Macewen sign (cracked-pot sign)

What it is

The Macewen sign (cracked-pot sign) is a characteristic hollow, resonant sound — likened to tapping a cracked pot — heard when the skull is gently percussed (tapped). It can occur in hydrocephalus when raised pressure and separated sutures are present.

Understanding Macewen sign (cracked-pot sign)

When the cranial sutures are separated (splayed) due to raised intracranial pressure and head enlargement, tapping the skull can produce a distinctive hollow sound, reflecting the change in the skull's structure. The Macewen sign is mainly relevant in infants and young children, whose sutures can still separate; it is one of the examination findings that can accompany hydrocephalus, alongside a bulging fontanelle, rapid head growth, and prominent scalp veins. It is a supportive sign rather than a definitive test, contributing to the overall clinical picture that, with imaging, establishes the diagnosis.

Why it matters

Understanding the Macewen sign helps families recognize one of the classic examination findings of hydrocephalus in young children, reflecting raised pressure and separated sutures, as part of the broader assessment.