Winning Abstracts from the 2007 Medical Student Abstract Competition: Lambl’s Excrescence: A Poorly Defined Source of Cerebral Emboli.
Henry Ho-jin Ra, Michigan State University College of Human Medicine, 2008
Lambl’s excrescence are small filiform processes found on the closure lines of aortic and mitral valves; formed by the organization of microthrombi on the valve’s contact margins. Discovered by transesophageal echocardiography (TEE) and often dismissed as an incidental finding, the frequency and clinical significance of these structures remains poorly defined. We present a case where Lambl’s excrescence is the most likely etiology of an ischemic stroke.
A 53-year-old female with multiple sclerosis was found unresponsive on her living room floor by her family. She had been unconscious for an unknown length of time. Her family history included stroke, diabetes mellitus, and myocardial infarction. Her brother died after a myocardial infarction at age 57. She had no other major medical problems. Physical examination showed expressive aphasia, right-sided hemiparesis and horizontal nystagmus. A brain MRI revealed moderate-to-large areas of left thalamic, left temporal and external capsule infarcts. Ultrasound and Doppler studies of her carotids and lower extremities were normal. TEE showed a filamentous density on a trileaflet aortic valve with fibrous dense and light areas suspicious of either Lambl’s excrescence or endocarditis. Antiphospholipid studies were normal, including the lupus anticoagulant and cardiolipin antibodies. Infective endocarditis seemed unlikely in the absence of fevers and chills; negative blood cultures; and an unremarkable physical examination. In light of no other source of emboli, the densities found on TEE were presumed to be Lambl’s excrescence, and the most likely cause of this patient’s stroke. Warfarin was started.
Lambl’s excrescence has been suspected as a cause of cerebral embolic events in a few studies. It has been identified more commonly in patients undergoing TEE assessment for cardiac sources of embolism versus patients referred for other indications (6.3% vs 0.3%). One report of 50 patients with cerebral emboli revealed 11 (22%) with Lambl’s excrescence of the mitral valve on TEE examination. Despite this association between Lambl’s excrescence and stroke, the literature on this phenomenon is limited A Pubmed search using the term “Lambl’s” returned only 34 articles—many of them only mentioning Lambl’s excrescence in comparison to cardiac papillary fibroelastomas (CPE). More importantly, research and recommendations on management of patients suspected of embolic stroke caused by Lambl’s excrescence is nearly non-existent. In cases of CPE, the current recommendation is to remove any tumors. Should this recommendation be applied to Lambl’s excrescence despite a different hypothesized mechanism of formation from CPE? Is anticoagulation therapy an alternative? If so, does it need to be life-long? Finally, can the etiology of previously identified cryptogenic strokes be attributed to Lambl’s excrescence?
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