If hydrocephalus is suspected, a series of steps confirms the diagnosis, identifies the type and cause when possible, and guides treatment. Understanding the diagnostic process can make it feel less daunting. The exact path depends on age and circumstances, but the building blocks are similar.
1. History and symptoms Diagnosis begins with the story — the symptoms, how they developed, and relevant background (such as prematurity, prior infections or bleeds, injuries, or a known related condition like spina bifida). In babies, a key part of the history is the pattern of head growth over time.
2. Physical and neurological examination A clinician examines for signs of hydrocephalus and raised pressure. This may include:
- Measuring head circumference in babies and plotting it on a growth chart.
- Checking the fontanelle (soft spot) in infants.
- Assessing eye movements and the optic nerves (an eye exam may reveal swelling of the optic nerve, called papilledema, a sign of raised pressure).
- Testing strength, coordination, balance, reflexes, and walking.
- In suspected NPH, carefully assessing gait and cognition.
3. Brain imaging — the cornerstone Imaging confirms enlarged ventricles and often reveals the cause. The main tools are:
- Cranial ultrasound — used in babies while the fontanelle is still open; safe, quick, and radiation-free.
- CT scan — fast and widely available; useful in emergencies and for quick assessment.
- MRI — provides the most detailed images, showing the ventricles, the pattern of fluid, and underlying causes (like a blockage or tumor) in fine detail.
These imaging tests are covered in their own articles. Imaging answers key questions: Are the ventricles enlarged? Where is the problem? Is there an obstruction, and what's causing it?
4. Identifying the type and cause Using the clinical picture and imaging, the team determines whether the hydrocephalus is obstructive or communicating, congenital or acquired, and whether a specific cause (a blockage, tumor, bleed, or infection) is present. This shapes treatment — for example, whether an ETV or a shunt is more appropriate.
5. Additional tests in specific situations Depending on the case, further tests may include:
- Tests for NPH — a large-volume spinal tap (tap test) or a few days of spinal fluid drainage, watching for temporary improvement in walking and thinking to predict whether a shunt will help.
- Specialized MRI techniques to assess CSF flow.
- Tests for an underlying cause — for example, evaluating a suspected infection or tumor.
- Pressure monitoring, in selected cases.
Putting it together The diagnosis of hydrocephalus is rarely based on a single test in isolation. Instead, the team combines the symptoms, examination, and imaging — and, when relevant, specialized tests — to confirm the diagnosis, understand its nature, and plan treatment. If hydrocephalus is confirmed, you'll be referred to (or already be under the care of) a neurosurgery team.
Being diagnosed can feel overwhelming, but each step has a clear purpose: to understand exactly what's happening so the right treatment can be chosen. Don't hesitate to ask your team to explain what each test shows and what it means for you.