Protein S deficiency manifesting with cerebral arterial and venous thrombosis in a young female with kissing carotids phenomenon.

Background: Majority of people with "kissing carotids", an anatomical variation of the cervical carotid arteries showing tortuosity, kinking or coiling and coming in proximity at the midline are asymptomatic. Less than 1% of the general population have Protein S Deficiency. This report discusses a rare case of a young female with co-existent Protein S deficiency and kissing carotids, who presented with sequential thrombosis in both arterial and venous cerebral circulation systems and further discusses potential mechanisms of arterial thrombosis in Protein S deficiency and medical options for secondary stroke prophylaxis in this context.

Case presentation: A 29-year-old female presented with sudden left hemiparesis and dysarthria. Index Brain MRI revealed acute non-haemorrhagic infarcts in the right middle cerebral artery (MCA) territory. Index brain MRA of cerebral vessels revealed abrupt cut off of the right MCA M1 segment following arterial thrombosis with extracranial kissing internal carotid arteries. Interval imaging of her brain and cerebral vasculature on day 4 of admission following a convulsion revealed left transverse cerebral venous sinus thrombosis. Laboratory workup confirmed low Protein S activity of only 18% (normal 55-123). She was started on rivaroxaban for lifelong secondary arterial stroke prophylaxis.

Conclusions: This is an index sub-Saharan case report of a young female with co-existent Protein S deficiency and kissing carotids phenomenon presenting with sequential cerebral arterial and venous thromboses. Potential mechanisms of arterial thrombosis in Protein S deficiency in which case warfarin may not be a preferred singular option for secondary arterial stroke prophylaxis are discussed.