A 3-year-old child presents with irritability, a 'sunset sign' (eyes forced downward), and enlarging head circumference. Fontanelle is tense. MRI shows periventricular T2 signal changes and ventricular enlargement. Vitamin A level is elevated (hypervitaminosis A). Which of the following is a correct pathophysiological link between hypervitaminosis A and raised intracranial pressure?

• A Excess retinol directly inhibits CSF absorption at arachnoid granulations
• B Hypervitaminosis A reduces aquaporin-4 expression in ependymal cells
• C Retinol in excess disrupts tight junctions of brain endothelium causing cerebral edema
• D Excess vitamin A increases CSF production by choroid plexus and may reduce CSF reabsorption via effects on dural venous sinuses ✓

Explanation

Hypervitaminosis A (acute toxicity from megadose supplements or chronic excess) causes pseudotumor cerebri/idiopathic intracranial hypertension. Excess retinoic acid is believed to increase CSF production by the choroid plexus and impair CSF resorption partly via effects on dural venous sinus pressures and arachnoid granulation function, raising ICP. This is a well-recognized clinical entity; treatment involves stopping vitamin A supplementation and using acetazolamide to reduce CSF production. The direct mechanism on arachnoid granulations (option A) is partly correct but the full mechanism involves both increased production and reduced resorption.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.