The nerve-altering issue is described as a compression or irriation between the lower neck and upper chest, the team announced.
"Markelle has been diagnosed with neurogenic thoracic outlet syndrome, a physical injury", Raymond Brothers, Fultz's agent, said in a statement to ESPN. The 20-year old guard has not appeared in a game since the team's November 19th win against the Phoenix Suns, after which he was evaluated by multiple specialists.
"Fultz will begin his physical therapy immediately, is out indefinitely, and further updates will be provided as appropriate".
On the advice of Brothers, Fultz visited with approximately 10 specialists over the past week or so, consultations that resulted in their bringing this diagnosis back to the organization.
Lamar Jackson has another strong outing, and the Ravens have a choice
When Jackson took over as the starter during the bye week, the Ravens had lost three games in a row and were spiraling downward. The Ravens piled up those yards against the Cincinnati Bengals and Oakland Raiders, two of the NFL's bottom-tier defenses.
Philadelphia traded up to select Fultz first overall in the 2017 NBA Draft, but he played only 14 games in his rookie season due to what was diagnosed at the time as a "scapular muscle imbalance" that caused him to severely struggle with his jumpshot.
"People were saying it was a mental problem and it is not", Brothers told ESPN on Tuesday night. "There's no way you're the No. 1 pick in the world and all of a sudden you aren't able to consistently raise your arms to shoot".
Fultz has had a tough season, averaging 8.2 points, 3.7 rebounds and 3.1 assists while shooting 41.9 percent from the field. "Now we have the answer to that problem". However, Wojnarowski also reports that the Sixers are hoping he's only sidelined three-to-six weeks.