Definition and Treatment of Rapidly Improving Stroke Symptoms Are Uncertain
SAN DIEGO—Neurologists have no generally accepted definition for rapidly improving stroke symptoms (RISS), according to a systematic literature review presented at the 2014 International Stroke Conference. In most cases, the diagnosis is based on physician judgment, which is variable.
A large proportion of patients with acute ischemic stroke who do not receive t-PA solely because of RISS have poor outcome. Yet certain subgroups of patients with RISS may benefit from t-PA, said Pirouz Piran, MD, Research Assistant at the State University of New York Downstate Medical Center in Brooklyn.
A Systematic Review of Literature on RISS
A large data set published in Stroke in 2011 showed that RISS is a frequently cited reason for not administering t-PA to a patient. Approximately 28% of patients with RISS are not discharged from the hospital. About 6% of patients with RISS were unable to ambulate at discharge, and about 23% required assistance to ambulate at discharge.
Perhaps the most important reason that patients with RISS do not receive t-PA is that the drug’s label states that treating patients with minor neurologic deficit or with RISS is not recommended. RISS was an exclusion criterion in a trial conducted by NINDS, but the manuscript did not provide a precise definition of the condition.
Dr. Piran and colleagues systematically reviewed the literature for published definitions of RISS and examined how these definitions affect clinical outcomes in patients who were treated with t-PA or untreated. The group identified 15 articles that had sufficient data, provided a definition for RISS, and reported RISS and minor stroke separately.
Nine articles defined RISS as being based on physician judgment. Two articles defined RISS as a reduction of four or more points in NIH Stroke Scale (NIHSS) score from initial presentation to t-PA decision time. The remaining articles each had different definitions of RISS.
One study defined RISS as a general impression of significant improvement before t-PA administration. One article defined RISS as an NIHSS score of 4 or lower that, by history and preimaging examination, had improved from a more severe deficit. Another paper defined RISS as major symptoms rapidly improving by the time of treatment decision. The last study defined RISS as significant improvement in at least four of the following items: motor paresis of the arm, motor paresis of the leg, motor paresis of the facial muscles, aphasia, dysarthria, and sensory deficit.
Outcomes Vary for Patients With RISS
Five studies reported clinical outcomes for patients with RISS. In one study, 15 of 19 patients with RISS who received t-PA had a favorable outcome (ie, modified Rankin scale and NIHSS scores of 0 to 1 at three months). In another study, 40% of patients with RISS were discharged home, and patients with RISS were more likely than patients without RISS to have a large artery occlusion. In a third study, 48% of patients with RISS had a favorable outcome, defined as minimal or no disability.
Two studies reported unfavorable outcomes for patients with RISS. One study of 39 patients with RISS found an association between NIHSS score of 10 or higher and unfavorable outcome at three months. In the other study, 44% of patients with RISS were dependent or died at discharge.
Planned Trial Will Evaluate t-PA for RISS
Future research is necessary to validate definitions of RISS and to determine how different definitions predict clinical outcomes, said Dr. Piran. Researchers will begin a randomized controlled clinical trial later this year to clarify the risk–benefit ratio of t-PA in patients with mild stroke or RISS, he added.
A recent NINDS task force comprising investigators, neurologists, and emergency physicians proposed, as an operational definition of RISS, a combination of NIHSS score and the assessment of potential disability by the patient and the physician. The task force agreed unanimously that patients with RISS who would be left with a potentially disabling degree of remaining neurologic deficit at the time of treatment decision should be treated with t-PA.
—Erik Greb