Sunnaas is the country's largest specialized hospital in physical medicine and rehabilitation.

During the polio epidemic, with its culmination in 1951, young patients needed long treatment and rehabilitation, Sunnaas was asked to receive as many of them as his institution's capacity permitted.

Sunnaas employing an experienced neurologist Nils Sponheim who thus was the first head medical doctor.

Over the following 20 years, Sponheim and a staff of doctors and physiotherapists made the hospital the country's foremost rehabilitation centre.

Oslo municipality took over ownership as a gift from the Sunnaas couple in 1979, but the city authorities wanted the state to take over the financial responsibility for the hospital.