What is the role of nerve blocks in the treatment of hemiplegic shoulder pain?

Updated: Feb 08, 2019
  • Author: Robert Gould, DO; Chief Editor: Stephen Kishner, MD, MHA  more...
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Many authors, including Wanklyn and colleagues, believe that shoulder pain relates significantly to restriction of external rotation secondary to spasticity. [25] For this reason, Chironna and Hecht felt that motor block to nerves innervating internal rotators would help relieve the pain caused by internal rotation synergy. [50]

Using a medial scapular approach, the 2 authors identified the motor points of the nerves to the subscapularis (upper and lower subscapular nerves) via electrical stimulation; then they injected phenol in these points. [50] An immediate improvement in external rotation, abduction, and flexion was noted, as well as a reduction in pain.

Hecht followed this up with a larger study that showed similar results in pain control and ROM, with the greatest improvement in external rotation. [51, 52] Hecht also reported on a subset of patients with a more spastic pectoralis major than subscapularis. These patients present with greater limitations and pain in abduction and flexion compared with external rotation.

A major complication reported with phenol motor point blocks and neurolysis of mixed nerves is the onset of delayed or chronic neuropathic pain. Fortunately, as reported by Chironna and Hecht, the subscapularis has no sensory nerve component, making the onset of true neuropathic pain unlikely. [50]

The effect of the block generally lasts from 3-9 months, with the procedure found to be a safe and effective adjunct to conservative treatment. The block is probably most efficacious if performed prior to the development of soft tissue contractures.

Botulinum toxin can be used as a replacement for phenol if the patient does not tolerate the phenol or if the injection is too painful. Botulinum toxin also is preferred when the desired outcome is for slower onset with shorter duration. [53, 54, 55] This procedure is sometimes used when the subscapularis and pectoralis major muscles require nerve block.

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