26th February 2025

A 25-year-old female with no past medical history is brought to the emergency department with left-sided weakness, which started 2 hours ago.

A 25-year-old female with no past medical history is brought to the emergency department with left-sided weakness, which started 2 hours ago. She is otherwise well, with no past medical history.

She works as a primary school teacher, does not smoke and drinks minimal alcohol. She is trying for pregnancy at the moment; however has unfortunately suffered 3 miscarriages in the past.

On examination, you notice a left facial droop, and power 4/5 throughout the left upper and lower limbs. Chest examination is clear, with normal heart sounds. You notice a lacework pattern rash on her thighs.

Urine pregnancy testing is negative.

Blood tests are performed, with results shown below:

 Syphilis serology: VDRL: positive; TPPA (Treponema pallidum particle agglutination): negative

CT head: hyperacute ischaemic right MCA territory infarct with acute thrombus within distal M1/proximal M2 branch of right MCA.

What is the most likely underlying diagnosis?

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