A 3-year-old girl is brought to the emergency department for sudden onset of weakness. She was well until this morning, when she woke up and was unable to climb out of bed. Her mother lifted her up, but the child was unable to bear weight on her right leg. She could not grasp her mother's hand to stand up. The patient has had no recent fevers or upper respiratory symptoms. She was adopted from Nigeria 6 months ago, and family history is unknown. The child has had no hospitalizations or illnesses since her adoption. Her developmental milestones have been appropriate for age. Temperature is 37.2 C (99 F), pulse is 140/min, and respirations are 18/min. The patient is awake and alert but has difficulty articulating. Her head is normocephalic and atraumatic. Pupils are 2 mm and react to light and accommodation. Tympanic membranes and pharynx are clear. Cardiovascular examination demonstrates tachycardia but normal S1 and S2 without murmurs. Lungs are clear on auscultation. There is significant weakness, hypotonia, and hyperreflexia of the right arm and leg. Neuroimaging studies are pending. Which of the following additional tests is most likely to reveal an underlying abnormality in this patient?

Question

A 3-year-old girl is brought to the emergency department for sudden onset of weakness.  She was well until this morning, when she woke up and was unable to climb out of bed.  Her mother lifted her up, but the child was unable to bear weight on her right leg.  She could not grasp her mother's hand to stand up.  The patient has had no recent fevers or upper respiratory symptoms.  She was adopted from Nigeria 6 months ago, and family history is unknown.  The child has had no hospitalizations or illnesses since her adoption.  Her developmental milestones have been appropriate for age.  Temperature is 37.2 C (99 F), pulse is 140/min, and respirations are 18/min.  The patient is awake and alert but has difficulty articulating.  Her head is normocephalic and atraumatic.  Pupils are 2 mm and react to light and accommodation.  Tympanic membranes and pharynx are clear.  Cardiovascular examination demonstrates tachycardia but normal S1 and S2 without murmurs.  Lungs are clear on auscultation.  There is significant weakness, hypotonia, and hyperreflexia of the right arm and leg.  Neuroimaging studies are pending.  Which of the following additional tests is most likely to reveal an underlying abnormality in this patient?

Quizplus · Accepted Answer

11ec25c8_d58c_6f42_bc81_ad9b5b82062b_MD0003_00 This patient presents with acute, focal neurologic deficits, which should raise concern for stroke. Clinical features of stroke typically include focal weakness, hemiparesis, aphasia, seizures, or altered mental status. Although stroke is more common in older adults, it can occur in children, and the most common cause of pediatric stroke is sickle cell disease (SCD). In addition, this patient's history of adoption from Nigeria, a country with a high prevalence of SCD, raises the likelihood of SCD. SCD is an autosomal recessive disorder in which a mutation in the beta globin chain of hemoglobin results in hemoglobin polymerization, red blood cell deformation, and microvascular occlusion. Diagnosis of SCD is made via hemoglobin electrophoresis, which can confirm the presence of sickle hemoglobin. Chronic vasoocclusion can result in endothelial damage, intimal proliferation, and eventual vascular stenosis, which increases the risk of cerebral ischemia, resulting in stroke. If concern for stroke exists, an MRI should be performed to confirm the diagnosis. (Choice A) The inflammation present in bacterial meningitis can result in vascular thrombosis and cerebral ischemia. Diagnosis is confirmed by bacterial culture of the cerebrospinal fluid. In the absence of fever, neck stiffness, or photophobia, meningitis is unlikely. (Choice B) Cardiac disorders, most commonly congenital, can cause ischemic stroke via many mechanisms, including cerebral ischemia from decreased cardiac output, paradoxical emboli (venous clot shunted across septum to arterial circulation), infective endocarditis with septic emboli, and intracardiac thrombus. Echocardiography can assess cardiac anatomy and function, but cardiac disorders are unlikely without known cardiac history or murmur. (Choice C) Seizures can be followed by Todd paralysis, which is focal weakness or paresis that typically resolves in minutes to hours after the event. Electroencephalography can assess for intermittent seizures or generalized slowing. Seizure is less likely in this patient given her garbled speech and no history of seizures. (Choice E) Mitochondrial myopathies, specifically mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS), can present with acute neurologic changes, including hemiparesis. Muscle biopsy can confirm this diagnosis. These myopathies are much less common than SCD. Further noninvasive workup (eg, serum lactate/pyruvate, creatine kinase) must be performed before biopsy even if MELAS is suspected. (Choice F) Urea cycle disorders result in hyperammonemia, which can cause acutely altered mental status. Most urea cycle disorders are diagnosed in the newborn period, and hyperammonemia leads to generalized confusion, not focal weakness. Educational objective: Sickle cell disease is the most common cause of pediatric stroke, and diagnosis can be confirmed by hemoglobin electrophoresis. References: Sickle cell disease and stroke: diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/26873822)

A 3-Year-Old Girl Is Brought to the Emergency Department for Sudden