Highlights
- •Transient loss of consciousness has a diverse etiology including syncope, orthostatic hypotension, seizures, psychogenic non-epileptic seizures.
- •Serum lactate can be a valuable tool to differentiate generalized tonic-clonic seizures from other forms of transient loss of consciousness.
- •In our study, we found no difference in serum lactate levels in patients with non- generalized tonic-clonic seizure types of transient loss of consciousness, such as syncope, and psychogenic non-epileptic seizures.
- •Serum lactate levels in patients with generalized tonic-clonic seizures were significantly higher than any other cause of transient loss of consciousness, including syncope.
Abstract
Introduction: Differentiating epileptic seizures from other causes of Transient Loss
of Consciousness (TLOC) remains a challenge in the Emergency Department (ED), where
it may lead to erroneous administration of anti-epileptic drugs. Although video electroencephalography
(EEG) is the gold standard for diagnosing epileptic seizures, it is not widely available
in ED settings. Therefore, simple and quick diagnostic techniques for patients with
TLOC in ED are needed. We performed a meta-analysis to review relevant literature
and determine the efficacy of serum lactate in differentiating epileptic seizures
from other causes of TLOC in the ED setting.
Methods: We performed a literature search of PubMed and Scopus from inception up to
April 2022. Randomized trials and observational (prospective or retrospective) studies
reporting lactate levels in adults ≤ 3 h after a TLOC episode were included. The primary
outcome of interest was the serum lactate level difference between patients with a
generalized tonic-clonic seizures (GTCS) and those with other forms of TLOC. Other
outcomes were the differences in serum lactate levels among patients with other types
of TLOC, such as psychogenic nonepileptic seizures (PNES), syncope, and non-GTCS.
Random-effects meta-analysis was performed to compare the mean difference in serum
lactate levels among different types of TLOC. The PROSPERO registration is CRD42022316163.
Results: We included eight studies (1348 patients) in our analysis. Serum lactate
levels from patients who had GTCS were significantly higher than those from patients
who had TLOC from any other cause (mean difference 5.27 mmol/L, 95% CI 1.73, 8.81, P = 0.004).
Similarly, there was statistically a significant difference in serum lactate between
patients with GTCS and non-GTCS (2.96 mmol/L, 95% CI 1.68, 4.24, P = 0.001), and patients
with GTCS and syncope (4.29 mmol/L, 95% CI 2.48, 6.10, P = 0.001). However, there
was no difference in mean lactate between syncope and PNES, and between syncope and
non-GTCS, demonstrating that the serum lactate levels between other forms of TLOC
other than GTCS were similar. A serum lactate concentration of 2.4 mmol/L provided
a good capability to differentiate between GTCS and non-GTCS, with AUROC ranging from
0.94 - 0.97.
Conclusion: Serum lactate can be a valuable tool to differentiate GTCS from other
forms of TLOC, but it is not valuable in distinguishing non-GTCS types of TLOC from
each other. However, lactate level should not be used as an absolute diagnostic tool
and should be interpreted along with proper clinical context.
Keywords
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Article info
Publication history
Published online: October 06, 2022
Accepted:
October 4,
2022
Received in revised form:
October 1,
2022
Received:
July 24,
2022
Identification
Copyright
© 2022 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.
