2025 American Academy of Neurology Abstract Website

Objective:

This pilot study aimed to investigate the prevalence of grapheme-color synesthesia (GCS) in patients with epilepsy and to characterize the epilepsy features associated with GCS experiences.

Background:

Synesthesia is a condition in which the stimulation of one sensory modality triggers unusual experiences in a second sensory modality such as colors or shapes. Synesthesia has been linked to specific neurological disorders such as migraine and autism spectrum disorder, although the mechanisms underlying synesthesia remain largely unclear.

Design/Methods:

Forty patients with epilepsy were recruited during their clinic encounter. Participants were first asked whether they reported experiences suggesting GCS. Those reporting GCS underwent a standard online consistency and congruency battery test (http://www.synesthete.org). Epilepsy features, electroencephalogram (EEG) findings, and magnetic resonance imaging (MRI) findings were collected and analyzed.

Results:

Of the 40 study participants (mean age was 49.9 years old; 52.5% females), 21 reported GCS experiences and 3 (7.5%) resulted synesthetes from the battery test. Analysis of the test results showed that participants with focal seizures had lower consistency scores (median score 1.2) and higher congruency scores (median score 76.4) compared to patients with generalized-onset seizures (median scores 2.9 and 51.4 respectively; p=0.006, p=0.001). Participants with non-motor seizures had lower consistency scores (median score 1.1) and higher congruency scores (median score 79.2) compared to patients with motor seizures (median scores 2.8 and 52.8, respectively; p=0.011, p=0.036).

Conclusions:

GCS may be more prevalent in patients with epilepsy than the general population. Focal and non-motor seizures may be associated with predisposition to GCS. Further larger scale studies are needed to confirm and expand on these observations.