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Indication for computed tomography of the brain in patients with first uncomplicated generalised seizure
1Department of Medicine, University Hospital, Basle, Switzerland.
Objectives:
To assess the yield of emergency computed tomography of the brain in patients with a first generalised epileptic seizure and to evaluate a four item screening questionnaire on alcohol misuse (CAGE questionnaire) as a triage tool to avoid unnecessary scans in cases of seizures related to withdrawal from alcohol.
Design:
Prospective, observational.
Setting:
Medical casualty unit in a university hospital.
Patients:
119 adult patients presenting to casualty within one hour of a generalised seizure.
Measurements:
A clinical examination focusing on focal neurological symptoms, the CAGE questionnaire, and computed tomography of the brain with contrast enhancement.
Results:
Computed tomography showed a focal, structural lesion of the brain in 40 patients (34% (95% confidence interval 25% to 42%)). In 20 patients (17% (10% to 24%)) an important therapeutic intervention resulted. The presence of a focal neurological deficit had a sensitivity of 50% and a specificity of 89% in predicting focal lesions on computed tomography. Answering "yes" to fewer than two CAGE questions had a sensitivity of 90% and specificity of 44% in identifying patients with focal computed tomography lesions. Focal lesions were not detected on computed tomography in any of the 35 patients (0% (0% to 10%)) who showed no focal neurological symptoms and answered "yes" to two or more CAGE questions.
Conclusions:
The diagnostic yield of computed tomography of the brain in adults after a first generalised seizure is high. Combined with the clinical examination, the CAGE questionnaire can reliably identify patients with uncomplicated seizures related to withdrawal from alcohol, in whom computed tomography may not be absolutely necessary.