Free-floating thrombus (FFT) of the carotid artery is an uncommon entity that usually presents as an acute emergency. Management is based on case reports and series because the natural history and optimal treatment are unknown. This study was conducted to systematically review the world literature in an attempt to better understand FFT, its presentation, distribution, management, and outcome. A literature search in all languages was performed of the PubMed database (> or =1950s) and Medline database (1966-November 2004). All relevant articles were reviewed and their references analyzed in a similar manner for further literature. Cases from the authors' institutions were reviewed as well. All cases within the reports were individually assessed for inclusion or exclusion. Inclusion required that the FFT originate or anchor within the carotid artery (ie, excluding emboli, arch thrombi with extensions into the carotid artery), be partially occluding (ie, excluding occlusions, "string-sign," microscopic thrombus), and ideally have an elongated or protrusive morphology, circumferential flow around the distal portion, and cyclical motion with the cardiac cycles. There were 61 reports reviewed, of which 43 contained FFT cases. These reports had 342 cases (including the current series) that were reviewed, of which 145 met our inclusion criteria. A database was created for qualitative and quantitative assessment of all cases. When data were pooled, appropriate statistical analysis was performed. A limitation of the study is that FFT is under-reported and ill defined, which limited the analysis in quantity and quality. In addition, reporting is not uniform, and therefore, significant data were not always present. In attempting to define FFT and include or exclude cases, subjectivity is inherent. FFT is more frequently reported in men than women, with a ratio of nearly 2:1 (P < .0001), and at a younger age than in most patients with carotid disease (P < .0001 when compared with North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and Asymptomatic Carotid Surgery Trial). Symptoms are present in 92% of patients. There was a trend for patients with FFT to be hypercoagulable (47% of those serologically tested). The internal carotid artery was the most commonly affected (75%), with atherosclerosis being the most common associated pathology. Medical and surgical management have both been used, with neither clearly superior to the other. Medical management for stabilizing neurologic deficits has less risk and less benefit than surgical intervention.
