Which condition is likely indicated by an asymmetrical Moro reflex?

An asymmetrical Moro reflex can indicate a neurological issue, and one of the primary conditions associated with this finding is Erb's palsy. The Moro reflex, or startle reflex, is a common reflex in infants that typically involves the symmetric motion of extending the arms and legs when they feel a sensation of falling or are startled. However, if the reflex is asymmetrical—meaning the response is different on one side—this can suggest damage to the nerves that control arm movement.

In cases of Erb's palsy, which is often caused by trauma during delivery (such as shoulder dystocia), the affected arm typically does not respond as vigorously as the uninjured arm due to nerve injury, specifically to the upper trunk of the brachial plexus. This difference in reflex response not only highlights the possible neurologic impairment but also directs clinicians toward further evaluation and diagnosis of the extent of nerve damage.

Other conditions listed might not exhibit asymmetrical responses in the Moro reflex. For example, cephalhematoma is associated with a collection of blood between the skull and its outer covering, which generally does not affect reflexes asymmetrically. Hydrocephalus involves increased intracranial pressure and can lead to developmental concerns but does not