The IMPACT study is a randomized, double-blind clinical trial evaluating two commonly used intravenous medications - metoclopramide and acetaminophen - for treating acute post-concussion symptoms in emergency department patients after mild head injury. The study aims to determine which treatment more effectively improves symptoms such as headache, dizziness, nausea, concentration difficulties, and emotional changes within the first week after injury.

Participants will be enrolled across two Montefiore emergency departments and followed using a validated post-concussion symptom questionnaire. Findings from this study may help improve evidence-based treatment strategies for patients experiencing concussion-related symptoms after head trauma.

Nearly 1.5 million patients present to US emergency departments (ED) annually following head trauma. Many, even with a low velocity mechanism of injury, report a variety of post-concussion symptoms, including headache, dizziness, and nausea. For most patients, post-concussion symptoms will resolve after several days, though up to 1/4 will develop persistent symptomatology that can last months or years.

Very few randomized studies are available to guide treatment of acute post-concussion symptoms. In the absence of evidence, most emergency physicians treat post-concussion symptoms using typical medications for the symptom - thus headache is treated with analgesic medication, nausea with antiemetics, and dizziness with medications such as meclizine. Other symptoms commonly described as part of post-concussion syndrome, such as fatigue, irritability, and poor concentration, are usually left untreated.

Two randomized studies among ED patients who experienced head trauma were recently completed at Montefiore EDs. In the first, one dose of IV metoclopramide, when compared to placebo, improved post-concussion syndrome both in the ED and one week later. In this study, IV metoclopramide was effective against a broad range of symptoms beyond just headache and nausea. Variables related to concentration (including concentration, remembering, and feeling like one is in a fog) were better in the metoclopramide arm at both one hour and at one week. Similarly, variables related to emotion (including feeling more emotional, irritability and sadness) were better in the active group. In the second study, adding IV dexamethasone to metoclopramide did not result in increased or prolonged efficacy.

Inclusion Criteria:

• Adults presenting to one of the study emergency departments (EDs)
• Acute minor traumatic brain injury/concussion as defined by the Zurich Consensus Statement, including symptoms in somatic, cognitive, emotional, behavioral, physical, cognitive impairment, or sleep domains
• ED visit occurring within 7 days of the head injury
• Overall pain intensity greater than >=6 on a 0-10 scale
• Rivermead Post-Concussion Questionnaire (RPQ) score of at least 10
• Reported post-concussion symptoms were not present prior to the injury
• Treating attending physician plans to administer a parenteral medication

Exclusion Criteria:

• Already treated with an anti-dopaminergic medication for post-concussion symptoms
• Contraindications to study medications, including:
• Pheochromocytoma
• Seizure disorder
• Parkinson's disease
• Use of monoamine oxidase (MAO) inhibitors
• Use of anti-rejection transplant medications
• Pregnant patients will not be excluded because both acetaminophen and metoclopramide are commonly used during pregnancy.