1. 2020;23;E461-E474Ultrasound-Guided Peripheral Nerve Stimulation for Shoulder Pain: Anatomic Review and Assessment of the Current Clinical Evidence
   Clinical Review
   Anthony Mazzola, MD, and David Spinner, DO.

BACKGROUND: The shoulder region is a common area for pain. The shoulder has the largest range of motion and the most complex mechanical anatomy. The shoulder girdle and related tendons allow for numerous painful disorders to occur. Also, given the overall use of the shoulder, arthritic deformities are all too common. Finally, pain from more complex states such as poststroke shoulder pain and status post total shoulder arthroplasty pain have always been a difficult diagnosis to treat with effectiveness. The innervation to the shoulder predominantly comes from the suprascapular and axillary nerves. Both nerves relatively follow an expected anatomic course and whereby they can be targeted with ultrasound or fluoroscopy. Recently, there has been an increase in evidence that suggests peripheral nerve stimulation can make a difference in these patients with shoulder pain.

OBJECTIVES: To provide a basic overview of peripheral nerve stimulator placement targeting the axillary and suprascapular nerves. Furthermore, to demonstrate the suggested implantation and current evidence of peripheral nerve stimulation for the treatment of shoulder pain.

STUDY DESIGN: Anatomic clinical review.

METHODS: A comprehensive review was performed regarding the available literature through targeting articles reporting on the use of peripheral nerve stimulation to treat pain of the shoulder region.

RESULTS: We compiled and discuss the current evidence available in treating shoulder pain utilizing peripheral stimulation. The strongest evidence currently is for peripheral nerve stimulation targeting either the axillary or suprascapular nerve, as well as placement targeting the motor points of the deltoid. The most common treated pathology is poststroke shoulder pain.

LIMITATIONS: Peripheral nerve stimulation has been trialed and is promising for several shoulder pain pathologies; however, there remains a need for large-scale, randomized, placebo-controlled clinical trials to further evaluate the efficacy of most treatments. Much of the current data relies on case reports without randomization or placebo controls.

CONCLUSIONS: Overall there is fair to moderate evidence for peripheral nerve stimulation to treat shoulder pain in hemiplegic poststroke patients. There is limited evidence when treating other shoulder pain etiologies. Utilizing ultrasound or fluoroscopic guidance, the procedure has proven to be safe allowing proper placement of the electrodes near the target nerves. Considering the high prevalence of shoulder pain from degenerative conditions and overuse, future studies are undoubtedly warranted to evaluate whether peripheral nerve stimulation can modify our treatment algorithm for management of these conditions.

KEY WORDS: Shoulder pain, suprascapular nerve, axillary nerve, ultrasonography, peripheral nerve stimulation, post stroke shoulder, osteoarthritis, rotator cuff, hemiplegic shoulder pain, adhesive capsulitis