A 3-year-old boy with a history of a unilateral, irregular stenosis of his proximal middle cerebral artery presents with a second arterial ischemic stroke. His initial stroke occurred 14 months ago following a varicella infection. Follow-up vascular imaging now shows progressive occlusion of his distal internal carotid arteries bilaterally. What is the most likely underlying diagnosis?
A 9-year-old girl presents with simultaneous onset of bilateral severe vision loss and paraparesis requiring ventilatory support. An orbital MRI shows longitudinally extensive optic neuritis involving the chiasm. A spinal MRI shows a longitudinally extensive transverse myelitis lesion. Serology is positive for myelin oligodendrocyte glycoprotein (MOG) antibodies. Which feature is more characteristic of her MOG-antibody-associated disease (MOGAD) than of aquaporin-4 (AQP4)-antibody-positive neuromyelitis optica spectrum disorder (NMOSD)?
A 5-year-old girl, diagnosed with classic Rett syndrome based on a period of developmental regression, loss of purposeful hand movements, and a pathogenic variant in MeCP2, has shown some stabilization but continues to have significant autistic behaviors and motor impairment. Her parents inquire about new, targeted therapies. Which medication is specifically approved for the treatment of Rett syndrome?
A 3-year-old boy presents with new-onset myoclonic seizures preceded by delayed language acquisition, followed by progressive ataxia and dementia. Fundoscopic examination reveals marked retinal vessel attenuation and optic atrophy. Genetic testing identifies biallelic pathogenic variants in the TPP1 gene, confirming deficient tripeptidyl peptidase-1 enzyme activity. What is the most likely diagnosis?
A 12-year-old girl presents with refractory status epilepticus. MRI shows inflammatory, contrast-enhancing parenchymal lesions not restricted to major vascular territories, and angiography is normal. CSF shows a mild lymphocytic pleocytosis. Which finding is most suggestive of small-vessel childhood primary angiitis of the CNS (SVcPACNS) over a demyelinating disorder?
A 14-year-old girl with a Chiari I malformation is found to have a large syringomyelia extending the length of her spinal cord on MRI. What is the most appropriate initial surgical management for her condition?
A 7-year-old child presents with an insidious onset of back pain that awakens him from sleep and a subtle gait disturbance. An MRI reveals a gadolinium-enhancing mass located within the substance of the thoracic spinal cord. A biopsy is performed. Which of the following is the most common histology for an intramedullary spinal cord tumor in a child?
A 15-year-old female with focal seizures is poorly controlled on levetiracetam. The clinician wants to add an agent that is least likely to have significant pharmacokinetic interactions with her current medication or require dose adjustments based on enzyme induction or inhibition. Which of the following is exclusively excreted by the kidney and would fit this requirement?
An 20-month-old girl with no significant past medical history is brought in for evaluation of breath-holding spells. The episodes are triggered by minor bumps, start with a silent cry and marked pallor, and are sometimes followed by brief tonic posturing. The presence of which of the following syndromes should be specifically ruled out?
A 10-year-old child living in a rural region of Uganda presents with daily episodes of involuntary, rapid, forward head-bobbing spells that last several minutes. These episodes are often triggered when he eats. On exam, he has stunted growth and cognitive delays. Which infectious organism is most strongly implicated as a trigger for this autoimmune-mediated epileptic disorder?
