Learn more about entrapment of the suprascapular nerve, a common and painful condition in many baseball players.
Dr. Keith Meister, Medical Director of Sports Medicine at Medical Center Arlington and Team Physician for the Texas Rangerscontinues to share important information about baseball injuries and sports medicine conditions. Today Dr. Meister discusses nerve conditions in overhand athletes.
An often common and potentially painful condition, but little discussed problem that is seen in the overhand athlete is entrapment of the suprascapular nerve. The suprascapular nerve is responsible for innervating two of the four muscles of the rotator cuff, the supra- and infraspinatus. The nerve originates from the upper trunk of the brachial plexus and mainly from cervical nerve roots five and six. The nerve passes deep to the trapezius muscle and has two points of potential entrapment as it winds its way around the shoulder blade (scapula); the suprascapular (ssl) and spinoglenoid (sgl) notches. (See figure above.)
The nerve can be injured by a number of mechanisms, but in throwers the most common mechanism is repetitive traction. It’s believed that during deceleration (the phase of throwing immediately after ball release) the infraspinatus contracts against the normal distraction forces of the arm during throwing. This constant pull of the muscle against the nerve can result in injury to the nerve.
If creating symptoms, the player may complain of pain in the area of the infraspinatus muscle in the back of the shoulder blade and or weakness in external rotation of the shoulder. Most of the time however, no pain is appreciated and the weakness that occurs is unrecognized by the athlete. Thus, the diagnosis is most typically made on screening examination prior to the season. Most times the player has known about his condition for many years but has not required treatment. Plain x-rays are typically normal. MRI scan of the shoulder may show a tear to the labrum of the shoulder that may have an associated paralabral cyst. This cystic collection of fluid that occurs may cause nerve entrapment by applying direct pressure to the nerve typically at the spinoglenoid notch. Additional nerve studies may be helpful in making the diagnosis but usually not necessary.
True intervention is only needed when the athlete is acutely symptomatic from the weakness or has pain. In the acute setting, treatment with anti-inflammatories, rest, and rehabilitation is the mainstay. If pain persists then either ultrasound or CT guided injection of the nerve can be very helpful. If pain continues then entrapment of the nerve from either a cyst or bony growth may require surgical decompression. Most surgical decompressions can be performed arthroscopically and are usually curative. Recovery of strength is not essential to the return of normal throwing or overhead activity, elimination of the pain is.