Differential Diagnosis for a 3-Month-Old Baby with a Large Head, Poor Feeding, Vomiting, Dilated Scalp Veins, and Eyes Deviated Downward

• Single Most Likely Diagnosis
  • Hydrocephalus (Obstruction of CSF flow): The symptoms described, such as a large head (macrocephaly), poor feeding, vomiting, dilated scalp veins, and eyes forcibly deviated downward (setting-sun sign), are classic for hydrocephalus. This condition is characterized by an accumulation of cerebrospinal fluid (CSF) within the brain, leading to increased intracranial pressure. The most common cause in infants is obstruction of CSF flow, which can be due to various reasons like congenital malformations or acquired conditions.
• Other Likely Diagnoses
  • CSF Overproduction: Although less common, overproduction of CSF can also lead to hydrocephalus. Conditions like choroid plexus papilloma can cause this.
  • Decreased CSF Absorption: This can occur due to conditions affecting the arachnoid villi, such as inflammation or hemorrhage, leading to impaired CSF absorption and subsequent hydrocephalus.
• Do Not Miss Diagnoses
  • Brain Tumor: Although less likely than hydrocephalus, a brain tumor could cause increased intracranial pressure and some of the symptoms described, such as vomiting and poor feeding. It's crucial to consider this diagnosis due to its severe implications.
  • Intracranial Hemorrhage: This could also lead to increased intracranial pressure and some of the symptoms mentioned. It's a critical condition that requires immediate attention.
• Rare Diagnoses
  • Dandy-Walker Malformation: A congenital malformation involving the cerebellum and the fourth ventricle, which can lead to hydrocephalus.
  • Vein of Galen Malformation: A rare congenital condition where there's an abnormal connection between arteries and veins in the brain, leading to high-output heart failure and increased intracranial pressure, which might present with some similar symptoms.

Each of these diagnoses has the potential to explain some or all of the symptoms presented by the 3-month-old baby. However, hydrocephalus due to obstruction of CSF flow is the most likely diagnosis given the combination of symptoms described.