Among his numerous achievements, which included more than 240 published papers and five books and four others he co-authored, he studied and named Lennox-Gastaut Syndrome, a form of epilepsy that he named for the two doctors who had discovered it in 1968.

His last published piece, "Alzheimer Dementia: An Overview and a Promising New Concept," was co-authored with Janet O. Ghigo and published last year in the American Journal of Electroneurodiagnostic Technology.

His monumental contribution to the field, "Electroencephalography," was first published in 1982 and went through five editions, the last under his direction being published in 2005. The sixth edition, which was edited by Dr. Donald Schomer, is now titled "Niedermeyer's Electroencephalography."

Mr. Mitchell, who at the time was an editor at Lippincott Williams & Wilkens, now part of Wolters Kluwer, a Dutch publishing and multimedia conglomerate at Camden Yards, worked closely with Dr. Niedermeyer on several editions of "Electroencephalogy."

"He was a fascinating fellow. I loved two things in particular about him: his Renaissance mind that had command of so much about so many things, and his life story," said Mr. Mitchell.

"He could converse in detail not only about medicine, science and the brain, the crux of our association, but his mind also ranged in depth across the American Civil War, Mozart's operas and the batting prowess of Oriole players."

Dr. Niedermeyer, who had lived for many years on Colonial Court in Towson before moving to the Pickersgill retirement community in 2010, was a talented classical pianist, who enjoyed attending concerts of the Baltimore Symphony Orchestra and the Metropolitan Opera in New York.

He was an avid hiker and mountaineer and during his lifetime had climbed 144 mountains. He continued walking a mile a day into his 10th decade.

Dr. Niedermeyer was an active communicant of Immaculate Conception Roman Catholic Church, Baltimore and Ware avenues, Towson, where a Mass of Christian burial will be offered at 10 a.m. Thursday.

In addition to his son, Dr. Niedermeyer is survived by his wife of 65 years, the former Anni Payr; three other sons, Karl Niedermeyer of Baltimore, Thomas Niedermeyer of Innsbruck, and Paul Niedermeyer of Eugene, Ore; a daughter, Ruth Andersson of Anchorage, Alaska; a brother, Hans Niedermeyer of Athens, Greece; a sister, Maria Schaetz of Krems, Austria; and six grandchildren.