Sims: Breaking Down Shaun Marcum’s Season-Ending Injury
By Abby Sims
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Mets starter Shaun Marcum began the 2013 season with what was diagnosed as right shoulder impingement syndrome, and his season ended this week with another type of impingement — that of the Thoracic Outlet.
Ed Coleman reported that Marcum is slated for surgery next week after an MRI confirmed the diagnosis. He has struggled at the mound recently and reported recurrent symptoms of tingling and numbness in his pitching hand. This, according to Mets assistant GM John Ricco, “was affecting his ability to grip the ball.” Thoracic Outlet is also sometimes implicated when a pitcher complains of a “dead arm.”
Thoracic Outlet Syndrome (TOS) is a condition that is not as uncommon as one might think, particularly amongst competitive overhead athletes — baseball and tennis players, as well as swimmers, especially. It entails the compression of the neurovascular bundle (nerves and/or blood vessels) that lies in the area known as the thoracic outlet. The boundaries of this space are the clavicle (collarbone), the first rib, the subclavius and scalene muscles as well as the costoclavicular ligament (which connects the first rib to the clavicle).
Compression most often occurs in the area under the first rib and can be contributed to by tightness in the surrounding muscles (the scalenes and pectoralis minor). Postural issues, trauma or exertion, as with exercise, all can alter the thoracic outlet space, compromising the structures within. Even everyday tasks, such as carrying heavy things or particularly weighty shoulder bags, can trigger TOS.
The structures lying within the thoracic outlet that are most affected by compression include the eighth cervical and first thoracic (C8 & T1) nerves of the brachial plexus — both of which lie between the anterior (front) and middle scalene muscles — and the subclavian artery and vein, which bring blood to and from the arm, head and neck. TOS involves neural compression more often than vascular.
Symptoms of numbness or tingling in the arm or hand are due to compression or tightness of the median and ulnar nerves, which are branches from the brachial plexus. Loss of strength in the hand is also common (this is due to weakness of the intrinsic muscles). Swelling in the upper extremity may be indicative of thrombosis (the formation or presence of a blood clot in a blood vessel) of an axillary vein. Dillon Gee of the Mets had surgery last season for a similar clot in an artery. In some cases, thoracic outlet syndrome is exacerbated by recurrent anterior shoulder instability.
Jarrod Saltamacchia recovered from successful surgery for TOS, as did pitchers Kenny Rogers, Matt Harrison and Jeremy Bonderman. Others, like third baseman Hank Blalock and pitcher John Rheinecker, had various issues in the aftermath of TOS surgery. You may also recall that David Cone had surgery for an arterial aneurysm (a localized enlargement of an artery caused by a weakening of the artery wall) in 1996, and Arizona Diamondback (and former Yankee) Ian Kennedy had similar surgery 13 years later.
An aneurysm in the blood vessels of the thoracic outlet is a variant form of TOS. In one of the saddest cases, pitcher J.R. Richard suffered a massive stroke after being untreated in spite of complaining of various symptoms (that implied Thoracic Outlet involvement) for some time. His stroke appears to have originally been due to exertion thrombosis. When a blood clot dislodges and travels through the blood vessels it is known as an embolus. An embolus that travels to the brain, blocking its access to oxygen, results in stroke.
Marcum will likely make a complete recovery and return at full strength next season. It is good that he made his symptoms known and that action will be taken.
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