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Neuroimaging is commonly used to rule out significant head trauma that results from patients who experience seizures in the ED. Neuroimaging is typically used to find the cause of the seizure, especially in patients experiencing a first seizure or who have a known neurologic illness. In 1996, the American Academy of Neurology (AAN) created practice parameters for neuroimaging in the emergency patient presenting with seizure. In 2007, these parameters were revisited, largely because of improved methodology for developing clinical practice guidelines and because of the advances made in neuroimaging. The goal of the AAN’s new parameters was to incorporate evidence into how neuroimaging might lead to an acute or urgent change in management. In addition, it aimed to determine which clinical and historical characteristics indicated a need for a neuroimaging study.

Highlighting Important Recommendations

Several important findings from the current base of evidence led to new recommendations for ED personnel managing these patients (Table 1). Published research has shown that cranial CT will change acute management in 9% to 17% of adult patients with a first seizure. In children with a first seizure, the use of CT in the ED was likely to change acute management in 3% to 8% of patients. These observed rates are high enough that they should motivate most ED personnel caring for seizures to perform a CT scan in certain situations.

Another important finding in the literature is that there appears to be no clear difference between rates of abnormal emergent CT for patients with chronic seizures when compared with patients who had a first seizure. In analyses of specific populations, the evidence demonstrated that children younger than 6 months of age who presented with seizures had clinically relevant abnormalities on CT scans about half the time. Persons with AIDS and first seizures also had high rates of abnormalities, and central nervous system toxoplasmosis was frequently found. In this context, abnormal neurologic examination, predisposing history, or focal seizure onset were probably predictive of an abnormal CT.

Management Plans May Change

One of the major points of this evidence-based review is that rates of abnormal CT scans that lead to change in emergency management vary depending on specific circumstances for each individual patient. Abnormalities found on CT scans that would most likely lead to changes in treatment included tumors, traumatic brain injury with skull fracture, and strokes that include bleeding in the brain. The evidence clearly supports that CT scanners should be readily available in EDs throughout the country.

More research into the use of neuroimaging in emergency seizures is needed. For example, data on the use of brain MRIs in seizures presenting at the ED and particularly the use of newer MRI scanners (which may have higher sensitivity than older models) may be beneficial. The role of contrast administration for both CT and MRI modalities needs to be assessed and more consideration should be paid to the risks in scanning potentially unstable patients. In addition, we need to collect better outcome and follow-up data, such as information on patients starting anti-seizure drugs or changing anti-seizure drug doses in the ED. When these gaps in knowledge are addressed, we may better understand when it’s best to use neuroimaging in this setting.

Cynthia L. Harden, MD has indicated to Physician’s Weekly that she has worked as a consultant for Valeant and GlaxoSmithKline. She has also worked as a paid speaker for UCB Pharma, GlaxoSmithKline, and Abbott Laboratories. She has received grants/research aid from the NIH, UCB Pharma, and Eisai.