Abstract

Objectives

Anion gap (AG) and serum bicarbonate concentration (BICARB) may help confirm a diagnosis of seizure in an unwitnessed collapse; however, little data exist to support this practice. Our objective was to assess the association between AG metabolic acidosis and generalized seizure and to derive a simple score to predict seizure.

Methods

This was a case-control study at an urban teaching hospital. Patients transported to our emergency department with witnessed loss of consciousness and final confirmed diagnoses of generalized seizure (cases) or syncope (controls) were eligible for enrollment. Multivariable logistic regression analysis was used to model associations between AG, BICARB, and seizure.

Results

In 49 cases and 40 controls, patients in the seizure group were more likely to have a lower median BICARB (17 [range, 14-34] vs 23 [range, 20-24], P < .0001) and a higher median AG (22 [range, 9-42] vs 13 [range, 7-21], P < .0001). The Denver Seizure Score was defined, using regression coefficient weighting, as the Δ BICARB plus twice the Δ AG [(24 − BICARB) + (2×(AG − 12))]. The score ranged from −16 to +74 and identified patients as low likelihood (score <0), moderate likelihood (score 0-20), or high likelihood (score >20), with 21% (95% confidence interval [CI], 5%-51%), 40% (95% CI, 26%-56%), and 96% (95% CI, 82%-100%) being categorized as seizure, respectively.

Conclusions

Anion gap metabolic acidosis is associated with generalized seizure. A Denver Seizure Score greater than 20 predicts generalized seizure in the emergency department and may be useful for differentiating patients with unwitnessed loss of consciousness.