By Noriana Jakopin

In the United States, the standard treatment for idiopathic Normal Pressure Hydrocephalus (iNPH) patients is a ventriculoperitoneal shunt (VPS). However, lumboperitoneal shunts (LPS) have also been shown to improve iNPH symptoms and are widely used in Japan. VPS treatment diverts CSF from the brain ventricle to the peritoneal (abdominal) cavity while LPS treatment diverts cerebrospinal fluid (CSF) from the spinal canal to the peritoneal cavity.  Each treatment has its own set of advantages and disadvantages as detailed in the medical literature.

A study recently published by lead author Dr. Massimiliano Todisco in the Journal of Neurology aimed to investigate the efficacy of LPS in treating iNPH. This prospective study recruited 78 iNPH patients, 44 of which received an LPS while the remainder elected to forgo any surgical intervention and served as the control group. The patients underwent clinical and neuropsychological evaluations at 6 and a 12-month follow-ups.

At 6 months, patients who had an LPS had improved gait and balance. Urinary incontinence also improved in these patients, though to a lesser extent. However, there were no significant cognitive changes. At 12 months, the LPS patients still had better gait and balance than they had before surgery, however they showed a slight decline from the 6-month follow-up. The improved urinary incontinence from the 6-month follow-up remained. However, there was still no significant changes to cognition. Control patients, who received no treatment, had a worsening of gait disturbances and urinary incontinence at the 12-month follow-up, though there was no significant change in balance and cognitive function.

At the 12-month follow up visit, patients also underwent repeat MRI scans. The imaging showed improvements in the LPS group related to the subarachnoid space. They also looked at white matter hyperintensities on the MRI. A white matter hyperintensity is a bright spot on an MRI scan which indicates changes or irregularities to the white matter structure in that region. They looked at both periventricular white matter (PWM) hyperintensities, which is the white matter surrounding the ventricles, as well as deep white matter (DWM) hyperintensities.

The study found that patients who responded well to the LPS also had a reduction of PWM hyperintensities after their surgery but no significant change of DWM hyperintensities. As a high number of PWM hyperintensities at baseline was associated with more gait and balance disturbances, the authors believe the reduction of the PWM hyperintensities may help explain the post-operative improvement to gait and balance. Urinary incontinence and cognitive function had no correlation to PWM hyperintensities at baseline, which may explain why less improvement was shown in these areas after LPS. In contrast, control patients had an increase in PWM hyperintensities at the 12 month follow up.

The authors conclude that LPS can improve symptoms in iNPH patients and is a safe option that surgeons may want to consider for patients who may be unable to undergo an intracranial operation. They also note that PWM hyperintensities may be a good marker for the clinical effectiveness of LPS.

However, at the beginning of the study (baseline), the control and LPS groups had different clinical presentations which limits the ability to directly compare the two groups. In addition, this study did not compare LPS to VPS treatment for iNPH. Therefore, no comparisons can be made between the two treatment methods.

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