Transient hyperammonemia in seizures: a prospective study.

PURPOSE

To investigate the incidence and duration of transient hyperammonemia in seizures and to verify the significant confounders related to transient hyperammonemia in seizures.

METHODS

One hundred twenty-one noncirrhotic adult patients with seizures admitted to the emergency department were enrolled in the study. Laboratory examination was performed, including plasma ammonia level assessment. In addition, the basic parameters, underlying systemic diseases, and seizure-related conditions were assessed. The patients were classified into a group with hyperammonemia on arrival and a group without, in order to compare seizure-related adverse events that occurred during a 9-month period.

KEY FINDINGS

The incidence of hyperammonemia in patients with seizures was 67.77%. Plasma ammonia levels in patients with generalized tonic-clonic (GTC) seizures were significantly higher than those in patients in the non-GTC seizure group (median 174.5 vs. 47 μg/dl; proportion 76.5% vs. 21.1%; p < 0.001). Median plasma ammonia levels decreased spontaneously from 250 to 54 μg/dl (p < 0.00001) in an average interval of 466.79 min. GTC seizures (p < 0.0001), male gender (p < 0.0001), bicarbonate (p < 0.0001), diabetes (p = 0.0139), and alcohol-related seizures (p = 0.0002) were significant factors associated with hyperammonemia on arrival. No significant differences related to admission rates or mortalities were found between the two groups.

SIGNIFICANCE

The presence of transient hyperammonemia in patients with seizures is significantly related to GTC seizures, male gender, bicarbonate, diabetes, and alcohol-related seizures. The appropriate period to study ammonia levels following a seizure event is within 8 h. Because these phenomena are self-limited, ammonia-lowering management are not necessary. Hyperammonemia on arrival is not necessarily related to adverse outcomes.