Normal Pressure Hydrocephalus Treatment & Management

Updated: Oct 19, 2018
  • Author: Michael J Schneck, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Treatment

Medical Care

A levodopa challenge may be helpful to rule out idiopathic Parkinson disease. Patients with normal pressure hydrocephalus (NPH) have no significant response to levodopa or dopamine agonists.

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Surgical Care

Surgical CSF shunting remains the main treatment modality. Prior to embarking upon surgical therapy, knowing which patients may benefit from surgery is necessary. Detailed testing is performed before and after CSF drainage.

Initially, patients are given a baseline neuropsychological evaluation (eg, Folstein test or formal neuropsychological evaluation) and a timed walking test. Patients then undergo a lumbar puncture with removal of approximately 50 mL of CSF. Testing is then repeated 3 hours later. A clear-cut improvement in mental status and/or gait predicts a favorable response to shunt surgery. Improvement in gait may be seen in the form of reduced time to walk a fixed distance, reduced gait apraxia, or reduced freezing of gait. Videotaping the gait evaluation before and after the large volume lumbar puncture or lumbar drain placement can be helpful in decision making. Reduction in bladder hyperactivity also may be a sign of good outcome from shunting. Occasionally, improvement may be delayed and appear 1-2 days after the large-volume lumbar punctures. For a more objective assessment, videotape the timed walking test before and after lumbar puncture.

While large volume lumbar puncture was the earliest invasive diagnostic test in predicting response to shunt surgery, external lumbar drainage (ELD) is being used with increased frequency. In this method, clinicians use an indwelling CSF catheter in lieu of repeated lumbar punctures. The drainage catheter is generally left in place for 3 days, allowing sufficient time for return of neuronal function. [14] This method carries a higher risk of meningeal infection but may allow for a more accurate prognosis. [15]

In a prospective study of 151 patients with suspected idiopathic NPH, all patients underwent ELD. Patients with clinical improvement after ELD were offered shunt surgery, 90% of whom improved. [16] Others have confirmed the positive predictive value of improvement after ELD. [14, 17] Less clear, however, is the negative predictive value of ELD. In one study, 64% of patients who underwent shunt surgery had improvement, despite a negative ELD result. [18] Thus, given the dramatic improvement in quality of life for shunt responders, some have advocated for less reliance on predictive testing. [19, 20] Given the potential morbidity and mortality of shunt surgery, however, this has not been widely adopted.

An alternative method of predicting response to shunt surgery is CSF infusion testing. In this test, 2 lumbar drains are placed. One drain is used for continuous pressure monitoring while the other drain is used to continuously infuse solution into the CSF space. Elevated pressures during infusion are specific for shunt-responsive NPH. However, due to a lower sensitivity and potential morbidity, this is infrequently used.

Patients with a good response to predictive testing should be considered for ventriculoperitoneal or ventriculoatrial shunting. The best results are reported in patients who have no adverse risk factors; have responded favorably to a large-volume lumbar puncture; and have definite evidence of dementia and ataxia, CT scan or MRI evidence of chronic hydrocephalus, and a normal CSF at lumbar puncture. Some evidence indicates that patients with gait disturbance, mild or no incontinence, and mild dementia fare best among shunt surgery patients. [19, 21]

Another modality without significant current use is isotope cisternography. The method involves injecting a radiolabeled isotope into the CSF space. Using this method, the excretion of the isotope can be monitored. Lack of visualization of the isotope over the brain (ie, impaired absorption of the arachnoid villa) suggests a diagnosis of NPH. This test is rarely used due to the low positive predictive value with regards to shunt-responsiveness.

The clinical usefulness of cisternography was evaluated in a large-scale study (n=76) by Vanneste et al. [22] The predictive value of a scale based on combined clinical and CT scan criteria was established first, followed by an assessment of the predictive value of cisternography. Predictions based on cisternograms were identical to those of the clinical/CT scan scale in 43%, better in 24%, and worse in 33%. This suggests that cisternography does not improve the diagnostic accuracy of combined clinical and CT scan criteria in patients with presumed normal pressure hydrocephalus.

In summary, an ideal candidate for shunt surgery would show imaging evidence of ventriculomegaly indicated by a frontal horn ratio exceeding 0.50 on imaging studies along with one or more of the following criteria:

  • Presence of a clearly identified etiology

  • Predominant gait difficulties with mild or absent cognitive impairment

  • Substantial improvement after CSF withdrawal (CSF tap test or lumbar drainage)

  • Normal-sized or occluded sylvian fissures and cortical sulci on CT or MRI

  • Absent or moderate white matter lesions on MRI

An alternative technique to shunt surgery is gaining some currency. This involves endoscopic third ventriculostomy (ETV). Although it has been previously used in noncommunicating hydrocephalus, its use has also been examined in patients with NPH.

One study examining this technique followed a series of 36 patients divided into a group of 29 patients with secondary communicating hydrocephalus and a group of 7 patients with normal pressure hydrocephalus. Sixteen (44.4%) of the patients had a previous ventriculoperitoneal shunt placement that presented with shunt malfunction. ETV was considered successful in 27 of 36 patients (75%). A Kaplan-Meier analysis revealed that the successful proportion of ETVs in secondary communicating hydrocephalus at 0.5, 1, and 3 months of follow-up was 0.83, 0.8, and 0.77, respectively; in the idiopathic NPH group, it was 0.83 initially and became stable at 0.66 after the first month. However, these results need to be replicated with larger series before the use of this technique is determined. [23]

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Consultations

A neurologist should be initially involved in the evaluation of suspected NPH, at which time a lumbar puncture is performed. For appropriate patients, a neurosurgical consultation should also be obtained.

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