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Giuseppe Lanzino and Ioannis Loumiotis

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R. Scooter Plowman, Alison Clarke, Mike Clarke and James V. Byrne

Object

Over a 16-year period, 570 patients presenting with acute aneurysmal subarachnoid hemorrhage were successfully treated using endosaccular coil embolization within 30 days of hemorrhage by a single surgeon. Patients were followed to assess the stability of aneurysm occlusion and its longer-term efficacy in protecting against rebleeding.

Methods

Patients were followed for 6 to 191 months (mean 73.7 months, median 67 months) by clinical review, angiography performed at 6 and 24 months posttreatment, and questionnaires sent via the postal service every 5 years. Late rebleeding was defined as > 30 days after treatment.

Results

Stable angiographic occlusion was evident in 74.5% of small, 72.2% of large, and 60% of giant aneurysms. Recurrent filling was found in 119 (26.3%) of 452 aneurysms. Rebleeding was diagnosed in 9 patients (6 treated aneurysms) and occurred between 2 and 114 months posttreatment. It was due to aneurysm recurrence in 6 patients, rupture of a coincidental untreated aneurysm in 2 patients, and rupture of a de novo aneurysm in 1 patient. Rebleeding occurred in 3 (2.5%) of 119 unstable aneurysms and in 3 (0.9%) of 333 stable aneurysms, as seen on initial follow-up angiography studies. Annual rebleeding rates ranged from 0.2% to 0.6% for all causes and from 0.2% to 0.4% for rebleeding of treated aneurysms. No rebleeding was recorded after the first decade, with 138 patients having more than 10 years of follow-up.

Conclusions

Periodic follow-up with angiographic studies after coil embolization is recommended to identify aneurysm recurrence and patients at a high risk of late rebleeding in the medium term. More frequent follow-up is recommended for patients harboring coincidental unruptured aneurysms.

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James V. Byrne, Min-Joo Sohn and Andrew J. Molyneux

Object. During a 5-year period 317 patients presenting with aneurysmal subarachnoid hemorrhage were successfully treated by coil embolization within 30 days of hemorrhage. The authors followed patients to assess the stability of aneurysm occlusion and its longer-term efficacy in protecting patients against rebleeding.

Methods. Patients were followed for 6 to 65 months (median 22.3 months) by clinical review, angiography performed at 6 months posttreatment, and annual questionnaires. Stable angiographic occlusion was evident in 86.4% of small and 85.2% of large aneurysms with recurrent filling in 38 (14.7%) of 259 aneurysms. Rebleeding was caused by aneurysm recurrence in four patients (between 11 and 35 months posttreatment) and by rupture of a coincidental untreated aneurysm in one patient. Annual rebleeding rates were 0.8% in the 1st year, 0.6% in the 2nd year, and 2.4% in the 3rd year after aneurysm embolization, with no rebleeding in subsequent years. Rebleeding occurred in three (7.9%) of 38 recurrent aneurysms and in one (0.4%) of 221 aneurysms that appeared stable on angiography.

Conclusions. Periodic follow-up angiography after coil embolization is recommended to identify aneurysm recurrence and those patients at a high risk of late rebleeding.

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David H. Edwards, James V. Byrne and Tudor M. Griffith

✓ The authors have investigated the hypothesis that loss of endothelium-derived relaxing factor (EDRF) activity contributes to cerebral vasospasm after subarachnoid hemorrhage. Adventitial exposure to hemoglobin was studied angiographically by injecting purified hemoglobin solution or autologous whole blood into the cisterna magna of anesthetized pigs. Both interventions induced intra- but not extracerebral vasoconstriction, which persisted for 2 and 7 days, respectively. Cyclic guanosine monophosphate (cGMP) levels were measured in isolated buffer-perfused pig intrathecal arteries to quantify inhibition of basal EDRF activity by hemoglobin. Adventitial exposure was less effective than intimal exposure, 10 µM hemoglobin applied adventitially for 30 minutes having an effect equivalent to that of 1 µM applied intraluminally for 5 minutes. The depression of cGMP levels by hemoglobin was reversible and equivalent to the effect of endothelial denudation or incubation with NG-nitro-L-arginine methyl ester, so that the effects of hemoglobin can be attributed to a specific action on EDRF rather than interaction with a nitric oxide-like substance produced by vascular smooth muscle or adventitial nerves. Cyclic GMP levels in isolated arteries were unchanged after in vivo exposure to hemoglobin for either 2 or 7 days or to whole blood for 2 days, and were reduced by intraluminal perfusion with 1 µM hemoglobin. In contrast, after 7 days of in vivo exposure to whole blood, cGMP levels were already depressed, and not further reduced by intraluminal perfusion with 1 µM hemoglobin. The findings support the view that adventitially applied hemoglobin can inhibit basal EDRF activity and that in vivo adventitial exposure to whole blood leads to a reduction in basal cGMP levels in association with vasoconstriction of intrathecal arteries. Both mechanisms could contribute to the clinical syndrome of cerebral vasospasm after subarachnoid hemorrhage.

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Andrew J. Molyneux, David W. Ellison, James Morris and James V. Byrne

✓ The authors report the pathological and histological findings in two patients with giant partially thrombosed aneurysms who were treated by means of Guglielmi detachable coils with subtotal occlusion of the aneurysms. Autopsies of these patients were performed 2 and 6 months after endovascular treatment. The histological findings revealed coils embedded in largely unorganized thrombus in the aneurysms; there was no clear reduction in size of the aneurysms over the period. There was no evidence of endothelialization of the aneurysm neck demonstrated in either case. The significance of these findings is discussed.

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Ioannis Ioannidis, Shivendra Lalloo, Rufus Corkill, Wilhelm Kuker and James V. Byrne

Object

Endovascular treatment of very small aneurysms poses a significant technical challenge for endovascular therapists. The authors review their experience with a series of patients who had intracranial aneurysms smaller than 3 mm in diameter.

Methods

Between 1995 and 2006, 97 very small aneurysms (defined for purposes of this study as < 3 mm in diameter) were diagnosed in 94 patients who were subsequently referred for endovascular treatment. All patients presented after subarachnoid hemorrhage, which was attributed to the very small aneurysms in 85 patients. The authors reviewed the endovascular treatment, the clinical and angiographic results of the embolization, and the complications.

Results

Five (5.2%) of the 97 endovascular procedures failed, and these patients underwent craniotomy and clip ligation. Of the 92 aneurysms successfully treated by coil embolization, 64 (69.6%) were completely occluded and 28 (30.4%) showed minor residual filling or neck remnants on the immediate postembolization angiogram. Complications occurred in 7 (7.2%) of 97 procedures during the treatment (3 thromboembolic events [3.1%] and 4 intraprocedural ruptures [4.1%]). Seventy-six patients were followed up angiographically; 4 (5.3%) of these 76 showed angiographic evidence of recanalization that required retreatment. The clinical outcomes for the 76 patients were also graded using the Glasgow Outcome Scale. In 61 (80.3%) cases the outcomes were graded 4 or 5, whereas in 15 (19.7%) they were graded 3. Seven patients (7.4%) died (GOS Grade 1), 2 due to procedure-related complications (intraoperative rupture) and 5 due to complications related to the presenting subarachnoid hemorrhage.

Conclusions

Endosaccular coil embolization of very small aneurysms is associated with relatively high rates of intraprocedural rupture, especially intraoperative rupture. With the advent of more sophisticated endovascular materials (microcatheters and microguidewires, soft and ultrasoft coils, and stents) endovascular procedures have become feasible and can lead to a good angiographic outcome.

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Alexander Andreou, Ioannis Ioannidis, Shivendra Lalloo, Nasis Nickolaos and James V. Byrne

Object

Microarteriovenous malformations (micro-AVMs) are an uncommon subgroup of brain AVMs defined by a nidus measuring < 1 cm in diameter. The clinical features, angiographic characteristics, and outcomes in patients with micro-AVMs who had been treated endovascularly after presenting with hemorrhage were reviewed to identify common features affecting prognosis.

Methods

Between 1997 and 2006, 25 patients (12 females and 13 males) with 26 micro-AVMs were treated. Twenty-four patients presented with intracerebral hematoma and 1 with subarachnoid hemorrhage only. All patients underwent CT on admission, diagnostic cerebral angiography, and 1 session of endovascular treatment during the acute phase.

Results

Procedure-related complications occurred in 3 patients (12%), which caused temporary hemiparesis in 1 (4%) and no clinical sequelae in 2 patients (8%). Complete nidus obliteration was achieved at the end of the embolization in 22 (84.6%) of 26 lesions. Two recurrences were evident on follow-up angiography 6 months postembolization, resulting in a complete obliteration rate of 77% (20 of 26 lesions) after a single treatment. Late angiography was performed in 12 patients, and no further recurrences were identified.

Conclusions

Immediate complete obliteration of a micro-AVM with a high permanent cure and low morbidity rates was accomplished using endovascular treatment. Early embolization after bleeding should be considered as an alternative to resection.

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Editorial

Coil embolization of very small intracranial aneurysms

Giuseppe Lanzino

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James V. Byrne, Min-Joo Sohn, Andrew J. Molyneux and B. Chir

Object

During a 5-year period 317 patients presenting with aneurysmal subarachnoid hemorrhage were successfully treated by coil embolization within 30 days of hemorrhage. The authors followed these cases to assess the stability of aneurysm occlusion and its longer-term efficacy in protecting patients against rebleeding.

Methods

These cases were followed for 6 to 65 months (median 22.3 months) by clinical review, angiography performed at 6 months posttreatment, and annual postal questionnaires.

Conclusions

Stable angiographic occlusion was evident in 86.4% of small and 85.2% of large aneurysms with recurrent filling in 38 (14.7%) of 259 aneurysms. Rebleeding was caused by aneurysm recurrence in four patients (between 11 and 35 months posttreatment) and by rupture of a coincidental untreated aneurysm in one patient. Annual rebleeding rates were 0.8% in the 1st year, 0.6% in the 2nd year, and 2.4% in the 3rd year after aneurysm embolization, with no rebleeding in subsequent years. Rebleeding occurred in three (7.9%) of 38 recurrent aneurysms and in one (0.4%) of 221 aneurysms that appeared stable on angiography. Periodic follow-up angiography after coil embolization is recommended to identify aneurysm recurrence and those patients at a high risk of late rebleeding.