'Non-criteria' neurologic manifestations of antiphospholipid syndrome: a hidden kingdom to be discovered

Neurological manifestations or disorders associated with the central nervous system are among the most common and important clinical characteristics of antiphospholipid syndrome (APS). Although in the most recently updated (2006) APS classification criteria, the neurological manifestations encompass only transient ischemic attack and stroke, diverse 'non-criteria' neurological disorders or manifestations (i.e., headache, migraine, bipolar disorder, transverse myelitis, dementia, chorea, epileptic seizures, multiple sclerosis, psychosis, cognitive impairment, Tourette's syndrome, parkinsonism, dystonia, transient global amnesia, obsessive compulsive disorder and leukoencephalopathy) have been observed in APS patients. To date, the underlying mechanisms responsible for these abnormal neurological manifestations in APS remain unclear. In vivo experiments and human observational studies indicate the involvement of thrombotic events and/or high titers of antiphospholipid antibodies in the neuro-pathogenic cascade of APS. Although different types of neurologic manifestations in APS patients have successfully been treated with therapies involving anti-thrombotic regimens (i.e., anticoagulants and/or platelet antiaggregants), antineuralgic drugs (i.e., antidepressants, antipsychotics and antiepileptics) and immunosuppressive drugs alone or in combination, evidence-based guidelines for the management of the neurologic manifestations of APS remain unavailable. Therefore, further experimental, clinical and retrospective studies with larger patient cohorts are warranted to elucidate the pathogenic linkage between APS and the central nervous system in addition to randomized controlled trials to facilitate the discovery of appropriate medications for the 'non-criteria' neurologic manifestations of APS.