Leon Fleisher, the brilliant American pianist who was in his 30s when fingers in his right hand suddenly stopped working — a fateful twist that cut short his playing career — and for three decades was one of the great enigmas of the classical-music world, died Aug. 2 at a hospice care center in Baltimore. He was 92.

The cause was cancer, said his son Julian Fleisher, a singer-songwriter and producer.

Mr. Fleisher’s mysterious hand malady — eventually diagnosed as a neurological disorder called focal dystonia — was a dramatic and harrowing turn of events for a onetime child prodigy who had spent his 20s on the post-World War II vanguard of young American pianists.

At 24, Mr. Fleisher became the first American to win the piano competition established by Queen Elisabeth of Belgium, one of the world’s premier musical contests. That victory launched a major new phase of his career. He performed in leading concert halls and became the preferred soloist of George Szell, the formidable conductor of the Cleveland Orchestra. His recordings with Szell remain benchmarks for their clarity, precision and sheer expressive musicality; Brahms’s first piano concerto was a touchstone.

At that pinnacle, Mr. Fleisher began noticing trouble that led to a cramping in the fourth and fifth fingers of his right hand. Redoubling his practice efforts only worsened the problem. On the eve of a historic tour of the Soviet Union with Szell and the Cleveland Orchestra in 1965, Mr. Fleisher realized that he wasn’t able to play at the required level. He canceled the tour and his other upcoming concerts.

The abrupt loss of movement sent him reeling, triggering a depression and a desperate quest to identify and cure what ailed him. “I tried everything from acupuncture to Zen Buddhism,” he later said.

He only gradually surmounted his malaise through a career metamorphosis. He learned the surprisingly large repertory for left-hand piano — and he staged the first of his halting comebacks in 1982 after regaining some use of his right hand. He remained, in critical estimation, a pianist of sublime musical intelligence whether playing with one hand or two. But he also gained renown off the stage as a conductor and an influential teacher.

His work with the baton led him to explore musical pathways he never would have followed as a pianist. As co-founder in 1968 of the Theater Chamber Players in Washington, long the resident chamber ensemble at the Kennedy Center, he performed contemporary chamber music; as music director of the Annapolis Symphony Orchestra and then associate conductor of the Baltimore Symphony Orchestra, he learned a wide range of orchestral classics.

His group master classes at the Peabody Institute of Johns Hopkins University in Baltimore, coupled with a stint at the Curtis Institute in Philadelphia, produced several generations of leading pianists, including André Watts, Yefim Bronfman and Jonathan Biss. Mr. Fleisher said his physical limitations forced him to think more profoundly about music, to put into words the technique and nuance that before had been instinctive. “Prior to my problems,” he once said, “I would sit down and play to show my students what to do.”

In the classical-music world, he became regarded as a guru, known for his ability to untangle pianistic problems, for his inspiration, and for a series of adages including “Practice less, think more.”

“One of the problems with young musicians today,” he said in his 2010 memoir, “My Nine Lives,” “is that they come in with such a sense of high seriousness. The idea of how great this music is tends to fill them with awe. But so much of what we do is about these guys just having fun. That earthiness is a very important part of life.”

Leon Fleisher was born in San Francisco on July 23, 1928, the second son of Jewish immigrants from Eastern Europe. His father, Isidor, was a milliner. His mother, the former Bertha Mittelman, had great ambitions for her children and insisted on piano lessons for her oldest son, Raymond.

Leon listened in to the lessons, sat down and played them more skillfully than his brother and was soon recognized by his first teachers as a major talent.

When he outstripped the teaching abilities of his early mentors, his mother and former San Francisco Symphony music director Alfred Hertz decided he should study with the eminent pianist Artur Schnabel. Schnabel didn’t work with children — he did not want to waste time on basics — but 9-year-old Leon was slipped into a dinner party at the Hertzes’ home and presented for a de facto audition. On the spot, Schnabel made an exception to his policy and admitted him to his class at Lake Como in Italy.

Mr. Fleisher’s mother accompanied her son across the Atlantic, then found them a place to live in Manhattan when Schnabel decided to leave for New York amid the approaching world war in Europe. In 1944, 16-year-old Leon made a rousing solo debut at Carnegie Hall with the New York Philharmonic, and guest conductor Pierre Monteux dubbed him the “pianistic find of the century.”

New York Times music critic Noel Straus, marveling at the pianist’s delicate power and the seeming ease of his mastery of an onerous Brahms concerto, called him “one of the most remarkably gifted of the younger generation of American keyboard artists.”

Like Schnabel, Mr. Fleisher became a major exponent of the German and Viennese classics, although as he aged he strayed into territory that his teacher eschewed or downright ignored, from French composers to, worst of all, Rachmaninoff, whose emotion and pyrotechnics Schnabel disdained.

So pervasive was Schnabel’s influence that Mr. Fleisher grew somewhat dependent on it. Needing to set off on his own path, he spent a period drifting in his teen years before ending up in Paris to begin forging his own identity as an artist. In 1951, he married Dorothy Druzinsky, known as Dot, who came from a noted family of harpists.

The next year, still living in Paris, Mr. Fleisher was encouraged to take part in the Queen Elisabeth of Belgium International Music Competition, and he impressed a lineup of judges that included pianist Arthur Rubinstein.

Despite his flourishing career, with Szell among others, Mr. Fleisher learned that he was technically unemployed when he was turned down for a credit card at a major department store. He addressed this failing by taking up his job at Peabody in 1959. Three years later, he divorced Dot and married Risselle Rosenthal, a young Baltimorean known as Rikki.

Mr. Fleisher was at the height of his career when he began noticing difficulties with his right hand. “It began as a sense of laziness in my right index finger, a slight sluggishness in its response when I wanted to play a trill,” he wrote in “Nine Lives.” “It continued as a growing sense of clumsiness and a feeling that my fingers weren’t doing what I wanted them to do. . . . I had probably been overworking my hand for years, ever since I started stepping up my practicing in the wake of the Queen Elisabeth Competition.”

Increasingly desolate, he leaned heavily on his second wife for emotional support. He also grew a beard and pony tail. “I was too chicken to buy a Harley,” he later quipped to a reporter, “so I bought a Vespa.”

As he struggled to find direction, Mr. Fleisher threw himself into teaching and conducting as well as learning the repertory for left-hand piano — most famously Ravel’s Concerto for the Left Hand, as well as other works written for the pianist Paul Wittgenstein, whose right arm was amputated after a combat injury in World War I. But he always blamed the stress surrounding his hand problems for the end of his second marriage.

Several new chapters in his life seemed to be opening by the early 1980s. He met and married Katherine Jacobson, who had been one of his Peabody students, and his hand seemed to improve through surgery for carpal-tunnel syndrome and other regimens. He decided he was ready for a full-fledged comeback, which he scheduled with the Baltimore Symphony Orchestra when it opened its new Meyerhoff Hall in 1982.

The event was televised live and made news across the country. But as he prepared for the event, Mr. Fleisher was forced to realize that his hand wasn’t where it needed to be. He managed to get through the evening, but his dream of a true rebound seemed over.

He later quipped that it was “an evening of pretense.”

In 1984, he became the artistic director of the Tanglewood Music Center, the training academy for gifted musicians held at the summer home of the Boston Symphony Orchestra. He held the position for 13 years, until he resigned amid a rift between BSO music director Seiji Ozawa and a number of the center’s administrators.

Meanwhile, in 1991, Mr. Fleisher had his first Botox shot in another attempt to cure his hand. He saw some improvement from this treatment and from a massage technique called Rolfing that is designed to release stress stored in the body’s connective tissues.

By the mid-1990s, he was cautiously attempting a few two-handed performances — first with his own chamber ensemble and, in 1995, with the Cleveland Orchestra. His 2004 recording “Two Hands,” which moves gradually into pieces of extraordinary complexity, was enthusiastically received, and he continued to play concerts all over the world.

Besides his wife, survivors include three children from his first marriage, Deborah, Richard and Leah; two children from his second marriage, Paula and Julian; and two grandchildren.

Mr. Fleisher was the subject of Nathaniel Kahn’s Oscar-nominated documentary short “Two Hands” (2006). His awards and honors included the Kennedy Center Honors in 2007. Uncertain about accepting the honor under a political administration he did not support, he wrote an open letter to The Washington Post, protesting the Bush White House’s policies regarding the Iraq War, torture of prisoners and other decisions that he said amounted to a “systematic shredding of our nation’s Constitution [that] have left us weak and shamed at home and in the world.”

The letter, which detailed his inner struggle about whether to accept the honor, stirred a certain amount of controversy, but made him even more of a hero in the eyes of many of his younger students.

“I am nearly 80 years old,” he wrote, “and have been making music for almost all of that time, sustained by the belief that, in the words that Beethoven inscribed in his copy of the ‘Missa Solemnis,’ the purpose of music is to communicate from the heart to the heart. Beethoven’s vision of music as a force capable of reconciling us to each other and to the world may today seem remote, but that renders it an ever more crucial ideal for which to strive.”

Midgette, a former Washington Post classical music critic, co-wrote Leon Fleisher’s 2010 memoir, “My Nine Lives.”