A 60 year-old male who had been admitted a month ago with a le | Neurology collections 2020

A 60 year-old male who had been admitted a month ago with a left hemiparesis due to a right thalamic
infarction re-presents with painful subluxation of his left shoulder.
Two weeks later he develops severe, constant burning left shoulder pain which radiates down his arm. He
found no relief from paracetamol.
Which of the following is most likely to relieve his pain?