[Postmortem increase in the galvanic threshold].

Abstract

The investigations of Joachim and Feldmann (1980) on the postmortem rise of muscular threshold were examined on a random sample of 20 bodies with known time of death. Muscular reaction on excitation was objectified using a sensitive force transducer pricked into the muscle (mostly thenar). The muscle was excitated (each half on hour) using rectangular impulses of 1 sec. duration with a current intensity which causes a muscular contraction of 2.5 mN until a current intensity of 80 mA doesn't reach this force any more. Ln of muscular threshold and time since death show a strong linear relationship (r = 0.965). Time since death was extrapolated with mean values for slope and intercept (calculated from the random sample) for all measured values of muscular threshold. Extrapolation from a single value with mean values also for the slope reveals a much more precise estimation of the time since death than extrapolation with an individual slope (according to Joachim) which requires repeated measurements of muscular threshold in an interval of 30 minutes. The procedure was examined at a random sample of 8 cases. The real time since death war always within the 95% limits of confidence of the calculated time since death.