Wednesday, October 31, 2007

Lanthanic Disease increasing because of MRI, reports NEJM

In this week's NEJM (http://content.nejm.org/cgi/content/short/357/18/1821) authors from the Netherlands report a large series of asymptomatic patients who had brain MRI scans. There was a [surprisingly?] large incidence of abnormalities, particularly [presumed] brain infarcts, the incidence of which [predictably] increased with age. This is a timely report given the proliferation and technical evolution of advanced imaging techniques, which we can expect to lead to the discovery of an increasing number of "abnormalities" in asymptomatic patients. As in the case of screening for lung cancer (http://jama.ama-assn.org/cgi/content/abstract/297/9/953?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=computed+tomography&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT), the benefits of early detection of an abnormality must be weighed against the cost of the technology and the diagnostic and therapeutic misadventures that result from pursuit of incidentalomas that are discovered. The psychological impact of the "knowledge" gained on patients must also be considered. Sometimes, ignorance truly is bliss, and therefore 'tis folly to be wise.

Lanthanic disease (with which I am familiar thanks to the sage mentorship of Peter B. Terry, MD, MA at Johns Hopkins Hospital) refers to incidentally discovered abnormalities in asymptomatic individuals. Not surprisingly, it generally is thought to have a better prognosis than disease that is discovered after symptoms develop, presumably because it is discovered at a less advanced stage or is behaving in a less sinister fashion.

The discovery of Lanthanic disease poses challenges for clinicians. Is the natural history of incidentally discovered disease different from what is classically reported? Should pre-emptive interventions be undertaken? What of the elderly female with mental status changes who presents to the ED and in whom a cortical infarct or SDH is discovered on an MRI? Can her current symptoms be attributed to the imaging abnormalities? Clinicians will do well to be aware of the high prevalence of asymptomatic abnormalities on such scans.

The authors' conclusions are perspicacious: "Information on the natural history of these lesions is needed to inform clinical management."

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