A 6-month-old infant is examined during immunization follow-up. On sudden head extension, there is still a full Moro response with abduction and then adduction of the limbs. The examiner notes this reflex was prominent at birth and has never changed in character. What does persistence of the Moro reflex at this age indicate?
- A An abnormal sign suggesting an upper motor neuron lesion such as cerebral palsy ✓
- B A normal finding up to 9 months of age
- C Benign familial exaggerated startle, requiring no workup
- D Sensory neural deafness affecting startle integration
Correct answer: A. An abnormal sign suggesting an upper motor neuron lesion such as cerebral palsy
Explanation
The Moro reflex is present at birth and should disappear by 3 to 4 months, certainly by 6 months. Persistence beyond this period indicates failure of cortical maturation and suppression of primitive reflexes, classically seen in spastic cerebral palsy or other upper motor neuron disorders. Option C describes hereditary hyperekplexia, a separate disorder with lifelong exaggerated startle, not a persistent neonatal Moro.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.