1st March 2024

A 32-year-old woman presents with progressive weakness. She is now struggling to grip objects

A 32-year-old woman presents with progressive weakness. She is now struggling to grip objects and perform everyday tasks. This improves after contracting her hands repeatedly for several seconds. On examination, she has increased hair loss along the forehead region, mild drooping of her eyelids bilaterally and unilateral foot drop. Percussion of her thenar eminence results in sustained contraction of the thenar muscles. An ECG shows a 1st-degree heart block.

Given the likely diagnosis, what is the likely aetiology for this condition

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