Greater Occipital Nerve Block Versus Metoclopramide

Inclusion Criteria: Eligible patients are adults who present with an acute moderate or severe headache meeting migraine headache criteria, as defined by the International Classification of Headache Disorders-3β (1.1, migraine without aura). Patients who meet criteria for Probable Migraine without Aura (1.5.1) will also be included, provided they have had at least one similar attack previously. Exclusion Criteria: Patients will be excluded if informed consent cannot be obtained, if there is concern for a secondary cause of headache, if the maximum documented temperature is greater than 100.3 degrees, for a new objective neurologic abnormality, skull defect, suspected infection overlying injection site, known bleeding disorder, ongoing use of anti-platelet agents including P2Y12 platelet inhibitors (clopidogrel, prasugrel, ticagrelor), heparins, warfarin, or 10a inhibitors (rivaroxaban, apixaban, edoxaban, fondaparinux), prior treatment with a greater occipital nerve block, allergy to the investigational medications, pheochromocytoma, seizure disorder, Parkinson's disease, use of MAO inhibitors, and use of anti-rejection transplant medications.