A 21-year-old hospitalized man is evaluated for confusion. He was admitted 2 days ago after an all-terrain vehicle rolled on top of him. He frequently binge-drinks alcohol and was drinking just prior to the incident. The patient has a right femoral midshaft fracture and right metatarsal fractures. He underwent operative fixation of the femoral fracture and received intravenous fluids and a blood transfusion. Cast immobilization of the metatarsal fractures was also performed. Temperature is 37.7 C (99.9 F), blood pressure is 130/80 mm Hg, pulse is 120/min, and respirations are 24/min. Pulse oximetry is 90% on room air and improves to 95% on 2 L of oxygen. The patient is restless, agitated, and confused. Breath sounds are normal and equal in both lungs. Cardiac auscultation is normal except for tachycardia. The abdomen is soft and nondistended. Left arm weakness is noted. Which of the following is the most likely cause of this patient's neurologic condition?

Question

A 21-year-old hospitalized man is evaluated for confusion.  He was admitted 2 days ago after an all-terrain vehicle rolled on top of him.  He frequently binge-drinks alcohol and was drinking just prior to the incident.  The patient has a right femoral midshaft fracture and right metatarsal fractures.  He underwent operative fixation of the femoral fracture and received intravenous fluids and a blood transfusion.  Cast immobilization of the metatarsal fractures was also performed.  Temperature is 37.7 C (99.9 F), blood pressure is 130/80 mm Hg, pulse is 120/min, and respirations are 24/min.  Pulse oximetry is 90% on room air and improves to 95% on 2 L of oxygen.  The patient is restless, agitated, and confused.  Breath sounds are normal and equal in both lungs.  Cardiac auscultation is normal except for tachycardia.  The abdomen is soft and nondistended.  Left arm weakness is noted.  Which of the following is the most likely cause of this patient's neurologic condition?

Quizplus · Accepted Answer

11ec25c8_d967_d488_bc81_fb7fb999d97f_MD0003_00 This patient's worsening respiratory status and neurologic dysfunction 2 days after a femur fracture are concerning for fat embolism syndrome (FES). FES occurs when fracture of a large, marrow-rich bone (eg, the femur) releases fat into the venous circulation. This may lead to mechanical disruption of capillary blood flow both in the pulmonary and the systemic circulation, which the fat emboli may enter as microemboli (small enough to pass through the pulmonary circulation) or via a shunt (eg, patent foramen ovale). Microvascular obstruction in the pulmonary capillaries can cause respiratory distress (eg, tachypnea, hypoxemia); in the systemic circulation (eg, brain, skin), it can cause neurologic dysfunction and/or petechiae. Neurologic dysfunction may range from confusion, visual field defects, or focal deficits (eg, left arm weakness) to seizures, obtundation, or coma. FES is typically diagnosed clinically; however, MRI of the brain is sometimes used and can visualize multiple small, hyperintense foci consistent with cerebral fat embolism. (Choice A) Sudden cessation of alcohol intake (eg, after hospitalization) may lead to severe alcohol withdrawal (eg, delirium tremens), which can cause confusion and autonomic hyperactivity (eg, tachycardia). However, focal neurologic deficits (eg, left arm weakness) and hypoxia are not expected. alcohol withdrawal (Choice B) Traumatic carotid artery dissection can cause cerebral ischemia with focal weakness but typically not respiratory distress. In addition, carotid dissection commonly presents with unilateral headache, neck pain, and/or ipsilateral partial Horner syndrome. carotid artery dissection (Choice D) Cerebral hemorrhage can be due to head trauma (eg, all-terrain vehicle accident) or stroke. However, hemorrhagic stroke would be unusual in this young patient and would likely be associated with hypertension. In addition, neurologic deficits (eg, confusion, unilateral weakness) associated with hemorrhage from head trauma typically progress over minutes to hours (vs days); and tachypnea with hypoxemia would be unusual. (Choice E) Cocaine (possibly used with alcohol) is a powerful vasoconstrictor that can cause cerebral vasospasm. Although the vasospasm may manifest as confusion or stroke-like symptoms, it typically occurs at the time of intoxication rather than 2 days after. (Choice F) Blunt head trauma can cause diffuse axonal injury, representing shearing of white matter tracts. Although neurologic symptoms can vary from mild (eg, headache, nausea) to severe (eg, coma), they typically present immediately after (vs 2 days after) injury and cause diffuse (vs focal) deficits. Educational objective: Fat embolism syndrome can occur following the fracture of large, marrow-rich bones (eg, the femur). Microvascular obstruction in the pulmonary circulation can lead to respiratory distress; obstruction in the cerebral circulation may cause neurologic dysfunction, including confusion and focal deficits. References: Fat embolism syndrome with cerebral fat embolism associated with long-bone fracture. (http://www.ncbi.nlm.nih.gov/pubmed/28005103) From the diagnosis to the therapeutic management: cerebral fat embolism, a clinical challenge. (http://www.ncbi.nlm.nih.gov/pubmed/30655686) Cerebral fat embolism syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/30972377)

A 21-Year-Old Hospitalized Man Is Evaluated for Confusion