Harvard Medical School professor emeritus C. Miller Fisher, whose commitment to clinical observation revolutionized the study of stroke while helping to raise a new generation of neurologists at Massachusetts General Hospital, died April 14 in Albany, New York. He was 98 years old.

Fisher’s death was confirmed by his daughter, Elizabeth Fisher ’63, on Tuesday, who said that her father died of the cumulative effects of old age.

“Arguably in the 20th century, he’s the finest physician that ever lived, both as a brilliant clinician, as a caregiver to his patients, and as an outstanding academician,” said neurology professor J. Phillip Kistler ’60, who worked closely with Fisher at MGH.

Beginning in the early 1950s, a string of successful research earned Fisher a reputation as the father of cardiovascular diagnosis and treatment. First at Montreal Memorial Hospital and then at MGH, Fisher studied and described the pathological details of each of the sub-types of ischemic stroke, building up an unprecedented body of knowledge.

“Over the course of 50 years, many of the essential thoughts and names given to the conditions of strokes came from his hand,” neurology professor Joseph B. Martin said.

Among his now-foundational findings, Fisher identified and named transient ischemic attacks—pre-stroke warning signs used to diagnose a stroke victim—and closely studied the links between strokes and arterial blockage, which allowed doctors to prevent subsequent strokes in patients.

“[His work has] allowed physicians to make sense of the causes of all varieties of stroke and neurological disease,” Kistler said, information that was not available before Fisher’s research.

Charles Miller Fisher was born Dec. 5, 1913 in Waterloo, Ontario. He graduated from the University of Toronto Medical School before serving as a surgical lieutenant in the British Royal and Canadian Navies. His ship, the HMS Voltaire, was sunk off the coast of Cape Verde in 1941, and Fisher was held in a Nazi prison camp for the next three and a half years.

After the war, Fisher returned to Canada and then to Boston and MGH, where he ultimately spent more than 50 years serving as both a teacher and clinician.

Fisher’s tireless curiosity and the long hours that he worked at MGH were legendary, former colleagues said. Dropped off by his wife around mid-morning each day, he often remained at the hospital well after midnight talking with students or observing stroke patients.

“He had an infinite sense of what it took, what it meant to understand, to learn,” said neurology professor Verne S. Caviness, who was a resident under Fisher. “He always said if you were to spend 48 hours at the bedside...you would see all of neurology flow before you.”

Fisher’s careful study, along with the work of MGH neurologist Raymond B. Adams, gave rise to a new, modern generation of neurological study.

“Not only did he create a legacy of his own work, but he created a whole generation of people who went on to do their own,” said Jay P. Mohr, one of Fisher’s former students.

Fisher’s awards were numerous and his reputation far-reaching. He received the Royal College of Physicians of Canada’s Prize in Medicine in 1952 and was inducted to the Canadian Medical Hall of Fame in 1998. Many conditions and tests bearing his name can be found in the field of neurology—a testament to the breadth of his impact.

Former colleagues remembered Fisher as a dedicated seeker of truth, loath of the “simple” answer, who gave his life to his patients and his work, sometimes at the expense of his personal life, but always with a sense of humor.

A dogged writer, Fisher was at work on the sixth volume of his memoirs when he died, friends said. In an essay in the journal Stroke in 2001, Fisher reflected on his prodigious run as a teacher and clinician.

“Is it a matter of striving? Not really, for in retrospect it seems to have been effortless,” Fisher wrote. “If there is a dictum, it would be that it is all a matter of being in the right place, at the right time, with the right mentor.”

Fisher was preceded in death by his wife of 68 years, Doris M. Fisher. He is also survived by two sons and a daughter.

A memorial service will be held at 11 a.m. on May 12 at the Winchester Unitarian Society.

—Staff writer Nicholas P. Fandos can be reached at nicholasfandos@college.harvard.edu.