**3.3 What types of cerebrovascular events occur in patients with APS?**

One of the unique aspects of APS is the diversity of types of vasculature involved—arteries and veins, small vessels, and large vessels. Multiple mechanisms of the prothrombotic state have been theorized and will be discussed in Section 4 of this chapter. APS has been implicated in multiple stroke etiologic subtypes including large-artery atherosclerosis, cardio-embolism, and small-vessel occlusion. However, the percentage breakdown between these etiologies has not been consistently reported.

As previously stated, APS is responsible for venous events as well as arterial events. In the cerebrovascular system, these include CVST. APS has been implicated in 6–17% of all cases of CVST and tends to predispose to CVST at a relatively younger age [44].

Vasculopathies, described in detail in Section 2, including Moyamoya and Sneddon's syndrome, overlap with APS at a rate of 21% and 50% respectively. Reversible cerebral vasoconstriction syndrome (RCVS) has also been described in patients with APS [46].

Other neurologic manifestations of the antiphospholipid syndrome include headache (20%), seizures (8%), and chorea (1.3–4.5%), with less frequent neurological manifestations including parkinsonism (especially progressive supranuclear palsy), dystonia, ballismus, myoclonus, cerebella ataxia, transverse myelitis, cognitive impairments, psychiatric symptoms, and peripheral neuropathy [4, 57].
