In a 2-week-old infant with irritability, rapid head growth, and distended scalp veins, which diagnosis is most likely?

In a 2-week-old infant with irritability, rapid head growth, and distended scalp veins, which diagnosis is most likely?

• A. Syndrome of inappropriate antidiuretic hormone (SIADH)
• B. Hydrocephalus
• C. Cerebral palsy
• D. Reye's syndrome

Answer: (B)

In infants, rapid head growth with irritability and distended scalp veins points to increased intracranial pressure from accumulating cerebrospinal fluid, i.e., hydrocephalus. Because the skull sutures aren’t yet fused, the head can enlarge as the ventricles dilate. The irritability reflects the infant’s discomfort from rising pressure, and the visible scalp veins come from venous congestion as pressure climbs. The other options don’t fit this pattern. SIADH would cause fluid and electrolyte disturbances without the characteristic rapid enlargement of the head or scalp vein prominence. Cerebral palsy is a chronic motor disorder usually evident later with abnormal tone and movement, not an acute head-growth pattern in a 2-week-old. Reye’s syndrome involves hepatic failure and encephalopathy after a viral illness, not a primary sign of increasing head size.

In infants, rapid head growth with irritability and distended scalp veins points to increased intracranial pressure from accumulating cerebrospinal fluid, i.e., hydrocephalus. Because the skull sutures aren’t yet fused, the head can enlarge as the ventricles dilate. The irritability reflects the infant’s discomfort from rising pressure, and the visible scalp veins come from venous congestion as pressure climbs.

The other options don’t fit this pattern. SIADH would cause fluid and electrolyte disturbances without the characteristic rapid enlargement of the head or scalp vein prominence. Cerebral palsy is a chronic motor disorder usually evident later with abnormal tone and movement, not an acute head-growth pattern in a 2-week-old. Reye’s syndrome involves hepatic failure and encephalopathy after a viral illness, not a primary sign of increasing head size.