The Nationals said the right-hander had surgery Friday to remove a part of a bone in his left wrist.
The team said Storen would miss three or four days after the procedure on the hook of his hamate bone.
Until the stitches are out, someone will catch the ball for Storen once he resumes throwing. He will also be able to throw simulated games behind a protective screen.
''He took a swing and it got him,'' Nationals manager Matt Williams said. ''It's an odd thing because you never expect anything like that to happen. But it happened to him.''
''The thing right now you have to be wary of the stitches,'' Williams said. ''When that's healed, he'll be ready to go.''