A spokesperson for the BSO told the Globe that Lieberson's back injury, which caused her to cancel a series of performances earlier this year, had "flare[d] up."
Lieberson's injury was first reported publicly when she canceled a performance of Mahler's Das Lied von der Erde at Carnegie Hall in January 2005. She later canceled a recital tour, a scheduled appearance in the world premiere of John Adams' Doctor Atomic, and other events. But she appeared in the world premiere of her husband Peter Lieberson's Neruda Songs in Los Angeles in May and in the same work in Boston, New York, and Cleveland in November and December.
When she canceled two Carnegie Hall performances in December 2005 and January 2006, a press release explained that she had been advised to "reduce her performing schedule in order to allow her back to heal and build her strength."
Lieberson is still scheduled to appear with the BSO in Schoenberg's Gurrelieder in February, on tour in March, and at Tanglewood in summer 2006, according to the Globe.
Performances of Missa Solemnis run January 19-21 at Symphony Hall. In addition to Grove, they will feature soprano Deborah Voigt, tenor Ben Heppner, and bass Ren_ Pape. BSO music director James Levine is the conductor.