Relationships and redundancies of selected hemodynamic and structural parameters for characterizing virtual treatment of cerebral aneurysms with flow diverter devices.

BACKGROUND AND PURPOSE: To quantify the relationship and to demonstrate redundancies between hemodynamic and structural parameters before and after virtual treatment with a flow diverter device (FDD) in cerebral aneurysms. METHODS: Steady computational fluid dynamics (CFD) simulations were performed for 10 cerebral aneurysms where FDD treatment with the SILK device was simulated by virtually reducing the porosity at the aneurysm ostium. Velocity and pressure values proximal and distal to and at the aneurysm ostium as well as inside the aneurysm were quantified. In addition, dome-to-neck ratios and size ratios were determined. Multiple correlation analysis (MCA) and hierarchical cluster analysis (HCA) were conducted to demonstrate dependencies between both structural and hemodynamic parameters. RESULTS: Velocities in the aneurysm were reduced by 0.14m/s on average and correlated significantly (p<0.05) with velocity values in the parent artery (average correlation coefficient: 0.70). Pressure changes in the aneurysm correlated significantly with pressure values in the parent artery and aneurysm (average correlation coefficient: 0.87). MCA found statistically significant correlations between velocity values and between pressure values, respectively. HCA sorted velocity parameters, pressure parameters and structural parameters into different hierarchical clusters. HCA of aneurysms based on the parameter values yielded similar results by either including all (n=22) or only non-redundant parameters (n=2, 3 and 4). CONCLUSION: Hemodynamic and structural parameters before and after virtual FDD treatment show strong inter-correlations. Redundancy of parameters was demonstrated with hierarchical cluster analysis.

Aneurysms of the posterior cerebral artery: classification and endovascular treatment.

BACKGROUND AND PURPOSE: We present a retrospective review of our experience in the endovascular treatment of posterior cerebral artery (PCA) aneurysms. We detail the anatomic location of these aneurysms, the technique of endovascular treatment, morphologic results, and clinical outcome. We also discuss the segmental anatomy of the PCA as it relates to the various neurologic deficits that may result from occlusion of the parent artery. METHODS: From 1993 to 1998, 20 patients (12 female, eight male; mean age, 44 yrs) harboring a PCA aneurysm were treated via an endovascular approach. One patient had two aneurysms, comprising a total of 21 lesions. Fourteen (66%) of 21 aneurysms were saccular in nature, five (24%) were giant serpentine aneurysms, and two (10%) were posttraumatic. All aneurysms were treated using Guglielmi detachable coils (GDC) either by selective obliteration of the aneurysm sac or by parent artery occlusion. RESULTS: Fourteen (66%) of the 21 aneurysms were successfully treated with preservation of the parent artery. In the remaining seven (33%), the parent artery was permanently occluded. The overall complication rate in this series was 15%, with a permanent morbidity rate of 10% and a 0% mortality rate. CONCLUSION: Aneurysms of the PCA are rare compared with other locations in the intracranial circulation. Saccular PCA aneurysms can be treated effectively, by use of GDC, to obliterate the aneurysm yet preserve the parent artery. Fusiform and giant serpentine aneurysms of the PCA can effectively be treated by permanent occlusion of the parent artery; in these cases, thorough knowledge of the PCA segmental anatomy is crucial in order to select the site of occlusion and to avoid major neurologic deficits.

Giant serpentine aneurysms: radiographic features and endovascular treatment.

PURPOSE: To describe the characteristic CT, MR, and angiographic features of giant serpentine aneurysms and discuss their endovascular treatment. METHODS: Thirteen patients with giant serpentine aneurysms were studied at our institution in the last 3 years. They all underwent CT and MR studies as well as cerebral angiography. More recently, some of the patients were studied with MR angiography. Seven patients had endovascular occlusion of the giant serpentine aneurysms, 3 with N-butyl cyanoacrylate, 2 with Guglielmi detachable coils, and 2 with detachable balloons. RESULTS: Giant serpentine aneurysms mimic cerebral neoplasms on CT and MR studies; they are often associated with mass effect and adjacent edema, and they enhance with contrast medium. The cerebral angiogram shows a residual irregular lumen of the partially clotted aneurysm, which continues into normal branches supplying the distal arterial territory. Six patients were treated successfully with an endovascular approach consisting of complete and permanent occlusion of the parent artery. CONCLUSION: Giant serpentine aneurysms from a subgroup of large intracranial aneurysms that have specific CT, MR, and angiographic features, which should be recognized before their treatment. The endovascular treatment of the aneurysm consists of permanent occlusion of the parent artery.

The influence of anulotomy selection on disc competence. A radiographic, biomechanical, and histologic analysis.

STUDY DESIGN: This study analyzed the radiographic, biomechanical, and histologic attributes of three commonly used anulotomy techniques. OBJECTIVES: This study defined the propensity of the anulus fibrosus to heal after discectomy and correlated biomechanical differences between subgroups of the motion segments studied. SUMMARY OF BACKGROUND DATA: No previous report that compares the influence of anulotomy selection on disc competence exists. METHODS: Anulotomies were performed on the anterolateral aspects of the lumbar discs of 54 adult goats. The goats were randomly assigned to one of three subgroups containing 18 animals. In subgroup A, a full-thickness anular window was excised. In subgroup B, a full-thickness cruciate anulotomy was accomplished. In subgroup C, a full-thickness anulotomy was developed by inserting a trocar, 2.5 mm in diameter, into the disc. RESULTS: Histologic analysis revealed that primary anular healing did not occur in any specimen. The anulotomy tracts in subgroup C (trocar) were consistently narrower than those of subgroups A and B. Discography demonstrated the presence of severe and early disc degeneration with subgroup A (anular window), a finding not observed within the trocar anulotomy group. Biomechanical testing demonstrated increased resistance to pull out by the trocar anulotomy group at 4 weeks, as well as increased torsional stiffness of the motion segment when compared to both window and cruciate anulotomy. CONCLUSIONS: The authors conclude that attempts should be made to minimize injury to the anulus fibrosus during the performance of discectomy.

A case of Pott's disease in a 20-year-old military dependent.

Tuberculous spondylitis (Pott's disease) is an uncommon complication of Mycobacterium tuberculosis infection that may have serious consequences if the diagnosis is missed or delayed. A case of tuberculous spondylitis in a military dependent is presented. Clinical presentation, radiologic findings, laboratory findings, and treatment are discussed.

Placement of a ferromagnetic intracerebral aneurysm clip in a magnetic field with a fatal outcome.

Magnetic resonance (MR) imaging may be contraindicated in patients with biomedical devices, among the most dangerous of which are intracranial aneurysm clips, owing to the possibility of torque and dislodgement. A case is presented in which a patient with a reportedly nonferromagnetic clip was placed in a magnetic field. The patient developed an acute intracerebral hemorrhage in the MR unit, with a fatal outcome. Imaging studies strongly suggested a torqued clip as the cause. Autopsy revealed a torn middle cerebral artery from clip movement, and the clip was identified as a ferromagnetic type. This is the first reported case, to the authors' knowledge, of a fatal outcome due to an intracranial aneurysm clip placed in a magnetic field.

Enlargement of basilar artery aneurysms following balloon occlusion--"water-hammer effect". Report of two cases.

Two patients with distal basilar aneurysms were treated with intra-aneurysmal balloon occlusion. After apparently successful therapy, follow-up angiograms demonstrated aneurysm enlargement with balloon migration distally in the sac. Geometric mismatch between the base of the balloons and the aneurysm neck together with transmitted pulsation through the 2-hydroxyl-ethylmethacrylate (HEMA)-filled balloon directly contributed to aneurysm enlargement. In this report, the authors discuss the problems of progressive aneurysm enlargement due to a "water-hammer effect" and the possibility of hemorrhage following subtotal occlusion.

De novo development of an aneurysm: case report.

A case of the de novo formation of an aneurysm in a young woman is presented. At age 13 years, she had a spontaneous subarachnoid hemorrhage. Cerebral angiography showed an aneurysm of the bifurcation of the left internal carotid artery and a small aneurysm of the left anterior choroidal artery. At surgery, the aneurysm of the internal carotid artery was clipped, and the aneurysm of the left anterior choroidal artery was wrapped with muslin. Thirteen years later, the patient had another subarachnoid hemorrhage. Cerebral arteriography showed four aneurysms that had developed at previously angiographically normal sites. This case suggests that young patients with aneurysms might benefit from follow-up angiography in search of late aneurysm formation.

Modified encephaloduroarteriosynangiosis as a surgical treatment of childhood moyamoya disease: report of five cases.

Moyamoya disease is an idiopathic disorder characterized by progressive occlusion of the internal carotid and anterior and middle cerebral arteries, with formation of an extensive abnormal collateral circulation at the base of the brain. Many neurosurgical procedures have been designed to bypass these occluded vessels. The results of one of these procedures, modified encephaloduroarteriosynangiosis was reviewed in five children followed for 3 1/2 to 19 1/2 years. Modified encephaloduroarteriosynangiosis performed unilaterally in one and bilaterally in four of the children, appeared to halt neurologic deterioration, despite angiographic progression, in four of the five children.

Elimination of a cirsoid aneurysm of the scalp by direct percutaneous embolization with thrombogenic coils. Case report.

Cirsoid aneurysms of the scalp are notoriously difficult lesions to manage. The authors report a patient in whom a large traumatic cirsoid aneurysm of the scalp was eliminated using a combined neurosurgical and interventional neuroradiological approach. Transarterial embolization was utilized to reduce arterial blood supply to the fistula. Thrombogenic Gianturco spring coils were then introduced via direct percutaneous puncture of the aneurysm. The aneurysm thrombosed and the multiple tortuous scalp vessels disappeared. One month after embolization, a small area of skin necrosis over the aneurysm necessitated surgical excision of the lesion. The thrombosed aneurysm was easily resected with minimal blood loss. Percutaneous embolization with thrombogenic coils in this case was a safe and effective ablative technique.