Application of correlation techniques in the analysis of corpus cavernosum electromyographic signals

Aim: To establish an objective, easy-to-use and comprehensive method to analyze corpus cavernosum electromyographic signals (CC-potentials). Methods: CC-potentials were recorded during flaccidity in 23 young healthy volunteers, with surface electrodes placed on the penile shaft bilaterally. Based on the correlation function of Matlab software, an application program for the analysis of CC-potentials was developed. Individual CC-potentials and their autocorrelation function were evaluated, yielding parameters amplitude (A), duration (D), and dominant frequency (DF). The cross-correlation function of both longitudinal and bilateral pairs of adjacent electrodes was calculated to assess the similarity and mutual delay of CC-potentials recorded simultaneously from different parts of the CC. The parameters derived were squared maximum cross-correlation coefficient (Rmax) and delay (τ). Based on the absolute value of τ and the corresponding inter-electrode distance, propagation velocity (PV) was calculated. Results: The values of the parameters were determined automatically. No significant difference related to the locations of the electrodes for parameters A, D, and DF was detected. The cross-correlation showed that both longitudinal and bilateral CC-potential pairs had highly similar waveforms (the absolute values of Rmax were 0.80 ± 0.05 and 0.87 ± 0.06, respectively). PV of longitudinal pairs was estimated as 6.15 ± 3.98 cm/s. Conclusion: The application program for correlation analysis of CC-potentials is a comprehensive and versatile method to analyze corpus cavernosum electromyographic recordings. Its objectiveness makes multi-center application possible.