Shoulder and Elbow cases suprascapular neuropathy
A 21-year-old, right-hand-dominant, male, college swimmer presents to clinic complaining of gradually worsening right shoulder pain for the past 6 months. He notes that his times at swim meets have been slowing with the onset of the pain but that he is still able to swim through the pain. Physical examination reveals: decreased muscle bulk over the infraspinatus fossa of the right shoulder compared with the contralateral side (shown in Fig. 2–64), full active range of motion, strength 4/5 for external rotation but otherwise normal strength, mild pain with cross-body adduction of the right shoulder, and mild tenderness to palpation over the AC joint. Imaging is shown in Figure 2–65.
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Figure 2–64
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Figure 2–65
Based on the information obtained thus far, what is the patient’s most likely diagnosis?
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Rotator cuff tendinitis
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Adhesive capsulitis
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Acromioclavicular joint arthritis
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Suprascapular neuropathy
Discussion
The correct answer is (D). This patient’s atrophy of the infraspinatus muscle leading to weakness with external rotation and with preserved strength in the other rotator cuff muscles is likely due to neuropathic process of the suprascapular nerve at a
point along its course off the upper trunk of the brachial plexus on its way to innervate the supraspinatus and infraspinatus muscles. Choice A is incorrect as rotator cuff tendinitis would not present with muscle atrophy. AC joint arthritis (Choice C), while often presenting with tenderness to palpation over the AC joint and pain with cross body adduction, is also not usually associated with infraspinatus atrophy and would likely present with narrowed joint space or AC joint osteophytes on plain films, unlike this patient. Choice B is incorrect as the patient has full active range of motion, while adhesive capsulitis would more likely present as decreased active and passive range of motion.
You send the patient for an MRI, which is shown in Figure 2–66.
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Figure 2–66
Based on the clinical examination and imaging, what is the most likely etiology of the patient’s symptoms?
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Suprascapular nerve entrapment at the spinoglenoid notch by the spinoglenoid ligament
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Suprascapular nerve entrapment at the suprascapular notch due to scapular body fracture
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Suprascapular nerve entrapment at the spinoglenoid notch by a paralabral cyst
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Suprascapular nerve entrapment at the suprascapular notch by the transverse scapular ligament
Discussion
The correct answer is (C). The patient’s clinical examination findings of isolated
weakness in external rotation and atrophy of the infraspinatus muscle point to suprascapular nerve entrapment at a location past the exit point for the branch to the supraspinatus muscle. Also, MRI reveals a posterior labral tear with a paralabral cyst that is compressing the suprascapular nerve at the spinoglenoid notch. Choice A, while fitting with the patient’s clinical examination, does not fit with the MRI showing paralabral cyst. Choices B and D are incorrect because entrapment of the suprascapular nerve at the suprascapular notch by scapular body fracture or by the transverse scapular ligament (more common) would lead to weakness/atrophy in both supraspinatus and infraspinatus muscles as the suprascapular notch is proximal to the nerve branch point to the supraspinatus muscle.
What nerve is innervated by the same spinal nerves as the suprascapular nerve?
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Axillary nerve
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Musculocutaneous nerve
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Dorsal scapular nerve
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Radial nerve
Discussion
The correct answer is (A). The suprascapular nerve branches off the upper trunk of the brachial plexus and consists of fibers from C5 to C6 spinal nerves. The axillary nerve is a terminal branch from the posterior cord of the brachial plexus and also consists of fibers from C5 to C6. The musculocutaneous nerve (Choice B) is a terminal branch from the lateral cord and consists of fibers from C5 to C7. The dorsal scapular nerve (Choice C) branches off the C5 nerve root and consists of fibers from C5. The radial nerve (Choice D) is a terminal branch from the posterior cord and consists of fibers from C5 to T1. See Figure 2–67 for a diagram of the brachial plexus.
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Figure 2–67 Reproduced with permission from Moran S, Steinmann S, and Shin A. Brachial plexus injuries: Mechanism, patterns of injury, and physical diagnosis. Hand Clin 2005;21:13–24 (Fig 2A).
What is the most appropriate treatment at this time?
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Physical therapy and NSAIDs
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Arthroscopic decompression of the paralabral cyst and labral repair
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EMG of bilateral upper extremities
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Open decompression of the spinoglenoid and suprascapular notches
Discussion
The correct answer is (B). The patient has a clear etiology for his suprascapular nerve decompression in the paralabral cyst with symptoms that have lasted for 6 months resulting in atrophy of the infraspinatus muscle. Given that he is a college-level athlete and likely wants to improve his athletic performance, surgical decompression of the suprascapular nerve at the spinoglenoid notch is indicated at this time, which can best be accomplished arthroscopically along with labral repair. Choice D is incorrect as the patient does not require decompression of the nerve at the suprascapular notch, since he shows no sign of weakness/atrophy of the supraspinatus muscle. Choice A would be appropriate for a patient with symptoms of suprascapular nerve compression for less than 6 months of duration, without atrophy, and without any compressive mass on MRI. Choice C could aid in establishing a baseline for treatment and could localize nerve entrapment sites in a patient whom the location of suprascapular nerve entrapment was unclear but is not the most appropriate treatment for this particular patient.
Objectives: Did you learn...?
Recognize the clinical presentation of suprascapular neuropathy?
Distinguish between suprascapular neuropathy at the suprascapular and spinoglenoid notch?
Treat a patient with suprascapular neuropathy?