26th August 2024

You are reviewing a 50-year-old woman on the stroke ward. She describes a history of severe pain

You are reviewing a 50-year-old woman on the stroke ward. She describes a history of severe pain (9/10) in the right upper lateral arm and shoulder. The pain came on suddenly, waking her up from sleep two weeks ago. Since then, she has noted the onset of weakness in the right shoulder and upper arm. The pain is similar at rest and on movement and is worse over the posterior aspect of the shoulder. She has never experienced anything similar before.

She initially consulted her GP who referred her urgently into hospital for a suspected stroke. However, CT and MRI imaging of the brain has been reported as normal, so she has been admitted for further investigation. An X-ray of the shoulder performed in A&E last night has also identified no pathology. On examination, she remains in severe pain and you note flaccid paralysis of the shoulder and upper arm, particularly in the deltoid. You notice marked winging of the scapula. There is no passive limitation of movement.  What is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.