Zheng-hui Sun

Microsurgical management of large and giant paraclinoid aneurysms

BACKGROUND Because of the complex topographic anatomical relationship between vascular, dural and bone structures, paraclinoid aneurysms, especially those of larger size, remain a great challenge for vascular neurosurgeons. We present our microneurosurgical experience of 51 consecutive patients with large and giant paraclinoid aneurysms to scrutinize our personal strategies related to surgical treatment. METHODS Fifty-one patients with large or giant paraclinoid underwent micorneurosurgical aneurysm treatment. Operative strategies were planned according to preoperative state-of-the-art imaging studies, and a pterional-transsylvian approach was routinely used. Proximal control of the internal carotid artery (ICA) was achieved by exposure of the cervical portion of the vessel. Intraoperative electroencephalogram and somatosensory evoked potential monitoring, indocyanine green (ICG) videoangiography and/or microvascular Doppler ultrasonography (MDU) were regularly used. A postoperative digital subtraction angiography or computed tomography angiography was performed to verify the efficacy of treatment. RESULTS Forty-three large and giant paraclinoid aneurysm necks (84%) were directly clipped, seven unclippable aneurysms (14%) were trapped with extra-intracranial high-flow revascularization, and one aneurysm (2%) was treated with only ICA proximal Hunterian ligation. Two patients (4%) died in the early postoperative period. In 84% of the patients, the Glasgow Outcome Scale score was 4 or 5 at discharge. At the 6-month follow-up examination, the Rankin Outcome Scale score was 0-2 in 90% of patients. CONCLUSIONS Temporary parent vessel occlusion, retrograde suction decompression, endoaneurysmectomy, parent vessel clip reconstruction, and bypass vascular anastomosis are essential techniques to treat complex paraclinoid aneurysms. The combined use of electrophysiological monitoring, MDU, intraoperative ICG videoangiography, and endoscopy can substantially improve microsurgical outcome.

Electrical stimulation of the vagus nerve protects against cerebral ischemic injury through an anti-infammatory mechanism.

Vagus nerve stimulation exerts protective effects against ischemic brain injury; however, the underlying mechanisms remain unclear. In this study, a rat model of focal cerebral ischemia was established using the occlusion method, and the right vagus nerve was given electrical stimulation (constant current of 0.5 mA; pulse width, 0.5 ms; frequency, 20 Hz; duration, 30 seconds; every 5 minutes for a total of 60 minutes) 30 minutes, 12 hours, and 1, 2, 3, 7 and 14 days after surgery. Electrical stimulation of the vagus nerve substantially reduced infarct volume, improved neurological function, and decreased the expression levels of tumor necrosis factor-ƒΏ and interleukin- 6 in rats with focal cerebral ischemia. The experimental findings indicate that the neuroprotective effect of vagus nerve stimulation following cerebral ischemia may be associated with the inhibition of tumor necrosis factor-ƒΏ and interleukin-6 expression.

Revascularization for Complex Cerebral Aneurysms

BACKGROUND AND PURPOSE Complex cerebral aneurysms may require indirect treatment with revascularization. This manuscript describes various surgical revascularization techniques together with clinical outcomes. METHODS Thirty-two consecutive patients with complex cerebral aneurysm were managed from November 2005 to October 2008. Techniques used for revascularization were high-flow bypass, low-flow bypass, branch artery reimplantion, and primary reanastomosis. Physiologic and anatomic monitoring technologies, including electroencephalography, somatosensory evoked potential monitoring, microvascular doppler ultrasonography, and/or indocyanine green videoangiography were used intraoperatively to assess both brain physiology and vascular anatomy. Patient outcome was determined using the Glasgow Outcome Scale at discharge and at a mean of 12 months post operation (range 6-25 months). RESULTS Two cervical carotid aneurysms (6%) were resected followed by primary reanastomosis, 21 aneurysms (66%) were trapped following saphenous vein high-flow bypasses, five (16%) were clipped after superficial temporal or occipital artery low-flow bypasses, and four (12%) middle cerebral branch arteries were reimplanted. Of the 32 patients at discharge, 29 (91%) had a Glasgow Outcome Scale of four or five, two (6%) had severe disability, and one (3%) died. CONCLUSION Cerebral revascularization remains an effective and reliable procedure for treatment of complex cerebral aneurysms. Low morbidity and mortality rates reflect the maturity of patient selection and surgical technique in the management of these lesions.

Wall shear stress in intracranial aneurysms and adjacent arteries.

Hemodynamic parameters play an important role in aneurysm formation and growth. However, it is difficult to directly observe a rapidly growing de novo aneurysm in a patient. To investigate possible associations between hemodynamic parameters and the formation and growth of intracranial aneurysms, the present study constructed a computational model of a case with an internal carotid artery aneurysm and an anterior communicating artery aneurysm, based on the CT angiography findings of a patient. To simulate the formation of the anterior communicating artery aneurysm and the growth of the internal carotid artery aneurysm, we then constructed a model that virtually removed the anterior communicating artery aneurysm, and a further two models that also progressively decreased the size of the internal carotid artery aneurysm. Computational simulations of the fluid dynamics of the four models were performed under pulsatile flow conditions, and wall shear stress was compared among the different models. In the three aneurysm growth models, increasing size of the aneurysm was associated with an increased area of low wall shear stress, a significant decrease in wall shear stress at the dome of the aneurysm, and a significant change in the wall shear stress of the parent artery. The wall shear stress of the anterior communicating artery remained low, and was significantly lower than the wall shear stress at the bifurcation of the internal carotid artery or the bifurcation of the middle cerebral artery. After formation of the anterior communicating artery aneurysm, the wall shear stress at the dome of the internal carotid artery aneurysm increased significantly, and the wall shear stress in the upstream arteries also changed significantly. These findings indicate that low wall shear stress may be associated with the initiation and growth of aneurysms, and that aneurysm formation and growth may influence hemodynamic parameters in the local and adjacent arteries.

Microsurgical management of posterior cerebral artery aneurysms: A report of thirty cases in modern era

Abstract Objective. We reviewed a series of 30 cases of posterior cerebral artery (PCA) aneurysms to examine the outcomes of microsurgical techniques, which is an important alternative to endovascular interventions in localities where access to the latter renders practical difficulty. We also aimed to introduce the initial experience about the clinical application of intraoperative computed tomography (CT) in treatment of PCA aneurysm. Methods. Thirty patients with PCA aneurysm treated using microsurgery in our department between January 1996 and July 2014 were reviewed retrospectively. Results. The case series included 13 females and 17 males with a mean age of 44 years, ranging from 8 to 78 years. Eighteen aneurysms were ruptured, five aneurysms caused a direct mass effect, and the remaining seven aneurysms were found incidentally. Most aneurysms were located in the P1 segment or the P1–P2 junction of the PCA (63%). Eighteen aneurysms (60%) were large or giant in size (≥10 mm). Seventeen aneurysms were directly clipped, six trapped, one wrapped, one electrocoagulated and resected, and five trapped or proximal clipped with a bypass. Intraoperative perfusion CT (PCT) and CT angiography (CTA) were applied to provide immediate information regarding cerebral hemodynamics and anatomy of vessels in six patients. Twenty-six patients (87%) showed good clinical outcomes according to the modified Rankin Scale score (≤2) at the mean clinical follow-up period of 34 (range: 1–78) months, including the patients using intraoperative CT, and one (3%) patient was dead. Conclusion. Microsurgical therapy for patients with PCA aneurysms can have a positive outcome with correctly selected techniques. Personalized microsurgical treatment paradigms are determined by the anatomical location, shape and size of the PCA aneurysm, and the clinical features of the patient. Intraoperative PCT and CTA can improve the efficacy of the surgical treatment.

Application of Multimodal Navigation together with Fluorescein Angiography in Microsurgical Treatment of Cerebral Arteriovenous Malformations

This study aimed to explore the clinical applications of multimodal navigation combined with indocyanine green (ICG) fluorescein angiography in microsurgical treatment of cerebral arteriovenous malformations (AVMs). We retrospectively collected 52 patients with AVMs. Assisted by anatomic image, we reestablished three-dimensional structure using preoperative functional magnetic resonance imaging (fMRI) and Diffusion tensor imaging (DTI). The operation for lesion resection was finished under the assistance of neuro-navigation. ICG fluorescein angiography was performed for 16 of the study subjects, meanwhile, FLOW800 was used to rebuild blood vessel color visual image. Brain angiography was performed 1 week after the operation to check residual malformations. The patients’ status was estimated by Modified Rankin Scale score. Of the AVMs, 92.3% (48/52) were totally removed, without severe side events. Among the patients, fluorescein angiography was carried out up to 58 times for 16 cases. All of these 16 cases were confirmed with malformations and 14 of them had draining vein. The total resection rate of these 16 cases reached 100%, and the occurrence rate of postoperative complications was not significantly increased. During the operation of lesion resection, the application of multimodal navigation could effectively protect functional cortex and conduction pathway.

Surgical management of recurrent aneurysms after coiling treatment

Abstract Objective: Aneurysms that recur after coiling treatment are difficult to manage. The microsurgical technique in these cases differs significantly from that in regular aneurysm clipping. We present our experience in surgical management of aneurysms that recurred more than 1 month after coiling in a series of 19 patients. Materials and methods: Between January 2004 and December 2014, 1437 patients were treated surgically for intracranial aneurysms in our institution. We performed a retrospective review of the clinical records, operation videos, and cerebral angiograms. We focused on patients in whom the initial aneurysm was treated by coiling, but the results were incomplete or the aneurysm recurred. Results: Nineteen patients underwent surgical clipping for recurrent aneurysm more than 1 month after initial coiling treatment. The sex ratio (male:female) was 0.9, and the average age was 51.3 years (range 35–72 years). One aneurysm was classified as giant (≥ 25 mm), two as large (10–25 mm), and 18 as small (≤ 10 mm). A good outcome (Glasgow Outcome Scale 4 or 5) was observed in 16 of 19 patients (84.2%). Conclusion: Microsurgical clipping can be safe and effective in the management of previously coiled residual and recurrent aneurysms.

Intraoperative Perfusion Computed Tomography in Carotid Endarterectomy: Initial Experience in 16 Cases

Background This study aimed to evaluate the changes in perfusion computed tomography (PCT) parameters in carotid endarterectomy (CEA), and to discuss the use of intraoperative PCT in CEA. Material/Methods Sixteen patients with carotid stenosis who also underwent CEA with intraoperative CT were recruited in this study. We calculated quantitative data on cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), and the relative parameter values, including relative CBF (rCBF), relative CBV (rCBV), and relative TTP (rTTP). The role of PCT was assessed and compared to conventional monitoring methods. Results There were no significant differences in any of the parameters in the anterior cerebral artery (ACA) territory (P>0.05). In the middle cerebral artery (MCA) territory, the CBF and CBV increased and TTP decreased in the operated side during CEA; the rCBF and rCBV increased and the rTTP decreased significantly (P<0.05). In 16 patients, CT parameters were improved, SSEP was normal, and MDU was abnormal. In 3 patients, CBF increased by more than 70% during CEA. Relative PCT parameters are sensitive indicators for detecting early cerebral hemodynamic changes during CEA. Cerebral hemodynamics changed significantly in the MCA territory during CEA. Conclusions Intraoperative PCT could be an important adjuvant monitoring method in CEA.

Intraoperative high-field MRI maximizes the extent of resection in intraventricular central neurocytoma surgery.

Central neurocytoma (CN) is a rare benign neuronal tumor of the ventricular system. Microsurgical resection is considered to be the mainstay of treatment for intraventricular CN, and the extent of resection is the most important prognostic factor. We describe our initial experience in the management of intraventricular CN with intraoperative MRI together with microscope-based neuronavigation. During a 5year period between February 2009 and June 2014, 18 consecutive patients with histologically proven CN were included in this study. Gross total tumor resection was achieved in 88.9% (16/18) of patients. There were no perioperative deaths, and the overall complication rate was 61.1% (11/18). The Karnofsky Performance Status score at the last follow-up was 100 in eight (44.4%), 90 in seven (38.9%), and ⩽70 in three patients (16.7%). We conclude that intraoperative high-field MRI combined with microscope-based neuronavigation can maximize the extent of resection in intraventricular CN surgery and minimize the risks of neurological impairment.

Simulated effects of perianeurysmal bone on a cerebral aneurysm: a case study

AIM Perianeurysmal structures can affect the hemodynamics and geometric evolution of intracranial aneurysms. The purpose of this study was to use computational models to explore the influence of contact with perianeurysmal bone on an intracranial aneurysm. MATERIAL AND METHODS A cerebral middle aneurysm in contact with an anterior clinoid process was selected. Two anatomic models were constructed from computed tomography angiography images: a non-contact model with elasticity of the entire aneurysm wall and a contact model with rigidity of the part of the aneurysm wall contacting bone. The blood flow pattern and wall stress and displacement were compared between the two models. RESULTS The contact and non-contact models exhibited similar wall shear stress and pressure but different degrees of von Mises stress and wall displacement. Displacement close to the bone contact part of the aneurysm wall was less in the contact model than in the non-contact model, whereas displacement of the part opposite to the contact part was larger in the contact model than in the non-contact model. Also, von Mises stress close to the contact part was larger in the contact model than in the non-contact model. CONCLUSION Contacting perianeurysmal bone affects the deformation and degree of von Mises stress but not the hemodynamics of intracranial aneurysms.