Dead arm syndrome

Definition/Description


“Dead Arm” is characterized by a sudden sharp or ’paralyzing’ pain when the shoulder is moved forcibly into a position of maximum external rotation in elevation or is subjected to a direct blow. The patient is no longer able to perform a throwing movement with the control and the velocity that he achieved before the injury due to pain and numbness. It’s also called recurrent transient subluxation of the shoulder.[1][2] 
The dead arm syndrome is typically associated with anterior instability and a damaged anterior labrum, probably as a result of subluxation of the humeral head. This causes a transient stretch to the brachial plexus during a hard throw.[3] 
The phenomenon is a disorder that can have different causes. Mostly it are problems of the rotator cuff or the labrum. Instability of the shoulder or posterior capsular contracture may be a reason for the development of the dead arm syndrome. In addition, it can also be caused by calcification in the ball and socket joint, bone spurs in the acromion, impingement of the shoulder ligaments, biceps tendonitis, micro-instability, internal impingement and SLAP lesion. Psychological factors can also cause this condition. This syndrome may also occur during throwing, repetitive forceful serving in tennis, or working with the arm in a strained position above shoulder.[1][2][3]  
The symptoms can exacerbate by the loss of the posterior rollback. This leads to anterior translation and results in greater internal impingement posteriorly.[4] 


There are 2 categories of the dead arm syndrome: aware or unaware of subluxation.


Epidemiology / Etiology

The dead arm syndrome is seen most commonly in young athletes (21-30 years) or individuals whose arms have been powerful hyperextended in elevation and external rotation of the shoulder. [1]  
It’s common for people who participate in repetitive throwing sports because the arm is repetitive being turned out backwards as far as possible (external rotation) to create potential energy in the wind up phase prior to the forward acceleration phase. It’s been postulated that the pain is due to an overstretched anterior capsule of the shoulder. Because of this, the ball of the shoulder can shift forward creating an impingement of structures lying in the front of the shoulder joint, which result in pain an the inability to throw. [2]  


Differential Diagnosis 

It’s often misdiagnosed as other shoulder pathology or cervical lesion. There are some factors that differentiate the dead arm syndrome from the other causes of shoulder disability. First it usually appears by young athletic adults (21-30 years). It also has a characteristic history of forceful overextension of the shoulder and there is a positive apprehension test with relocation. [1]


Examination 

There is a positive apprehension test. This test can be carried out when the patient is either in a standing or in a lying position. The shoulder is moved passively into maximum external rotation and in abduction. Then forward pressure is applied to the posterior aspect of the humeral head. The therapist give pressure against the caput humeri to anterior. The test is positive when the patient suddenly becomes apprehensive, complains of pain in the shoulder and has the feeling that the shoulder will come out of the joint considered a positive test. 
In the absence of a strongly positive apprehension test, one should suspect that the shoulder disability is caused by something other than transient subluxation. [1]




Management / Intervention

Treatment includes physical therapy similar to that outlined for shoulder instability and labrum injuries. Surgery may be needed to correct the instability, as well as to repair injuries to the glenoid labrum.[3] 
Once the inflammation and pain have resolved, the patient is subjected to a return to throw program. This takes about 4 weeks.[1] 


Return of full ROM and flexibility is needed before beginning strengthening exercises. These included resisted internal rotation, external rotation, and abduction of the shoulder to strengthen the muscles of the rotator cuff which stabilize the head of the humerus. This program, which is best carried out for three to four months, can decrease the pain and disability.[1][5][3] Rehabilitation of athletes with the dead arm syndrome must include the entire kinetic chain.[1]


Sometimes, it evolves into a full clinical picture of the posteo-superior impingement with a development of a SLAP lesion. Then there is need of a surgical treatment.[6] 
SLAP lesions are repaired through arthroscopy, there are different types of SLAP lesions and the type would determine the repair option.[7]  


Resources


References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 CR Rowe and B Zarins, Recurrent transient subluxation of the shoulder, J Bone Joint Surg Am. 1981;63:863-872. level of evidence: 2B
  2. 2.0 2.1 2.2 http://www.coreconcepts.com.sg/mcr/the-disabled-throwing-shoulder-the-“dead-arm”/
  3. 3.0 3.1 3.2 3.3 Richard B. Birrer,Bernard A.. Griesemer,Mary B. Cataletto, M.D.Pediatric sports medicine for primary care, 2002, p348
  4. Donald H. Johnson, M.D, Practical orthopaedic sports medicine & arthroscopy, 2007
  5. Ho CY, The effectiveness of manual therapy in the management of musculoskeletal disorders of the shoulder: a systematic review, Man Ther. 2009 Oct;14(5):463-74. doi: 10.1016/j.math.2009.03.008. Epub 2009 May 21.
  6. Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med 1998;26:325-337
  7. http://orthoinfo.aaos.org/topic.cfm?topic=A00627
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