At Sheikh Khalifa Hospital, Quetta, one thing we’ve learned over time is: big heads come with even bigger differentials 🧠. And while macrocephaly might initially trigger visions of rare syndromes and MRI rabbit holes, most of the time, it’s surprisingly… predictable.
Let’s walk through the “Big HEAD” mnemonic — a lifesaver during rounds when your senior suddenly turns into a viva machine without warning.
Causes of Macrocephaly Mnemonic
| Mnemonic | Cause | Brief Explanation |
|---|---|---|
| B | Bleeds (e.g. subdural hematoma) | Chronic subdural collections can enlarge head circumference, esp. in shaken babies. |
| I | Increased CSF (Hydrocephalus) | Classic culprit. Obstructive or communicating — either way, ventricles go ballooning. |
| G | Genetic/Overgrowth Syndromes | E.g. Sotos, Beckwith-Wiedemann. Big genes, big heads. |
| H | Hemoglobinopathies | Like thalassemia major — extramedullary hematopoiesis = skull bossing. |
| E | Extracranial causes (e.g. Cephalohematoma) | Sometimes the problem’s on the outside of the cranium. |
| A | Achondroplasia | Disproportionate macrocephaly is part of the skeletal dysplasia picture. |
| D | Demyelinating/Storage diseases | Think Canavan, Alexander, Tay-Sachs — white matter disease with big heads. |
A Day in Pasni (Balochistan, Pakistan) with a Baby Having Macrocephaly 👶
We had a 9-month-old referred from Pasni, with head circumference cruising at the 98th percentile, and mom worried the child might “tip over while sitting.” 😅 Dr. Bilal Chaudhary and I took one look and suspected hydrocephalus — and sure enough, cranial US showed dilated ventricles with aqueductal stenosis. A textbook “I” in “BIG HEAD” if there ever was one.
What I didn’t expect was Dr. Behroz Rahim chiming in later to ask whether the large head might reflect underlying psychosocial stress in the parents. Trust the psychiatrist to bring Freud into foramen magnum territory.
Quick Clinical Nuggets 🩺
Not every big head is hydrocephalus. Trust me, you don’t want to order CTs on every dome-shaped baby just because you’re on call.
Measure parental head circumferences — I once almost referred a totally normal kid from Mashkel for MRI, until I realized both parents were walking bobbleheads.
Look for red flags: vomiting, bulging fontanelle, sunsetting eyes — these aren’t normal. That’s when you do scan.
I hope that you find this medical useful in your studies/clinical practice. Happy learning! 🙂
Authored by:
Dr. Aurangzaib Qambrani
MBBS | PLAB | MRCP-UK
General Medicine, Gastroenterology & CCU
Sheikh Khalifa Bin Zayed Hospital, Quetta 🏥
