OSeO3, by combining resonant soft X-ray scattering (RSXS) experiment and micromagnetic simulation. This compound is found to undergo a triangular-to-square lattice transformation of metastable skyrmions by sweeping magnetic field (B). Our simulation suggests that the symmetry change of metastable SkL is mainly triggered by the B-induced modification of skyrmion core diameter and associated energy cost at the skyrmion-skyrmion interface region. Such internal deformation of skyrmion particle has further been confirmed by probing the higher harmonics in the RSXS pattern. These results demonstrate that the size/shape degree of freedom of skyrmion particle is an important factor to determine their stable lattice form, revealing the exotic manner of phase transition process for topological soliton ensembles in the non-equilibrium condition.

Electrical magnetochiral effect induced by chiral spin fluctuations.

Chirality of matter can produce unique responses in optics, electricity and magnetism. In particular, magnetic crystals transmit their handedness to the magnetism via antisymmetric exchange interaction of relativistic origin, producing helical spin orders as well as their fluctuations. Here we report for a chiral magnet MnSi that chiral spin fluctuations manifest themselves in the electrical magnetochiral effect, i.e. the nonreciprocal and nonlinear response characterized by the electrical resistance depending on inner product of current and magnetic field. Prominent electrical magnetochiral signals emerge at specific temperature-magnetic field-pressure regions: in the paramagnetic phase just above the helical ordering temperature and in the partially-ordered topological spin state at low temperatures and high pressures, where thermal and quantum spin fluctuations are conspicuous in proximity of classical and quantum phase transitions, respectively. The finding of the asymmetric electron scattering by chiral spin fluctuations may explore new electromagnetic functionality in chiral magnets.The magnetism-induced chirality in electron transportation is of fundamental importantance in condensed matter physics but the origin is still unclear. Here the authors demonstrate that the asymmetric electron scattering by chiral spin fluctuations can be the key to the electrical magnetochiral effect in MnSi.

Prophylactic intra-arterial administration of fasudil hydrochloride for vasospasm following subarachnoid haemorrhage.

PURPOSE: We evaluated patients treated with prophylactic intra-arterial administration of fasudil hydrochloride (IAF) after subarachnoid haemorrhage (SAH). MATERIALS AND METHODS: Between August 1998 and December 2012, 92 patients with aneurysmal SAH were treated with IAF for angiographic vasospasm without ischemic symptoms after their follow-up angiography. Patients comprised 50 women and 42 men, aged 24-83 (mean 56.6) years. IAF consisted of 15 mg of fasudil hydrochloride dissolved in 20 ml physiological saline and injected through a catheter during approximately 15 min, after diagnostic angiography. The clinical outcome was evaluated using the Glasgow Outcome Scale (GOS) at discharge and ischemic lesions resulting from vasospasm were assessed on computed tomography (CT) scan at discharge. RESULTS: Forty-eight patients underwent surgical clipping and 44 patients underwent endovascular coiling. Angiographic improvement was observed in all patients (100 %). At discharge, 76 (83.0 %) of 92 patients showed good recovery on GOS. Nine patients developed progression of delayed ischemic neurological deficits (DIND) and three of these patients had ischemic lesions on CT scans. No patient had any significant changes in vital signs or any other adverse effects resulting from IAF. CONCLUSION: IAF therapy was safe and effective for patients with vasospasm following SAH. Prophylactic IAF therapy may prevent symptomatic vasospasm.

Intra-arterial Administration of Fasudil Hydrochloride for Vasospasm Following Subarachnoid Haemorrhage: Experience of 90 Cases.

BACKGROUND: we investigated the clinical efficacy of intra-arterial administration of fasudil hydrochloride for cerebral vasospasm. METHOD: we reviewed 90 cases treated with intra-arterial administration of fasudil hydrochloride between August 1998 and April 2009 and investigated the clinical efficacy for cerebral vasospasm. FINDINGS: angiographic improvement of vasospasm was noted in all procedures. Eight had ischemic lesion on CT at discharge in Group A, which included 39 patients who presented angiographic and symptomatic vasospasm. However, 4 (50%) of these eight were recovered with a condition of GR. No patients showed ischemic lesion on CT in Group B, which included 51 patients who presented angiographic vasospasm without symptoms. Two (3.3%) of 59 patients who presented angiographic vasospasm without symptoms at the initial follow-up angiography had ischemic lesion on CT at discharge. The 1-year follow-up showed 78.9% of GR. No patient showed any adverse effects resulting from intra-arterial administration of fasudil hydrochloride. CONCLUSION: intra-arterial administration of fasudil hydrochloride was an effective and safe management technique for vasospasm.

Endovascular trapping for a giant aneurysm of the cervical internal carotid artery: a case report.

SUMMARY: We describe a case of giant cervical internal carotid aneurysm successfully treated by endovascular trapping. A 57-year-old woman with a history of maxillary contusion seven years before presented with pharyngeal discomfort during swallowing. MRI revealed a 4 cm mass in the right parapharyngeal space. A common carotid angiogram revealed a giant aneurysm with a wide neck originating from the cervical internal carotid artery; kinking of the internal carotid artery was noted at a point distal to the carotid bifurcation. Analysis of cerebral blood flow by SPECT during a balloon occlusion test showed no hypoperfusion areas, and the patient underwent endovascular trapping. There were no neurological or other complications after the procedure. A follow-up MRI revealed complete thrombosis of the aneurysm. Our results show that endovascular trapping for pseudoaneurysm of the cervical internal carotid artery can be a reliable and effective treatment in patients who tolerate a balloon occlusion test.

Rupture of a large vertebral artery aneurysm following proximal occlusion.

SUMMARY: Proximal occlusion of the vertebral artery is regarded as a safe and effective method of treating aneurysms of the vertebral artery or the vertebrobasilar junction unsuitable for treatment by neck clipping. Complications known to develop after this procedure include ischemic lesions of the perforators and other areas. There are only a limited number of reports on early rupture of aneurysm following proximal occlusion of the vertebral artery for the treatment of unruptured aneurysm. We recently encountered a case of large aneurysm of the vertebral artery identified after detection of brainstem compression. This patient underwent proximal occlusion of the vertebral artery with a coil and developed a fatal rupture of the aneurysm ten days after proximal occlusion. The patient was a 72-year-old woman who had complained of dysphagia and unsteadiness for several years. An approximately 20 mm diameter aneurysm was detected in her left vertebral artery. She underwent endovascular treatment, that is, her left vertebral artery was occluded with coils at a point proximal to the aneurysm. Her initial post-procedure course was uneventful. However, she suddenly developed right-side hemiparesis nine days after procedure. At that time, CT scan suggested sudden thrombosis of the aneurysm. Right vertebral angiography revealed a small part of the aneurysm. She was treated conservatively. Ten days after the procedure, she suffered massive subarachnoid haemorrhage. Both the present case and past reports suggest that proximal occlusion of the vertebral artery is effective in treating relatively large aneurysms unsuitable for treatment by neck clipping or trapping. However, when the bifurcation of the posterior inferior cerebellar artery (PICA) is distal to the occluded point in cases where the PICA bifurcates from the aneurysm or the neck region, blood supply to the aneurysm may persist because anterograde blood flow to the PICA may be preserved. Therefore, clinicians must consider the possibility of aneurysm rupture after proximal occlusion in the following cases: 1) when the aneurysm is large or giant, but non-thrombosed; 2) when thrombosis occurs soon after the procedure; 3) when postoperative angiography shows partial filling of the aneurysm with contrast agent through the contralateral vertebral artery of basilar artery or the cervical muscle branches.

MR imaging of uncommon recurrence of fibrolipomatous hamartoma of the ulnar nerve.

We present the MR and histopathologic findings of fibrolipomatous hamartoma (FLH) of the ulnar nerve in a 54-year-old woman, a lipomatous process that rarely affects the ulnar nerve. The case illustrated is further unusual as a local soft tissue recurrent mass developed over a remarkably long course of the disease.

Parental loss in childhood and social support in adulthood among psychiatric patients. Group for Longitudinal Affective Disorders Study (GLADS).

Psychoanalytic theories hypothesize that early attachment experiences with parents shape the structure and function of adult interpersonal relationships. The present paper aims to examine if parental loss experiences in childhood is related to perceived social support in adulthood. We directly interviewed 1247 patients representative of 31 psychiatric clinics and hospitals all over Japan as to their parental loss experiences in childhood and also administered them Sarason et al.'s Social Support Questionnaire. It was found, to our surprise, that those who had lost the father or mother through death reported as many current support persons as those who had not and that those who had experienced separation from the mother (but not the father) reported greater satisfaction with social support than those who had not. Several hypotheses are advanced to explain these unexpected findings and it is concluded that we must at least entertain some doubt on the direct continuity hypothesis between disruptions of parent-child relationships and the individual's later capacity to enjoy social support.

Embolization of scalp AVF.

We report scalp arteriovenous fistulas (AVFs) in which we performed embolization and examine the treatment method. The subjects were four cases of scalp AVF treated by embolization. All cases were male and three had a past history of scalp injury. As the feeding artery, we found a single artery in one case and multiple arteries in three cases. In three cases we employed a transarterial approach by cutting down the scalp and embolized the fistula with NBCA (N-butyl-cyanoacrylate). We conducted the embolization procedure as follows in order to securely occlude the fistula; 1) we obtained the precise location of fistula by the superselective angiography; 2) we induced the tip of microcatheter to immediately in front of fistula; 3) when high flow shunt was manifested, we controlled the flow by retaining the balloon catheter in the external carotid artery; 4) and injected NBCA by compressing around the fistula from above the scalp with a cylindrical instrument to prevent the migration of embolic material to the venous side. As a result, all cases were completely cured and there was no major complication except for transient postoperative pain. If the transfemoral approach to fistula is impossible, it is considered effective to cut down near the fistula and embolize the scalp AVF by direct puncture to the feeding artery with NBCA as embolic material.

Morphological Study of Carotid Artery of WHHL Rabbit after Balloon Dilatation.

SUMMARY: We performed balloon dilatation in the carotid artery of WHHL rabbits and examined subsequent morphological alteration over time. The balloon was inserted as far as the carotid bifurcation and observations were made on the morphological alteration after dilatation in the atherosclerotic intimal thickening from immediately after balloon dilatation over a period of ten months. Immediately after balloon dilatation, endothelial cells came of circularly and stretching, fragmentation off elastic fibers and coming off of smooth muscle cells of the media were confirmed. No change in the degree of thickening after dilatation was seen in the atherosclerotic intimal thickening of the carotid bifurcation. Three weeks later, endothelium covering except some parts, circular neointima and fibrosis of the media were observed; foamy cells had accumulated in the upper layer of the atherosclerotic intimal thickening, and that region was not yet covered with endothelial cells. The progress of fibrous intimal thickening so as to keep the lumen smooth was seen up to six months later, but foamy cells were not found in the neointima.

New screening system for unruptured cerebral aneurysms--combination of an expert system and DSA examination.

We have designed a screening system to diagnose unruptured aneurysms, including the use of digital subtraction angiography (DSA). We surveyed 115 patients who had undergone clipping procedures after subarachnoid hemorrhage (SAH) and questioned them with regard to the subjective symptoms. Sixty-eight of 92 patients who returned the questionnaire reported, prior to rupture, headache, eye pain, and neck pain most frequently, and also impairment of extraocular movements, ptosis, visual field defects, and motor and sensory disturbances. Nineteen (47.5%) of 40 patients who had complete pain relief after surgery complained of headache from 1 week to 1 month before SAH. In addition, nine patients (22.5%) complained of headache for several years, and were also pain-free after surgery. For the indication of DSA, we employed an expert system based on fuzzy set theory. Seven groups of parameters are: Group 1, a basic questionnaire concerning age, sex, and past and family histories; Group 2, 15 warning signs selected on the basis of retrospective study; and Groups 3-7, detailed questions concerning each sign. Scoring weights assigned to each condition based on the results of the retrospective study, and threshold values were determined by several neurosurgeons. The certainty factors for intermediate hypotheses were calculated from these weights and threshold values and summed up, from which the conclusion was obtained. Twelve new cases of unruptured cerebral aneurysm were diagnosed using this screening system. This system may improve the ability to diagnose cerebral aneurysms before rupture.