Gamma Knife radiosurgery of saccular aneurysms in a rabbit model.

OBJECTIVEIntracranial aneurysms are vascular abnormalities associated with neurological morbidity and mortality due to risk of rupture. In addition, many aneurysm treatments have associated risk profiles that can preclude the prophylactic treatment of asymptomatic lesions. Gamma Knife radiosurgery (GKRS) is a standard treatment for trigeminal neuralgia, tumors, and arteriovenous malformations. Aneurysms associated with arteriovenous malformations have been noted to resolve after treatment of the malformation. The aim of this study was to determine the efficacy of GKRS treatment in a saccular aneurysm animal model.METHODSAneurysms were surgically produced using an elastase-induced aneurysm model in the right common carotid artery of 10 New Zealand white rabbits. Following initial observation for 4 years, each rabbit aneurysm was treated with a conformal GKRS isodose of 25 Gy to the 50% margin. Longitudinal MRI studies obtained over 2 years and terminal measures obtained at multiple time points were used to track aneurysm size and shape index modifications.RESULTSAneurysms did not rupture or involute during the observation period. Whole aneurysm and blood volume averages decreased with a linear trend, at rates of 1.7% and 1.6% per month, respectively, over 24 months. Aneurysm wall percent volume increased linearly at a rate of 0.3% per month, indicating a relative thickening of the aneurysm wall during occlusion. Nonsphericity of the average volume, aspect ratio, and isoperimetric ratio of whole aneurysm volume all remained constant. Histopathological samples demonstrated progressive reduction in aneurysm size and wall thickening, with subintimal fibrosis. Consistent shape indices demonstrate stable aneurysm patency and maintenance of minimal rupture risk following treatment.CONCLUSIONSThe data indicate that GKRS targeted to saccular aneurysms is associated with histopathological changes and linear reduction of aneurysm size over time. The results suggest that GKRS may be a viable, minimally invasive treatment option for intracranial aneurysm obliteration.

Cervical spine dural arteriovenous fistula with coexisting spinal radiculopial artery aneurysm presenting as subarachnoid hemorrhage: case report.

BACKGROUND AND IMPORTANCE: We present a patient with a cervical spine dural arteriovenous fistula associated with a radiculopial artery aneurysm at the same vertebral level presenting with subarachnoid hemorrhage. CLINICAL PRESENTATION: A 45-year-old Native American man presented with sudden-onset severe headache, lethargy, and right hemiparesis. Computed tomography (CT) of the head showed subarachnoid hemorrhage and hydrocephalus. A subsequent CT of the neck showed an anterior spinal subdural hematoma from C2 to C4 causing mild cord compression. Carotid and vertebral angiography failed to demonstrate an intracranial aneurysm, but showed a spinal dural arteriovenous fistula originating from the right vertebral artery at the C5 neuroforamen. The severity of the patient's symptoms, atypical for rupture of a dural arteriovenous fistula, prompted more thorough angiographic evaluation. Thus, injection of the right thyrocervical trunk was performed, demonstrating a 4-mm spinal radiculopial artery aneurysm. Following ventriculostomy, a hemilaminectomy from C4 to C7 was performed with disconnection of the fistula from its drainage system. Subsequent resection of the aneurysm, which was determined to be the cause of the hemorrhage, was accomplished. The patient improved neurologically and was discharged to rehabilitation. CONCLUSION: Spinal cord aneurysms from a separate vascular distribution may coexist with spinal dural arteriovenous fistulas. In the setting of spinal hemorrhage, especially in situations with an atypical clinical presentation, comprehensive imaging is indicated to rule out such lesions.

[A case of idiopathic bronchial artery aneurysm connecting to the pulmonary artery].

Case. A 54-year old woman was found to have an abnormal shadow in a regular checkup chest X-ray film. We suspected a bronchial artery aneurysm based on a contrast-enhanced chest CT. Aortography, bronchial arteriography and pulmonary arteriography showed a bronchial artery aneurysm, 2 cm in diameter, connecting the right bronchial artery, inferior phrenic artery, and pulmonary artery. Bronchoscopy revealed dilatation and hypervascularity of moniliform submucosal vessels below the right truncus intermedius. She underwent bronchial artery embolization several times, but new feeding vessels developed each time. We considered this case required surgical resection. Bronchoscopy after aneurysmectomy revealed decrease of moniliform submucosal vessels. Histological examination revealed a three-layer structure leading to both the pulmonary and bronchial arteries. Conclusion. We diagnosed idiopathic bronchial artery aneurysm connecting to a pulmonary artery.

Effect of radioactivity on stent-graft incorporation after endovascular treatment of aneurysms: An animal study.

Poor stent-graft (SG) incorporation into the vessel wall, following endovascular repair of abdominal aortic aneurysms (EVAR), can lead to endoleaks and SG migration. Low-dose radiation can prevent aneurysm recurrence after coil embolization, and has been associated with a "paradoxical" increase in neointima formation after stenting in a few studies. It was hypothesized that in situ beta radiation emitted from SG could improve its incorporation by preventing the persistence of circulating channels between the implant and the vessel wall and increasing neointima formation around the SG. Phosphorus 32 ((32)P, 200 or 400 kBq per SG (n = 6 each)) was ion implanted on the external surface of balloon-expandable SGs. Twelve radioactive and six non-radioactive SGs were deployed in iliac arteries of nine Mongrel dogs. Neointima formation inside the graft and the persistence of circulating flow through an artificial groove created during the endovascular procedure were assessed by follow-up imaging and by blinded, computerized histomorphometric analysis after animal sacrifice at 3 months. Occlusion occurred in four radioactive SGs. A lesser number of patent grooves was observed along high-activity SGs than along control SGs (1/3 versus 4/4). No difference in neointima formation was observed in radioactive and non-radioactive SGs. Alteration of external graft surface was observed after ion implantation. Ion implantation of (32)P on SGs does not seem to be a viable strategy to improve incorporation and prevent type-I endoleak after EVAR.

Beta radiation and inhibition of recanalization after coil embolization of canine arteries and experimental aneurysms: how should radiation be delivered?

BACKGROUND AND PURPOSE: Beta radiation prevents recanalization after coil embolization. We sought to determine the effects of varying coil caliber, length, activity of 32P per centimeter of coil or per volume, and spatial distribution of coils on recanalization. METHODS: We studied the angiographic evolution of 81 canine maxillary, cervical, and vertebral arteries implanted with a variety of nonradioactive (n=29 arteries) or radioactive (n=52) devices. We compared 1- or 2-caliber 0.015 or 0.010 coils ion-implanted or not with 3 different activity levels (0.05 to 0.08, 0.06 to 0.12, 0.18 to 0.32 microCi/cm) of 32P and totaling 4, 8, and 16 cm in length for the same arterial volume. We also compared inhibition of recanalization by beta radiation delivered by stents, after coil occlusion proximal to or within the stent, with that delivered by coils placed within nonradioactive stents. We finally studied the angiographic evolution of canine lateral wall carotid aneurysms treated with 1 or 2 stents of various activity levels positioned inside the parent artery across the neck. Animals were killed at 4 and 12 weeks for macroscopic photography and pathological examination. RESULTS: All arteries (29 of 29) occluded with nonradioactive devices were recanalized, while 49 of 52 arteries (94%) implanted with 32P devices were occluded at 4 weeks. All aneurysms treated with stents, radioactive or not, demonstrated residual filling of the sac or of channels leading to the aneurysms at follow-up angiography at 4 weeks. CONCLUSIONS: The recanalization process found in the canine arterial occlusion model is minimally affected by coil caliber, number, and length or packing density. Beta radiation reliably inhibits this process, but thrombosis is an essential condition for the efficacy of a radioactive coil strategy.

Celiac artery aneurysm: a case evaluated preoperatively with three-dimensional computed tomographic angiography.

In a 63-year-old woman computed tomography (CT) incidentally detected a celiac artery aneurysm approximately 3 cm in diameter. While conventional angiography suggested that the splenic artery and common hepatic artery arose from the celiac artery aneurysm, three-dimensional CT angiography indicated that the aneurysm involved only the mid portion of the celiac artery. Considering the risk of eventual aneurysm rupture, surgery was performed. Aneurysmectomy and devascularization of hepatic, splenic, and celiac arteries were carried out following complete cross-clamping of the celiac artery. The distal segment of the celiac artery was directly anastomosed to the proximal segment in an end-to-end fashion. Histologically, the aneurysm wall showed atheromatous changes. Contrast-enhanced abdominal CT confirmed complete removal of the celiac artery aneurysm, and postoperative angiography confirmed good arterial flow. The patient recovered uneventfully after surgery, with normalization of transiently abnormal hepatic function parameters. In this case of celiac artery aneurysm, three-dimensional CT angiography was found to be valuable in determining the relationships of the aneurysms to important arterial branches.

Bleeding aneurysm of the axillary artery, managed by a combined approach: interventional radiology and extra-anatomic bypass.

Twenty-two years after an obvious radical mastectomy with axillary lymph node dissection and postoperative conventional radiotherapy for carcinoma of the right breast, an 80-year-old lady was admitted because of the third bleeding episode within one year originating from the axilla. An aneurysm from the axillary artery was identified as the source of hemorrhage. Since the sites of irradiation had to be avoided, an extra-anatomic reversed saphenous vein graft was run from the right common carotid to the brachial artery. In the same session the bleeding was finally controlled by therapeutic embolization of the aneurysm using Gianturco-Anderson-Wallace coils. The postoperative angiogram showed the patent graft. Bleeding did not reoccur during the follow-up period of 17 months.