Localizing value of verbal automatisms, vocal automatisms, singing, and humming: A systematic review
Vit Vsiansky, Martin Pail, Milan BrazdilAbstract
Objective
We performed a systematic review of the localizing and lateralizing value of verbal automatisms, vocal automatisms, ictal singing, and humming in focal epilepsy with the view to summarize the state‐of‐the‐art clinico‐anatomical correlations in the field and help guide interpretation of ictal semiology within the framework of presurgical evaluation.
Methods
A systematic review of the published evidence according to the Preferred Reporting Items for Systematic Review and Meta‐Analysis (PRISMA) statement was conducted. We performed a database search in PubMed and Embase with keywords vocalizations, vocal automatisms, verbal automatisms, singing, and humming combined with seizure or epilepsy. Obtained studies that met the eligibility criteria were evaluated for risk of bias in a QUADAS2‐based approach and assessed for epileptogenic zone and lateralization confidence level. Relevant data from these studies were meta‐analyzed using a random‐effects model.
Results
A total of 44 studies consisting of video‐EEG series, surgical series, case reports and case series were included in this review. Vocal automatisms were significantly more common in frontal lobe epilepsy (summary proportion = 0.41, 95% CI = 0.36–0.47) compared to temporal lobe epilepsy (0.30, 95% CI = 0.22–0.37; p = 0.019). A non‐significant trend toward a higher likelihood of vocal automatisms in left versus right‐sided epilepsy was observed (odds ratio [OR] 2.19, 95% CI 0.91–5.24, p = 0.079). For verbal automatisms, singing and humming, most of the available literature consisted of case reports indicating a possible association with temporal lobe epilepsy and right‐sided localization for verbal automatisms and an extensive network of frontal and temporal lobe structures for ictal singing and humming.
Significance
Vocal automatisms are more frequent in frontal lobe epilepsy than in temporal lobe epilepsy and nonsignificantly more frequent in left‐sided/dominant epilepsy. Verbal automatisms inconsistently localize to the temporal lobe and the nondominant hemisphere. Ictal singing and humming have limited localizing and lateralizing value due to the extensive and variable localization of the music‐specific neural network in the temporal and frontal lobes.