Long term follow-up of shunted idiopathic normal pressure hydrocephalus patients: a single center experience

17 years of experience with shunt systems in normal pressure hydrocephalus - From differential pressure to gravitational valves

Objective

Complication rate of shunting for normal pressure hydrocephalus (NPH) has significantly improved over the last decades. Especially the use of overdrainage protection has reduced the incidence of subdural hematoma and collections. However, gravitational valves were associated with other complications of shunt dysfunction. We present our 17 years of experience with patients with normal pressure hydrocephalus who changed from a differential pressure valve to a gravitational valve system.

Methods

We retrospectively identified all patients with the diagnosis of normal pressure hydrocephalus, in whom primary shunt implantation was performed between 2004 and 2020. Shunt implantation was performed as per our internal standard. Review of imaging, charts and patient reports was performed.

Results

In total, 409 patients were included in the analysis. Mean age was 73.0 ± 7.1years. Between 2004 and 2010, predominantly Hakim valves (n = 100, 24.4%) were implanted, whilst from 2009 until 2020, proGAV valves (n = 296, 72.4%) were used. Mean follow-up was 8.9 ± 4.5 years. Initial subjective improvement of symptoms was reported in 69.9%, whilst this number decreased at the last follow-up to 29.8%. No significant differences were observed between the valves in the frequency of surgery for subdural hematoma. Shunt assistant implantation was performed in 17% of patients with Hakim valve, in 9.5% of patients with proGAV, a shunt assistant was added. Shunt obstruction was significantly higher in proGAV valves (p < 0.001).

Conclusions

Our findings confirm the observation of frequent overdrainage in shunts without anti-siphon/gravitational component. Gravitational valves on the other hand may be associated with more obstruction.

Fixed versus Adjustable differential pressure valves in case of idiopathic normal pressure hydrocephalus treated with ventriculoperitoneal shunt. A systematic review and meta-analysis of proportion

INTRODUCTION

Idiopathic normal pressure hydrocephalus is a common cause of communicating hydrocephalus in adult age, presenting with classic Hakim-Adam's triad. Ventriculoperitoneal shunting is the treatment of choice in these cases. The main objective of this study is to compare the complication rate of Adjustable differential pressure valves with fixed differential pressure valves in these cases.

LITERATURE SEARCH

We systematically searched PubMed/Medline, Embase, LILACS, and ClinicalTrials.gov from their date of inception to 30th Jan 2023. We included observational studies, Randomized Controlled Trials (RCTs), and comparative and noncomparative studies in the search. The literature search resulted in 1394 studies, and only 22 studies were eligible to be included in the meta-analysis. We performed the meta-analysis of proportion to compare incidence rates by performing a Freeman-turkey double arcsine transformation.

RESULTS

The summary of the proportions of the incidence rate of complications was less for Adjustable Differential Pressure Valves (ADPV) as compared to Fixed Differential Pressure Valves (FDVP) but the confidence intervals overlapped. The summary proportion of surgical revision of shunt in the case of ADPV was 0.081 (95% CI (0.047, 0.115)), and in the case of FDPV was 0.173 (95% CI (0.047, 0.299)). Similarly, the summary proportion of subdural fluid collection in the case of ADPV was 0.090 (0.058, 0.122), and in the case of FDPV was 0.204 (0.132, 0.277). The incidence of complication was low in population implanted with DPV along with gravitational or anti-siphon unit (GASU).

CONCLUSION

Complication rates in the case of ADPV plus GASU were the lowest. Though the summary proportion of complication rate in the case of ADPV was low as compared to FDPV, the statistical significance of this difference is doubted due to overlapping confidence intervals.