In his more than 50 years in research, Dr. Mark Hallett increased scientists’ understanding of how the brain controls movement and worked on a litany of high-profile projects, including a study of the mysterious Havana Syndrome and the use of Botox to help a renowned pianist recover use of his right hand.

Hallett, of Bethesda, died on Nov. 2 of glioblastoma, a form of brain cancer. He was 82.

His wife of 59 years, Judith Hallett, shouldered her own heavy load as a scholar, teaching and publishing as a Latin language and literature professor at the University of Maryland at College Park.

Friends, she said, would remark on her accomplishments. “Compared to my husband,” she would respond, “I’m in a coma.”

Mark Hallett’s work, primarily with the National Institutes of Health in Bethesda, continued until his retirement in December 2022.

He was born on Oct. 22, 1943, in Philadelphia. He graduated from Harvard College and Harvard Medical School, and began work at the NIH in 1970. His career took him and Judith to Massachusetts and England.

The Halletts — parents to Nicholas and Victoria — returned to Bethesda in 1984, where he established what’s now the National Institute of Neurological Disorders and Stroke at NIH. Mark mentored many younger medical professionals from around the world in Bethesda, where some found community and their romantic partners, Judith said.

“He was unusually collaborative and extremely generous and very protective of these people who were his colleagues because he wanted to make sure that their work was given credit and that he could help them move wherever they wanted to professionally,” Judith said.

Fixing Leon Fleisher’s hand

One of Mark Hallett’s most notable medical cases was his work with the preeminent classical pianist, Leon Fleisher. The musician lost the use of his right hand in 1964 because of focal dystonia, a neurological condition characterized by symptoms such as muscle spasms.

Fleisher continued performing a repertoire of songs with his left hand, and tried several alternative therapies, including acupuncture and Rolfing, said Julian Fleisher, the pianist’s son. But he could still not use his right hand fully.

Fleisher continued performing a repertoire of songs with his left hand and became a music director of the Annapolis Symphony Orchestra and associate conductor of the Baltimore Symphony Orchestra.

In the early 1990s, Fleisher’s doctors at Johns Hopkins referred him to Hallett, who was experimenting with therapeutic uses for botulinum toxin, better known as Botox.

“The prospect of his being able to return to the repertoire that made him the figure that he was was pretty exciting,” Julian said. “It was also fraught and often tense, but I think overall his work with Dr. Hallett opened the door to a new era in my family’s life which was very exciting and very meaningful.”

Leon Fleisher regained use of his right hand following Hallett’s Botox treatment and was able to play a selection of arrangements, Julian said, until his death in Baltimore in 2020.

While Mark Hallett’s work with Fleisher was one of his more publicized cases of a musician seeking a neurological consult, his son Nicholas Hallett has heard from his father’s peers and collaborators about the breadth of his medical inquiry.

“It was amazing to have a dad who on the surface, his career was a neurologist but he also seemed to be a super sleuth,” Nicholas said about Mark’s under-lock-and-key research with federal agencies including the CIA and FBI.

Nicholas Hallett became a vocalist and artist, and now teaches music in New York City. He said his busy father always made time for family, and remembers how his parents fostered his love for the arts by sending him to theatrical and musical camps. He said his father set an example, for his children and many others, by living a purposeful life.

“At an early age, it was clear he would be a tough act to follow,” Nicholas said. “He proved to be an incredible role model for me; someone who always encouraged me to do my best but someone for whom I always wanted to do my best.”