The real usefulness and indication for migraine diagnosis of neurophysiologic evaluation

According to IHS criteria, a correct clinical history is fully adequate for a diagnosis of migraine. Patients usually perform many useless instrumental and laboratoristic exams and specialistic evaluations. In particular, electroencephalogram (EEG) is often prescribed as a first-line study in migraine patients. The objective is to analyze the indications of EEG in migraine and to evaluate whether its performance may negatively influence the time necessary to obtain a correct diagnosis. In particular, we compared the effects of EEG performance with those related to neuroradiological examinations in terms of time necessary to obtain a migraine diagnosis. 400 consecutive patients affected by migraine without aura were enrolled. Demographic and clinical data were collected. We used an ordinal regression model considering diagnostic delay as the main outcome and EEG and radiological examinations (in particular brain CT) as predictors. Delay was defined as a time to diagnosis greater than 1-year. Age, sex, number of specialists and examinations were included in the model as covariates. EEG represented the most often performed non-radiologic examination in our sample (20 %). It was associated with a significant risk of diagnostic delay [OR 1.66 (95 % CI 1.65-1.66, p < 0.001)]. An appropriate workup, including CT scan and early referral to a headache center was the most time-saving approach, being associated to the lowest probability of diagnostic delay [OR 0.72 (95 % CI 0.63-0.82, p < 0.001)]. EEG is a frequently prescribed exam in migraine. Our data show that it can contribute to diagnostic delay, highlighting only uncertain and unspecific elements. These data confirm the usefulness of a wide application of IHS guidelines, not recommending this exam for migraine detection.