26th June 2023

A 40-year-old lady presents with a 4-month history of progressive double vision. On examination, she has a right-sided facial palsy

A 40-year-old lady presents with a 4-month history of progressive double vision. On examination, she has a right-sided facial palsy involving her forehead and mouth. She also reports loss of sensation over the right side of her face. On examination, she has maximal double vision on looking laterally to her right. Peripheral nerve examination of the limbs is normal. A cerebellar examination, otoscopy and fundoscopy findings are all normal, and she has no speech, hearing, or swallowing difficulty.

What is the most likely unifying cause of her symptoms?