At a glance
What it is
Communicating hydrocephalus in which CSF accumulates in the cerebral ventricles despite initially normal or borderline CSF pressure. Most cases are idiopathic; secondary NPH follows subarachnoid haemorrhage, head injury, meningitis, or brain tumour. Predominantly affects adults over 60. Causes progressive ventricular enlargement that compresses and stretches periventricular white matter tracts, producing the characteristic triad of symptoms.
Symptoms
Classic triad — gait disturbance (magnetic, shuffling, wide-based gait; the earliest and most prominent symptom), urinary urgency or incontinence (often follows gait decline), and cognitive slowing with short-term memory difficulty (dementia-like). Each symptom alone has many other causes in older adults; diagnosis requires the combination plus supporting imaging and response to CSF drainage.
Approach
Multi-disciplinary evaluation: MRI (ventricular enlargement disproportionate to atrophy), CSF drainage trial (lumbar tap or 2–3-day lumbar drain) with objective gait and cognitive testing before and after. Improvement with drainage predicts > 80% chance of sustained benefit from VP shunt surgery. Shunt contains a magnetically programmable valve to allow fine-tuning post-implantation. Endoscopic third ventriculostomy (ETV) is an option in cases with identifiable CSF flow obstruction.
What normal pressure hydrocephalus is
Cerebrospinal fluid (CSF) is produced continuously in the cerebral ventricles at roughly half a litre per day. It circulates through the ventricles, around the brain and spinal cord, and is reabsorbed over the brain surface into venous sinuses. Hydrocephalus occurs when this cycle is disrupted — CSF accumulates in the ventricles, enlarging them and compressing surrounding brain tissue.
In normal pressure hydrocephalus, CSF accumulates despite the absence of a clear obstructing lesion (communicating hydrocephalus) and with CSF pressure that may be normal or only intermittently elevated. The enlarged ventricles stretch and distort periventricular fibres — particularly those controlling gait and bladder function — producing the clinical triad.
**Why it is difficult to diagnose**
- Each of the three cardinal symptoms (gait impairment, incontinence, dementia) has many independent causes in the elderly population - Symptoms develop gradually and may be dismissed as normal ageing - Ventricular enlargement also occurs with normal ageing and with Alzheimer's disease - No single test is perfectly specific or sensitive
A multidisciplinary team evaluation — combining neurology, neuroimaging, and neurosurgery — is essential to avoid missed or incorrect diagnosis.
**The CSF drainage trial**
The critical diagnostic step is a formal CSF drainage trial. A lumbar catheter is placed and CSF is drained over 2–3 days while gait (video-analysed), balance, and cognition are tested before and after. Objective improvement with drainage has an > 80% positive predictive value for sustained improvement following VP shunt surgery. A single large-volume lumbar puncture (spinal tap) is a less accurate alternative when inpatient admission is not possible.
**Treatment**
*Ventriculoperitoneal (VP) shunt:* A soft catheter (< 2mm diameter) is placed from the lateral ventricle, tunnelled under the scalp and neck skin, to the peritoneal (abdominal) cavity. A one-way programmable valve regulates flow. All shunts at Alimran Medical Center contain a magnetically programmable valve, allowing non-invasive adjustment of drainage pressure post-implantation to minimise over- or under-drainage complications.
*Endoscopic third ventriculostomy (ETV):* A small hole is made endoscopically in the floor of the third ventricle, allowing CSF to bypass the obstructed pathway. Avoids shunt hardware and has a lower infection risk; most effective when a focal obstruction is identifiable.
**Outcomes**
Patients who respond to CSF drainage have an > 80% chance of sustained gait improvement after shunt implantation. Cognitive and urinary function improvement is more variable but occurs in over half of patients. Long-term shunt valve programming is often required to optimise benefit as the condition evolves.
Treatment options at Alimran Medical Center
Neurosurgery
- Ventriculoperitoneal (VP) shunt with programmable valve
- Endoscopic third ventriculostomy (ETV)
Injection & advanced therapies
- Botox® injections
- Ozone injection
- Trigger point injections
- Pulsed radiofrequency
- Acupuncture
Physiotherapy
- Electrical stimulation
- Short and long wave therapy
- Laser therapy
- Ultrasound therapy
- Gait retraining and balance rehabilitation
Book a consultation
The secretary schedules first appointments during clinic hours; please have prior imaging, operative notes and a current medication list available at the time of the call.
This page provides general information about normal pressure hydrocephalus and is not a substitute for individual medical assessment. If your symptoms are severe or worsening, contact a clinician promptly.