In a premature infant with hypertonic lower extremities and brisk reflexes, what is the most likely diagnosis?

In a premature infant exhibiting hypertonic lower extremities and brisk reflexes, the clinical presentation is most suggestive of cerebral palsy. This condition often arises from injury to the brain during development, which can occur in the context of premature birth due to factors such as intraventricular hemorrhage or other perinatal insults.

Hypertonicity in the limbs, particularly when observed as increased tone in the lower extremities, along with brisk reflexes, points towards an upper motor neuron lesion. Cerebral palsy is characterized by a range of motor dysfunction due to such lesions, often manifesting as spasticity and hyperreflexia. The context of prematurity further supports this diagnosis, as infants born preterm are at heightened risk for the types of neurological injuries that can lead to cerebral palsy.

Other options do not align with the observed signs. Spinal muscular atrophy typically presents with reduced muscle tone (hypotonia) and weakness rather than hypertonicity and increased reflexes. Neuromuscular junction disorders are characterized by fluctuating muscle weakness and fatigability rather than hypertonicity and brisk reflexes. Muscular dystrophies are generally associated with progressive muscle weakness and atrophy, which again contradicts the findings of