Embolization of middle meningeal artery (EMMA) is a relatively new treatment for chronic subdural hematoma (CSDH). To date, an objective method that assesses or describes the extent of EMMA for the treatment of CSDH does not exist. Recently, the concept of a novel grading scale for EMMA in patients with CSDH has emerged. However, this has not been applied to a clinical case setting and inter-rater reliability has not yet been studied. The purpose of this study was to validate the grading scale in clinical practice and to assess for inter-rater reliability.

We retrospectively examined consecutive patients who underwent EMMA for CSDH. Patients were included if the whole head angiogram from common carotid as well as external carotid arteries before and after EMMA were available in the arterial, capillary as well as venous phases. Two independent readers, each with more than 5 years of experience in independent practice, assessed the angiograms for the grading of EMMA and assigned a score ranging between 0 and 3. The grading score between the two readers were compared using Cohen’s Kappa score to assess the inter-rater reliability.

In 19 patients, we found that EMMA had no periprocedural morbidity and mortality. The number of cases in each EMMA grading score category are as follows: 0 n =1; 1 n =3; 2 n =1; and 3 n =10. There was substantial inter-rater reliability for the assessment of grading of EMMA (Kappa = 0.74).

The novel EMMA grading scheme demonstrated substantial inter-rater reliability and appears promising.