<unk>  is a sign of insufficient cerebral blood flow and it should be evaluated for the underlying cause. Possible underlying risk factors of cardiac<unk>  include older age (>60 y), male sex, presence of known ischemic heart disease, structural heart disease, previous arrhythmias, or reduced ventricular function, brief prodromes such as palpitations or sudden loss of consciousness  without a prodrome,<unk>  during exertion,<unk>  in the supine position, low number of<unk>  episodes (1 or 2), abnormal cardiac examination, family history of inheritable conditions or premature  sudden cardiac death (SCD) (<50 y of age), or presence of known congenital heart disease. Common risk factors associated with noncardiac causes of<unk>  include younger age, no known cardiac disease,<unk>  only in the standing position, positional change from supine or sitting to standing, presence of prodrome: nausea, vomiting, feeling warm, presence of specific triggers ||||( dehydration, pain, stressful stimulus, medical environment), situational triggers( cough, laugh, micturition, defecation, deglutition), history of<unk>  with similar characteristics and frequent recurrence
Syncope risk factors
Heat stroke risk factors
Ischemic stroke risk factors
Headache risk factors
Sleep Apnea risk factors
Bradycardia risk factors
Transient ischemic attack risk factors
Epilepsy risk factors