Suprascapular Neuropathy Workup

Updated: Oct 11, 2018
  • Author: Thomas H Trojian, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Workup

Imaging Studies

When suprascapular neuropathy is suspected, radiography should be performed. In addition to standard views, suprascapular notch and Stryker views can be ordered. [27, 28] In suprascapular neuropathy, conventional radiographic findings in the shoulder girdle are typically unremarkable in the absence of bony trauma that may account for the condition (eg, fractured clavicle). Conventional radiography of the cervical spine is warranted if concern exists about a possible radicular etiology for the patient’s symptoms.

Shoulder MRI may reveal supraspinatus or infraspinatus muscle edema in acute cases and atrophy with fatty replacement in more chronic cases. [42]

MRI may also reveal a ganglion cyst or other mass such as a paralabral cyst with resultant suprascapular nerve compression. [29, 43, 44]

3T magnetic resonance neurography has been shown to be a valuable diagnostic tool in clinically suspected suprascapular neuropathy. It can demonstrate the nerve abnormality and any secondary muscle denervation changes. [45, 46]

Ultrasonography is a reasonable, less expensive initial imaging option. [42] The suprascapular nerve can be identified under ultrasound, and can be used to screen for parascapular ganglia or masses. [40] Spinoglenoid notch cysts can be identified with ultrasound, particularly in a lean athletic population. [41]

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Other Tests

The clinical diagnosis may be confirmed with electrodiagnostic testing and has been the criterion standard for diagnosis of suprascapular neuropathy.

The normal distal motor latencies to the supraspinatus muscles during stimulation at the Erb point are 2.7 msec ± 0.5 and and to the infraspinatus muscles, 3.3 msec ± 0.5.

Side-to-side differences greater than 0.4 msec suggest focal entrapment of the SSN or other neural injury.

Electromyography may reveal the following:

  • Evidence of denervation, such as positive sharp waves and fibrillation potentials

  • Motor unit recruitment abnormalities, such as motor unit dropout in acute cases and polyphasic motor unit action potentials in cases of long-term neuropathy. (This latter finding suggests a degree of reinnervation.)

  • The physical examination and electrodiagnostic test results should enable the clinician to rule out underlying cervical radiculopathy, brachial plexopathy, or axillary neuropathy and to localize the site of SSN impairment (see Differentials).

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