A 15-month-old boy is brought to the emergency department by ambulance after an episode of "jerking movements" at home. The patient was sitting in the living room with his toys when he suddenly developed uncontrollable rhythmic jerking of his extremities that lasted approximately 2 minutes. His eyes deviated leftward, and he was nonresponsive during this event. The patient did not hit his head before or after the incident. He creeps but has not begun crawling or pulling to stand. The patient says "mama" but speaks no other words. Growth parameters are at the 50th percentile for age and sex. His vital signs are within normal limits. Physical examination shows hypopigmented lesions on the patient's back. Cardiopulmonary examination is unremarkable. Item 1 of 2 Which of the following tests should be performed in evaluation of this patient?

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Explanation: 11ec2b69_c00b_9e90_8f63_534555e94761_MD0005_00 11ec2b69_c00b_9e91_8f63_d12d62304a7e_MD0005_00 This child's seizure, hypopigmented skin lesions ("ash-leaf spots"), and mild developmental delays are concerning for tuberous sclerosis complex (TSC). TSC is caused by a mutation in 1 of 2 proteins, hamartin (TSC1 gene) or tuberin (TSC2 gene). These proteins form a complex that plays a role in cell division and differentiation. Mutations in these genes can be inherited in an autosomal dominant fashion, or they can be a de novo mutation (>80% of cases). Affected patients can develop benign tumors throughout the body, including the skin (eg, "ash-leaf spots," angiofibromas, shagreen patches), central nervous system (eg, glioneuronal hamartomas - the "tubers" of TSC), heart (eg, rhabdomyomas), and kidney (eg, angiomyolipoma). The initial evaluation of a patient with suspected TSC should include a thorough cutaneous examination, funduscopy, and a brain MRI to evaluate for hamartomas. An electroencephalogram (EEG) is also indicated, as seizures are a predominant symptom that generally worsens over time. Seizures can be focal, general tonic-clonic, or subclinical (eg, behavioral changes). Normal EEGs serve as a baseline for future testing, while abnormal EEGs require antiepileptic therapy. Abdominal imaging to evaluate for renal lesions is recommended. If the diagnosis is uncertain, genetic testing for mutations in TSC1 and TSC2 can be performed. (Choice A) Cardiac rhabdomyomas usually develop in utero and are seen commonly during antenatal sonography. Most rhabdomyomas are asymptomatic and resolve spontaneously during infancy. Routine echocardiography is not recommended in asymptomatic patients with suspected TSC. (Choice C) The gene mutations of TSC1 or TSC2 cannot be identified on routine karyotyping nor is genetic testing indicated as part of the initial evaluation for suspected TSC. (Choice D) Cerebrospinal fluid is normal in patients with TSC. In the absence of suspected infection (as in this patient), lumbar puncture provides no additional information. Instead, brain imaging should be initiated. (Choice E) Hypocalcemia from hypoparathyroidism can lead to seizures. However, this child has cutaneous findings (hypopigmented skin lesions) and developmental delays that are suspicious for TSC, and so evaluation for TSC takes precedence over testing for other rare causes of seizures. Educational objective: Tuberous sclerosis complex is a genetic syndrome that leads to benign tumors throughout the body. Clinical manifestations most commonly include cutaneous and central nervous system involvement. The initial evaluation should include a thorough skin examination, central nervous system and abdominal imaging, and electroencephalography if seizures are suspected. References: Cortical tubers, cognition, and epilepsy in tuberous sclerosis. (http://www.ncbi.nlm.nih.gov/pubmed/21481739) Long-term neurological outcome in children with early-onset epilepsy associated with tuberous sclerosis. (http://www.ncbi.nlm.nih.gov/pubmed/22142783) The Tuberous Sclerosis 2000 Study: presentation, initial assessments and implications for diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/21813552)

A 15-Month-Old Boy Is Brought to the Emergency Department by Ambulance