Overview
Neuroimaging has become a key diagnostic tool in the emergency department. Complaints of weakness, dizziness, headache, and trauma lend themselves to rapid evaluation and diagnosis through the use of computed tomography (CT) and magnetic resonance imaging (MRI). This article focuses on the basic principles and key considerations in ordering and interpreting neuroimaging in the emergency department in conjunction with the radiologist.
Trauma is the leading cause of death in patients younger than 45 years. Cranial trauma accounts for a substantial proportion of morbidity and mortality in all age groups and is the leading cause of death in patients younger than 30 years. Accurate, rapid, noninvasive assessment of people with cranial trauma is required for appropriate triage and management.
Approximately 1.4 million people sustain traumatic brain injury (TBI) annually in the United States resulting in more than 50,000 deaths. TBI is twice as likely in men as in women. Children (< 14 y) and elderly persons (>60 y) are at the highest risk for TBI and TBI-related hospitalizations and death, respectively. Child abuse accounts for more than 1 million cases of TBI each year. The overall direct and indirect medical costs including lost productivity and permanent disability from TBI totaled an estimated $60 billion in the United States in 2000.
Computed tomography is the diagnostic procedure of choice for acute injury, while magnetic resonance imaging has greater value for evaluation in the subacute and long term.
Although TBI from closed head and penetrating trauma account for the majority of cerebral injuries, other processes, such as acute cerebral infarction (stroke) or subarachnoid hemorrhage (SAH) due to rupture of intracranial aneurysms, may mimic a traumatic injury on presentation and radiologic evaluation.
Another major indication for neuroimaging in the emergency department is stroke. Stroke is the third leading cause of death in the United States behind heart disease and cancer and is the leading cause of long-term disability.
An estimated 80-85% of strokes are ischemic (either thrombosis or embolism), whereas 15-20% of strokes are hemorrhagic. Stroke syndromes can present along a wide spectrum of disease from transient ischemic attacks with complete resolution of symptoms to large intracranial hemorrhages with uncal or tonsillar herniation. Rapid evaluation and neuroimaging is standard of care for all patients with suspected strokes and guides the decision to administer thrombolytics, intra-arterial intervention, or medical management. Also see Ischemic Stroke in Emergency Medicine and Hemorrhagic Stroke.