The Leibniz-Institute of Atmospheric Physics operates medium frequency (MF) radars for more than one solar cycle to monitor the middle atmosphere at polar and mid-latitude regions. MF-radars allow continuous observations of this atmospheric region by partial reflections due to the presence of sufficient electron density and its fluctuations for the given radar frequency. The actual altitude coverage generally depends on the current state of the atmosphere controlled by the sun, dynamics as well as high natural variability of the mesosphere like e.g. particle precipitation events. At times, the latter are exceptionally frequent in the polar latitudes, partially reaching up to 50 percent occurrence rate with the tendency of appearing in single or multiple distinct layers. We will present examples of such layered mesospheric perturbation events observed with MF radars, their influence to the measurements and further analysis results. Furthermore we will present the statistical analysis of these events for the mentioned period and their relationship to other radar phenomena.