Setting sun sign is the downward deviation of an infant’s or young child’s eyes, producing a visible rim of sclera above the irises. It usually indicates increased intracranial pressure (ICP) from hydrocephalus, intracranial mass, hemorrhage, or cerebral edema. It may appear intermittently, sometimes disappearing when the infant is upright.

Although occasionally seen in healthy infants <4 weeks (or up to 9 months when stimulated), its persistence—especially with other neurologic symptoms—signals a late and ominous stage of raised ICP.

Pathophysiology

• Pressure on cranial nerves III, IV, and VI and the midbrain vertical gaze center interferes with upward gaze.

• Raised ICP causes downward rotation of both eyes, revealing scleral rim above irises.

• Associated effects:

  • Compression of brainstem structures controlling ocular movement

  • Venous congestion and stretching of ocular motor nerves

  • Progressive loss of upgaze as pressure increases

History and Physical Examination

History:

• Onset and duration of eye deviation

• Precipitating events: trauma, falls, infections, or space-occupying lesions

• Early symptoms of ICP: irritability, poor feeding, vomiting, high-pitched cry, reduced sucking reflex

• Developmental milestones and recent changes in alertness or activity

Physical Examination:

• Assess level of consciousness (awake, irritable, lethargic)

• Observe ocular position and pupillary reaction to light

• Inspect anterior fontanelle (bulging), sutures (widened), scalp veins (distended)

• Measure head circumference and compare with growth records

• Check muscle tone, posture (opisthotonos), and presence of seizure automatisms

• Observe breathing pattern (Cheyne–Stokes respirations may accompany ICP rise)

• Elicit primitive reflexes (e.g., Moro); diminished responses suggest worsening ICP

Medical causes

Special considerations

• Elevate head of crib 30° to improve venous drainage.

• Monitor vital signs, neurologic status, and head circumference.

• Restrict fluids and prepare for ICP monitoring.

• Insert IV line for diuretics (e.g., mannitol) or hypertonic saline if ICP rises.

• If severe, prepare for endotracheal intubation, controlled ventilation, barbiturate coma, or hypothermia therapy.

• Keep environment calm; avoid unnecessary handling to prevent ICP spikes.

• Prepare family for possible surgical treatment (shunt or mass removal).

Patient counseling

• Explain that persistent setting sun sign often reflects raised ICP and requires prompt evaluation.

• Discuss diagnostic tests (ultrasound, CT, MRI) and potential treatments (shunt, surgery).

• Teach parents to monitor for warning signs: worsening irritability, vomiting, bulging fontanelle, or seizures.

• Offer emotional support and encourage involvement in care.

Pediatric pointers

• Common in infants with hydrocephalus or post-hemorrhagic ventricular dilatation.

• Always assess in conjunction with other ICP signs: head enlargement, bulging fontanelle, altered feeding or cry.

• In healthy infants, ensure transient episodes are stimulus-related and not accompanied by neurologic decline.

References

1. Berkowitz CD. Berkowitz’s Pediatrics: A Primary Care Approach. 4th ed. USA: American Academy of Pediatrics; 2012.

2. Buttaro TM, Tybulski J, Bailey PP, Sandberg-Cook J. Primary Care: A Collaborative Practice. St. Louis, MO: Mosby Elsevier; 2008.

3. Sommers MS, Brunner LS. Pocket Diseases. Philadelphia, PA: F.A. Davis; 2012.