Setting-sun sign refers to the downward deviation of an infant’s or young child’s eyes as a result of pressure on cranial nerves III, IV, and VI. With this late and ominous sign of increased intracranial pressure (ICP), both eyes are rotated downward, typically revealing an area of sclera above the irises; occasionally, the irises appear to be forced outward. Pupils are sluggish, responding to light unequally. (See Identifying setting-sun sign
The infant with increased ICP is typically irritable and lethargic, and feeds poorly. Changes in level of consciousness (LOC), lower-extremity spasticity, and opisthotonos may also be obvious. Increased ICP typically results from space-occupying lesions—such as tumors—or from an accumulation of fluid in the brain’s ventricular system, as occurs with hydrocephalus. It also results from intracranial bleeding or cerebral edema. Other signs include a globular appearance of the head (light bulb sign), a loss of upgaze, and distended scalp veins.
Setting-sun sign may be intermittent—for example, it may disappear when the infant is upright because this position slightly reduces ICP. The sign may be elicited in a normal infant younger than age 4 weeks by suddenly changing his head position, and in a normal infant up to age 9 months by shining a bright light into his eyes and removing it quickly.
HISTORY AND PHYSICAL EXAMINATION
If you observe the setting-sun sign in an infant, evaluate his neurologic status; then obtain a brief history from his parents. Has the infant experienced a fall or even a minor trauma? When did this sign appear? Ask about early nonspecific signs of increasing ICP: Has the infant’s sucking reflex diminished? Is he irritable, restless, or unusually tired? Does he cry when moved? Is his cry high pitched? Has he vomited recently?
Next, perform a physical examination, keeping in mind that neurologic responses are primarily reflexive during early infancy. Assess the infant’s LOC. Is he awake, irritable, or lethargic? Keeping in mind his age and level of development, try to determine his ability to reach for a bright object or turn toward the sound of a music box. Observe his posture for normal flexion and extension or opisthotonos. Examine muscle tone, and observe for seizure automatisms.
Examine the infant’s anterior fontanel for bulging, measure his head circumference and compare it with previous results, and observe his breathing pattern. (Cheyne-Stokes respirations may accompany increased ICP.) Check his pupillary response to light: Unilateral or bilateral dilation occurs as ICP rises. Finally, elicit reflexes
that are diminished in increased ICP, especially Moro’s reflex. Keep endotracheal intubation equipment available.
Increased ICP. Transient or intermittent setting-sun sign often occurs late in patients with increased ICP. The infant may have bulging, widened fontanels, increased head circumference, and widened sutures. He may also exhibit a decreased level of consciousness, behavioral changes, a high-pitched cry, pupillary abnormalities, and impaired motor movement as ICP increases. Other findings include increased systolic pressure, widened pulse pressure, bradycardia, changes in breathing pattern, vomiting, and seizures as ICP increases.
Care of the infant with setting-sun sign includes monitoring of vital signs and neurologic status. Elevate the head of the crib to at least 30 degrees, and monitor intake and output. Monitor ICP, restrict fluids, and insert an I.V. line to administer a diuretic. For severely increased ICP, endotracheal intubation and mechanical hyperventilation may be required to reduce serum carbon dioxide levels and constrict cerebral vessels. Therapy to induce a barbiturate coma or hypothermia therapy may be required to lower the metabolic rate.
Try to maintain a calm environment and, when the infant cries, offer comfort to help prevent stress-related ICP elevations. Perform nursing duties judiciously because procedures may further increase ICP. Prepare the child and family for surgical management of increased ICP and hydrocephalus as appropriate. Encourage the parents’ help, and offer them emotional support.