Localizing value of ictal hypersalivation/sialorrhea and ictal spitting: A systematic review

Abstract

Objective: We performed a systematic review on the localizing value of ictal hypersalivation and ictal spitting in focal epilepsy with the aim of summarizing the state-of-the-art anatomo-clinical correlations in the field and aiding the interpretation of ictal semiology within the framework of pre-surgical evaluation.

Methods: We conducted a review and meta-analysis of the published evidence and reported the results according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. We searched in PubMed for relevant articles using the following key words: (hyper)salivation, sialorrhea, drooling, spitting, insular, opercular, epilepsy, seizure, ictal, EEG, and surgery. We evaluated the risk of bias and the diagnostic accuracy quality of each publication using the Quality of Diagnostic Accuracy Studies (QUADAS)-2-adapted tool. We assessed the level of confidence (very high, high, moderate, and low) in the reported epileptogenic zone (EZ) based on the availability of findings from MRI, intracerebral EEG, and postoperative outcomes.

Results: We reviewed the full text of 65 articles that fulfilled the criteria for evidence synthesis. Thirty-two studies and 11 case reports (173 patients) on ictal hypersalivation and 15 studies and 13 case reports (54 patients) on ictal spitting were eligible. Ictal hypersalivation was reported in approximately 11% of (mesio)-temporal and approximately 23% of insular, opercular, and insulo-opercular epilepsies with >70% high-confidence cases due to seizure-free postsurgical outcomes. Ictal spitting was very rarely observed in focal epilepsies, including mesio-temporal epilepsies (incidence of 1% and 1.6%, respectively), but was significantly associated with a nondominant mesio-temporal EZ.

Significance: There is strong evidence that ictal hypersalivation is more common in insular, opercular, and insulo-opercular seizures than in temporal lobe seizures, with the mid-insula and central operculum most consistently identified as symptomatogenic zones. Ictal spitting is a rare complex motor automatism pointing to seizures originating in nondominant mesio-temporal structures.

Keywords: anatomo‐clinical correlation; epilepsy surgery; etiology: dysplasia; hypersalivation; ictal; localization: left, non‐dominant, temporal; phenomenology: ictal, hypersalivation, spitting; semiology; spitting; syndrome: mesio‐temporal; systematic review.