From the Research
Nausea and vomiting in head trauma primarily result from direct stimulation of the vomiting center in the medulla oblongata due to increased intracranial pressure (ICP). When head trauma occurs, brain tissue swelling, hemorrhage, or cerebral edema can elevate ICP, which directly stimulates the chemoreceptor trigger zone (CTZ) and the vomiting center 1. Additionally, vestibular pathway disruption from trauma to the inner ear or vestibular nuclei can trigger nausea and vomiting through abnormal balance signals. Trauma to specific brain regions, particularly the posterior fossa structures like the cerebellum and brainstem, is especially associated with persistent vomiting. The release of inflammatory mediators following brain injury can also sensitize the CTZ.
Pathophysiology of Nausea and Vomiting
The pathophysiology of nausea and vomiting in head trauma involves:
- Increased intracranial pressure (ICP) stimulating the vomiting center in the medulla oblongata
- Vestibular pathway disruption causing abnormal balance signals
- Trauma to specific brain regions, such as the posterior fossa structures
- Release of inflammatory mediators sensitizing the CTZ
Management of Nausea and Vomiting
Management of nausea and vomiting in head trauma typically includes:
- Antiemetics such as ondansetron (4-8mg IV/PO every 8 hours) or metoclopramide (10mg IV/PO every 6 hours) 2, 3
- Measures to reduce ICP, including head elevation, adequate oxygenation, and in severe cases, osmotic diuretics like mannitol or hypertonic saline
- It is crucial to recognize that persistent vomiting after head trauma may indicate worsening ICP or developing complications like intracranial hemorrhage, requiring immediate medical attention and neuroimaging 1.
Recent Evidence
A recent study published in 2022 found that ondansetron and metoclopramide had similar effects on nausea in patients with mild head trauma, but metoclopramide was most effective in 15 minutes and ondansetron in 30 minutes after injection 3. However, another study published in 2015 found that metoclopramide was associated with a higher incidence of drowsiness and anxiety compared to ondansetron 2.
Clinical Considerations
In clinical practice, it is essential to consider the potential risks and benefits of each treatment option and to monitor patients closely for signs of worsening ICP or other complications. The treatment effectiveness of ondansetron and metoclopramide are similar, but ondansetron may be a better option due to its lower incidence of side effects 2, 3.