A 3-month-old infant born to a mother with primary CMV infection during the first trimester presents with developmental delay, microcephaly, and progressive bilateral sensorineural hearing loss. Neuroimaging reveals periventricular calcifications. The virus marked **D** in the diagram is responsible for this clinical presentation. Which of the following is the MOST COMMON congenital manifestation of the infection caused by the organism at **D**?

Explanation

## Why Sensorineural hearing loss (often delayed onset) is right CMV (HHV-5), marked as **D**, is the MOST COMMON congenital viral infection in newborns and the MOST COMMON viral cause of congenital sensorineural hearing loss. The hearing loss is often progressive and may have delayed onset (appearing weeks to months after birth), making it a hallmark and frequently the most clinically apparent manifestation. This is a core fact from Murray 9e and Harrison 21e Ch 192, and distinguishes CMV from other TORCH agents. ## Why each distractor is wrong - **Diffuse intracranial calcifications with hydrocephalus**: This is the classic imaging triad of TOXOPLASMOSIS (not CMV). Congenital CMV causes PERIVENTRICULAR (not diffuse) calcifications and does not typically cause hydrocephalus as a primary feature. - **Congenital cataracts with chorioretinitis**: While chorioretinitis can occur in congenital CMV, congenital cataracts are the hallmark of RUBELLA (not CMV). CMV causes chorioretinitis more commonly in immunocompromised adults (HIV/AIDS with CD4 < 50). - **Microcephaly with intracranial hemorrhage**: Although microcephaly is a feature of congenital CMV, intracranial hemorrhage is not a primary manifestation. Microcephaly alone is not the MOST COMMON presenting feature; hearing loss is. **High-Yield:** Congenital CMV = most common congenital infection + most common viral cause of congenital hearing loss (often delayed); periventricular calcifications (not diffuse) on imaging; "blueberry muffin" rash from extramedullary hematopoiesis. [cite: Murray 9e; Harrison 21e Ch 192]