Methods, complications and chemical paradigms for intra-aural tick removal (otoacariasis) – a systematic review of evidence and regional protocol for the Western Himalayan region

Abstract

Human otoacariasis is the infestation of the external auditory canal (EAC) by ticks which presents an acute otological emergency common to agricultural zones like Himachal Pradesh. Historical clinical custom relies on topically instilling local anaesthetics (lignocaine) before mechanical extraction. However, international laboratory data challenges this technique's biological efficacy. The objective of the study was to systematically review extraction methods, clinical profiles, and chemical reagent efficacies in human otoacariasis, proposing a validated protocol that reconciles traditional Indian practices with controlled experimental data. A systematic literature search of PubMed, Embase, Scopus, and the Cochrane library was conducted following PRISMA 2020 guidelines. Eligible papers focused on human intra-aural tick extraction within India or laboratory data directly evaluating chemical agent timelines on ear canal ticks. Data from pooled regional clinical cohorts (over 230 consolidated cases) show that blind mechanical extraction without chemical assistance increases the risk of tympanic membrane (TM) perforation and retained mouthparts. Experimental literature reveals that 4% lidocaine fails to kill or detach ticks (100% survival after 20 minutes). Instead, acetone achieves rapid acaricidal inactivation (mean nymph death: 185.1 seconds) but presents risks of ototoxicity if the eardrum is perforated. The perceived clinical utility of lignocaine drops stems from numbing the sensitive human ear canal rather than direct effects on the tick. For areas with limited resources like rural Himachal Pradesh, a two-tiered clinical protocol using safe chemical agents followed by microscopic or endoscope-assisted removal is recommended.