Modified Rankin Scale and Short-Term Outcome in Cranial Neurosurgery: A Prospective and Unselected Cohort Study

BACKGROUND: The modified Rankin Scale (mRS) was developed to monitor functional recovery after stroke, but nowadays it is a treatment outcome measure in elective neurosurgery. Our objective was to study how mRS changes associate with short-term postoperative outcome. METHODS: Preoperative, in-hospital, and 30-day mRS scores came from a prospective, consecutive and unselected cohort of 418 adult elective craniotomy patients enrolled between December 2011 and December 2012 in Helsinki, Finland. Recorded data included subjective and objective postoperative in-hospital complications as well as changes in mRS score after surgery. RESULTS: Minor or major complications were detectable in 46% of the patients. In-hospital and 30-day postoperative increases in mRS score were inconsistent; among patients with no complications, 17% had a greater mRS score at discharge and 24% at 30 days, whereas 28% of the patients with major complications showed no increase in mRS score at discharge. Of individual complications, only new or worsened hemiparesis, silent stroke, and pneumonia were associated with postoperative increase (>2) in mRS score after multivariable analysis. For mRS-score difference >1 at discharge in detecting major complications (including mortality), sensitivity was 45% and specificity 94%. CONCLUSIONS: The mRS changes after elective cranial neurosurgery are inconsistent. The mRS seems to represent functional changes, which do not necessarily associate with detected in-hospital complications.