Distinguishing stroke 'mimic' from real stroke subject of clinical study

Thursday, April 17, 2008

SCOTTSDALE, Ariz. – It's not unusual for patients to show up in the emergency room, worried they are experiencing a stroke. But other medical conditions, such as tumors, systemic infections and hematomas, can actually "mimic" a stroke.

In fact, previous studies have revealed a stroke "mimic rate" of 9 to 19 percent, meaning that medical personnel must act quickly in the emergency room setting to distinguish between actual stroke and other disorders.

Thrombolysis (treatment to break up abnormal blood clots) is an established therapy for acute ischemic stroke, and requires identification of a potential stroke and clinical assessment within a three-hour treatment window.

Mayo Clinic physicians in Arizona were part of a new study to develop a clinical prediction model to identify stroke mimics. Doing so can allow physicians to deliver more targeted therapy. Results will be presented at the American Academy of Neurology Annual Meeting in Chicago on April 16.

In the study, "stroke alerts" were identified from July 2005 to March 2006 at a primary stroke center. Thirty-one clinical variables were identified by chart review, and final diagnosis of stroke was defined as the most probable diagnosis at discharge, or if necessary, upon further follow up.

During the study period, 196 patients presented with stroke alert status, and 22 percent were classified as stroke mimics. The strongest predictor of a stroke mimic was the absence of initial lateralizing signs, meaning localization of a function, such as speech, to the right or left side of the brain. Forty-three percent of patients without initial lateralizing signs were stroke mimics, while only 10 percent of those with lateralizing signs were stroke mimics.

Investigators, including Bentley J. Bobrow, M.D., Bart Demaerschalk, M.D. and Joseph G Hentz, MS, Mayo Clinic in Arizona, found that low diastolic blood pressure, history of stroke/TIA, and the absence of signs of lateralizing, were independently related to symptoms being classified as a stroke mimic. Patients with these criteria had a 75 percent chance of being a mimic while patients who did not had a 21 percent chance of being a mimic.

The relevance of the study, according to Drs. Bobrow and Demaerschalk, is that low diastolic blood pressure, history of stroke/TIA, and the absence of lateralizing signs were strong, positive indicators of stroke mimic.

###

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 244-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

###

To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. MayoClinic.com is available as a resource for your health stories.