Ictal semiology in lateral temporal epilepsy: A systematic review and meta-analysis

We performed a systematic review of the ictal semiology of the lateral temporal lobe in focal epilepsy aiming to summarize the state-of-the-art anatomo-clinical correlations in the field and help guide interpretation of ictal semiology within the framework of pre-surgical evaluation.

After preregistration of the study protocol (PROSPERO-ID CRD42024498889), we used the PRISMA-based approach and systematically searched PubMed and EMBASE for relevant literature on the semiology of lateral temporal lobe epilepsy (TLE). A random-effects meta-analysis with the inverse variance method was used to calculate pooled estimates.

Six studies with 94 patients fulfilled our inclusion criteria. All studies also included patients with TLE confined to other neocortical temporal structures without performing analyses specifically on lateral temporal structures. The most common signs comprised oral automatisms, manual automatisms, and behavioral arrests; however, these likely do not manifest at seizure onset but during propagation. Overall, GRADE evaluation indicated very low evidence for any signs or symptoms being associated with anatomic localization. We performed a meta-analysis of the diagnostic accuracy of the presence or absence of relevant ictal signs and symptoms for differentiating seizures in lateral versus mesial TLE. The presence of auditory auras was highly specific for lateral TLE (.98 [95% CI .88-1.00]) with an overall sensitivity of .06 [95% CI .02-.22]. Lack of epigastric or olfactory/gustatory aura was associated with a high sensitivity for differentiating lateral from mesial TLE (.93 [95% CI .80-.98] and .96 [95% CI .84-.99], respectively); specificity was .38 [95% CI .26-.51] for lack of epigastric aura and .13 [95% CI .06-.25] for lack of olfactory/gustatory aura.

The six studies included in this systematic review defined the boundaries of the lateral temporal lobe quite heterogeneously and only about two-thirds of patients unambiguously had lateral temporal lobe epilepsy likely explaining the wide spectrum of ictal semiologies. Furthermore, there is often no differentiation into seizure onset versus propagation. Auditory auras represent the only specific semiology for lateral TLE, though this symptom occurs in less than every 10th patient. Comparing lateral versus mesial temporal lobe epilepsy, the presence of epigastric auras and even more so of olfactory/gustatory auras indicates mesial rather than lateral seizure onset.