An infant born at 28 weeks gestation suffered a grade III germinal matrix hemorrhage in the first week of life. At 4 weeks of age the head circumference is crossing centiles upward and the anterior fontanelle is full. Imaging shows dilatation of all four ventricles out of proportion to sulcal size. The hydrocephalus results primarily from which mechanism?

• A Obstruction at the aqueduct of Sylvius by clot
• B Impaired CSF absorption through arachnoid granulations ✓
• C CSF overproduction by choroid plexus papilloma
• D Outflow obstruction at the foramina of Magendie and Luschka

Explanation

Posthemorrhagic hydrocephalus after intraventricular hemorrhage is classically a communicating hydrocephalus: blood breakdown products and inflammatory debris impair CSF reabsorption across the arachnoid granulations, producing dilatation of all ventricles including the fourth. Obstruction at the aqueduct would spare the fourth ventricle and produce disproportionate lateral and third ventricular enlargement instead.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.