James suffered the injury in the final seconds of the third quarter of Cleveland's 103-95 win in Detroit on Tuesday when he tumbled over Pistons guard Jodie Meeks and broke the fall with his hands.
James received an MRI at the Cleveland Clinic on Wednesday afternoon which revealed the extent of the injury.
Tests showed no structural damage in his wrist, a source told ESPN.com.
James is considered doubtful for Friday's game against the Sacramento Kings.
The 12-year veteran shrugged off the injury on Tuesday, classifying it as a "stinger" after he was able to re-enter the game to start the fourth quarter and close out the game after the fall had occurred.
"I finished the game, so I'm OK," James said.
James did admit the fall scared him, however, citing a similar fall he had after his sophomore year of high school which caused him to break his left wrist.
"I broke my wrist before," James said Tuesday. "I landed on my wrist like that and actually, it was the other way around. I actually got taken out the air in high school and broke my wrist.
"So tonight I was on my way to either falling on my face, facedown or using my hands. My arms, just both of them, kind of just numbed up and I was a little scared too, for sure. Just trying to brace my fall with my hands."
Wednesday's game will mark James' 10th missed game this season, the most games he's missed in a single season in his career.
"He is sore and we're gauging that because he took a tough fall last night, as you know," Cavs coach David Blatt said before the game. "And we're gauging how he's going to feel ... because he did have a hard tumble. He came back great and he sure helped us to victory last night, but we're going to keep our eyes on that."
James previously sat out against Oklahoma City in mid December and then missed a stretch of eight straight games to rehabilitate strains to his left knee and lower back.
Since returning from his rest period, James had been averaging 30.5 points, 6.8 rebounds and 6.4 assists and the Cavs went 7-1.
Shawn Marion started in James' place against the Blazers.