13th February 2025

A 30-year-old female, complaining of pins and needles in her fingertips, presents with double vision.

A 30-year-old female, complaining of pins and needles in her fingertips, presents with double vision.

On looking to the left there is nystagmus in the left eye and there appears to be limitation of adduction in the right eye. On rightward gaze, eye movements are normal.

On further questioning, she states that she has had previous episodes of loss of vision in the right eye with pain on eye movement which self resolved after 3 weeks. She also mentions that her symptoms worsen sometimes when she takes a hot bath. She has no other significant past medical history.

Which investigation is most likely to be useful for diagnosis?

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