A 9-month-old boy is brought to the clinic by his parents for a well-child check. The mother says that he cannot roll over, sit without support, or crawl. The patient can reach for toys with his left hand but not with his right. He was born at 28 weeks gestation, and Apgar scores were 5 and 6 at 1 and 5 minutes, respectively. The patient's birth weight was 1.2 kg (2 lb 10 oz), and he was admitted to the neonatal intensive care unit for 3 months. Head circumference and length are at the 50th percentile; weight is at the 15th percentile. Vital signs are normal. On examination, the patient keeps his right hand fisted shut. Muscle tone and deep tendon reflexes are increased in the right arm and leg. Which of the following is the most likely cause of this patient's condition?

Question

A 9-month-old boy is brought to the clinic by his parents for a well-child check.  The mother says that he cannot roll over, sit without support, or crawl.  The patient can reach for toys with his left hand but not with his right.  He was born at 28 weeks gestation, and Apgar scores were 5 and 6 at 1 and 5 minutes, respectively.  The patient's birth weight was 1.2 kg (2 lb 10 oz), and he was admitted to the neonatal intensive care unit for 3 months.  Head circumference and length are at the 50th percentile; weight is at the 15th percentile.  Vital signs are normal.  On examination, the patient keeps his right hand fisted shut.  Muscle tone and deep tendon reflexes are increased in the right arm and leg.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec160b_39b4_209c_9249_4db872e7f5e9_MD0001_00 This premature infant has gross motor delay, hypertonia, and hyperreflexia, findings concerning for cerebral palsy (CP). CP is a nonprogressive neurologic injury that causes motor dysfunction. Spastic CP is the most common subtype and can affect the bilateral lower extremities (diplegia), unilateral arm and leg (hemiplegia), or in more severe cases, all four extremities (quadriplegia). CP is more common in premature and low birthweight infants because they are susceptible to white matter loss (ie, periventricular leukomalacia) around the lateral ventricles. In contrast to term infants, in whom watershed injury of the cerebral cortex is more likely to occur with poor perfusion, premature infants have sparse vascularization of the periventricular cerebral white matter. Ischemia to this area disrupts normal myelination, leading to neuronal cell death and cystic necrosis. In addition, prematurity is also associated with increased risk for intraventricular hemorrhage, which can further contribute to the development of CP. However, in some cases, no underlying cause is identified. Delayed gross motor milestones are often the first sign of CP in infancy, as seen in this patient (age 6 months when corrected for gestation) who cannot roll over or sit up. Early hand preference (age <1) is also common with spastic hemiplegia, as seen in this infant whose right hand remains fisted and unable to relax due to increased tone. (Choice A) Brachial plexus injuries are typically the result of birth trauma and present with arm weakness and low tone. Reflexes are usually diminished or absent in the affected upper extremity, and the lower extremities would not be affected. (Choice B) Diffuse cerebral atrophy can be seen in premature infants with cerebral palsy but would present with global neurologic deficits involving bilateral extremities. This patient's spastic hemiparesis is most likely due to a focal left-sided brain lesion. (Choice C) Holoprosencephaly is due to incomplete division of the forebrain during embryologic development. This brain abnormality can cause spasticity, but bilateral findings would be expected. In addition, a midfacial defect is typically present in these patients. (Choice D) Mesial temporal sclerosis is a characteristic MRI finding in patients with focal temporal lobe epilepsy and is not associated with CP. Moreover, the temporal lobe is responsible for sensory processing and memory formation, not motor function. Educational objective: Cerebral palsy is a nonprogressive neurologic injury that most commonly presents with delayed gross motor milestones, spasticity, and hyperreflexia. Premature infants are particularly susceptible due to periventricular leukomalacia (white matter necrosis).

A 9-Month-Old Boy Is Brought to the Clinic by His