Normal Pressure Hydrocephalus: Diagnosis and Treatment Options

Alfonso Fasano, MD, PhD

Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital and Division of Neurology, University of Toronto, Toronto, Ontario, Canada, Krembil Research Institute, Toronto, Ontario, Canada.

CLINICAL TOOLS

Abstract: Normal pressure hydrocephalus (NPH) is a relatively frequent but underdiagnosed geriatric disorder with symptoms of impaired gait and balance, overactive bladder, and cognitive decline in the presence of neuroimaging evidence of ventriculomegaly. Cerebrospinal fluid shunting is an effective treatment, although patients' response is variable, sometimes of short duration, and not always predictable. This might be due to poor patient selection or delayed surgery. Nevertheless, recent trials have indicated that shunt surgery is cost-effective and should therefore be recommended. Family physicians and general neurologists play a crucial role in ensuring a proper diagnosis and timely intervention.
Key Words: normal pressure hydrocephalus, diagnosis, treatment.

Family physicians have a crucial role in ensuring a proper diagnosis and timely intervention. In this respect, a few rules should be remembered:
1. NPH is common among elderly populations in Western countries, but it is largely underdiagnosed and undertreated.8
2. NPH is one of the few reversible chronic neurological conditions in the elderly because neurosurgical shunting is an effective treatment, especially if performed early.36
3. Gait and balance impairment are early signs of NPH and not all 3 of the triad symptoms should be present in order raise a suspicion of NPH and refer the patient to a neurologist.36
4. Any patient with at least one symptom of the NPH triad should undergo a brain MRI or computed tomography CT (if MRI is contraindicated).36
5. Important MRI/CT findings are an Evans index >0.3 and DESH, which should be investigated because it might mimic brain atrophy.33
A suspicion of NPH should be raised for those patients with gradually progressive gait disorders characterized by instability (broad base) and shuffling steps; no other parkinsonian signs should be noticed, particularly in the upper body. Urinary dysfunction might be absent and cognitive problems are typically less severe than the motor problem (particularly at onset). In a patient with a clinical suspicion of NPH, brain MRI should be ordered and a referral to a neurologist should be made.
The neurologist will exclude other neurodegenerative conditions and other clinically relevant diseases affecting gait (e.g. neuropathy, spinal stenosis). Afterwards a tap test will be arranged, bearing in mind that the sensitivity of the test is far from ideal and that patients are prone to placebo response. When the suspicion of NPH remains high (also in case of negative tap test) a referral to neurosurgeon is made by the neurologist. In less clear-cut cases, another tap test or prolonged lumbar drainage can be done. Some other cases are only clinically followed-up, however taking into account that a delayed intervention might not provide the benefit of early surgery.
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This article was published as part of Managing the Health of Your Aging Patient: Therapies that Could Help Improve Quality of Life eCME resource. The development of Managing the Health of Your Aging Patient: Therapies that Could Help Improve Quality of Life eCME resource was supported by an educational grant from Medtronic Canada.