đź§ Cerebral atrophy and hydrocephalus can look similar on imaging, but reflect very different processes.
Hydrocephalus = pressure-driven ventricular enlargement.
Atrophy = volume loss with compensatory ventricular/sulcal widening.
Differentiation is critical for correct management.
🔎 Radiological Clues
- Temporal horns: Enlarged in hydrocephalus; normal in atrophy (except enlarged in Alzheimer’s from hippocampal loss).
- Third ventricle: Convex bulging in hydrocephalus; concave/flattened in atrophy.
- Fourth ventricle: Normal or enlarged in hydrocephalus (depends on obstruction site); normal in atrophy unless cerebellar loss.
- Corpus callosum: Stretched/thinned in hydrocephalus; may be thinned in neurodegeneration but not distended.
- Trans-ependymal oedema: Present in hydrocephalus (CSF seepage); absent in atrophy.
- Sulci: Flattened in hydrocephalus (compression); widened in atrophy (volume loss).
đź“‹ Clinical Context
- Hydrocephalus (acute): Obstructed CSF flow → raised ICP (headache, vomiting, ↓ consciousness, papilloedema).
In infants: ↑ head size, bulging fontanelle.
- Hydrocephalus (chronic/normal pressure): Gait disturbance, urinary incontinence, cognitive decline (classic triad).
- Cerebral Atrophy: Neuronal loss from ageing, Alzheimer’s, stroke, alcohol misuse, TBI.
Presents with gradual cognitive decline, focal deficits depending on region (e.g. memory loss with hippocampal atrophy).
🖼️ Radiological Insights
- Hydrocephalus: Ventricles enlarged out of proportion to sulci; periventricular lucency = trans-ependymal oedema; convex third ventricle.
- Atrophy: Ventricles + sulci enlarged in proportion; no oedema; overall “wasted” appearance.
⚕️ Management
- Hydrocephalus: Acute → urgent CSF diversion (ventriculostomy, shunt).
Chronic → ventriculoperitoneal (VP) shunt or endoscopic third ventriculostomy (ETV).
- Atrophy: No surgical correction. Supportive therapy: treat cause (e.g. dementia management, alcohol cessation), cognitive rehab, MDT care.
✨ Key Differentiation Points
- Hydrocephalus: disproportionate ventricular enlargement + signs of raised ICP.
- Atrophy: proportionate sulcal + ventricular enlargement + gradual clinical decline.
- Ambiguous cases: advanced MRI techniques (e.g. CSF flow studies, DTI) help.
đź’ˇ Exam Tip: On CT head, always compare ventricles with sulci.
Flattened sulci + periventricular lucency = hydrocephalus.
Widened sulci with matching ventriculomegaly = atrophy.