Makoto Sonobe

Small Unruptured Intracranial Aneurysm Verification Study: SUAVe Study, Japan

Background and Purpose— The natural history and optimal management of incidentally found small unruptured aneurysms <5 mm in size remain unclear. A prospective study was conducted to determine the optimal management for incidentally found small unruptured aneurysms. Methods— From September 2000 to January, 2004, 540 aneurysms (446 patients) were registered. Four hundred forty-eight unruptured aneurysms <5 mm in size (374 patients) have been followed up for a mean of 41.0 months (1306.5 person-years) to date. We calculated the average annual rupture rate of small unruptured aneurysms and also investigated risk factors that contribute to rupture and enlargement of these aneurysms. Results— The average annual risks of rupture associated with small unruptured aneurysms were 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms. Patient <50 years of age (P=0.046; hazard ratio, 5.23; 95% CI, 1.03 to 26.52), aneurysm diameter of ≥4.0 mm (P=0.023; hazard ratio, 5.86; 95% CI, 1.27 to 26.95), hypertension (P=0.023; hazard ratio, 7.93; 95% CI, 1.33 to 47.42), and aneurysm multiplicity (P=0.0048; hazard ratio, 4.87; 95% CI, 1.62 to 14.65) were found to be significant predictive factors for rupture of small aneurysms. Conclusions— The annual rupture rate associated with small unruptured aneurysms is quite low. Careful attention should be paid to the treatment indications for single-type unruptured aneurysms <5 mm. If the patient is <50 years of age, has hypertension, and multiple aneurysms with diameters of ≥4 mm, treatment should be considered to prevent future aneurysmal rupture.

Treatment of chronic subdural hematoma by closed-system drainage without irrigation

BACKGROUND Recurrence of chronic subdural hematoma after surgery has not been eliminated. We sought to determine whether irrigation influences recurrence rate. METHODS Patients who had undergone surgery for chronic subdural hematoma were reviewed retrospectively. RESULTS Between 1986 and 1993, 186 cases of chronic subdural hematoma were treated surgically at Mito National Hospital. Recurrence was limited to six cases (3.2%). A closed drainage system without irrigation has been used since 1988 in 119 patients. Before 1988, 67 cases were treated with single burr hole irrigation and drainage. The rate of recurrence with the closed drainage system was 3.4% (four cases), compared with 3.0% (two cases) for irrigation and drainage. CONCLUSION Compared with irrigation and drainage, the closed drainage system without irrigation was safe and effective, and recurrence of chronic subdural hematoma is not influenced by irrigation.

Determinants of Poor Outcome After Aneurysmal Subarachnoid Hemorrhage when both Clipping and Coiling Are Available: Prospective Registry of Subarachnoid Aneurysms Treatment (PRESAT) in Japan

OBJECTIVE To examine current determinants of poor outcome after aneurysmal subarachnoid hemorrhage (SAH) when ruptured aneurysms are treated with either microsurgery (clipping) or endovascular treatment (coiling) depending on each patients characteristics. METHODS Between March 2006 and February 2007, 534 patients with SAH were enrolled in the Prospective Registry of Subarachnoid Aneurysms Treatment (PRESAT) project. Patients were treated according to the preference of investigators who were experienced in performing both clipping and coiling. Factors influencing poor outcome (12-month modified Rankin Scale [mRS], 3-6) were determined using multivariate logistic regression analyses. RESULTS In this cohort, 32.4% of patients were World Federation of Neurosurgical Societies (WFNS) grade IV-V, and 28.1% had a poor outcome. Clipping was preferably performed for small aneurysms with a wide neck and for middle cerebral artery (MCA) aneurysms, whereas coiling was preferred for larger, internal carotid artery (ICA) and posterior circulation aneurysms. In addition to increasing age, admission WFNS grade IV-V, preadmission aneurysmal rerupture, vasospasm-induced cerebral infarct, pneumonia, sepsis, shunt-dependent hydrocephalus and seizure, postclipping hemorrhagic complications (odds ratio 4.8, 95% confidence interval 1.5-15.3, P < 0.01), and postcoiling ischemic complications (odds ratio 4.4, 95% confidence interval 1.3-15.2, P < 0.05) significantly caused poor outcomes, although the complications did not affect mortality. Type of treatment modality and size and location of aneurysms did not influence outcome. CONCLUSIONS Introducing an endovascular treatment option has made aneurysm characteristics less important to outcome, but procedural complications are problematic and should be reduced to improve outcome.

Prediction model for 3‐year rupture risk of unruptured cerebral aneurysms in Japanese patients

To build a prediction model that estimates the 3‐year rupture risk of unruptured saccular cerebral aneurysms.

Parasagittal meningioma en plaque with extracranial extension presenting diffuse massive hyperostosis of the skull

BACKGROUND We describe a case of convexity meningioma en plaque (MEP) invading the skull and scalp with diffuse massive hyperostosis, presenting striking radiological findings. CASE DESCRIPTION A 48-year-old woman was admitted to our hospital with headache, general fatigue, diplopia, and blurred vision. A skull X-ray film, computed tomography (CT), and 3-dimensional CT demonstrated diffuse significant hyperostosis and sclerosis in the cranial vault. Magnetic resonance (MR) imaging revealed a frontoparietal, well-enhanced extra-axial mass lesion, which is compatible with findings of MEP. The tumor was partially resected. Histological examination revealed massive tumor invasion into the dura mater, hyperostotic skull, and scalp. CONCLUSION Hyperostosis is frequently observed in MEP, although there has been no report of a case of MEP such as ours demonstrating diffuse tumor extension and diffuse hyperostosis. Analyzing the CT finding of hyperostotic bone is useful for differentiation of MEP from other diseases that include a hyperostotic condition.

Continuous recording of cerebral blood flow by means of a thermal diffusion method using a Peltier stack.

The thermal diffusion method is known to be effective for making quantitative measurements of blood flow, but cannot be easily applied to problems concerning quantitative changes in blood flow. Carter et al. found that the thermal diffusion technique using a Peltier stack as the probe produced extremely stable recordings and was suitable for quantitative work. We made a more stable probe containing an air space and having a stainless cap that added weight. A stable recording of blood flow was then possible. For calibration of the probe, we used blood flow values measured by means of an electrolytic technique and the equation proposed by Carter et al. In the present study, we have shown that it is theoretically possible to perform the calibration even without obtaining data on blood flow after cardiac arrest. Experimentally, the validity of such calibration was confirmed. This technique for measuring blood flow should be applicable in various fields and its use in a clinical setting, particularly in the monitoring of blood flow during neurosurgical operations, can be expected.

Carotid artery stenting without post-stenting balloon dilatation

Purpose To evaluate the clinical outcome and MRI findings after carotid artery stenting (CAS) without post-dilatation. Methods Between May 2005 and April 2012, a total of 169 consecutive patients (61.4% symptomatic) underwent 176 CAS procedures performed with an embolic protection device (GuardWire, n=116; FilterWire EZ, n=60). All stents were deployed without post-dilatation. Periprocedural complications and mid-term outcomes were analyzed. Results The stroke rate was 2.3% within 30 days post-CAS (asymptomatic patients 1.5%; symptomatic patients 2.8%). Cerebral infarction occurred in one asymptomatic patient (1.5%) and one symptomatic patient (0.9%). Intracranial hemorrhage occurred in two symptomatic patients (1.9%). Post-CAS diffusion-weighted imaging (DWI) revealed a high-intensity area in 26 of 176 procedures (14.8%). Ipsilateral stroke after 31 days occurred in two patients (1.1%) and restenosis occurred in six (3.4%). A post-CAS comparison of the embolic protection devices revealed no difference in stroke incidence within 30 days and in DWI high-intensity area. Conclusions Our CAS procedure without post-dilatation is feasible, safe and associated with a low incidence of stroke and restenosis.

Japanese society of neuro-endovascular treatment specialist qualification system. Six years' experience and introduction of an animal model examination.

Recent advances in devices and materials, and therapeutic technical improvements in interventional neuroradiology practice make it possible to use this therapeutic method for the treatment of neurovascular disease. In view of the spread of this treatment and increasing numbers of the procedures, there is a social demand to maintain a certain therapeutic quality. One of the methods used to present the therapeutic quality of doctors to the public is technical and knowledge authorization by an official organization or society. According to the ideas of the Japanese Society of Neuro-Endovascular Therapy (JSNET) “The basic therapeutic standard should be secured by the Society to avoid unnecessary complications which are caused by improper techniques and immature experiences.” JSNET start to develop a Specialist Qualification System in 1997, and the first examination was held in 2002. Details of the development of the system and the requirement of specialists have previously been reported1. It has been ten years since development of this system and we have had eight examinations since 2002. Following six years of experience and two years of examinations using an animal model, we would like to introduce the JSNET Specialist Qualification System.

A case of nontraumatic spinal epidural hematoma caused by extradural varix: consideration of etiology.

BACKGROUND CONTEXT Many cases of nontraumatic spinal epidural hematoma (SEH) have been reported, although the etiology of SEH remains unclear. PURPOSE Our purpose was to report a rare case of nontraumatic acute SEH caused by extradural varices and to discuss the etiology of this entity. STUDY DESIGN/SETTING Case report. PATIENT SAMPLE A 27-year-old man. OUTCOME MEASURES Resolution of the patients paraplegia, and pathological examination of the epidural vein of the patient and three other patients with cervical spondylosis. METHODS Not applicable. RESULTS The patient recovered from paresis of both hands, although paraplegia remains complete. Pathological examination of the patient revealed abnormal veins that had thickened walls, varying caliber, and internal elastic lamina. In two of the three patients with cervical spondylosis, abnormally dilated veins resembling those in the SEH patient were observed. CONCLUSIONS We describe a rare case of SEH caused by extradural varices. It is speculated that spinal epidural veins can possibly develop an abnormal structure and fragility as seen in the present case and in spondylotic cases.

The First Specialist Qualification Examination of the Japanese Society of Intravascular Neurosurgery (JSIN)

In the past 25 years, interventional neuroradiology (IVNR) has widened its application not only to cerebrovascular diseases but also to vertebroplasty and tumor embolization. Gradually the positive evidence of its usefulness has accumulated in many diseases, and along with the progress of IVNR, the membership of the JSIN rapidly increased. Members now number 1431 (5/24/2002) and include 1200 (83.9%) neurosurgeons, 96 (6.7%) radiologists (neuroradiologist), 31 (2.2%) physicians, eight (0.6%) emergency doctors and 96 (6.6%) others. IVNR requires a great deal of knowledge, techniques and experience to do with the important but vulnerable central nervous system. The basic therapeutic level should be secured by the Society to avoid unnecessary complications which are caused by improper techniques and immature experiences. Hence, there arose the expectation to provide a proper educational system and a rigid selection system for the specialist in JSIN.