Normal pressure hydrocephalus is a condition which is most common in the elderly. There is no imaging test which diagnoses normal pressure hydrocephalus with 100% accuracy, although CT and MRI will show large ventricles (fluid channels in the brain).
Normal pressure hydrocephalus typically causes three symptoms:
- Urinary incontinence, due to impaired function of the frontal lobes
- Gait impairment, where individuals walk with a ‘magnetic gait’ as though their feet are stuck to the ground
- Memory loss, often masquerading as dementia
Making a diagnosis of normal pressure hydrocephalus can be difficult; a useful test is a lumbar drain procedure, where CSF is drained slowly via a tube inserted in the lumbar spine (lower back), and the effect of this on symptoms is measured over several days. This can also be helpful in predicting which patients are likely to benefit from a ventriculoperitoneal shunt.
The treatment of normal pressure hydrocephalus generally involves a procedure called a ventriculoperitoneal shunt insertion. This involves the implantation of a system of tubes and valves, allowing diversion of cerebrospinal fluid from the brain to the abdomen, where it is reabsorbed.
The prognosis of normal pressure hydrocephalus which is treated with a ventriculoperitoneal shunt depends on the main symptoms present at the time of treatment: poor balance and gait improve the most reliably; memory loss often does not improve.