Endovascular mechanical thrombectomy for the treatment of acute ischemic stroke due to arterial dissection.

Arterial dissections account for 2% of strokes in all age groups, and up to 25% in patients aged 45 years or younger. The safety of endovascular intervention in this patient population is not well characterized. We identified all patients in the Merci registry - a prospective, multi-center post-market database enrolling patients treated with the Merci Retriever thrombectomy device - with arterial dissection as the most likely stroke etiology. Stroke presentation and procedural details were obtained prospectively; data regarding procedural complications, intracerebral hemorrhage (ICH), and the use of stenting of the dissected artery were obtained retrospectively. Of 980 patients in the registry, ten were identified with arterial dissection (8/10 ICA; 2/10 vertebrobasilar). The median age was 48 years with a baseline NIH stroke scale score of 16 and median time to treatment of 4.9 h. The procedure resulted in thrombolysis in cerebral ischemia (TICI) scores of 2a or better in eight out of ten and TICI 2b or better in six out of ten patients. Stenting of the dissection was performed in four of nine (44%). The single complication (1/9; 11%) - extension of a dissected carotid artery - was treated effectively with stenting. No symptomatic ICH or stroke in a previously unaffected territory occurred. A favorable functional outcome was observed in eight out of ten patients. Despite severe strokes on presentation, high rates of recanalization (8/10) and favorable functional outcomes (8/10) were observed. These results suggest that mechanical thrombectomy in patients with acute stroke resulting from arterial dissection is feasible, safe, and may be associated with favorable functional outcomes.

Frequency and clinical context of decreased apparent diffusion coefficient reversal in the human brain.

PURPOSE: To determine the probability that regions of decreased apparent diffusion coefficient (ADC) return to normal without persistent symptoms or T2 change and the settings in which these ADC reversals occur. MATERIALS AND METHODS: Three hundred magnetic resonance (MR) imaging studies were selected at random from a database of 7,147 examinations to determine the probability of a pathologically decreased ADC. In cases with decreased ADC, the clinical history was recorded and, if available, follow-up MR imaging findings were evaluated. Five cases of ADC reversal became known during the same period and were evaluated to determine the initial ADC decrease, clinical outcome, and findings at follow-up imaging. RESULTS: Findings in 116 of 300 MR imaging studies revealed regions of decreased ADC. In 49 of 116 studies, follow-up MR imaging examinations were performed at least 4 weeks after the onset of symptoms; ADC did not reverse. Five cases of ADC reversal were identified in the same period, giving an estimated 0.2%-0.4% probability of ADC reversal. Clinical settings were venous sinus thrombosis and seizure (n = 3), hemiplegic migraine (n = 1), and hyperacute arterial infarction (n = 1). Both white matter (n = 3) and gray matter (n = 3) regions were involved. CONCLUSION: Reversal of ADC lesions is rare, occurs in complicated clinical settings, and can involve white or gray matter.

Combined surgical and endovascular techniques of flow alteration to treat fusiform and complex wide-necked intracranial aneurysms that are unsuitable for clipping or coil embolization.

OBJECT: Certain intracranial aneurysms, because of their fusiform or complex wide-necked structure, giant size, or involvement with critical perforating or branch vessels. are unamenable to direct surgical clipping or endovascular coil treatment. Management of such lesions requires alternative or novel treatment strategies. Proximal and distal occlusion (trapping) is the most effective strategy. In lesions that cannot be trapped, alteration in blood flow to the "inflow zone," the site most vulnerable to aneurysm growth and rupture, is used. METHODS: From 1991 to 1999 the combined neurosurgical-neuroendovascular team at the Massachusetts General Hospital (MGH) managed 48 intracranial aneurysms that could not be clipped or occluded. Intracavernous internal carotid artery aneurysms were excluded from this analysis. By applying a previously described aneurysm rupture risk classification system (MGH Grades 0-5) based on the age of the patient, aneurysm size, Hunt and Hess grade, Fisher grade, and whether the aneurysm was a giant lesion located in the posterior circulation, the authors found that a significant number of patients were at moderate risk (MGH Grade 2; 31.3% of patients) and at high risk (MGH Grades 3 or 4; 22.9%) for treatment-related morbidity. The lesions were treated using a variety of strategies--surgical, endovascular, or a combination of modalities. Aneurysms that could not be trapped or occluded were treated using a paradigm of flow alteration, with flow redirected from either native collateral networks or from a surgically performed vascular bypass. Overall clinical outcomes were determined using the Glasgow Outcome Scale (GOS). A GOS score of 5 or 4 was achieved in 77.1%, a GOS score of 3 or 2 in 8.3%, and death (GOS 1) occurred in 14.6% of the patients. Procedure-related complications occurred in 27.1% of cases; the major morbidity rate was 6.3% and the mortality rate was 10.4%. Three patients experienced aneurysmal hemorrhage posttreatment; in two patients this event proved to be fatal. Aneurysms with MGH Grades 0, 1, 2, 3, and 4 were associated with favorable outcomes (GOS scores of 5 or 4) in 100%, 92.8%, 71.4%, 50%, and 0% of instances, respectively. CONCLUSIONS: Despite a high incidence of transient complications, intracranial aneurysms that cannot be clipped or occluded require alternative surgical and endovascular treatment strategies. In those aneurysms that cannot safely be trapped or occluded, one approach is the treatment strategy of flow alteration.

Rheolytic thrombectomy of the occluded internal carotid artery in the setting of acute ischemic stroke.

BACKGROUND AND PURPOSE: Acute thromboembolic stroke complicated by ipsilateral carotid occlusion may present both mechanical and inflow-related barriers to effective intracranial thrombolysis. We sought to review our experience with a novel method of mechanical thrombectomy, in such cases, using the Possis AngioJet system, a rheolytic thrombectomy device. METHODS: A review of our interventional neuroradiology database revealed three patients in whom an occluded cervical internal carotid artery was encountered during endovascular treatment for acute stroke and in whom thrombectomy was attempted, using the 5F Possis AngioJet thrombectomy catheter. The medical records and radiographic studies of these patients were reviewed. RESULTS: Three patients were identified (ages, 52--84 years). Two patients had isolated occlusion of the internal carotid artery; in one patient, thrombus extended down into the common carotid artery. Treatment was initiated within 190 to 360 minutes of stroke onset. Thrombectomy of the carotid artery was deemed necessary because of poor collateral flow to the affected hemisphere (chronic contralateral internal carotid artery occlusion [one patient] and thrombus extending to the carotid "T" [one patient]) or inability to pass a microcatheter through the occluded vessel (one patient). Adjunctive therapy included pharmacologic thrombolysis with tissue plasminogen activator (all patients), carotid angioplasty and stenting (two patients), and middle cerebral artery angioplasty (one patient). Patency of the carotid artery was reestablished in two patients, with some residual thrombus burden. In the third patient, the device was able to create a channel through the column of thrombus, allowing intracranial access. CONCLUSION: Rheolytic thrombectomy shows potential for rapid, large-burden thrombus removal in cases of internal carotid artery thrombosis, allowing expedient access to the intracranial circulation for additional thrombolytic therapy.

Results after surgical and endovascular treatment of paraclinoid aneurysms by a combined neurovascular team.

OBJECTIVE: Advances in surgical and endovascular techniques have improved treatment for paraclinoid aneurysms. A combined surgical and endovascular team can formulate individualized treatment strategies for patients with paraclinoid aneurysms. Patients who are considered to be at high surgical risk can be treated endovascularly to minimize morbidity. We reviewed the clinical and radiographic outcomes of 238 paraclinoid aneurysms treated by our combined surgical and endovascular unit. METHODS: From 1991 to 1999, the neurovascular team treated 238 paraclinoid aneurysms in 216 patients at the Massachusetts General Hospital. The modality of treatment for each aneurysm was chosen based on anatomic and clinical risk factors, with endovascular treatment offered to patients considered to have higher surgical risks. One hundred eighty aneurysms were treated by direct surgery, 57 were treated by endovascular occlusion, and one was treated by surgical extracranial-intracranial bypass and endovascular internal carotid artery balloon occlusion. Locations were transitional, 12 (5%); carotid cave, 11 (5%); ophthalmic, 131 (55%); posterior carotid wall, 38 (16%); and superior hypophyseal 46 (19%). Lesions contained completely within the cavernous sinus were excluded from this analysis. RESULTS: Using the Glasgow Outcome Scale (GOS), overall clinical outcomes were excellent or good (GOS 5 or 4), 86%; fair (GOS 3), 7%; poor (GOS 2), 4%; and death (GOS 1), 3%. Among the surgically treated patients, 90% experienced excellent or good outcomes (GOS 5 or 4), 6% had fair outcomes (GOS 3), 2% had poor outcomes (GOS 2), and 3% died (GOS 1). Among the endovascularly treated patients, 74% had excellent or good outcomes (GOS 5 or 4), 12% had fair outcomes (GOS 3), 10% had poor outcomes (GOS 2), and 4% died (GOS 1). The overall major and minor complication rate from surgery was 29%, with a 6% surgery-related permanent morbidity rate and a mortality rate of 0%. The overall major and minor complication rate from endovascular treatment was 21%, with a 3% endovascular-related permanent morbidity rate and a 2% mortality rate. Visual outcomes for patients who presented with visual symptoms were as follows: improved, 69%; no change, 25%; worsened, 6%; and new visual deficits, 3%. In general, angiographic efficacy was lower in the endovascular treatment group. CONCLUSION: A combined team approach of direct surgery and endovascular coiling can lead to good outcomes in the treatment for paraclinoid aneurysms, including high-risk lesions that might not have been treated in previous surgical series.

Surgical and endovascular flow disconnection of intracranial pial single-channel arteriovenous fistulae.

INTRODUCTION: Intracranial pial single-channel arteriovenous (AV) fistulae are rare vascular lesions of the brain. They differ from AV malformations in that they lack a true "nidus" and are composed of one or more direct arterial connections to a single venous channel. They often are associated with a venous varix because of their high-flow nature. The pathological aspects of pial AV fistulae arise from their high-flow dynamics; therefore, we think that disconnection of the AV shunt is enough to obliterate the lesion, and that lesion resection is unnecessary. Flow disconnection can be accomplished via surgical or endovascular means. Certain lesions have angiogeometric configurations, however, that are unfavorable for endovascular treatment. We reviewed the experience in our combined neurosurgical and neuroendovascular unit in the treatment of patients with pial single-channel AV fistulae. METHODS: From 1991 to 1999, the combined neurovascular unit at the Massachusetts General Hospital treated nine consecutive patients with nontraumatic intracranial pial single-channel AV fistulae. Carotid-cavernous fistulae and vein of Galen malformations were excluded from this analysis. The combined neurovascular team planned the treatment strategy for each patient on the basis of the anatomic location and the angiogeometry of each lesion. We retrospectively reviewed the medical records, office charts, operative reports, endovascular reports, and x-rays for each patient. Radiographic outcome was assessed by use of posttreatment angiography. Clinical outcome was assessed by an independent nurse practitioner. RESULTS: A treatment strategy of flow disconnection was used in all nine patients and was accomplished surgically in six patients, endovascularly in two patients, and by combined techniques in one patient. All nine lesions were completely obliterated as demonstrated radiographically, including obliteration of the venous varices associated with three of the lesions. With a mean long-term clinical follow-up of 3.2 years (range, 0.3-8.4 yr), four patients were neurologically excellent with no deficits, two patients had pretreatment neurological deficits that did not worsen after treatment, one patient had transient dysphonia and dysphagia postoperatively that resolved, one patient had mild weakness after treatment, and one patient had moderate homonymous hemianopia after treatment. CONCLUSION: Single-channel pial AV fistulae can be treated by a strategy of flow disconnection. Resection of the lesion is not necessary. Flow disconnection can be accomplished either surgically or endovascularly; however, certain angiogeometric configurations are more favorable for surgical treatment. An experienced combined neurosurgical and neuroendovascular team can carefully determine the most appropriate treatment modality on the basis of patient-specific and angiospecific factors.

Diffusion-weighted MR imaging: diagnostic accuracy in patients imaged within 6 hours of stroke symptom onset.

PURPOSE: To evaluate the diagnostic accuracy of diffusion-weighted magnetic resonance (MR) imaging performed within 6 hours of the onset of stroke symptoms. MATERIALS AND METHODS: The authors reviewed the patient records and images from all patients hospitalized in a 10-month period in whom diffusion-weighted imaging was performed within 6 hours of the onset of strokelike symptoms (n = 22). Analyses included comparison of the initial interpretation of the diffusion-weighted images with the final clinical diagnosis; blinded reviews of computed tomographic (CT) scans and conventional and diffusion-weighted images; and determination of lesion contrast-to-noise ratios (CNRs). RESULTS: Diffusion-weighted images indicated stroke in 14 patients, all of whom had a final diagnosis of acute stroke. Diffusion-weighted images were negative in eight patients, all of whom had a final clinical diagnosis other than stroke (100% sensitivity, 100% specificity, chi 2 = 23.00, P < .0001). Blinded reviews yielded 100% sensitivity and 86% specificity for diffusion-weighted MR imaging (chi 2 = 15.43, P < .0005); 18% sensitivity and 100% specificity for conventional MR imaging (chi 2 = 2.85, P > .2); and 45% sensitivity and 100% specificity for CT (chi 2 = 4.40, P > .10). Lesion percentage CNRs were 77% for diffusion-weighted imaging, 5.5% for CT, 9.8% for T2-weighted MR imaging, and 3.1% for proton-density-weighted MR imaging (P < .002 for diffusion-weighted imaging vs others). CONCLUSION: Diffusion-weighted MR imaging is highly accurate for diagnosing stroke within 6 hours of symptom onset and is superior to CT and conventional MR imaging.

Regional ischemia and ischemic injury in patients with acute middle cerebral artery stroke as defined by early diffusion-weighted and perfusion-weighted MRI.

BACKGROUND AND PURPOSE: We sought to map early regional ischemia and infarction in patients with middle cerebral artery (MCA) stroke and compare them with final infarct size using advanced MRI techniques. MRI can now delineate very early infarction by diffusion-weighted imaging (DWI) and abnormal tissue perfusion by perfusion-weighted imaging (PWI). METHODS: Seventeen patients seen within 12 hours of onset of MCA stroke had MR angiography, standard MRI, and PWI and DWI MRI. PWI maps were generated by analysis of the passage of intravenous contrast bolus through the brain. Cerebral blood volume (CBV) was determined after quantitative analysis of PWI data. Volumes of the initial DWI and PWI lesion were calculated and compared with a final infarct volume from a follow-up imaging study (CT scan or MRI). RESULTS: Group 1 (10 patients) had MCA stem (M1) occlusion by MR angiography. DWI lesion volumes were smaller than the volumes of CBV abnormality. In 7 patients the final stroke volume was larger or the same, and in 3 it was smaller than the initial CBV lesion. Group 2 (7 patients) had an open M1 on MR angiography with distal MCA stroke. In 6 group 2 patients, the initial DWI lesion matched the initial CBV abnormality and the final infarct. CONCLUSIONS: Most patients with M1 occlusion showed progression of infarction into the region of abnormal perfusion. In contrast, patients with open M1 had strokes consistent with distal branch occlusion and had maximal extent of injury on DWI at initial presentation. Application of these MRI techniques should improve definition of different acute stroke syndromes and facilitate clinical decision making.

Imaging of cerebral metastases.

MR imaging with intravenous gadolinium has greatly enhanced our ability to detect and delineate intracranial metastases as well as to differentiate them from other disease processes. Techniques such as magnetization transfer and triple dose gadolinium imaging have further improved lesion detection. Consideration of these radiologic techniques, including the issues and controversies of screening and cost effectiveness, suggests a reasonable approach to imaging patients with possible intracranial metastases. Newer modalities such as echo planar imaging, spectroscopy, PET, and SPECT, may in the future, prove to be very useful in the evaluation of patients with intracranial metastases. Proper imaging is also critical to appropriate diagnosis and management of meningeal metastases, calvarial metastases, and paraneoplastic disease.

Lipomatous tumors of the pelvis in women: spectrum of imaging findings.

Pelvic tumors that contain fat are common findings in women. Although the majority of these lipomatous tumors are benign cystic ovarian teratomas, other diseases should be considered in the differential diagnosis: malignant degeneration of a benign cystic ovarian teratoma, nonteratomatous lipomatous ovarian tumors, lipomatous uterine tumors, benign pelvic lipomas, and pelvic liposarcomas. Although these diseases are rare, their differentiation can be clinically significant. While most of these tumors are treated by surgical excision, asymptomatic lipomatous uterine tumors and benign pelvic lipomas may require no therapy. Additionally, correct identification of a malignant lipomatous tumor will affect both prognosis and surgical planning. The purpose of this essay is to illustrate the imaging findings of these conditions.

Lipomatous uterine tumors: diagnosis by ultrasound, CT, and MR.

Lipomatous uterine tumors are rare benign neoplasms that can be difficult to differentiate from benign cystic ovarian teratomas. However, if a fat containing mass can be clearly identified to be of uterine origin, the diagnosis of a lipomatous uterine tumor can be made. We present two cases in which a lipomatous uterine tumor was suggested by ultrasound and confirmed by CT and magnetic resonance.