A 3-year-old presents with multiple poorly healing fractures, burn marks on his hands, and several missing teeth. His parents report he rarely cries with injury. He also has recurrent episodes of high fever, especially in warm weather, and his skin appears thick and calloused. This combination of congenital insensitivity to pain and anhidrosis (HSAN type IV) is caused by a loss-of-function variant in a gene encoding a receptor for what molecule?
A newborn, whose mother has myasthenia gravis, presents with generalized hypotonia, a weak suck, and respiratory insufficiency within 24 hours of birth. What is the underlying pathophysiology of this infant’s condition?
An infant is brought in for evaluation due to a weak cry, feeding difficulties, and early respiratory failure requiring ventilatory support. A chest x-ray reveals diaphragmatic eventration. His weakness is noted to be more prominent distally. These findings are most suggestive of which rare motor neuron disease?
A 4-month-old infant presents with severe, symmetric generalized muscle weakness, a frog-leg posture, and absent deep tendon reflexes. His parents report he has never achieved head control. What is the most definitive first-step diagnostic test for this condition?
A 9-month-old infant with congenital hypothyroidism presents with generalized hypotonia and proximal weakness. The pediatrician notes that the infant’s muscles appear unusually large, giving a “Herculean” appearance. What is the name of this syndrome characterized by pseudohypertrophy of weak muscles in cretinism?
An 8-year-old boy develops an acute, unilateral facial droop involving both his forehead and mouth two weeks after a mild upper respiratory infection. He has no other neurological deficits. Which virus is most commonly implicated in this condition?
A 16-year-old girl presents with progressive difficulty raising her arms overhead and prominent winging of her scapulae. She also reports that she has never been able to whistle or drink through a straw, and her family notes she sleeps with her eyes slightly open. The weakness appears more pronounced on her right side. In addition to muscle weakness, which of the following is an important associated feature to screen for in this patient?
A 2-year-old child of Ashkenazi Jewish descent is being evaluated for poor feeding, recurrent pneumonias, and developmental delay. On examination, he has absent deep tendon reflexes and a smooth-appearing tongue. Which clinical finding is considered a universal feature of familial dysautonomia (Riley-Day syndrome)?
A 10-year-old girl presents with a rigid spine, progressive scoliosis, and significant respiratory impairment that seems disproportionate to her mild proximal limb weakness. Her neck muscles are notably weak, giving her a “dropped-head” appearance, and she has an asthenic build. A pathogenic variant in which of the following genes is most likely responsible for this phenotype?
A 7-year-old develops rapidly symmetric weakness and areflexia, requiring hospitalization. The weakness began 12 days after a Campylobacter jejuni infection. A lumbar puncture is performed. Which cerebrospinal fluid finding is most characteristic of the underlying condition?