Validation of a smartphone-based EEG among people with epilepsy: A prospective study

Erica D. McKenzie, Andrew S. P. Lim, Edward C. W. Leung, Andrew J. Cole, Alice D. Lam, Ani Eloyan, Damber K. Nirola, Lhab Tshering, Ronald Thibert, Rodrigo Zepeda Garcia, Esther Bui, Sonam Deki, Liesly Lee, Sarah J. Clark, Joseph M. Cohen, Jo Mantia, Kate T. Brizzi, Tali R. Sorets, Sarah Wahlster, Mia Borzello, Arkadiusz Stopczynski, Sydney S. Cash, Farrah J. Mateen

Our objective was to assess the ability of a smartphone-based electroencephalography (EEG) application, the Smartphone Brain Scanner-2 (SBS2), to detect epileptiform abnormalities compared to standard clinical EEG. The SBS2 system consists of an Android tablet wirelessly connected to a 14-electrode EasyCap headset (cost ~ 300 USD). SBS2 and standard EEG were performed in people with suspected epilepsy in Bhutan (2014-2015), and recordings were interpreted by neurologists. Among 205 participants (54% female, median age 24 years), epileptiform discharges were detected on 14% of SBS2 and 25% of standard EEGs. The SBS2 had 39.2% sensitivity (95% confidence interval (CI) 25.8%, 53.9%) and 94.8% specificity (95% CI 90.0%, 97.7%) for epileptiform discharges with positive and negative predictive values of 0.71 (95% CI 0.51, 0.87) and 0.82 (95% CI 0.76, 0.89) respectively. 31% of focal and 82% of generalized abnormalities were identified on SBS2 recordings. Cohen's kappa (κ) for the SBS2 EEG and standard EEG for the epileptiform versus non-epileptiform outcome was κ = 0.40 (95% CI 0.25, 0.55). No safety or tolerability concerns were reported. Despite limitations in sensitivity, the SBS2 may become a viable supportive test for the capture of epileptiform abnormalities, and extend EEG access to new, especially resource-limited, populations at a reduced cost.