After a two-year stretch of confusion, frustration, internet conspiracies, and unpredictability, Markelle Fultz, the Philadelphia 76ers’ 2017 No. 1 draft pick who suddenly couldn’t shoot a basketball, was finally diagnosed with thoracic outlet syndrome (TOS). This ailment, often untraceable even by MRI, is the cause of Fultz’s inability to shoot a basketball properly from any distance, according to agent Raymond Brothers.

The Sixers announced on Dec. 4 that Fultz would be out indefinitely, and his next steps included three-to-six weeks of physical therapy, according to ESPN’s Adrian Wojnarowski. Philly’s dealt with many fits and stops in this process, so many that I’ve timelined every single way Fultz, his coaches, his teammates, and the team itself has tried to identify what’s wrong.

But TOS is a very real, frustrating, and difficult-to-describe ailment. That may explain why it took so long to diagnose.

I spoke with Dr. Jacques Hacquebord, a peripheral nerve surgery specialist and assistant professor in Orthopaedic and Plastic Surgery at NYU Langone Health, to understand how TOS is discovered, why the disorder can be mentally straining on patients, why Fultz was able to do everything on the court but shoot, and why surgery for TOS is dangerous.

This interview has been lightly edited for clarity:

TOS, EXPLAINED

SB NATION: What is thoracic outlet syndrome?

JACQUES HACQUEBORD: You have all these nerves that come out of your cervical spine. After those surgical nerve roots leave the spine, they form this web of nerves that flow in and out together. It’s a very complex region of nerves called the brachial plexus.

On one end, you have these nerves that come out of the spine. At the other end, you have the nerves that go down into your arm, and they go to specific muscles. Between the nerves that leave the spine, and nerves that go into specific muscles and provide sensation, that whole region is called the brachial plexus, where the nerves are flowing in and out together.

What thoracic outlet really means, it’s where the nerves are leaving the thorax. In that outlet out of the thorax, there’s compression.

SB: Why did it take so long for Fultz to be diagnosed with TOS?

JH: The diagnosis for it is notoriously difficult, and for many, you can’t find a focal area of compression because the MRI imaging or ultrasound imaging is inadequate. Or, maybe because there isn’t a focal area of compression that can be found because it doesn’t anatomically exist.

TOS involves the brachial plexus, but it’s an undefined diagnosis. In reality, the region where those nerves could be potentially compressed or irritated is a large region. Most of the time, [TOS] is a diagnosis by exclusion, which means you’ve ruled everything else out, so then you fall onto thoracic outlet as a possible scenario.

“Most of the time, [TOS] is a diagnosis by exclusion.”

Patients start with vague symptoms that start with a relatively minor event or possibly no event at all. This is a vague pain, vague weakness, vague dysfunction.

Thoracic outlet syndrome is often a difficult diagnosis to make because it’s difficult to find a specific spot where the problem is. Sometimes people have an accessory rib, or an extra rib that comes off pretty high, and that rib can be compressing on the brachial plexus. Or, they could have really large muscles that surround the brachial plexus.

SB: How does someone get TOS?

JH: Almost never do people with TOS complain about it for their whole life. Almost always, there’s a specific point in time when their symptoms started. Then you have to wonder, if they didn’t have a motorcycle crash where the brachial plexus was torn or a bone broke and it’s compressing the brachial plexus, why would they start having symptoms now?

[On the other hand,] when people are doubtful of a diagnosis for those reasons, then I bring up carpal tunnel syndrome. It’s one of the most common diagnoses that hand surgeons treat. It’s when the nerve in the wrist gets compressed.

You hear about little old ladies that are complaining about carpel tunnel syndrome, or secretaries, or construction workers. But if a nerve can get irritated in that level of their wrist or elbow, then why couldn’t nerves get irritated out of the blue at other levels?

Like with TOS, these things can just pop up and happen and we don’t know why.

SB: Is Markelle Fultz really young to develop TOS? He’s only 20.

JH: TOS tends to be a younger population of patients in their 20s, 30s, and 40s. It’s unclear why.

I do think that some people have a disposition for thoracic outlet syndrome, so I don’t think every person on the planet under the same circumstances would develop thoracic outlet syndrome. Maybe it’s because people have an anatomic disposition, it’ll tend to present earlier in life just because they’re at risk of it, and it takes less for it to manifest.

SB: TOS is much more common in baseball, where pitchers like Matt Harvey and Chris Carpenter have been diagnosed. But it’s never been diagnosed in basketball. Why is that?

JH: Pitchers are putting a tremendous amount of force in an unnatural position for the arm. The overhead throw, over and over and over, is rotating that shoulder, moving that scapula, and pulling and pushing on the brachial plexus. In pitching, they might have had a predisposition for it, but they most definitely had some sort of activity that put their shoulder in significant torque hundreds of times.

You also have to think about the traction. As a pitcher, all that momentum and force, when you pitch, the arm wants to continue to move away from your body. So every time you pitch, you’re pulling on the brachial plexus, you’re pulling on those nerves.

So I’m not surprised the instances in pitchers are higher than most other athletes.

WHY TOS IS SO HARD TO SPOT

SB: You mentioned that TOS is a diagnosis often made through a process of elimination. Is it misdiagnosed disproportionately in any way?

JH: The data on this doesn’t exist. We just don’t know. But I suspect that it’s under-diagnosed more than it’s over-diagnosed.

The majority of people who have TOS do not undergo surgery, so it’s hard to know definitively if they actually have it. If they get treated for it with physical therapy, then the question is, are they better because TOS is resolved, or is it because they had some other process that was self-limiting or benefitted from therapy?

SB: Can you ever definitively say someone has TOS?

JH: There are some patients, 100 percent, you know they have TOS. You can see the nerves compressed, you can see the anatomical variant they have, like an accessory rib or hypertrophied muscles or compression by the vessels. You can see it, you can find it, and you can treat it surgically.

“I suspect that TOS is under-diagnosed more than it’s over-diagnosed.”

There are other patients where it’s a little fuzzy.

I have one patient now where we’ve done an ultrasound and I’m as positive as I can be that she has TOS, but she has an atypical type. She doesn’t have an accessory rib, but she has an area where I push on her clavicle near her collarbone and that reproduces her symptoms. When we got the ultrasound, looking at the brachial plexus, when there was pressure in that area, it reproduced her symptoms and was an area that looked compressed under the ultrasound.

For that patient, there’s a high degree of belief that she has TOS in an atypical spot.

SB: In 2017, Fultz was diagnosed with scapular muscular imbalance. Did that lead to TOS?

JH: It’s not impossible that could’ve actually been thoracic outlet syndrome. The scapula has 12 or 13 muscles that attach to it or originate from it, meaning every one of those muscles plays some role in the motion of the scapula.

The scapula motion is incredibly important. One third of your shoulder motion where you raise your arm in the air comes from your scapula, not your shoulder. Moving your arm forward and backward, a huge part of that is coming from your scapula.

HAVING TOS REALLY, REALLY STINKS

SB: What kind of pain do people with TOS feel, and what restrictions do they have from someone who’s healthy?

JH: If [Fultz] has TOS, I have a tremendous amount of sympathy for him. The pain that patients have is this nondescript, aching pain. It goes down the arm.

You know how if your leg falls asleep, when it starts waking up, you have a burning, tingling pain. It’s numb, but tingling. A lot of these patients complain about this uncomfortable numbness. When your leg falls asleep, and you first wake up, it’s just dead to the world. Then as it starts waking up, you get this general sense of discomfort, and then it slowly comes back. People who have nerve compression complain of this dull ache and this numbness, not in the sense that they can’t feel anything, just a decreased sensation that’s uncomfortable.

If you have a blister and you go on a hike, you’re completely incapacitated from a tiny little blister. You’re wondering how on Earth could a tiny little blister be so detrimental to me when everything else is fine? That’s something we need to appreciate. Pain is this incredibly debilitating thing to humans. You cannot ignore pain. Someone says ‘play through the pain.’ You can’t! You can’t put the pain out of your mind. We’re naturally programmed to avoid doing things that are painful.

So if he has a dull ache or pain that radiates down his arm, he will naturally be trying to change things because his body is telling him, ‘when you do A, it hurts. So do B.’ And then he’ll do B, but then B hurts, so he’ll try C. And he’ll constantly be changing it, and that might explain why his shot looks different. He can’t find a way to do something that isn’t uncomfortable.

SB: Why is TOS especially frustrating for those who suffer from it?

JH: If you can’t define the problem, immediately people think that you’re making it up. And if people think that you’re making it up, and you have real pain, then that just makes you so much more frustrated and depressed. It also makes you start questioning yourself. ‘Is this real? Is there something actually wrong with me?’ And that just gets you down a really, really bad cycle.

“For patients that have chronic pain, it’s a psychological torment for them.”

For patients that have chronic pain, especially if you don’t know why they have pain, it’s a psychological torment for them. People don’t take them seriously, people label them, people think that they’re making it up, people think that they’re weaklings, that they’re doing this for secondary gain.

And if people don’t have sympathy for you, that really sucks.

SB: Fultz was still plenty capable of playing defense, passing and even dunking a basketball. Why might the rest of his game be ok, but his jump shot suffer most visibly?

JH: When you pass or play defense, you’re not typically required to elegantly and athletically move your arm up in a graceful manner. Also, with dunking, you have to jump and put the ball through the hoop, and yes your arm is in an overhead position, but you don’t have to let go of the ball and make sure it goes through a small hoop 20 feet away and worry about being accurate. When you dunk, you don’t have to be accurate. If you can jump, you can dunk.

However, to hit a jump shot, no matter how high you can jump or how strong you are or how long your arms are, you can’t necessarily hit a jump shot. That requires incredible finesse and technique. It’s possible that maybe he has the same symptoms when he dunks, but his accuracy of a dunk isn’t affected much.

SO WHAT HAPPENS NOW?

SB: How do you treat TOS? What might Fultz be doing in physical therapy?

JH: I don’t know what he might be doing in physical therapy that he hasn’t done already. Many times when patients have a problem, and you don’t really know what’s really going on, the reflex is to say, ‘Well, let’s do some physical therapy.’

A majority of the time, patients get better. Do they get better because of physical therapy? Probably not. They got better because it’s a self-limiting disease process and they were going to get better anyway.

Unless it’s a definable area of constriction, like an accessory rib, or you get an ultrasound and you can see a specific area where the brachial plexus is getting compressed. For those patients, non-operable management is only appropriate if they say ‘I really don’t want surgery and my symptoms aren’t that bothersome.’

“They just try [physical therapy] because it’s morbid to go straight to surgery.”

If a patient has what you think is TOS, but you don’t know where the compression is, you try therapy with the hopes that things get better. What exactly is that therapy going to be? I don’t know. And I don’t think a lot of other people know. They just try it because it’s morbid to go straight to surgery.

If you’re going to take someone to the operating room for TOS, your degree of belief has to be very high that they have TOS and you should have strong evidence that there’s a focal area of compression, and you should know where that area is. If you don’t know where that area is, you shouldn’t take them to the operating room.

SB: If Fultz does elect to get surgery, what is that process like?

JH: Operative management can be relatively morbid. You’re operating around the brachial plexus, around the subclavian artery and the carotid artery.

You expose the brachial plexus, and there’s typically an incision around the clavicle in the neck. For a brachial plexus surgeon, it’s a straightforward procedure, but you are operating around large blood vessels and operating around crucial nerves, so you have to be so incredibly meticulous and careful. A lot of it is done under the microscope.

The recovery after it is relatively minor, much less significant than an ACL repair or rotator cuff repair. Much quicker recovery.

However the consequences if something were to go wrong in the surgery are astronomically greater than if something went wrong in an ACL or rotator cuff surgery. If you hit a major blood vessel, you could cause a stroke, or the patient could lose a tremendous amount of blood. Or, you could paralyze certain muscle groups in that arm, which would end his career.

The likelihood of something going bad with a good, skilled brachial plexus surgeon, though, is low.