The differential diagnosis of BACNS, the diagnosis that could be mistaken for this condition, include reversible vasospasm due to medications
(such as pseudoephedrine often used in cold medications
, vasospasm related to pregnancy, exercise, cocaine use etc). Also, secondary types of angiitis such as lupus, infections, and several others. The differentiation between all the types of angiitis can be made based on blood tests and imaging in most cases, but sometimes brain biopsy is required.