moyamoya), and hypercoagulable states (e.g., antithrombin III, protein C and S deficiencies, and factor V Leiden mutations) Other more common hypercoagulable states include pregnancy, malignancy, infections, and severe dehydration Recent studies have shown increased risk associated with hypertension, diabetes, obesity, and hypercholesterolemia in younger teenage populations Substance abuse with tobacco, alcohol, cocaine, and amphetamines are also associated with cerebral infarction Atherosclerosis and atrial fibrillation, common culprits in adult stroke, remain rare causes of stroke in children Embolic causes that should be considered in pediatric patients include children with congenital heart disease, mitral valve prolapse, or a history of rheumatic fever Transient ischemic attacks (TIAs) often present with resolving weakness TIAs are defined as transient neurologic deficits referable to a cerebral artery territory in a child whose cranial magnetic resonance imaging (MRI) shows no acute ischemia, but whose history/workup suggests cerebrovascular disease Transient focal deficits are common after a seizure and are called Todd paralysis Deficits usually resolve within minutes to hours after a seizure, but one study demonstrated a mean symptom duration of 15 hours and persistence of up to 36 hours In this same study, 8/14 patients with Todd paralysis had an underlying CNS lesion Because a Todd paralysis resolves with time, if the patient is regaining function in 30 to 45 minutes, the differential diagnosis should be broadened to ensure a cerebrovascular event or mass lesion is not the cause of the focal weakness Cranial imaging is crucial in cases of prolonged postictal paralysis, especially if the mental status remains impaired, or if other focal deficits persist The reference standard study is MRI However, access to MRI may be limited or may not be immediately practical (e.g., need for deep sedation) Consequently, a computed tomography (CT) scan of the head is often the initial study of choice The head CT is most useful to rule out acute bleeds and large mass lesions In some cases, a CT angiogram is necessary to identify vascular lesions or anomalies Traumatic injuries may seriously damage or compress the spinal cord Spinal cord concussion is defined as a transitory disturbance in spinal cord function caused by a direct blow to the back Symptoms may include flaccid paraplegia or quadriplegia, a sensory level at the site of injury, loss of tendon reflexes, and urinary retention Recovery usually begins within a few hours and is usually complete within a week Spinal epidural hematoma may cause spinal cord compression as the hematoma expands Emergent spinal MRI scanning is indicated when an epidural hematoma is suspected Other traumatic injuries