From the Research
The setting sun appearance in hydrocephalus occurs due to increased intracranial pressure causing downward displacement of the eyes and impaired upward gaze. This condition is a result of the pressure exerted by the accumulation of cerebrospinal fluid (CSF) in the brain, which pushes the brain upward and causes the eyes to be displaced downward with the upper eyelids retracted. The provided evidence 1, 2, 3, 4, 5 primarily focuses on the comparison of surgical procedures for hydrocephalus, such as endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS), rather than the pathophysiology of the setting sun appearance. However, it is essential to understand that the setting sun appearance is a clinical indicator of increased intracranial pressure, which can be caused by hydrocephalus. The downward gaze occurs due to pressure on the midbrain tectum, which contains centers for vertical eye movement control, disrupting normal eye movement pathways and resulting in impaired upward gaze. This sign is most commonly seen in infants with hydrocephalus because their unfused skull sutures allow the head to enlarge in response to pressure, but the pressure still affects the position of the eyes. Key points to consider include:
- Increased intracranial pressure pushes the brain upward, causing the eyes to be displaced downward.
- The setting sun appearance is characterized by the sclera being visible above the iris, with the iris appearing to be "setting" like the sun on the horizon.
- This sign is an important clinical indicator that requires immediate medical attention, as it suggests significant intracranial pressure that could damage the brain if left untreated.
- The choice of surgical method, such as ETV or VPS, should be based on the patient's clinical features and hematoma location, as suggested by the study 5.