Digital conversion of paper electroencephalograms using a hand scanner.

We report a method of quantifying the analog signal of paper-recorded EEGs that involves readily available technology, including a standard personal computer and a compatible hand scanner. Simulations assessed the effects of erroneously scanning the paper at a slight angle and estimating pen arc distortion; these effects were demonstrated to be insignificant. The method allows application of several quantitative techniques, including power spectral analysis and determination of the squared coherence between homologous regions. In a companion study, we applied this technique to compare the coherence in patients with alpha pattern coma to coherence in normal subjects.