Serum Lactate–Based Stratification for Seizure Diagnosis in Resource-Limited Neurologic Emergency Settings

Background Epileptic seizures (SZ) and postictal neurological deficits are common stroke mimics that challenge acute clinical decision-making, especially in emergency settings with limited diagnostic resources. MRI or EEG is often unavailable at initial presentation. We aimed to determine whether routinely available serum lactate levels could distinguish SZ from stroke based on information accessible immediately on hospital arrival.

We retrospectively reviewed 22,430 consecutive emergency department visits and analyzed 637 patients transferred by ambulance with suspected neurologic emergencies identified via keyword screening at the regional emergency call center. All patients underwent venous blood gas analysis and non-contrast CT on arrival. We evaluated whether serum lactate and other routine laboratory variables (pH, actual base excess, glucose, WBC count, platelet count, and PT-INR) correlated with final neurological diagnoses. Classification and Regression Tree (CART) analysis was used to identify cutoffs predictive of SZ.

Age, pH, lactate, and actual base excess were significantly associated with final diagnoses. Lactate levels were significantly higher in SZ and subarachnoid hemorrhage groups than in other groups. For distinguishing SZ from ischemic stroke (infarction and TIA), CART analysis yielded a serum lactate cutoff of 4.05 mmol/L. Among patients with lactate ≥4.05 mmol/L and age <59.5 years, SZ probability was 100%. A four-quadrant model combining lactate and age stratified SZ probabilities from 9.1% to 100%. The area under the ROC curve for lactate in distinguishing SZ from stroke was 0.800.

Serum lactate, when assessed upon emergency department arrival, may contribute significantly to differentiating seizures from acute ischemic stroke. A simple decision model using only lactate and age may aid in diagnostic stratification in neurologic emergencies—even in resource-limited settings where advanced imaging or EEG is not readily available. Registration None. Competing Interest Statement The authors have declared no competing interest. Funding Statement This work was not supported by any funding. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocol was approved by the Hachinohe City Hospital Ethics Committee (Approval No. 1601). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability Data not provided in the article may be shared (anonymized) at the request of any qualified investigator for the purposes of replicating the procedures and results. To ensure participant confidentiality, the conditions of our ethics approval do not permit public archiving of study data. Readers seeking access to the data should contact the corresponding author (S.O.).