Normal Pressure Hydrocephalus and Hypertension
Normal pressure hydrocephalus (NPH) does not typically present with increased blood pressure as a primary manifestation, though systemic hypertension is significantly more prevalent in NPH patients than in the general population and may occasionally present as a secondary finding.
Prevalence of Hypertension in NPH
The relationship between NPH and hypertension is primarily one of association rather than causation:
Patients with idiopathic NPH demonstrate a significantly higher prevalence of systemic hypertension compared to age-matched controls with dementia and the general US population 1. In one series, 14 of 19 NPH patients (74%) had systemic hypertension, with 10 of 14 patients who improved after shunting having pre-existing hypertension 1.
Hypertension appears to be a comorbid condition rather than a presenting feature of NPH 1. The classic triad of NPH consists of gait disturbance (the cardinal sign where feet appear "glued to the floor"), cognitive impairment, and urinary incontinence 2.
Rare Cases of New-Onset Hypertension
While uncommon, new-onset hypertension has been documented in specific NPH contexts:
In post-traumatic NPH, new-onset systemic hypertension may occasionally serve as a clinical sign suggestive of developing hydrocephalus 3. A retrospective review found that 25% of post-traumatic NPH patients demonstrated significant blood pressure changes temporally related to shunt placement 3.
When hypertensive cerebrovascular disease coexists with NPH, the presence of hypertension and focal neurological findings should alert clinicians to this specific etiology 4. However, these patients typically have poor outcomes with shunting 4.
Intracranial vs Systemic Pressure
It is critical to distinguish between intracranial pressure and systemic blood pressure:
NPH is characterized by elevated pulsatile intracranial pressure (ICP) with normal static ICP in shunt responders 5. This is fundamentally different from systemic arterial blood pressure.
Static and pulsatile arterial blood pressure (ABP) are not altered in NPH shunt responders 5. The correlation between ICP and ABP is generally low and does not differ between responders and non-responders 5.
Clinical Pitfalls
Do not confuse "normal pressure" in the name NPH with systemic blood pressure—it refers to CSF pressure, not arterial pressure.
The presence of hypertension in an NPH patient is more likely a cardiovascular comorbidity than a direct manifestation of the hydrocephalus 1.
In post-traumatic cases, monitor for new-onset hypertension as it may suggest developing NPH, particularly when other signs are masked by post-traumatic amnesia 3.