Gruessner was born in 1957 in Mainz, Germany and completed medical school at the Johannes Gutenberg University (The University of Mainz) and  he was awarded summa cum laude for his doctoral thesis.
Gruessner was born in 1957 in Mainz, Germany and completed medical school at the Johannes Gutenberg University. The University of Mainz (full name Johannes Gutenberg University Mainz) (German: Johannes Gutenberg-Universitat Mainz) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. In 1983, he was awarded "summa cum laude" for his doctoral thesis. 
