26th August 2024

A 19-year-old man presents with problems with weakness of his arms. His girlfriend has noticed

A 19-year-old man presents with problems with weakness of his arms. His girlfriend has noticed recently that he seems to smile less and generally seems less expressive.

On examination, you note weakness of facial muscles with inability to whistle or close his eyes tightly. He also has marked winging of his scapulas, marked weakness of his upper arms bilaterally, and an exaggerated lumbar lordosis. Signs seem to be more marked on the right-hand side.

What is the most important investigation to establish the diagnosis?

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