April 29, 2011

Collateral Damage

Thoracic Park

by Corey Dawkins and Marc Normandin

Phil Hughes, NYA (Thoracic Outlet Syndrome)
As briefly discussed here, the Yankees finally put a name to the weakness and dead arm feeling that has limited Hughes so far this year. After almost eight hours of testing over two days, the medical staff believes that Hughes may be suffering from a condition called Thoracic Outlet Syndrome (TOS) rather than simple fatigue or weakness.

TOS is a clinical diagnosis drawing upon the entire spectrum of symptoms, rather than radiographs alone. It offers no “Oh, he has [condition] as evidenced by the X-ray, therefore he will have TOS” moment—if only it were that simple.

Human anatomy is an amazing combination of simplicity and complexity rolled into one. Relatively simple mechanisms such as nerves, blood vessels, muscles, non-contractile soft tissue, and bones all must act together in order to allow the complex functions of the human upper extremities to work normally. Nerves exit the spine to form the brachial plexus, right next to the subclavian artery and vein, as they pass from the neck, under the collarbone, and through the shoulder to the level of the armpit, then finally travel down the arm—let's see Dr. Nick try to explain that through "Them Bones." Muscles called the scalenes—which the nerves pass through at the sides of the neck just above the collarbone—as well as the pectoralis minor muscle, are normally flexible and supple enough to allow the nerves to transmit signals without any difficulties.

TOS has many different potential causes, but there are only two ways to be predisposed to it, one of them congenital and the other acquired. It is important to note that the presence of either predisposition does not mean the athlete will definitively have TOS. One major potential congenital predisposing condition is the presence of a cervical rib. This effects approximately one percent of the population and occurs when an extra rib comes off the C7 vertebra (normally, the first well-developed rib comes off the T1 vertebra).

A cervical rib permits a much narrower area for everything to travel through, placing pressure on nerves and blood vessels. The cervical rib is asymptomatic in most cases, and even people with TOS do not know they have one until it is seen via X-ray or MRI. Other congenital predisposing factors include variants on the first thoracic rib or where the scalene muscles insert on the rib.

TOS can also develop as a result of some other injury or medical condition, including poor posture combined with scapulothoracic weakness. In cases of poor posture, the shoulder blade is rotated upward and causes pinching of the neurovascular structures because of muscular tightness of the scalenes and pectoralis minor.

Other injuries can cause weakness and atrophy of the upper back muscles and allow the scapula to drop down over time. This places more tension on the structures and causes an increased amount of force to be applied where normally it wouldn't be. Improper healing of clavicular fractures can also decrease the amount of space for the neurovascular structures to pass through.

Hughes did have a rib injury in 2008, but it was a stress fracture. While this would not provide a direct cause for the TOS, indirectly it may very well have played a role. If the stress fracture caused him to change his mechanics, there were likely some soft tissue changes throughout the upper extremities that would not have been noticeable visually, but which certainly could have prompted major changes underneath the skin, including atrophy of certain muscles while others grew bigger and tighter.

As we said before, TOS is diagnosed clinically and not through imaging. One of the difficulties of making the diagnosis is that the manner in which it presents is very individualized. The compression could be on either the nerves, the artery, or the veins as they pass through the constricted space. Commonly, an athlete reports neurological symptoms—such as numbness or tingling in the hand and fingers—in the absence of an injury, unlike "stingers," which arise when there is a clear force applied to the nerves. There can also be reports of fatigue or weakness that do not resolve with physical therapy and rest.

If the blood vessels are compressed, different symptoms such as swelling, color changes, or fatigue can set in. Often, especially in the early stages, the symptoms only occur during sport-specific activities—in this case, pitching. That is probably why the Yankees and Hughes had such a hard time figuring out what was going on. X-rays, MRI, EMG, and nerve conduction studies all play a role, but they should be used more as a means to rule out other pathologies than to rule in TOS.

Initially, treatment is always conservative (and attempts are made to avoid surgery at all costs, unless there is another life- or limb-threatening diagnosis, such as a blood clot). Conservative treatment involves physical therapy exercises to focus on improved posture and strength of the entire shoulder, along with flexibility of the neck musculature. This routine is followed for several months, because any changes will not happen overnight.

If this approach fails and/or there is significant vascular compromise such as a blood clot, one of many surgical procedures will be performed. Most surgeons report the surgeries as a success–surprise, surprise–but anecdotal evidence suggests otherwise in the professional baseball player. In the general population the surgery will likely be a complete success, but none of the pitchers listed with the injury in our database returned in the same season.

So what does that mean for Hughes? If it is TOS, then he will likely be out for a while, even if there is no surgery to be performed. If surgery is involved, he will most likely be done for the year, and he faces a long and difficult road to regain his form. Once we hear more from Dr. William Thompson, a TOS expert, we will have a better idea as to what is going on.

Mark DeRosa, SFN (Wrist inflammation)
DeRosa seemed like a nifty pickup for the Giants heading into 2010, but at this point, he has amassed -0.3 WARP and played in all of 36 games over two years for San Francisco thanks his left wrist woes. There is a reason he was rated as high-risk across the board this preseason.

DeRosa's wrist is giving him issues again, and he was placed on the 15-day disabled list. Healthy wrists are of vital importance for hitters, and there have been multiple instances of wrist injuries sidetracking careers, with Nomar Garciaparra being one of the latest examples (yes, both of us cringed after recalling the end of Nomar's peak due to injury).

DeRosa's tendon and tendon sheath are fine, but he has been limited by inflammation surrounding the area. Dr. Thomas Graham–DeRosa's wrist surgeon–recommended a week of rest before resuming any baseball activities. There is an outside chance that DeRosa will return in the minimum, but with his history we wouldn't hold our breaths.

Casey Blake, LAN (Left elbow infection)
Infections can be rather serious—just ask Casey Blake, who was placed on the disabled list with an infection of the olecranon bursa in his left elbow. His was serious enough to require IV antibiotics, and he may require minor surgery to drain and clean the area out.

The Dodgers are expecting Blake to miss about three to four weeks and will be conservative in bringing him back, so as not to risk a recurrence. Because of the location of the bursa, it is susceptible to re-injury during the course of a baseball game by sliding and landing on the elbow.

Blake was one of the few Dodgers hitting prior to going down with the elbow infection (posting a .333 True Average to start the year), and while that wasn't expected to last, this does put a damper on his rebound from a disappointing 2010 campaign.

Darren O'Day, TEX (Labrum surgery–hip)
The Rangers are not having too much luck keeping their pitchers healthy, and O'Day is the latest one to end up on the disabled list. The righty was placed on the 60-day DL and was reportedly going to have surgery on Thursday to repair a labral tear in his left hip. Several months are needed before a player is ready to return from that injury, especially given the repetitive nature of pitching. The earliest O'Day will be able to return is in late June, but that may be a little optimistic. There is a chance he will be out longer if they have to address any major bone injuries.

Flesh Wounds: Joe Thatcher will have exploratory surgery on his troublesome left shoulder. He will likely need a minimum of two to three months to return but could possibly end up missing more. That news comes as a blow to the Padres bullpen, as the southpaw has dominated the past two years (11.3 K/9, 4.0 K/BB, 2.14 ERA in 80 relief innings)... Delmon Young was placed on the disabled list with soreness in his ribs. Apparently the medical staff got sick of asking him if he was feeling better every day... Joe Blanton was placed on the disabled list with right elbow impingement. Vance Worley will start in his place tonight against the Mets (9.9 K/9 and 4.2 K/BB in Triple-A this April, and the #14 prospect in the Phillies' system according to Kevin Goldstein)... Sean Rodriguez dislocated his left pinkie finger yesterday, but we won't know about a possible timetable for his return until late Friday or early Saturday… Jonathan Broxton has been suffering from right elbow soreness recently, possibly providing a reason for his struggles this year.

Corey Dawkins is an author of Baseball Prospectus. Follow @CoreyDawkinsBP
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