Robert D. Brown

Natural history, evaluation, and management of intracranial vascular malformations.

Intracranial vascular malformations are seen increasingly in clinical practice, primarily because of advances in cross-sectional brain and spinal cord imaging. Commonly encountered lesion types include arteriovenous malformations, cavernous malformations, venous malformations, dural arteriovenous fistulas, and capillary telangiectasias. Patients can experience various symptoms and signs at presentation. The natural history of vascular malformations depends on lesion type, location, size, and overall hemodynamics. The natural history for each lesion subtype is reviewed, with special consideration of the risk of hemorrhage or other adverse outcomes after the lesion is detected and any known predictors of hemorrhage or other outcomes. In practice, these data are compared with the risk of available treatment options as the optimal management is clarified. A multidisciplinary approach including neurosurgery, radiosurgery, interventional neuroradiology, and vascular neurology is most useful in determining the best management strategy.

Carotid Revascularization for Prevention of Stroke: Carotid Endarterectomy and Carotid Artery Stenting

Carotid endarterectomy (CEA) has been used for the past several decades in patients with carotid occlusive disease. Large randomized controlled trials have documented that CEA is a highly effective stroke preventive among patients with carotid stenosis and recent transient ischemic attack or cerebral infarction. In asymptomatic patients with carotid stenosis, clinical trial data suggest that the degree of stroke prevention from CEA is less than among symptomatic patients. However, otherwise healthy men and women with an asymptomatic carotid stenosis of 60% or greater have a lower risk of future cerebral infarction, including disabling cerebral infarction, if treated with CEA compared with those treated with medical management alone. More recently, carotid artery stenting has been performed Increasingly for patients with carotid occlusive disease. As technology has improved, procedural risks have declined and are approaching those reported for CEA. The benefits and durability of CEA compared with carotid artery stenting are still unclear and are being studied in ongoing randomized controlled trials.

Clinical Manifestations and Survival Rates among Patients with Saccular Intracranial Aneurysms: Population-based Study in Olmsted County, Minnesota, 1965 to 1995

OBJECTIVETo report presenting clinical symptoms, previous medical history, and survival rates for people with saccular intracranial aneurysms (IAs), in a defined population. METHODSThe medical records of all residents of Olmsted County, Minnesota, with possible IAs were reviewed. Clinical manifestations at the time of diagnosis, previous medical history, demographic factors, and survival rates after diagnosis were determined. RESULTSOf 270 people with IAs detected between 1965 and 1995, 188 exhibited symptoms at the time of diagnosis, including 74% of women and 63% of men (P = 0.054). Intracranial hemorrhage (ICH) was the most common presenting symptom (60% of all patients and 86% of patients who exhibited symptoms), followed by cranial nerve palsy, transient ischemic attacks, and seizures. Survival rates after detection (with the exclusion of cases that were first detected during autopsies) were dependent on the occurrence of ICH; 23% of patients who presented with ICH died by 1 day after diagnosis, compared with 5% of those who did not exhibit symptoms or exhibited symptoms but without ICH at presentation. At 5 years, 44.7% of patients with hemorrhage had died, compared with 29.4% of patients with symptoms other than hemorrhage. After the first 24 hours after detection, survival rates did not differ significantly for those presenting with or without hemorrhage. Predictors of better survival rates also included lower age and later calendar year of presentation. CONCLUSIONThis study provides the first data on aneurysm characteristics, clinical symptoms, and survival rates among people with IAs in a defined population. During the study period, most aneurysms were detected in the context of an aneurysm-related symptom (particularly among women), with a large proportion of patients presenting with ICH. After the acute phase of hemorrhage, long-term survival rates among people with IAs were similar for those presenting with or without ICH.

Associations between Cardioembolic Stroke and Obstructive Sleep Apnea.

STUDY OBJECTIVES To assess etiology of ischemic stroke in patients with obstructive sleep apnea (OSA) compared with controls. This information may aid in determining how OSA increases stroke risk and facilitate recurrent stroke prevention in patients with OSA. DESIGN Retrospective, case-control study. SETTING Academic tertiary referral center. PATIENTS Consecutive patients who underwent polysomnography and had an ischemic stroke within 1 year were identified. Stroke subtype was determined using two validated algorithms. Polysomnographic results were used to separate patients into OSA cases and controls. Information regarding cardiovascular risks, neuroimaging, and echocardiographic data were collected. INTERVENTIONS N/A. MEASUREMENTS AND RESULTS In 53 subjects, cardioembolic (CE) strokes were more common among OSA cases than controls (72% versus 33%, P = 0.01). The majority of CE strokes occurred in those with moderate to severe OSA. Atrial fibrillation (AF) was more frequent in OSA cases (59% versus 24%, P = 0.01). The association between OSA and CE stroke remained significant after controlling for AF (P = 0.03, odds ratio 4.5). CONCLUSIONS There appears to be a strong association between obstructive sleep apnea (OSA) and cardioembolic (CE) stroke. In patients with OSA presenting with cryptogenic stroke, high clinical suspicion for CE is warranted. This may lead to consideration of diagnostic studies to identify CE risk factors such as paroxysmal atrial fibrillation (AF). CE strokes are more common in patients with OSA even after adjusting for AF. This finding may reflect a high rate of occult paroxysmal AF in this population; alternatively, OSA may lead to CE strokes through mechanisms independent of AF.

Stabilization of 2-column thoracolumbar fractures with orthoses: A cadaver model

Study Design. A gross anatomic and motion analysis study in cadavers. Objective. Assess spinal motion in a cadaveric spinal fracture model and investigate the ability of external orthoses to control this motion. Summary of Background Data. External orthoses are frequently prescribed for patients who have experienced burst fracture of the thoracolumbar spine. Despite the substantial expense involved, there is little data confirming their value. Methods. A T12 burst fracture model was created in 5 lightly embalmed cadavers by resecting the anterior and middle columns of the T12 vertebra through a thoracolumbar anterior approach to the spine. An electromagnetic motion tracking and analysis system was used to track angular and linear displacement at the fracture during routine patient maneuvers. Several commonly used orthoses, including an extension brace and both an “off-the-shelf” and custom-molded thoracic-lumbar-sacral orthosis (TLSO), were applied to the cadavers and the affect on fracture site motion was assessed. Results. Application of all 3 styles of brace resulted in angular motion of 8° to 12° in flexion-extension, 11° to 20° in axial rotation, and 8° to 10° of lateral bending. Brace application resulted in linear displacement of 29 to 46 mm in the medial-lateral plane, 21 to 23 mm in the axial plane, and 21 to 37 mm in the anterior-posterior plane. During logrolling maneuvers, TLSO style braces diminished angular motion, although residual motion in the range of 5° remained. TLSO style braces had little effect on linear translation. When placed in a seated position in bed, TLSO style braces diminished flexion and extension modestly, but did not influence lateral bending or linear translation. Extension style braces had no effect on fracture motion during any activity tested. Conclusion. In a cadaver model of a burst fracture, there is surprising angular and linear motion at the fracture during common hospital activities. TLSO orthoses can decrease angular motion but do not effect translation at the fracture. An extension orthosis had no effect on motion at the spinal fracture site.