com·mis·sur·ot·o·my 
(kŏm′ə-sh-rŏtə-mē)
(kŏm′ə-sh-rŏtə-mē)n. pl. com·mis·sur·ot·o·mies
Surgical incision of a commissure in the body, as one made in the heart to relieve constriction of the mitral valve or one made in the brain to treat seizure disorders.
[COMMISSUR(E) + -TOMY.]