The morphology of the internal carotid artery (ICA) bifurcation is increasingly being recognized as the cause of atherosclerosis and vulnerable plaque leading to cerebral infarction. In this study, we investigated the relationship between carotid bifurcation angle and carotid plaque volume evaluated using black blood magnetic resonance imaging (BB-MRI). Among the 90 patients who underwent revascularization for atherosclerotic symptomatic carotid stenosis between April 2016 and October 2022 using BB-MRI, carotid plaque was evaluated in 57 patients. Relative overall signal intensity (roSI) was defined as the signal intensity of the plaque on T1-weighted images relative to the signal intensity of the sternocleidomastoid muscle in the same slice as the common carotid bifurcation. Regions showing roSI ≥ 1.0 were defined as plaque, and the plaque volume and relative plaque volume were measured from roSI ≥1.0 to ≥2.0 in 0.1 increments. We calculated the angles between the common carotid artery (CCA) and the ICA and between the CCA and the external carotid artery (ECA) on magnetic resonance angiography. We classified two groups according to carotid bifurcation angles based on the ICA angle: Group A = <35° and Group B = ≥35°. Compared with Group A (n = 42), Group B (n = 15) showed a greater relative plaque volume between roSI ≥ 1.3 and roSI ≥ 1.5. A significant correlation was identified between relative plaque volume with roSI ≥ 1.4 and ICA angle (p = 0.049). Vulnerable plaque was significantly more frequent in the group with an ICA angle of ≥35. Moreover, the ICA angle was significantly greater in patients with a roSI of ≥1.4.

Surgery on spinal tumors becomes challenging when the tumor is ventral to the spinal cord. Conventionally, we approach it posteriorly through bilateral laminectomy and rotate the cord after sectioning the dentate ligament and nerve roots. However, manipulating the cord can be hazardous, and a long bilateral laminectomy can be invasive. Meanwhile, a narrow operative field and a limited lateral viewing angle in a unilateral approach constrained the surgeon. To overcome these problems, we previously reported a technique of modified unilateral approach where we incised the skin and the fascia horizontally and placed a pair of retractors longitudinally.

The current article reports our experience applying this approach in 15 patients with ventrally located spinal tumors. The approach was performed on 10 schwannomas, 2 meningiomas, and 3 others. We evaluated paraspinal muscle atrophy on postoperative magnetic resonance imaging.

The modified unilateral approach provided an excellent surgical field for removing ventrally located tumors. Gross total removal was achieved in 11 patients (92% of benign tumors). No neurological complications occurred except for one case of transient weakness. We encountered no wound-related late complications such as pain or deformity. The reduction of the cross-sectional area of the paraspinal muscles on the approach side (compared to the nonapproach side) was 0.93 (95% confidence interval: 0.72-1.06), indicating 7% atrophy (statistically nonsignificant, p = 0.48).

We believe this simple technique can be useful for removing spinal tumors located ventral to the spinal cord.

Rebleeding from a ruptured intracranial aneurysm has poor outcomes. Although numerous factors are associated with rebleeding, studies on computational fluid dynamics (CFD) on hemodynamic parameters associated with early rebleeding are scarce. In particular, no report of rebleeding in ultra-early phase exists. We aimed to elucidate the specific hemodynamic parameters associated with ultra-early rebleeding using CFD. In this study, the rebleeding group included patients with aneurysmal subarachnoid hemorrhage (aSAH) that rebled within 6 h from the onset. The control group included patients without rebleeding, observed for >10 h following the initial rupture. Clinical images after initial rupture and before rebleeding were used to build 3D vessel models for hemodynamic analysis focusing on the following parameters: time-averaged wall shear stress (WSS), normalized WSS, low shear area, oscillatory shear index, relative residence time, pressure loss coefficient, and aneurysmal inflow rate coefficient (AIRC). Five and 15 patients in the rebleeding and control groups, respectively, met the inclusion criteria. The World Federation of Neurosurgical Surgeons grade was significantly higher in the rebleeding group (p = 0.0088). Hemodynamic analysis showed significantly higher AIRC in the rebleeding group (p = 0.042). The other parameters were not significantly different between groups. There were no significant differences or correlations between SAH severity and AIRC. AIRC was identified as a hemodynamic parameter associated with ultra-early rebleeding of ruptured intracranial aneurysms. Thus, AIRC calculation may enable the prediction of ultra-early rebleeding.

This study aims to evaluate the academic activities of female neurosurgeons at all branch meetings of the Japan Neurosurgical Society and identify related issues they encountered. The programs of all seven branch meetings of the Japan Neurosurgical Society (Hokkaido, Tohoku, Kanto, Chubu, Kinki, Chugoku/Shikoku, and Kyushu) were used to determine the number of presentations and chairpersons by sex. The covered period was from January 2008 to December 2020, which was available for viewing during the survey. Of note, only the Kinki branch used data from January 2008 to December 2019. The Neurologia Medico-chirurgica (NMC), the journal of the Japan Neurosurgical Society, was also reviewed to identify publication achievements during the same period. In all seven branches, the percentage of presentations given by female physicians increased from 7.9% in 2008 to 9.6% in 2020 (p < 0.05).

Conversely, the percentage of female chairpersons in all branch meetings did not change over time and it was significantly lower (1.1%) than that of female presenters (7.9%) for all branch meetings combined in over 13 years (p < 0.01). In the NMC, the number of articles with female physicians as first authors did not increase or decrease over the years. We conclude that efforts to smoothly promote female neurosurgeons as chairpersons and increase the number of female first authors are necessary to facilitate their academic activities.

Aneurysmal subarachnoid hemorrhage (SAH) treatment has progressed, and patients are rapidly aging in Japan. Consequently, dynamic changes must have emerged in the clinical practice of SAH. This study aimed to elucidate chronological changes of aneurysmal SAH and the prognostic factors in the previous quarter century in Japan. We conducted a retrospective survey regarding aneurysmal SAH in eight institutions in Japan. The study included 848, 863, and 781 patients in the first (1989-1993), second (1999-2003), and third (2009-2013) periods, respectively. The chronological changes of factors that influenced the poor outcomes and differences between the nonelderly (<75 years) and elderly patients were investigated. Mean age was significantly higher in patients in the third period (61.4 years) than in those in the other two periods (first, 57.8 years; second, 59.5 years). During these periods, the proportion of good outcomes did not change; however, the mortality rate significantly decreased from 19% in the first period to 11% and 9.2% in the second and third periods, respectively. The poor outcome was mainly caused by the significantly higher incidence of systemic complication and procedural complication in the first period and the significantly lower incidence of delayed ischemic neurological deficit in the third period. The elderly patients had significantly poorer clinical outcomes than the nonelderly ones. During the last 25 years, the age of patients with aneurysmal SAH has rapidly increased. The study results may contribute to the improvement of the treatment strategy of SAH in advanced countries with a rapidly aging population.

Closed spinal dysraphism (CSD) encompasses a heterogeneous group of spinal cord deformities, which can be accompanied by several types of skin stigmata. These skin stigmata may include inconspicuous features, such as sacral dimples and deformed gluteal clefts, but the association between such mild skin stigmata and CSD is uncertain. This study aimed to reevaluate the indication for magnetic resonance imaging (MRI) in patients with skin stigmata while considering the indication for surgery. A retrospective analysis was conducted on magnetic resonance images of 1255 asymptomatic children with skin stigmata between 2003 and 2015. Skin stigmata classification was based on medical chart data. All subtypes of CSDs except for filum terminale lipomas (FTL), FTL thicker than 2 mm or with low conus medullaris, were considered to meet the surgical indication. CSD prevalence was estimated while considering the surgical indications and assessed after excluding all FTL cases. Skin stigmata were classified into seven types, dimple, deformed gluteal cleft, hair, subcutaneous mass, appendage, discoloration, and protruding bone, and included 1056 isolated and 199 complex ones. The prevalence of CSD was 19.5%, 6.8%, and 0.5% among patients with isolated dimples (n = 881) and 13.9%, 5.8%, and 0.7% among those with isolated deformed gluteal clefts (n = 136) for all cases, surgical indications, and patients without FTL, respectively. Dimples and deformed gluteal clefts had a low prevalence of CSD requiring surgical intervention, and cases without FTL were rare. Asymptomatic patients with mild skin stigmata may not require immediate MRI.

Delayed foreign body reactions to either or both clipping and coating materials have been reported in several small series; however, studies in the titanium clip era are scarce. This study aims to survey the contemporary status of such reactions to titanium clips and coating materials. Among patients who received a total of 2327 unruptured cerebral aneurysmal surgeries, 12 developed delayed intraparenchymal reactions during outpatient magnetic resonance imaging (MRI) follow-up. A retrospective investigation was conducted. The patients' average age was 58.6 (45-73) years, and 11 were women. The aneurysms were located in the middle cerebral artery (n = 7), internal carotid artery (n = 4), or anterior communicating artery (AComA, n = 1). In 10 patients, additional coating with tiny cotton fragments was applied to the residual neck after clipping with titanium clips; however, only the clipping with titanium clips was performed in the remaining two. The median time from surgery to diagnosis was 4.5 (0.3-60) months. Seven (58.3%) patients were asymptomatic, and three developed neurological deficits. MRI findings were characterized by a solid- or rim-enhancing lobulated mass adjacent to the clip with surrounding parenchymal edema. In 11 patients, the lesions reduced in size or disappeared; however, in one patient, an AComA aneurysm was exacerbated, necessitating its removal along with optic nerve decompression. In conclusion, cotton material is a strongly suspected cause of delayed foreign body reactions, and although extremely rare, titanium clips alone may also induce such a reaction. The prognosis is relatively good with steroid therapy; however, caution is required when the aneurysm is close to the optic nerve, as in AComA aneurysms.

In revascularization of internal carotid stenosis with carotid vertebrobasilar anastomoses, attention should be paid not only to the anterior circulation but also to the posterior circulation cerebral infarction. A 74-year-old man was referred for treatment of carotid artery stenosis; NASCET 75% stenosis in the right internal carotid artery and acute cerebral infarction were confirmed. Occlusion of the left subclavian artery and vascular anastomosis between the right external carotid artery and the vertebral artery were indicated, such that the right external carotid artery may maintain blood flow to the vertebrobasilar artery. Therefore, dual shunts were used for the common and internal carotid arteries and the common and external carotid arteries to maintain blood flow during carotid endarterectomy. Management of the dual shunts is difficult due to the instable parallel placement of the common carotid artery shunt balloons. To solve this problem, the "dual internal shunts technique" was performed. The first shunt was inserted into the external and common carotid arteries, and the second into the internal and common carotid arteries. The shunt balloon on the common carotid artery side was placed distal to the first shunt balloon so that the dual balloons were placed in a tandem position. The proximal balloon was subsequently deflated gradually to improve flow in both shunts. The procedure is technically easy and safe.