**2.4 Other neurologic manifestations**

While intracranial hemorrhage (ICH) is not a common manifestation of APS, there have been reports of reversible vasoconstriction syndrome (RCVS) [46] which is characterized by thunderclap headaches (severe pain peaking in seconds), and focal neurologic deficits.

Moyamoya disease, a progressive narrowing of cerebral vasculature with collateralization, has also been reported to have associations with APS. Of the 16 cases reported in a small series of moyamoya and aPL, 21% fulfilled APS criteria [47].

Sneddon syndrome is a rare entity that may be considered during workup for APS. It is a chronic disorder, usually non-inflammatory, notable for generalized livedo racemosa (which may be confused with livedo reticularis seen in APS), and recurrent strokes [48]. Livedo racemosa is characterized by a violaceous netlike patterning of the skin similar to the familiar livedo reticularis, although it differs by its location (more generalized and widespread, found not only on the limbs but also on the trunk and/or buttocks). Approximately 40–50% of patients with Sneddon's syndrome present aPL antibodies, suggesting that some patients should be classified as APS [49].

Cognitive dysfunction has been reported 19–40% in aPL-positive patients [50]. While many believe that the cognitive decline is due to multiple subcortical infarcts, there have been theories that it is multifactorial, with genetic predisposition, antibody specificity, and direct antibody effects as potential contributors [51].

Migraines are the most prevalent neurologic manifestation in APS, estimated prevalence of around 20% [52].

Other rare clinical manifestations of APS include seizures, acute ischemic encephalopathy, transverse myelitis, amaurosis fugax, optic neuropathy, and other neuropsychiatric disorders.
