In suspected normal pressure hydrocephalus, what is considered a first-line step?

• A. Lumbar puncture
• B. Ventriculoperitoneal shunt
• C. MRI brain
• D. Trial of acetazolamide

Answer: (A)

In suspected normal pressure hydrocephalus, the first-line step is a diagnostic lumbar puncture with CSF removal to perform a tap test. Draining CSF can reveal whether the patient’s gait (and sometimes cognition) improves after drainage. This improvement suggests that the symptoms are at least partly due to reversible CSF dynamics and predicts a good chance of benefit from a ventriculoperitoneal shunt, which is the definitive treatment.

Imaging like MRI can support the diagnosis by showing ventriculomegaly, sometimes with DESH patterns, but it doesn’t by itself determine reversibility or guide initial management. A shunt is a treatment step, not a first-line diagnostic test. An acetazolamide trial isn’t a standard diagnostic approach for predicting shunt responsiveness and is not typically used as the initial evaluation.