Value of tongue biting in the differential diagnosis between epileptic seizures and syncope

Background: Tongue biting (TB) may occur both in epileptic seizures and in syncope. A comprehensive search of the literature to determine the accuracy of this physical finding and its prevalence in epileptic seizures and syncope is still lacking.

Aims: To undertake a systematic review and a meta-analysis of studies evaluating the prevalence of TB in patients with epileptic seizures and syncope, and to determine sensitivity, specificity and likelihood ratios (LR) of this physical finding.

Method: Studies comparing the prevalence of TB in epileptic seizures and syncope were systematically searched. Prevalence of TB was analyzed calculating odds ratio (OR) with 95% confidence intervals (CIs). Sensitivity, specificity, positive and negative likelihood ratio (pLR, nLR) of TB were determined for each study and for the pooled results.

Results: Two studies (75 epilepsy patients and 98 subjects with syncope) were included. There was a significantly higher prevalence of TB in patients with epileptic seizures (OR 12.26; 95% CI 3.99-37.69). Pooled accuracy measures of TB for the diagnosis of epileptic seizures were: sensitivity 33%, specificity 96%, pLR 8.167 (95% CI 2.969-22.461) and nLR 0.695 (95% CI 0.589-0.82).

Conclusions: A pooled analysis of data from the literature shows that TB has great value in the differential diagnosis between epileptic seizures and syncope. Given a certain pre-test probability of seizures, the presence of TB greatly increases the chance that the patient had an epileptic seizure. Systematic reviews with pooled analyses (meta-analyses) of data from the literature allow an increase in statistical power and an improvement in precision, representing a useful tool to determine the accuracy of a certain physical finding in the differential diagnosis between seizures and other paroxysmal events.