science

Macewen's sign

Macewen's sign is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Macewen's sign rather than just read about it. In short: Macewen's sign or Macewen sign ( mə-KEW-ən) is a sign used to help to diagnose hydrocephalus (accumulation of excess cerebrospinal fluid) and brain abscesses. Tapping (percussion) the skull near the junction of the frontal, temporal, and parietal bones will produce cracked pot sound.

Key takeaways

Macewen's sign belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Macewen's sign to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Macewen's sign from memory before moving on to harder problems.

Reference excerpt

Macewen's sign or Macewen sign ( mə-KEW-ən) is a sign used to help to diagnose hydrocephalus (accumulation of excess cerebrospinal fluid) and brain abscesses. Tapping (percussion) the skull near the junction of the frontal, temporal, and parietal bones will produce cracked pot sound. Positive test is indication of separated sutures. This is due to raised intracranial tension. The sign was discovered and described by Sir William Macewen (1848–1924), a surgeon and professor of the University of Glasgow, Scotland, who also described Macewen's operation for inguinal hernia. McEwan's sign in alcohol intoxication is different: Pupils are contracted, but external painful stimulation of the person (e.g. by pinching or slapping) causes the pupil to dilate followed by slow constriction. It is suggestive of alcoholic coma.

References

Illustrations

Worked examples

Example 1 — a first encounter with Macewen's sign

Start with the simplest possible case. Write down what Macewen's sign claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Macewen's sign before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Macewen's sign ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Macewen's sign

In research: Macewen's sign appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Macewen's sign in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Macewen's sign is common in secondary-school and first-year university syllabi. It links to neighbouring topics Medical sign stubs, Symptoms and signs: Nervous system, so understanding it makes those chapters shorter.
In everyday life: Look for Macewen's sign outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Macewen's sign in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Macewen's sign means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Macewen's sign out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Macewen's sign in simple terms?

Why does Macewen's sign matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Macewen's sign?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Macewen's sign.