Natural history of cerebral saccular aneurysms

Cerebral saccular aneurysms are relatively common, and are most commonly located at the branching points of large arteries of the circle of Willis. Many are asymptomatic and only discovered incidentally. Available evidence suggests that these aneurysms develop as a result of a combination of congenital or inherited defects weakening the arterial wall, and acquired degenerative vascular disease. It appears that most untreated cerebral aneurysms will get larger, and that all aneurysms have the potential to rupture. The only consistent significant predictor of aneurysmal rupture in most studies is the size of an aneurysm. Aneurysms less than 5mm have a very low rupture rate while those greater than 10mm have a significant risk of subsequent rupture. There is no consensus on the influence of the other reported risk factors such as hypertension, cigarette smoking and aneurysm location, on aneurysmal rupture. Those who have suffered a ruptured aneurysm are at a high risk for a recurrent haemorrhage shortly after the initial one.

Analysis of intraoperative rupture in the surgical treatment of 1694 saccular aneurysms

OBJECTIVE

Intraoperative rupture (IOR) of an aneurysm is a known risk in the surgical management of intracranial aneurysms. The purpose of this study was to determine the incidence of IOR in a modern surgical series and to assess which factors bear upon it.

METHODS

This study retrospectively examined 1269 patients with saccular aneurysms treated surgically between 1986 and 1998. Three vascular neurosurgeons performed 1435 operations on 1694 aneurysms. Multiple factors, including the magnitude and time of occurrence of IOR, aneurysm location, subarachnoid hemorrhage, timing of surgery, and use of temporary occlusion, were analyzed.

RESULTS

There were 113 instances of IOR (7.9% per surgery; 6.7% per aneurysm; 8.9% per patient). If the 59 "minor leaks" are excluded (as in previously published reports), the incidence becomes 3.8% per surgery, 3.2% per aneurysm, and 4.3% per patient. Posteroinferior cerebellar artery and anterior and posterior communicating artery aneurysms were more liable to rupture intraoperatively. The IOR rate was greater in ruptured than unruptured aneurysms (10.7 versus 1.2%, P < 0.0001). There was a lower rate of IOR in operations using temporary arterial occlusion (3.1 versus 8.6%, P < 0.0001). The occurrence of IOR for early surgery was not significantly higher than for surgery performed more than 3 days after subarachnoid hemorrhage (11.1 versus 10.0%, P = 0.6234).

CONCLUSION

The rate of significant IOR can be kept low. Aneurysm location, subarachnoid hemorrhage, and temporary arterial occlusion seem to be important factors affecting the incidence of IOR.

The role of contrast-enhanced spiral CT imaging versus chest X-rays in surgical therapeutic concepts and thoracic aortic injury: a 29-year Swiss retrospective analysis of aortic surgery

BACKGROUND

Blunt chest trauma accounts for 90% of chest trauma in the civilian population in Europe and the United States and causes 20% of trauma-related deaths. Missed aortic injuries can rupture and lead to subsequent death of the patient.

MATERIALS AND METHODS

This retrospective study compared two different imaging strategies, chest X-rays compared to additional contrast-enhanced spiral CT imaging, in patients suffering from blunt thoracic trauma. The study also questioned whether the additional information obtained from CT scans changed further surgical therapeutic concepts or the decision for immediate surgery.

RESULTS

Between 1971 and 2001, 39 patients were detected with thoracic trauma and aortic lesions. Of the 28 patients who underwent initial CT scanning, 12 (31%) had an emergency thoracotomy (sternotomy) performed on them, which the other 16 did not require. In four (10%) of these 16 patients, the aorta was stabilised and a possible leak was covered with endovascular stenting. In another eight (21%) of them, the concomitant injuries were initially treated and, following regular check-ups, an elective repair of the aortic lesion was performed after a number of months. In four (10%) patients with intramural haematomas or minor leakage, no intervention was necessary. Eleven (28%) patients did not have a chest CT scan on admission and the diagnosis of a contained aortic rupture was missed. They were readmitted to the hospital between four months and 29 years after the initial accident with symptomatic posttraumatic pseudo-aneurysm of the thoracic aorta.

CONCLUSIONS

We believe that helical CT evaluation of the mediastinum should be performed in all patients who undergo blunt thoracic trauma, irrespective of chest radiographic findings. Missed diagnoses can occur after angiography or ultrasound alone, and false-positive diagnoses can also be made. Following the current literature, we therefore recommend a primary routine chest CT scan in all patients with a history of motor vehicle accident (MVA) at a speed of more than 16 km/h (unrestrained) or 48 km/h (restrained). Furthermore, we recommend a CT scan even if the height fallen was as little as seven metres.

Laparoscopic nephroureterectomy complicated by rupture of adrenal artery pseudoaneurysm

We present a case of ruptured adrenal artery pseudoaneurysm as a complication of laparoscopic nephroureterectomy. An 87-year-old woman with hematuria and transitional cell carcinoma on imaging underwent laparoscopic nephroureterectomy. Her postoperative recovery was uneventful until day 17, when she presented with severe abdominal pain, syncope, and significant anemia. An aneurysm was suspected on computed tomography and Doppler ultrasonography. Selective angiography showed a pseudoaneurysm of the adrenal artery that could not be successfully embolized. Exploratory laparotomy obtained hemostasis, and the pseudoaneurysm was identified as involving an adrenal artery next to a surgical clip, which is speculated to be the cause.

Berry splenic artery aneurysm rupture in association with segmental arterial mediolysis and portal hypertension

A rare case of berry splenic artery aneurysm (SAA) rupture associated with segmental arterial mediolysis (SAM) and portal hypertension is reported. A 66-year-old woman, diagnosed as having liver cirrhosis and portal hypertension 6 years earlier, suddenly developed a lancinating pain in the upper abdomen and lost consciousness. She recovered consciousness while being transferred to hospital by ambulance. During the investigations, her level of consciousness suddenly deteriorated. Ultrasonography showed a massive intraperitoneal hemorrhage, and she died 5(1/2) h after admission. On gross examination at autopsy it was not possible to find the rupture point of the vessel because the pancreas was embedded in a massive hematoma. However, careful dissection of the pancreatic tail after fixation revealed a berry aneurysm measuring 0.8 cm in diameter in a branch adjacent to the bifurcation in the distal third of the main splenic artery. Microscopic examination detected a rupture of the aneurysm. The histology of the arterial wall proximal to the aneurysm showed typical SAM. In general, berry SAA caused by SAM is rare and unlikely to rupture. The SAA in the present case likely occurred and ruptured due to the combination of SAM and portal hypertension.

The endovascular management of pericallosal artery aneurysms

AIM

to describe our experience with a series of 18 patients with pericallosal artery aneurysms, in whom endovascular coil insertion was attempted.

METHOD

the CT and angiographic appearances, coiling techniques and patient outcomes are discussed.

RESULTS

we encountered a higher than expected level of technical difficulty and procedure related complication than when coiling aneurysms in more common locations. In particular the distal position of the aneurysms lead to poorer control over the microcatheter position. Procedure related rupture occurred in three cases. Coiling was not possible in one case only. An association between an angulated bifurcation of the anterior cerebral artery and a sidewall aneurysm configuration was noted.

CONCLUSION

despite the technical difficulties and high procedure related rupture rate, coiling of pericallosal aneurysms is feasible and has good outcome.

[Spontaneous rupture of common iliac artery after hysterectomy for malignant gynecologic tumor]

Authors described a serious, iatrogenic, vessel complications after hysterectomy for uterus sarcoma. After successful abdominal hysterectomy spontaneous rupture of right common iliac artery occurred causing massive exsanguination into intraperitoneal space. During secondary laparotomy procedure large, partial loss of arterial wall was recognized and provided with non-absorbable Prolene 4-0 suture. Subsequently, the injury was replaced by arterial artificial prosthesis gore-tec 8. Intraoperatively, ventricular fibrillation and cardiac arrest took place with subsequent acute respiratory and circulatory distress syndrome. Throughout next several days after reoperation patient was deep unconscious and hospitalized on Intensive Care Unit. She manifested symptoms of damaged extrapyramidal tracts. In spite of further unfavourable prognosis, after almost a month of respiratory therapy, she fully recovered without symptoms of brain damage and visual sequelae.

Parameterization of the shape of intracranial saccular aneurysms using Legendre polynomials

Our recent studies of the nonlinear mechanics of saccular aneurysms suggest that it is unlikely that these lesions enlarge or rupture via material (limit point) or dynamic (resonance) instabilities. Rather, there is a growing body of evidence from both vascular biology and biomechanical analyses that implicate mechanosensitive growth and remodeling processes. There is, therefore, a pressing need to quantify regional multiaxial wall stresses which, because of the membrane-like behavior of many aneurysms, necessitates better information on the applied loads and regional surface curvatures. Herein, we present and illustrate a method whereby regional curvatures can be estimated easily for sub-classes of human aneurysms based on clinically available data from magnetic resonance angiography (MRA). Whereas Legendre polynomials are used to illustrate this approach, different functions may prove useful for different sub-classes of lesions.

Risk of rupture associated with intact cerebral aneurysms in the Japanese population: a systematic review of the literature from Japan

Object. Knowing the rate of rupture associated with unruptured cerebral aneurysms (UCAs) can help surgeons determine a case management strategy in patients harboring these lesions. According to large-scale cohort studies involving populations in North America and Europe, small unruptured aneurysms carry a very low risk of rupture. In Japan, however, there have been sporadic reports of higher rates of rupture. To identify the rupture risk associated with UCAs in the Japanese population, the authors systematically reviewed retrospective studies of the natural course of these lesions.

Methods. The authors searched Medline and the Japan Medical Abstract Society Index for reports of UCAs in Japan. Two of the authors verified the eligibility of the reports and extracted data independently. Additional information was directly obtained from the authors of the original reports.

Thirteen reports covering a total of 3801 patient-years fulfilled the criteria for our study. Subsequent rupture was documented in 104 patients and the annual rupture rate was 2.7% (95% confidence interval 2.2–3.3%). Large, posterior-circulation, and symptomatic aneurysms were associated with significantly higher rates of rupture (relative risks 6.4, 2.3, and 2.1, respectively). The risk of rupture determined by the authors' review was significantly higher than that reported by investigators from international cohort studies.

Conclusions. Although a selection bias of patients may be the cause of the higher rupture risk, untreated UCAs that have been followed in Japanese institutions have a considerably high rate of rupture. The natural course of UCAs should be carefully estimated in countries not included in the international studies.

Thoracic aortic pseudoaneurysm after spine trauma in ankylosing spondylitis. Case report

Ankylosing spondylitis (AS) is a rheumatic disease characterized by consolidation of the articulating surfaces and inflammation of the vertebral column. Because of its associated spine stiffness and secondary osteoporosis, patients with this disorder are at increased risk of vertebral fractures. Ankylosing spondylitis presents a significant challenge to spine surgeons because of its complex effects on the spine, extraarticular organ manifestations, and potential neurological and functional sequelae. Traumatic thoracic and lumbar spine injuries in this patient population may be associated with injury to the aorta either due to direct mechanical trauma or to blunt forces associated with the spine fracture. This complication and association is thought to be the result of pathophysiological changes that cause the aorta to become firmly adherent to the anterior longitudinal ligament. The authors present a case of AS in a patient with a thoracic spine fracture and in whom a delayed thoracic aortic pseudoaneurysm ruptured. To the best of the authors' knowledge, only five cases of this complex condition have been reported since 1980. Recognition of the potential for aortic injury in patients with AS should prompt early investigation of the aorta in cases involving numerous fractures and assist in surgical planning to avoid this lethal injury.

Ruptured abdominal aortic aneurysm secondary to tuberculous spondylitis

A 69-year-old man was admitted with low back pain and signs of nerve root compression. A computed tomography (CT) scan showed abscess formation in the left psoas region, spondylodiscitis L3-L4 and a ruptured abdominal aortic aneurysm. The aortic aneurysm was replaced with a bifurcated vascular graft. One week later, laminectomy at the L4-level was done. In a small abscess, Mycobacterium bovis was found. The condition was considered to be a mycobacterial spondylitis secondary to BCG instillations of the urinary bladder for carcinoma. The patient received antituberculous medication for 9 months. Subsequently bone transplantation and internal fixation of the spine became necessary. Three years after surgery he is in good condition and there are no signs of graft infection on CT. Spondylitis and mycotic aortic aneurysm should be kept in mind in patients who have been treated for carcinoma of the bladder with BCG instillations.

Fourier analysis of intracranial aneurysms: towards an objective and quantitative evaluation of the shape of aneurysms

Shape irregularities of intracranial aneurysms may indicate an increased risk of rupture. To quantify morphological differences, Fourier analysis of the shape of intracranial aneurysms was introduced. We compared the morphology of 45 unruptured (UIA) and 46 ruptured intracranial aneurysms (RIA) in 70 consecutive patients on the basis of 3D-rotational angiography. Fourier analysis, coefficient of roundness and qualitative shape assessment were determined for each aneurysm. Morphometric analysis revealed significantly smaller coefficient of roundness (P < 0.02) and higher values for Fourier amplitudes numbers 2, 3 and 7 (P < 0.01) in the RIA group, indicating more complex and irregular morphology in RIA. Qualitative assessment from 3D-reconstructions showed surface irregularities in 78% of RIA and 42% of UIA (P < 0.05). Our data have shown significant differences in shape between RIA and UIA, and further developments of Fourier analysis may provide an objective factor for the assessment of the risk of rupture.

Rabbit aneurysm model mediated by the application of elastase

The concentrations and application methods of elastase in the rabbit aneurysm model were optimized to control the initiation of aneurysms and to cause rupture in a stepwise, controlled fashion. The common carotid artery of male Japanese albino rabbits was exposed. No aneurysm was generated if the adventitia was not dissected. After gentle removal of the adventitia, a two-fold dilution series of elastase was applied to the lesion and observed over a period of 2 hours. Various stages of aneurysmal lesions, from spindle-shaped enlargement to rupture, were produced in proportion to the elastase concentration. Application of elastase stock solution (5 U/mg of type I porcine pancreatic elastase) resulted in rupture within 30 minutes in all six animals. Elastase 1:2 solutions caused oozing in all animals, but subsequent rupture in only three of six animals. Histological examination found serious destruction of the internal elastic lamina and media, with expansion of the very thin wall. Elastase 1:4 to 1:16 solutions caused spindle-like distention of the entire artery and the development of tortuosity at the lesion. Elastase 1:32 or weaker solutions caused only localized dilatations. Overall, the destruction of the tunica media became less severe with decreased elastase concentration. Furthermore, the bursting pressure of the aneurysms decreased with increasing elastase concentrations. In particular, aneurysms produced by the elastase 1:2 solution ruptured at less than 150 mmHg, whereas aneurysms induced by the elastase 1:4 or weaker solutions did not rupture within the physiological range of blood pressure. The present aneurysm model requires shorter preparation time and enables accurate control of aneurysm development and rupture.

Perforated aneurysm on the posterior leaflet of the mitral valve

We present a case of a 71-year-old homeless diabetic man who was hospitalized due to bilateral cellulitis of the lower limbs. Because of severe calcific aortic stenosis, he had undergone valve replacement by a bioprosthesis 3 years earlier. Except from the two preadmission days, he reported no fever, malaise, or weight loss at any time after surgery. On examination, no specific signs or symptoms suggesting infective endocarditis were noted. After six blood cultures were taken, the patient was put on cloxacillin, clindamycin and gentamicin. All the six blood cultures were finally proven to be negative.

Ruptured Aneurysm of the Subclavian Artery in a Patient With von Recklinghausen's Disease

A vascular manifestation of von Recklinghausen's disease is rare, but may be fatal if it is disrupted. A 39-year-old male with von Recklinghausen's disease presented with a large and tender bruise extending from his left neck to his left shoulder and arm. Computerized axial tomography revealed a ruptured aneurysm of the left subclavian artery. The patient underwent emergency surgery to exclude the aneurysm, and cross-over bypass grafting of both subclavian arteries was performed. We present a brief review of vascular maintestation of von Recklinghausen's disease, as well as a discussion regarding the strategy for treating this rare presentation.

Thoracic aneurysm rupture due to graft perforation after endovascular stent-grafting via median sternotomy

We performed emergency repeat surgery for aneurismal rupture due to graft perforation with mechanical stress of the Z stent in a kinking graft after frozen elephant trunk procedure. Graft kinking occurred due to cranial migration of the Z stent. It is important to prevent stent dislodgement in order to achieve long-term durability and reliability in the frozen elephant trunk procedure.

[Four cases of the infectious cerebral aneurysms]

The authors evaluated various clinical courses of ruptured infectious cerebral aneurysms associated with infective endocarditis in 4 patients. The first case: A 60-year-old male, who had a large hematoma resulting from rupture of a distal anterior cerebral artery aneurysm at the left frontal lobe co-existing with cerebral infarction at the right temporo-occipital lobe, with complications of renal and liver embolisms and pyogenic spondylitis, was treated with antibiotic therapy. However, he died of rupture of another newly formed aneurysm 29 days after onset. The second case: A 71-year-old female presented cerebral infarction in the right occipital lobe at onset. Two days later, abrupt occurrence of a large hematoma at the left parietal lobe led to deterioration of her consciousness. She underwent emergent evacuation of a large hematoma containing the infectious cerebral aneurysm proven histologically afterwards. The third patient: A 49-year-old female was suffered from a large hematoma and subdural hematoma accompanied distal posterior cerebral artery aneurysm at the right occipital lobe. She was operated by removal of the hematoma and the aneurysm proven as a bacterial infectious aneurysm. The fourth patient: A 71-year-old female had hemiplegia caused by a brain abscess and cerebral hemorrhage in the right temporal lobe and a distal middle cerebral artery aneurysm adjacent to the same region. Trapping of the aneurysm was undertaken and clinical course was uneventful. Attention needs to be paid to the various cerebrovascular condition arising from the bacterial embolus of infective endocarditis.

Experimental microaneurysms in rats: I. Model for induction

BACKGROUND

Small aneurysms (lesser than 2 mm) in humans called sessile, baby aneurysms, or microaneurysms, generally are not able to be clipped or to be coil-packed through endovascular route. Among the modalities of treatment that have been used for treating microaneurysms, bipolar coagulation and wrapping of the lesion are outstanding. Nevertheless, demonstration of the efficacy of these treatments is difficult because most reported experimental models for inducting aneurysms are complex and difficult to be reproduced. This study aimed to develop a simple and reproducible model for inducing microaneurysms.

METHODS

Microaneurysms were induced using a mechanical lesion of the bifurcation of the aorta in 72 rats. Three groups of 10 animals were sacrificed 7, 14, and 21 days after the lesion and 2 groups (35 and 7 animals) after 30 days. The aortic bifurcation was macro/microscopically analyzed in the first 4 groups and a resistance test was applied in the fifth group.

RESULTS

Microaneurysms occurred in 77.8% of cases. Microscopically, degenerative changes were observed in the intima, media, and adventitia and in the internal elastic lamina. The bursting pressure ranged from 368 to 1,472 mm Hg during the resistance test in the fifth group.

CONCLUSIONS

The presented model of experimental microaneurysm induction is simple, reproducible and gives a high rate of positivity.

Surgical versus endovascular treatment of traumatic thoracic aortic rupture

OBJECTIVES

Blunt traumatic thoracic aortic rupture is a life-threatening surgical emergency associated with high mortality and morbidity. The recent development of endovascular stent-graft prostheses offers a potentially less invasive alternative to open chest surgery, especially in patients with associated injuries. We sought to compare the results of conventional surgical repair and endovascular treatment of traumatic aortic rupture in a single center.

METHODS

From July 1998 to January 2004, 20 patients with acute blunt traumatic aortic rupture underwent treatment at our institution. All patients had a lesion limited to the isthmus, and associated injuries. Initial management included fluid resuscitation, treatment of other severe associated lesions, and strict monitoring of blood pressure. Eleven patients (9 men, 2 women; mean age, 32 years) underwent surgical repair, including direct suturing in 6 patients and graft interposition in 5 patients. Ten patients were operated on with cardiopulmonary support (left bypass with centrifugal pump, n = 2; extracorporeal circulation, n = 8). The delay between trauma and surgery was 2.6 days (range, 0-21 days). Nine patients (8 men, 1 woman; mean age, 32 years) underwent endovascular treatment with commercially available devices (Excluder, n = 2; Talent, n = 7). In all patients 1 stent graft was deployed. In 2 patients the left subclavian artery was intentionally covered with the device. The delay between trauma and endovascular treatment was 17.8 days (range, 1-68 days).

RESULTS

One patient in the surgical group (9.1%) died during the intervention. Three surgical complications occurred in 3 patients (27%), including left phrenic nerve palsy (n = 1), left-sided recurrent nerve palsy (n = 1), and hemopericardium 16 days after surgery that required a repeat intervention (n = 1). No patient in this group had paraplegia. In the endovascular group successful stent-graft deployment was achieved in all patients, with no conversion to open repair. No patient died, and no procedure-related complications, including paraplegia, occurred in this group. Control computed tomography scans obtained within 7 days after endovascular treatment showed exclusion of pseudoaneurysm in all cases. Length of follow-up for endovascular treatment ranged from 3 to 41 months (mean, 15.1 months). Computed tomography scans obtained 3 months after endovascular treatment showed complete disappearance of pseudoaneurysm in all patients.

CONCLUSION

In the treatment of blunt traumatic thoracic aortic rupture, the immediate outcome in patients who receive endovascular stent grafts appears to be at least as good as observed after conventional surgical repair. Long-term follow-up is necessary to assess long-term effectiveness of such management.