Using McGurk effect to detect speech-perceptional abnormalities in refractory epilepsy

•Mc Gurk effect is an interaction between hearing and vision in speech perception.•It is the combined effect of the auditory and visual components of two sounds.•Chronic epilepsy affects the audiovisual integration during speech perception.•Mc Gurk effect can detect early subtle abnormalities in speech perception.•Mc Gurk effect can help detecting speech defects in chronic epilepsy patients. McGurk effect is a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. A wide range of neuropsychological deficits have been described in people with long-standing epilepsy, which affect multimodal integration in speech perception and hence refractory epilepsy patients are ideal for testing the McGurk effect. We studied the McGurk effect in 50 patients diagnosed with medically refractory left or right hemispheric epilepsy based on clinical, radiological, and electrophysiological data. The McGurk effect was better perceived (p = 0.006) in patients with left hemispheric epilepsy (n = 12, 71%) compared to right (n = 5, 29%). The other factors which compromised the perception of the McGurk effect were impairments in visual memory (p = 0.041), facial emotion recognition (p = 0.001), and lip-reading (p = 0.006). Perception of the McGurk effect reduced significantly (p = 0.006) when the epilepsy duration was 10 years or beyond. The McGurk effect can be used in refractory epilepsy patients, to detect subtle abnormalities in speech perception, before significant irreversible speech and language dysfunction become evident.