jueves, 11 de diciembre de 2014

AHRQ WebM&M: Morbidity and Mortality Rounds on the Web ► A Stroke of Error: Case & Commentary—Part 1, Commentary by Kevin M. Barrett, MD, MSc

AHRQ WebM&M: Morbidity and Mortality Rounds on the Web

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A Stroke of Error Spotlight Case
Commentary by Kevin M. Barrett, MD, MSc

Case & Commentary—Part 1

A 67-year-old man with a history of untreated hypertension presented to the emergency department (ED) after a fall. On presentation, he was noted to have a systolic blood pressure of 220 mm Hg and word-finding difficulties of unclear duration. Laboratory results were notable for an elevated troponin of 0.2 μg/L and an elevated creatinine of 1.9 mg/dL (but there was no baseline comparison for the latter). To further evaluate his neurologic deficit, the ED obtained a CT scan of his brain without contrast before admitting him to the cardiology service with a working diagnosis of hypertensive emergency. The head CT demonstrated extensive white matter hypoattenuation, which was greater than expected for his age, but no focal findings. The cardiology team ordered an MRI to further characterize these findings, but the patient was unable to tolerate it due to his altered mental status. Neurology was not formally consulted.

The initial neurologic evaluation of a patient with suspected stroke necessitates a rapid and focused assessment. The history should center on establishing the time of symptom onset or the time the patient was last known to be neurologically normal if the time of symptom onset cannot be confidently established. The interval between symptom onset and clinical assessment will determine whether acute reperfusion therapy for ischemic stroke can be considered. The neurologic examination should focus on identifying signs of lateralized hemispheric or brainstem dysfunction consistent with stroke. The National Institutes of Health Stroke Scale (NIHSS) is a validated 15-item scale (Table) that assesses key components of the standard neurologic examination (1) and has been widely adopted into routine clinical practice. Brain imaging is the only reliable means to differentiate between ischemic and hemorrhagic stroke.(2,3) Non-contrast head computed tomography (CT) is the imaging modality most readily available in most stroke centers. CT is sensitive to intracranial hemorrhage and may be rapidly performed as part of the acute stroke evaluation.

Blood pressure is commonly elevated in patients with acute stroke and may be related to the stress of cerebral infarction, pre-existing hypertension, or a response to increased intracranial pressure.(4) Arterial blood pressure spontaneously declines in most patients with ischemic stroke within the first 24 hours of admission.(5) Extreme elevations of blood pressure can result in end-organ damage manifesting as cerebral, cardiac, or renal dysfunction. In this case, the elevated serum troponin and creatinine may have indicated cardiac and renal involvement secondary to uncontrolled systolic blood pressure. Disturbances of cerebral function due to hypertension typically result in diffuse symptoms that may include headache, change in mental status, or seizures. Focal symptoms are less common. In the acute setting, it may be difficult to differentiate between blood pressure elevation as the primary cause of end-organ dysfunction or as a secondary consequence of stroke. Framing effects, anchoring, and overreliance on test results are potential sources of diagnostic error.(6)

Neurological consultation in the emergency department can be considered when signs or symptoms of central or peripheral nervous system dysfunction are evident. Many common neurological presentations, such as migraine headache, can be reliably diagnosed and effectively treated by emergency department providers without neurological consultation. Patients with transient or persistent symptoms suggestive of hemispheric, brainstem, cerebellar, or retinal dysfunction warrant neurological consultation. In this case, the presentation was sufficiently complex to warrant neurological consultation in the emergency department. Detailed neurological examination by an experienced neurologist may identify subtle localizing signs suggestive of a vascular event and reduce the risk of missing an opportunity to offer acute reperfusion therapy to a potentially eligible patient. In hospitals without timely access to on-site neurological expertise, telemedicine has been leveraged to provide remote teleneurological evaluation.(7)

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