2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/130829For a given morphism of schemes f:X->S, a sheaf F on X, a geometric point x on X, and s=f(x), the morphism f\_x : X(x) -> S(s) between the strict henselizations doesn't necessarily behave (with respect to F) like a proper morphism. However, we know it is so (assuming constructibility of F etc.) if S is the spectrum of a dvr (P. Deligne, SGA 4 1/2, [Th. finitude]). In this article, we prove it becomes so after an appropriate modification of the base S. The main ingredient is a theorem by A.J. de Jong on plurinodal fibrations. An application of this formalism to Lefschetz pencils is given.In French. Submitted to IMRNAlgebraic GeometryModifications et cycles évanescents sur une base de dimension supérieure à untext