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  • Flow-regulated vs Pressure-regulated shunts: A Prospective Analysis in Patients with Idiopathic Normal Pressure Hydrocephalus

    Final Number:

    Phillip G. St. Louis MD; Jennifer Clements

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting - Late Breaking Science

    Introduction: Guidelines for treatment of Idiopathic Normal Pressure (INPH)indicate ventriculoperitoneal shunt placement as an effective intervention. Current literature comparing Differential Pressure (DP) versus Flow Regulated (FR) Valves for is lacking. This prospective study evaluates one year outcome data of 43 patients randomized to either a DP or FR valve.

    Methods: All patients completed pre-operative and post-operative evaluations to assess hallmark indicators of INPH such as magnetic gait (BERG Balance Scale), cognitive dysfunction (Neuropsychological Assessment Battery [NAB]), and ventriculomegaly (MRI/CT). Patients who consented were then randomized to a DP or FR valve.

    Results: Baseline testing of the DP Group (N=22) was NAB: 78.16 and BERG 34.2. Significant improvement was demonstrated at 6 and 12 months post-operatively with NAB: 86.5 and 87.75, and BERG 43.06,44.17 scores. Baseline testing for the FR Group (N=21) was NAB: 77.4 and BERG: 39. Improvement was noted at 6 and 12 months post operatively with NAB: 86.25 and 89.17. There was a slight decrease in the 6 and 12 month BERG: 47.2 and 46.11 scores. There were no shunt infections. There was one subdural hematoma in the FR Group requiring surgical intervention in the immediate post-operative period, and 3 subdural hematomas in the DP Group requiring 1 surgical intervention. The number of follow up appointments was slightly increased in the DP Group, which was primarily related to patients who required shunt reprogramming.

    Conclusions: Both shunt systems appear to be effective in treatment of INPH. Improvement was noted in both NAB and BERG at 6 and 12 months post-operatively when compared to baseline. There was a distinct trend of more striking improvement at 6 months in the FR Group. A significantly higher incidence of subdural hematomas was demonstrated in the DP Group, most of which were successfully managed by shunt reprogramming.

    Patient Care: This data will provide more evidence for decision in shunt selection.

    Learning Objectives: Patients with Flow Regulated Valves demonstrated a more striking improvement at 6 months. Patients with Differential Pressure Valves experienced a larger incidence of subdural hematomas, however most of which were managed by shunt reprogramming. Both groups demonstrated overall improvement when compared to baseline

    References: 1. Gangemi M, Maiuri F, Naddeo M, Godano U, Mascari C, Broggi, et al: Endoscopic Third Ventriculostomy in Idiopathic Normal Pressure Hydrocephalus: An Italian Multicenter Study. Neurosurg, 63: 62-69, 2008. 2. Hanlow P, Cinalli G, Vandertop P, Faber J, Bogeskov L, Borgesen S, et al: Treatment of hydrocephalus determined by the European Orbis Sigma Valve II survey: a multicenter prospective 5-year shunt survival study in children and adults whom a flow-regulating shunt was used. J Neurosurg 99: 52-57, 2003. 3. Philippe D, Barat J, Duplessis E, Leguerinel C, Gendrault P, and Keravel Y: Shunt failure in adult hydrocephalus: Flow-controlled shunt versus differential pressure shunts- A cooperative study in 289 patients. Surg Neurol 43:333-339, 1995. 4. Weiner H, Shlomo C, Cohen H, Wisoff J: Current Treatment of Normal-pressure Hydrocephalus: Comparison of Flow-regulated and Differential-pressure Shunt Valves. Neurosurg, 37(5):877-884, 1995. 5. Zemack G, and Romner B: Adjustable Valves in normal-pressure hydrocephalus: A retrospective study of 218 patients. Neurosurg 51:1392-1402, 2002. 6. Knutsson E, Lying-Tunell U. Gait apraxia in normal-pressure hydrocephalus: Patterns of movement and muscle activation. Neurology 35, 135-160. 7. Bugalho P, Guimaraes J. Gait disturbance in normal pressure hydrocephalus: A clinical study. Parkinsonism and Related Disorders 13, 434-437, 2007. 8. St Louis P, Horn G, Gorman P, Johnson-Markve B, Wong B, Brustch B, Baez-Torres S, Cole A, Tuppeny M, Johnson R. Neurotransmission. 4, 1 2012. 9. Ravdin et al. Features most responsive to tap test in normal pressure hydrocephalus. Clin Neurol Neurosurg.2008 May; 110 (5): 455-461. 10. Shprecher D, Schwalb J, Kurlan R. Normal Pressure Hydrocephalus: Diagnosis and Treatment. Curr Neurol Neurosci Rep. 2008 September; 8(5): 371-376. 11. Merten T. Neuropsychology of Normal Pressure Hydrocephalus [in German]. Nervenarzt 70:496-503, 1999. 12. Relkin N, Marmarou A, Klinge P, Bergsneider M, Black P. Diagnosing Idiopathic Normal-Pressure Hydrocephalus. Neurosurgery. 57:3, 2005. 13. Vaneste JA. Diagnosis and management of normal pressure hydrocephalus. J Neurol. 2000;247:5-14. 14. Donoghue D; Physiotherapy Research and Older People (PROP) group, Stokes EK. (2009). How much change is true change? The minimum detectable change of the Berg Balance Scale in elderly people. J Rehabil Med. 41(5):343-6. 15. Stern, R. A. & White T. (2003). Neuropsychological Assessment Battery: Administration, Scoring, and Interpretation Manual,Psychological Assessment Resources, Inc., Lutz, FL. 16. Duff K. Evidence-based indicators of neuropsychological change in the individual patient: Relevant concepts and methods; Kevin Duff; archives of clinical neuropsychology; May 2012; 27(3): 248-261.

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