(Marco Garcia/AP)

Spokesman Peter Boylan said Inouye’s injury, a cut on his head, was minor and probably would require only a few stitches and some precautionary tests.

Inouye, a recipient of the Medal of Honor for his service in World War II, initially didn’t want to seek medical attention after falling and cutting his head, Boylan said. “The old warrior wanted to get in his car and get to work, but his wife insisted” that he get it checked out, Boylan said.

Because of his military service and security clearance, he was taken to Bethesda Naval.

The Hawaii Democrat, 88, is the most senior senator. And as President pro tempore of the Senate, Inouye is third in line for presidential succession, behind Vice President Joe Biden and House Speaker John Boehner.

Inouye is the second oldest senator behind Sen. Frank Lautenberg (D-N.J.), also 88 (but eight months older than Inouye), and is the second-longest serving senator after the late Sen. Robert Byrd (D-W. Va.).

He’s expected back at work shortly, Boylan said.

Update: as of Thursday afternoon, Boylan said Inouye was “fine and resting at home.”