Derivation of a clinical decision instrument to identify patients with status epilepticus who require emergent brain CT.

BACKGROUND: Studies have shown the value of CT brain imaging in adults with first-time seizures, but there are no recommendations regarding emergent brain CTs in persons with an established seizure disorders. Our study aimed to derive a clinical decision instrument (CDI) to determine which patients with status epilepticus (SE) require emergent brain imaging. METHODS: This was a retrospective chart review of patients who presented to our emergency department with SE between 2010 and 2018. Patients with first-time seizures were excluded. A priori, we defined high risk criteria for emergent imaging as well as positive findings on brain CT. High risk criteria included known malignancy, trauma, and immunosuppression. Positive CT scans included findings such as intracranial hemorrhage (ICH) and mass. RESULTS: We identified 214 patients who met inclusion criteria Of the 181 patients without high risk criteria, 3% had positive CT scans. Of the 33 patients with high risk criteria, 10% had positive CT scans. The sensitivity, specificity, PPV, and NPV for our initial CDI were 38%, 85%, 9%, and 97%. Adding the criterion of prior ICH would have lowered our miss rate to 0.6%. Modifying our CDI to 1) History of ICH, 2) Malignancy, 3) Immunosuppression, and 4) Trauma would result in a CDI with sensitivity, specificity, PPV, and NPV of 87.5%, 87.4%, 21.2%, and 99.5%. CONCLUSIONS: By using four criteria to identify high risk patients, we can defer CT scanning in the vast majority of patients with SE and known seizure disorders. This CDI should be prospectively validated before adoption.

Validation of a clinical decision instrument for emergent neuroimaging after a seizure: Let's image malignancy, intracranial hemorrhage, and trauma (LIMIT).

BACKGROUND: Given the many causes of seizures, emergency physicians often utilize brain computed tomography (CT) to evaluate for intracranial pathology. However, a CT exposes patients to 100 times more radiation than a chest radiograph. Previously, we developed a four-item clinical decision instrument (CDI) to determine which patients with status epilepticus (SE) do not require emergent neuroimaging. In this study, we seek to prospectively validate our CDI in patients with a history of seizures with both SE and generalized tonic-clonic seizures. METHODS: This was a prospective observational study of 1,739 consecutive patients who were recruited from two urban hospitals in Philadelphia, Pennsylvania. All patients, 18 years and older, who presented with a chief complaint of seizure and had emergency neuroimaging performed were eligible for inclusion. Patients were excluded from analysis if this was a first-time seizure, had a ventriculoperitoneal shunt, or had focal neurologic deficits. RESULTS: A total of 376 patients were in the final analysis. Of the 376 patients, 10 patients (3%) had positive CTs. Nine of the 10 of the patients were identified by our CDI, resulting in a negative predictive value (NPV) of 99.5%. On secondary analysis, we refined our CDI from four to three criteria: 1) history of intracranial hemorrhage (ICH), 2) active malignancy, and 3) trauma. These criteria also had a NPV of >99% when applied to patients in SE. CONCLUSION: The validation of our CDI showed improved NPV when compared to the derivation set. Use of the criteria of history of ICH, active malignancy, and trauma could have reduced the use of emergent neuroimaging in our cohort by up to 49%. This CDI should be validated in a larger subset of patients and in multiple centers prior to widespread adoption.