BALTIMORE — Dr. John M. Freeman, a longtime Johns Hopkins University pediatric neurologist and medical ethicist who was known as an expert in pediatric epilepsy, died Jan. 3 of cardiovascular disease at Johns Hopkins Hospital in Baltimore. He was 80.

Freeman’s iconoclastic questioning of established medical practices revolutionized the treatment of pediatric epilepsy and became the hallmark of his work.

He became a forceful advocate of two long-abandoned therapies – one that required a strict, unconventional high-fat ketogenic diet known as KD, the other involving surgery to remove half of the brain of children who were tormented by unremitting epileptic seizures – which led to their revival and current acceptance as effective treatments.

“Few Hopkins physicians have had a more profound effect than John Freeman on how we treat young patients who suffer from epilepsy and congenital abnormalities – and how we address the often-difficult ethical issues surrounding these potentially heart-breaking cases,” said Ronald R. Peterson, president of the Johns Hopkins Hospital and Health System and executive vice president of Johns Hopkins Medicine.

Dr. Guy McKhann, founding head of Johns Hopkins’ Department of Neurology, explained in a Hopkins announcement of Freeman’s death that his “resurrection of KD,” which completely eliminated the epileptic seizures of many patients, was accomplished “virtually all by himself, against great skepticism and opposition.”

John Mark Freeman was born Jan. 11, 1933, in Brooklyn, N.Y. He earned a bachelor’s degree in 1954 from Amherst College, where he was an honors graduate,and went on to complete his medical studies in 1958 at the Johns Hopkins University School of Medicine.

Freeman returned to Hopkins in 1969. From 1969 to 1990, he was director of the Pediatric Neurology Service at Hopkins Hospital, and he was concurrently director of the Birth Defects Treatment Center at the East Baltimore hospital.