Validation of clinical criteria for referral to head imaging in the neurologic emergency setting

In recent decades, diagnostic imaging became an important generator of large increases in medical spending. Inappropriate head CT referrals also increase population irradiation and unnecessarily burden and frighten patients. To validate previously proposed clinical criteria for referral to head imaging (age > 55 years, focal neurological deficit, changed mental state, nausea or vomiting, coagulation disorder, cancer) in a setting of emergency neurological service. We retrospectively analyzed electronic records of 500 consecutive referrals to neurological emergency and 500 referrals to emergency head imaging. In patients with several referrals, only results of the first evaluation were further analyzed. We calculated relations between clinical predictors, referrals, and findings of head imaging. Of 486 first referrals of consecutive patients, 216 (44%) were referred to the emergency, and 100 (21%) to non-emergency head imaging. Remaining 170 (35%) were not referred to head imaging. Clinical predictors of pathologic head imaging fulfilled 77%, 41%, and 43% of patients, respectively. Pathologic head imaging had 153 of 490 (31%) referred patients. Referral criteria fulfilled 146 (sensitivity 95%) of them. Intracranial pathology was found in 7 of 125 patients not fulfilling referral criteria (negative predictive value 94%): 3 reported transient neurological symptoms, 2 sudden headache, and 2 headache with nausea and vomiting. We confirmed utility of previously proposed clinical criteria for referral to head CT in emergency neurological setting. In addition, we found transient neurological symptoms, sudden severe headache, and headache with nausea or vomiting as additional independent indications for emergency head imaging.