A 2-year-old boy is brought to the office for the first time by his parents for a well visit. The family recently moved to the area, and the child has not been seen for routine child care since age 12 months. No complications occurred during pregnancy, and the patient was born full term. At age 4 months, he was hypotonic; he did not sit unsupported until age 10 months. Three months ago, the patient developed spasticity and dystonia with involuntary movements of the hands and feet. Over the past month, he has started biting his fingers and hands, pinching himself, and banging his limbs against the wall. Family history is unremarkable. On examination, the patient is nonverbal and hypertonic. There is hyperreflexia of the upper and lower extremities and extensor plantar reflexes bilaterally. Several new and healing abrasions are present on the fingers and hands. Which of the following is the most likely diagnosis in this patient?

Question

A 2-year-old boy is brought to the office for the first time by his parents for a well visit.  The family recently moved to the area, and the child has not been seen for routine child care since age 12 months.  No complications occurred during pregnancy, and the patient was born full term.  At age 4 months, he was hypotonic; he did not sit unsupported until age 10 months.  Three months ago, the patient developed spasticity and dystonia with involuntary movements of the hands and feet.  Over the past month, he has started biting his fingers and hands, pinching himself, and banging his limbs against the wall.  Family history is unremarkable.  On examination, the patient is nonverbal and hypertonic.  There is hyperreflexia of the upper and lower extremities and extensor plantar reflexes bilaterally.  Several new and healing abrasions are present on the fingers and hands.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d6f6_5eff_bc81_5162adfe7935_MD0003_00 Lesch-Nyhan syndrome is an X-linked recessive disorder caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase, an enzyme involved in purine metabolism. This deficiency results in the accumulation of hypoxanthine and uric acid in the urine, serum, and central nervous system. The development of dopaminergic pathways appears to be particularly affected, which may explain the progressive neuropsychiatric manifestations of the condition. Presentation begins in early infancy with delayed milestones and hypotonia. By age 3, children develop the extrapyramidal symptoms of dystonia and chorea as well as the pyramidal symptoms of spasticity and hyperreflexia. A distinct finding in Lesch-Nyhan syndrome is self-mutilation (eg, biting of the fingers and hands, banging of the head and limbs), as shown in this child. In untreated, late disease, excessive uric acid can lead to gouty arthritis and obstructive nephropathy. (Choice A) Autism spectrum disorder may present with impaired language development and social skills as well as self-injurious behaviors. Severe motor abnormalities, such as dystonia and chorea, are not seen. (Choice B) Cerebral palsy is a nonprogressive motor disorder that can present with dystonia and spasticity. Lesch-Nyhan syndrome may be incorrectly diagnosed as cerebral palsy in infancy due to nonspecific neurologic findings; however, the distinguishing feature of self-mutilation in early childhood makes cerebral palsy unlikely. (Choice D) Phenylketonuria is caused by an accumulation of phenylalanine and presents with intellectual disability if untreated. Most cases are identified on routine newborn screening, and presentation does not include self-mutilation. (Choice E) Rett syndrome, a neurodevelopmental disorder in girls, is characterized by normal development until age 6 months, followed by regression of speech and motor function as well as development of stereotypical hand movements (eg, wringing). This patient is a boy who has had delayed milestones since early infancy and who has self-mutilating behaviors. (Choice F) Sydenham chorea is a manifestation of acute rheumatic fever, a sequela of a group A Streptococcus infection. Acute rheumatic fever does not typically occur in young children and is not associated with pyramidal symptoms (eg, spasticity). (Choice G) Tourette syndrome classically presents in school-age children with motor (eg, eye blinking) and vocal (eg, echolalia) tics. Patients do not have developmental delay or pyramidal/extrapyramidal symptoms. Educational objective: Lesch-Nyhan syndrome is caused by a deficiency in hypoxanthine-guanine phosphoribosyltransferase. Neurologic findings begin with developmental delay and hypotonia in infancy and progress to chorea, dystonia, and spasticity in early childhood. Cardinal findings include self-mutilation and gouty arthritis. References: Lesch-Nyhan syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/20301328) Lesch-Nyhan syndrome: models, theories, and therapies. (http://www.ncbi.nlm.nih.gov/pubmed/27920633)

A 2-Year-Old Boy Is Brought to the Office for the First