Tag: Gravitational valve

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Ultra-low-pressure hydrocephalic state in NPH: benefits of therapeutic siphoning with adjustable antigravity valves

Acta Neurochirurgica (2020) 162:2967–2974

Idiopathic normal-pressure hydrocephalus (NPH) is a condition of the elderly treated by ventriculoperitoneal shunt (VP) insertion. A subset of NPH patients respond only temporarily to shunt insertion despite low valve opening pressure. This study aims to describe our experience of patients who benefit from further CSF drainage by adding adjustable antigravity valves and draining CSF at ultra-low pressure.

Methods Single-centre retrospective case series of patients undergoing shunt valve revision from an adjustable differential pressure valve with fixed antigravity unit to a system incorporating an adjustable gravitational valve (Miethke proSA). Patients were screened from a database of NPH patients undergoing CSF diversion over 10 consecutive years (April 2008– April 2018). Clinical records were retrospectively reviewed for interventions and clinical outcomes.

Results Nineteen (10F:9M) patients underwent elective VP shunt revision to a system incorporating an adjustable gravitational valve. Mean age 77.1 ± 7.1 years (mean ± SD). Eleven patients (58%) showed significant improvement in walking speed following shunt revision. Fourteen patients/carers (74%) reported subjective improvements in symptoms following shunt revision.

Conclusions Patients presenting symptoms relapse following VP shunting may represent a group of patients with ultra-low pressure hydrocephalus, for whom further CSF drainage may lead to an improvement in symptoms. These cases may benefit from shunt revision with an adjustable gravitational valve, adjustment of which can lead to controlled siphoning of CSF and drain CSF despite ultra-low CSF pressure.

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Female gender predisposes for cerebrospinal fluid overdrainage in ventriculoperitoneal shunting

Female gender predisposes for cerebrospinal fluid overdrainage in ventriculoperitoneal shunting

Acta Neurochir (2016) 158:1273–1278

Gravitational valves (GVs) prevent overdrainage in ventriculoperitoneal shunting (VPS). However, there are no data available on the appropriate opening pressure in the shunt system when implementing a GV. We performed a retrospective analysis of hydrocephalic patients who were successfully treated with VPS which included one or more GV.

Method In this retrospective study in adult VPS patients with GVs, we analysed all available data, including the most recent computed tomography (CT) scans, to determine the best adjustments for alleviating any symptoms of overdrainage and underdrainage. Vertical effective opening pressure (VEOP) of the entire shunt system, including the differential pressure valve, was determined.

Results One hundred and twenty-two patients were eligible for the study. Of these, female patients revealed a higher VEOP compared with males (mean, 35.6 cmH2O [SD ± 2.46] vs 28.9 cmH2O [SD±0.87], respectively, p=0.0072, t-test). In patients older than 60 years, lower VEOPs, by a mean of 6.76 cmH2O± 2.37 (p = 0.0051), were necessary. Mean VEOP was found to be high in idiopathic intracranial hypertension (IIH; 41.6 cmH2O) and malresorptive and congenital HC (35.9 and 36.3), but low in normal pressure HC (27.5, p =0.0229; one-way ANOVA). In the total cohort, body mass index (BMI) and height did not correlate with VEOP. Twelve patients required a VEOP of more than 40 cmH2O, and in eight of these patients this was accomplished by using multiple GVs. All but one of these eight patients were of female gender, and none of the latter were treated for normal pressure hydrocephalus (NPH) (p = 0.0044 and p = 0.0032, Fisher’s exact test).

Conclusions In adult VPS patients, female gender increases the risk of overdrainage requiring higher VEOPs. Initial implantation of adjustable GV should be considered in female patients treated with VP shunts for pathology other than NPH.

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