Gravitational shunts in longstanding overt ventriculomegaly in adults

Long-Standing Overt Ventriculomegaly in Adults: A Systematic Review and Meta-Analysis of Endoscopic Third Ventriculostomy Versus Ventriculoperitoneal Shunt as First-Line Treatment

BACKGROUND

Long-standing overt ventriculomegaly in adults (LOVA) is a heterogeneous term describing forms of adult hydrocephalus. LOVA incidence is increasing, yet the optimal treatment strategy for symptomatic cases remains unclear. We compared success rates and complication rates between endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS) as first-line treatment for LOVA.

METHODS

A systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. Three databases were searched, and articles published from 2000 to October 2022 were included (last search date October 24, 2022). Success rates and complications of both ETV and VPS were compared using random-effects models.

RESULTS

Of 895 articles identified, 22 studies were included in the analysis (556 patients: 346 in ETV group, 210 in VPS group). Mean age was 44.8 years. The most common presenting symptoms were gait disturbance (n = 178), headache (n = 156), and cognitive decline (n = 134). Combined success rates were 81.8% (n = 283/346) in the ETV group and 86.7% (n = 182/210) in the VPS group (median follow-up 41 months). There was no difference in success rates between ETV and VPS groups (odds ratio 0.94, 95% confidence interval 0.86-1.03, I2 = 0%). Combined complication rates were 4.6% (n = 16/346) in the ETV group and 27.1% (n = 57/210) in the VPS group. ETV had a lower rate of postoperative complications (odds ratio 0.22, 95% confidence interval 0.11-0.33, I2 = 0%).

CONCLUSIONS

Symptomatic LOVA can be successfully managed with surgical intervention. ETV and VPS have similar success rates when used as first-line treatment. VPS has a higher complication rate.

Surgical Treatment of Long-Standing Overt Ventriculomegaly in Adults (LOVA): A Comparative Case Series between Ventriculoperitoneal Shunt (VPS) and Endoscopic Third Ventriculostomy (ETV)

Background: Long-standing overt ventriculomegaly in adults (LOVA) is an uncommon type of adult chronic hydrocephalus. In recent years, conflicting case series described different outcomes after treatment of LOVA with endoscopic third ventriculostomy (ETV) or ventriculoperitoneal shunt (VPS). The aim of this study is to report a single institutional surgical experience of patients with LOVA in order to evaluate the clinical outcome of those patients treated with one or, sometimes, both surgical procedures, analyzing the main clinical features of these patients, before and after surgery. Methods: We conducted a retrospective study on 31 patients with diagnosis of LOVA, who were treated in our University Hospital between December 2010 and October 2020. We reported gender, age, clinical presentation, surgical treatment, and clinical outcome according to the Kiefer index (KI). Evans’ index, head circumference, aqueductal stenosis and expanded/destroyed sella turcica were assessed on preoperative MRI. Results: The most common clinical manifestation was gait disturbances (100%) followed by urinary incontinence in 23 (74.2%) patients and cognitive deficits in 22 (71%) patients. On preoperative MRI, the overall mean Evans’s Index was 0.49, whereas the overall mean head circumference was 57.3 cm. Twenty-three patients (74.2%) had obliterated cortical sulci, 20 (64.5%) patients had aqueductal stenosis, and 22 (71%) patients had an expanded/destroyed sella turcica on preoperative MRI. Fifteen (48.4%) patients underwent ETV and sixteen (51.6%) were treated with VPS as first surgical procedure. Four (26.6%) out of fifteen patients treated with ETV required a subsequent VPS. The overall median age of patients was 64 (IQR: 54.5–74) and the overall median follow-up was 57 months (IQR 21.5–81.5). Overall morbidity was 22.5%. Mean recovery index (RI), according to KI, was 3.8 ± 4.3 and 2.2 ± 5.6 (p = 0.05) at last follow-up in patients treated with ETV and VPS, respectively. Conclusions: The choice of surgical treatment of LOVA remains under discussion. Although EVT is a tempting option for patients with LOVA, conversion to VP shunt is not uncommon.

Longstanding overt ventriculomegaly in adults (LOVA) with patent aqueduct: surgical outcome and etiopathogenesis of a possibly distinct form of chronic hydrocephalus

Purpose

Longstanding overt ventriculomegaly in adults (LOVA) represents a form of chronic adulthood hydrocephalus with symptomatic manifestation in late adulthood. Based on the patency of the aqueduct, two different subcohorts of LOVA can be distinguished. Surgical treatments of this condition are also debated. Therefore, we analyzed preoperative characteristics and clinical outcome after different surgical treatments in a subgroup of LOVA patients with a patent aqueduct.

Methods

Eighteen LOVA patients with a patent aqueduct consecutively treated at our institution between July 2013 and December 2019 were analyzed for this study. Median age was 70 years. Preoperative radiological and clinical features, surgical procedures (ventriculo-peritoneal shunt or endoscopic third ventriculostomy), and outcomes were collected. Successful outcome was qualitatively defined as an improvement or a halt of progression of the presenting symptoms at follow-up, and quantitatively by changes in mRS and iNPHGS scales.

Results

Twelve patients underwent an ETV as a primary treatment, while 6 underwent VPS. A total of 22.2% of them were lost to follow-up. Median follow-up time was 38 months. Six patients (66.7%) in the ETV cohort achieved a successful outcome after treatment, with a complication rate of 11.1%. Two patients underwent rescue VPS after ETV failure with a good outcome. Four patients (100%) underwent primary VPS and achieved a satisfactory outcome after treatment, with a reported complications rate of 25%.

Conclusion

LOVA with patent aqueduct represents, in our opinion, a distinct clinical form of chronic hydrocephalus. For this subgroup, as well as for other forms of LOVA, ETV remains an acceptable first-line treatment option considering the good results, and the low complication rate, obtained in those patients and the hypothesis that hydrocephalus is due to an “intracisternal” obstruction.

Long-Standing Overt Ventriculomegaly in Adults (LOVA): Diagnostic Aspects, CSF Dynamics with Lumbar Infusion Test and Treatment Options in a Consecutive Series with Long-Term Follow-Up

BACKGROUND

Long-standing overt ventriculomegaly in adults is a chronic form of hydrocephalus without a clear pathophysiological description and a consensus about the treatment. We present the results of endoscopic third ventriculostomy (ETV) in a consecutive series with a mean follow-up of 79 ± 23 months, highlighting how the preoperative lumbar infusion test could facilitate understanding the pathophysiology of the disease.

METHODS

We retrospectively collected data regarding clinical assessment, neuroradiological findings, and preoperative lumbar infusion tests in 22 symptomatic patients.

RESULTS

In the majority of cases, patients reported imbalance and gait disorders, and 8 subjects had headaches. The preoperative lumbar infusion test demonstrated a mean opening pressure of 13.95 ± 2.88 mm Hg, with plateau values ranging from 22 to 39 mm Hg. The resistance to outflow was 11.21 ± 2.00 mm Hg/mL/min. After the procedure, all patients reported improvement or halted progression in their presenting symptoms, whereas no significant reduction was demonstrated in Evans' index. One subject underwent a second ETV procedure after more than 2 years because of the failure of the endoscopic approach.

CONCLUSIONS

A progressive exhaustion of brain compliance plays an important role in explaining the dichotomy between severe ventriculomegaly and mild clinical symptoms in patients with long-standing overt ventriculomegaly in adults. The role of the aqueductal stenosis as a diagnostic criterion might be reconsidered. The preoperative infusion test data support this observation. Preoperative assessment should include not only clinical and neuroradiological evaluation but also the study of cerebrospinal fluid dynamics. ETV should be considered the treatment of choice because of its safety and efficacy. Long-term follow-up is mandatory.

[Decompensation of chronic internal hydrocephalus in an adult patient]

We report a rare case of decompensated chronic internal hydrocephalus in an adult patient. A 35-year-old woman experienced acute intracranial hypertension in 3 weeks after relief of postoperative inflammation in the oral cavity (tooth extraction). MRI revealed severe internal hydrocephalus. Third ventriculostomy was followed by significant clinical improvement. However, postoperative survey and subsequent neuroimaging confirmed no reduction of ventricular system. Thus, decompensation of chronic hydrocephalus following dental intervention and subsequent oral inflammation was assumed. Impaired venous outflow from the brain and destabilization of CSF circulation can be considered as a pathogenetic mechanism.

The applicability of fixed and adjustable gravitational shunt valves in two different clinical settings

BACKGROUND

Gravitational shunt valves and most recently the adjustable proSA® gravitational valve have been designed to counteract overdrainage and thereby improving clinical outcome. So far, the applicability in a broader mix of hydrocephalus patients is unrevealed. The aim of this study was to evaluate the utility of gravitational valves in two different clinical settings.

METHODS

This retrospective double-center cohort study was enabled by two different shunt management policies. At Rigshospitalet, patients with a complicated shunt history receiving a proGAV® and proSA® shunt system during surgical revision were included, and clinical outcome in the follow-up periods before and after was compared. At Aarhus University Hospital, a combination of a proGAV® and a fixed (SA®) or adjustable (proSA®) gravitational valve was used in all shunt procedures. Clinical outcome in a 2-year follow-up period was compared to a cohort receiving non-gravitational valves in the period before the transition to gravitational valves.

RESULTS

Twenty-two patients were included at Rigshospitalet. Mean follow-up time before and after proGAV® and proSA® implantation was 2.3 and 1.5 years, respectively. In each patient, roughly two surgical revisions (p 0.031) and two hospitalizations (p 0.009) were avoided each year after proGAV® and proSA® implantation. At Aarhus University Hospital, 90 patients with non-gravitational valves and 98 patients with gravitational valves were included. Changes in clinical outcome parameters and shunt survivals were either stable or statistically insignificant.

CONCLUSIONS

Gravitational valves are safe and useful in clinical practice and represent an equivalent alternative as a first-line shunt valve in a broad mix of patients, while proSA® valves should be considered for complex shunt patients.

Gravity-assisted valve (GAV) systems to prevent low-pressure headaches in patients with lumboperitoneal shunts

OBJECTIVES

Low-pressure symptoms after lumboperitoneal (LP) shunting for idiopathic intracranial hypertension (IIH) remain a significant problem. Gravity-assisted valves (GAV) operate at a higher pressure in a vertical position and therefore aim to reduce postural over-drainage. We audited patients with GAV valves inserted in their shunt system to assess their efficacy in reducing low-pressure symptoms and ascertain whether the additional cost of such device can be justified.

METHOD

Using a standard proforma, we reviewed patient medical notes and recorded indications and post-operative outcomes in symptom control.

RESULTS

In total, 24 patients had the GAV system inserted, 12 had low-pressure symptoms after LP and had LP shunts inserted with GAV valves and 11 in developed low-pressure symptoms after insertion of plane LP shunts and had GAV valves added as secondary procedures. One patient was excluded from the study because the indication for the GAV system was secondary to the presence of low lying cerebellar tonsils (secondary Chiari) rather than headache in a patient with IIH who had undergone previous LP shunt insertion. The GAV system was introduced to prevent further tonsillar decent.Out of 23 patients, 17 patients who had the system inserted to prevent or improve low-pressure symptoms reported improvement in their symptoms.

CONCLUSIONS

GAV inserted into LP shunts were effective in reducing low-pressure headaches induced by changes in posture whilst still sufficiently lowering ICP to ameliorate high-pressure symptoms.

Surgical treatment of long-standing overt ventriculomegaly in adults (LOVA)

BACKGROUND

Longstanding overt ventriculomegaly in adults (LOVA) is characterised by chronic hydrocephalus presumed to begin during infancy, but arresting before becoming clinically detectable. Later in life clinical features of hydrocephalus ensue, typically in the 5th or 6th decades. Only a relatively small number of LOVA case series have been published, and ambiguity remains regarding optimal management. This case series describes a series of patients with LOVA treated successfully at a single neurosurgical institution using endoscopic third ventriculostomy (ETV).

METHODS

A series of 14 patients were diagnosed with LOVA using established clinical and radiological criteria. All patients underwent an ETV and their clinical conditions were followed up for up to 5 years post-operatively.

RESULTS

Fourteen patients (100 %) reported either improvement or halt of progression in their presenting symptoms 3 months after ETV; 93 % of patients (n = 13) did not require any further surgical intervention. One patient (7 %) reported deterioration in symptoms beyond 3 months post-operatively, which necessitated further surgery (ventriculoperitoneal shunt). These promising outcomes after ETV are mirrored in numerous other LOVA case series. Other works have analysed the value of CSF shunting procedures in LOVA, with mixed results. A direct, prospective comparison of outcomes after shunt procedures and ETV, with a specific focus on LOVA patients, is yet to be completed. A minority of patients fail to respond, or develop recurrence of symptoms, months or years after initial surgical intervention.

CONCLUSIONS

ETV is an attractive option for surgical treatment of LOVA. After surgical treatment for LOVA, long-term follow-up should be considered to screen for late recurrence of the condition.

[Clinical symptoms of hydrocephalus]

CLINICAL ISSUE

A correct interpretation of radiological data in cases of suspected hydrocephalus is not possible when ignoring patient age and clinical symptoms.

STANDARD TREATMENT

An in-depth knowledge of clinical findings is accordingly essential.

INNOVATIONS

New pathophysiological findings and a detailed assignment of previously unrecognized or ignored clinical symptoms to various entities of the spectrum of hydrocephalus disorders allow a coherent diagnosis drawn from clinical and radiological data. For this purpose it is necessary to know the specific symptoms of hydrocephalus in relation to age. Especially in chronic hydrocephalus, this is of utmost importance to avoid misdiagnosis.

DIAGNOSTIC WORK-UP

The radiological method of choice depends on the age and the specific issue to be addressed.

ACHIEVEMENTS

The typical clinical symptoms of different hydrocephalus entities presented here must be considered as confirmed knowledge.

PRACTICAL RECOMMENDATIONS

Only the synopsis of clinical and radiological findings currently allows correct interpretation of imaging. There is a threat of misdiagnosis if interpretation is restricted purely to radiological findings as the sole predictive value of modern imaging is still too limited despite all innovations.

[Treatment of hydrocephalus]

CLINICAL/METHODICAL ISSUE

Modern treatment of hydrocephalus. STANDARDS OF CLINICAL AND RADIOLOGICAL METHODS: Clinically: shunting and endoscopy. Radiologically: MRT, CCT.

METHODICAL INNOVATIONS

Important innovations are gravitational valves and neuroendoscopy standing for new challenges in preoperative imaging and for sufficient interpretation of postoperative imaging.

PERFORMANCE

G-valves reduce the complication rate (especially overdrainage) in shunting significantly. While lacking appropriated clinical studies, the UK Shunt Registry still provides the best comparison between shunting and neuroendoscopy, after which the long-term revision rates of both methods are identical. The perioperative risk of endoscopic surgery seems to be higher than for shunts.

ACHIEVEMENTS

The superiority of the G-valves in chronic hydrocephalus in comparison with other valves has recently been demonstrated in a class 1 evidence-based study. The neuroendoscopy, has been,-in the absence of a contraindications -, indicated by a guidelines' committee of the German Society of Neurosurgery as method of choice in occlusive hydrocephalus alternatively to shunting.

PRACTICAL RECOMMENDATIONS

Preoperatively, to clarify etiology, comorbidity, and surgical planning, MRI is preferable; with planned neuroendoscopy as high-resolution detailed MRI of access-trajectory and region of interest. In post-operative CT or MRI (after endoscopic procedures always MRI) a differentiation between (sub-)acute and chronic hydrocephalus is important for correct interpretation of imaging: a normalization of ventricular size is physiological only in (sub-)acute hydrocephalus, in chronic hydrocephalus, yet, sign of overdrainage. In chronic hydrocephalus, ventricles shrink usually only marginally. Solely, better delineated, vertex-near cisternae are there evidence of sufficient drainage.

Long-term performance of a CE-approved telemetric intracranial pressure monitoring

Telemetric intracranial pressure (ICP) monitoring has been a challenge throughout several decades. Major obstruction was to minimize zero drift of absolute pressure sensors. A new promising product demonstrating in-vitro excellent long-term stability has been tested for its reliability in an animal model with a follow-up of up to 2 years. In "minipigs" sub-dural (Raumedic-STel®, Helmbrechts Germany) and intraparenchymal (Raumedic-PTel®) telemetric ICP probes have been inserted. Standard ICP probes (Raumedic Neurovent P®) served as controls. In regular intervals of 3 months the telemetrically and conventionally measured ICP have been compared. For each control a new conventional ICP probe has been inserted frontally to the telemetric device in the generalized anesthetized minipigs, resulting in overall 38 comparisons. Bland-Altman-plots, Chi2-tests and matched pair T-tests (significance level < 0.05) were used for data-analysis. The zero-shift was -1.7 ± 7.6 mm Hg (limits of agreement: 4.4 ± 1.9 mm Hg) and -3.0 ± 6.0 mm Hg (limits of agreement: 3.6 ± 2.6 mm Hg) in STel and PTel respectively meeting well the devices specification of ± 2 mm Hg drift per year. The reliability of both telemetric probes has been proved as quite comparable (p=0.2). These new telemetric ICP probes demonstrate reliable data during at least the first 6 months after implantation.

A comparative result of ventriculoperitoneal shunt, focusing mainly on gravity-assisted valve and programmable valve

OBJECTIVE

Despite rapid evolution of shunt devices, the complication rates remain high. The most common causes are turning from obstruction, infection, and overdrainage into mainly underdrainage. We investigated the incidence of complications in a consecutive series of hydrocephalic patients.

METHODS

From January 2002 to December 2009, 111 patients underwent ventriculoperitoneal (VP) shunting at our hospital. We documented shunt failures and complications according to valve type, primary disease, and number of revisions.

RESULTS

Overall shunt survival time was 268 weeks. Mean survival time of gravity-assisted valve (GAV) was 222 weeks versus 286 weeks for other shunts. Survival time of programmable valves (264 weeks) was longer than that of pressure-controlled valves (186 weeks). The most common cause for shunt revision was underdrainage (13 valves). The revision rate due to underdrainage in patients with GAV (7 of 10 patients) was higher than that for other valve types. Of 7 patients requiring revision for GAV underdrainage, 6 patients were bedridden. The overall infection rate was 3.6%, which was lower than reported series. Seven patients demonstrating overdrainage had cranial defects when operations were performed (41%), and overdrainage was improved in 5 patients after cranioplasty.

CONCLUSION

Although none of the differences was statistically significant, some of the observations were especially notable. If a candidate for VP shunting is bedridden, GAV may not be indicated because it could lead to underdrainage. Careful procedure and perioperative management can reduce infection rate. Cranioplasty performed prior to VP shunting may be beneficial.

Miethke DualSwitch Valve in lumboperitoneal shunts

INTRODUCTION

Despite the existence of wide variety of shunt systems, physiological regulation of intracranial pressure in shunted patients remains a utopian dream. Lumboperitoneal shunts (LPS) have long been used for treating idiopathic intracranial hypertension and other types of "communicating" hydrocephalus. Although they can provide rapid and effective symptom resolution, cerebrospinal fluid (CSF) over-drainage remains a common complication of LPS. We introduce the use of the Miethke DualSwitch Valve (M-DSV) for LPS and describe our preliminary experience with these valves in managing and avoiding CSF over-drainage. This is the first description of the use of M-DSV for LPS.

MATERIALS AND METHODS

Over 6 months, we treated five patients with LPS using M-DSV. Prior to the use of the M-DSV, four patients experienced significant over-drainage symptoms secondary to LPS. Data was collected prospectively, including preoperative details and clinical outcome.

RESULTS

Five patients (age range, 22 to 71 years) were operated upon. Three patients had pseudotumor cerebri, one patient had an LPS for treatment of a posterior fossa pseudomeningocele, and one had an LPS for treatment of cauda equina syndrome secondary to lumbar dural ectasia. Four patients had a history of clinical over-drainage secondary to pre-existing LPS systems. The fifth patient had an LPS revision after the previous LPS migrated. Follow-up ranged from 5 to 11 months (mean, 7.8 ± 3 months). All patients had a good outcome with immediate resolution of over-drainage symptoms and are currently asymptomatic.

CONCLUSIONS

The use of M-DSV in LPS is an effective alternative for avoiding posture-related over-drainage and managing patients with LPS-related over-drainage symptoms. Further experience is required to address the long-term outcome, balancing sufficient drainage while preventing over-drainage.

The Adjustable proGAV Shunt

OBJECTIVE

To evaluate the reliability of the gravitation-assisted adjustable proGAV shunt system with a prospective multicenter study conducted in 10 German hospitals.

METHODS

Enrollment for this observational study began in April 2005 and concluded in February 2006. The protocol required re-examinations 3 and 6 months postoperatively and fixed the endpoint of follow-up at 12 months after implantation. Patients with different types of adult, juvenile, and pediatric hydrocephalus were included and 165 patients were enrolled; 9 died and 12 had incomplete follow-up.

RESULTS

Of the assessable 144 patients, 130 completed the protocol after 12 months, whereas 14 failed because of the need to explant the device, mainly because of infection. In 12 patients, components of the shunt, not the valve, were revised. In 65 of the 144 patients, there were 102 readjustments of the valve in 67 incidences because of underdrainage and in 35 because of overdrainage. In 1 case, readjustment was not possible. Determination of pressure level with the verification instrument was safe and corresponded to the required x-ray controls after adjustments. No unintended readjustments were noted.

CONCLUSION

The proGAV is a safe and reliable device.

Huge thrombosis as a consequence of VA-shunts

OBJECTIVE

Thrombosis is a rare but serious consequence of VA-shunts. We present two cases of near fatal thrombosis and its successful (but in case 2, atypical) management.

RESULTS

Case 1: A 38-year-old woman with VA-shunt suffered from rapidly progressing heart failure and later from progressing underdrainage signs nine years after shunting due to a thrombus on the atrial shunt catheter that occluded >80% of the right atrium. Cardio-surgical removal of thrombus and VA-shunt catheter and VP-shunting normalized neurological and cardiological state. Case 2: A 40-year-old woman received a VA-shunt 5 years before she suddenly suffered dyspnea and venous congestion. Secondarily, underdrainage occurred. The underlying huge thrombosis of the superior caval vein could not be excised because the necessary thoracotomy would have interrupted vital venous bypasses along the thoracic wall. Anticoagulants (heparin, cumarin) and ETV relieved all neurological and cardiological symptoms.

CONCLUSION

Sudden or unexpected symptoms of cardiac failure in the presence of a VA-shunt must be recognized as serious. Interestingly, despite distal shunt occlusion, underdrainage symptoms might be initially mild.

Does idiopathic normal pressure hydrocephalus always mean a poor prognosis?

OBJECTIVE

The objective was to assess whether idiopathic normal-pressure hydrocephalus (iNPH) has a worse prognosis than other forms of hydrocephalus, as has been suggested.

METHODS

A total of 125 patients with chronic hydrocephalus, 75 of whom suffered from iNPH and the remaining (non-INPH) from sNPH or non-communicating hydrocephalus, were shunted using gravitational valves. Clinical state was assessed with our clinical grading (KI) and a co-morbidity index (CMI). Average follow-up was 5.1 +/- 1.6 years.

STATISTICS

Spearman, Kruskal-Wallis, ANOVA, chi(2)- and the Wilcoxon U tests at a significance level of pi < 0.05 were used.

RESULTS

Shunt responder rates for iNPH and non-iNPH were 72% and 86%, respectively. With shorter anamnesis (< or =1 year) or preoperative KI < 6 points, iNPH patients had a similar or even better outcome than non-iNPH patients with longer anamnesis or a worse KI. Most impressive was the influence of co-morbidity: 86% of iNPH patients with a low CMI (< or =3 points) experienced clinical improvement after shunting, which was contrasted by a responder rate of 64% for non-iNPH with worse CMI.

CONCLUSION

The diagnosis of iNPH does not by itself mean a worse prognosis, and iNPH patients with favorable preconditions may have a similar or better prognosis than patients with any other kind of hydrocephalus. The worse overall clinical results of iNPH result from late recognition and in most instances worse preconditions.

Gravitational shunt complications after a five-year follow-up

INTRODUCTION

Gravitational shunts (G-valves) for ventriculo-peritoneal (VP) shunting have been available since 1996. We analyzed shunt complications in patients with a complete minimum follow-up of 5 years.

MATERIAL AND METHODS

Between 1996 and 2002, we implanted 282 VP G-valves in various forms of adult chronic hydrocephalus, of which 130 provided a complete data set with an annual follow-up. Adjustable and non-adjustable G-valves were used: the Miethke Dual-Switch valve, the Miethke GAV-valve and a combination of adjustable Codman-Hakim valves with the Miethke Shunt-Assistant. In cases of supposed mechanical shunt failure, the explanted shunts were examined in a bench test.

RESULTS

The total complication rate was 21%:3% shunt infections, 3% catheter dislocation/fracture, 5% underdrainage and 9% overdrainage occurred. Half of the overdrainage complications could be managed conservatively. Underdrainage complications resulted from the chosen opening pressure being too high (n = 3), a secondary increase in intraperitoneal pressure (n = 2) or from "real" shunt failure in one case according to bench test results.

CONCLUSION

G-valves demonstrate sufficient long-term performance over multiple years, and real shunt-related complications are rare. The frequency of revision due to overdrainage is low (4.5%).

Gravitational valves in supine patients with ventriculo-peritoneal shunts

BACKGROUND

In the subgroup of bedridden hydrocephalic patients with ventriculo-peritoneal shunts and gravitational valves, we occasionally observed persisting hydrocephalic complaints even when mechanical or infection-related obstruction was excluded.

METHODS

To investigate the cause of these hydrocephalic symptoms, in vitro and in vivo analyses were used to determine valve opening, intra-abdominal and hydrostatic pressure of an Aesculap-Miethke 10/40 cm H2O gravitational valve at different angles of upper body and head inclination.

FINDINGS

Since hydrostatic pressure is lacking, the resulting intra-ventricular pressures are shown to peak up to 27 cm H2O in supine patients with head, but not upper body inclined.

CONCLUSIONS

We conclude that in the subgroup of bedridden patients with ventriculo-peritoneal shunts and gravitational valves, upright posture is a prerequisite for proper cerebrospinal fluid drainage.

First experiences with an adjustable gravitational valve in childhood hydrocephalus

OBJECT

The goal of this report was to describe the authors' initial experiences with an adjustable gravity-assisted valve (GAV) called the ProGAV in treating childhood hydrocephalus.

METHODS

The ProGAV was implanted in 53 children (29 boys and 24 girls, median age 7.3 years) with hydrocephalus of various origins. The ProGAV consists of a differential-pressure unit with adjustable opening pressures and a gravitational unit with a fixed opening pressure.

RESULTS

The mean follow-up period was 15.2 months (range 6-44 months). The authors did not observe any valve-related complications. Four infections (7.5%) occurred, warranting the removal of the shunt. In 19 children, the opening pressure was changed at least once during the follow-up period, for underdrainage in 10, overdrainage in 8, and shunt weaning in 1, with substantial clinical improvement in 18 children. Overall, good clinical results were obtained in 47 (88.7%) of the 53 valve placements.

CONCLUSIONS

With an overall success rate of 88.7%, the first experiences with the ProGAV in childhood hydrocephalus are promising and justify its further use in the pediatric population.

A mathematical model of survival in a newly inserted ventricular shunt

OBJECT

The object of this study was to mathematically model the prognosis of a newly inserted shunt in pediatric or adult patients with hydrocephalus.

METHODS

A structured search was performed of the English-language literature for case series reporting shunt failure, patient mortality, and shunt removal rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to predict the outcome of a shunt after insertion. Separate models were used to predict shunt survival rates for children (patients < 17 years old) and adults.

RESULTS

Shunt survival rates in children and adults were calculated for 1 year (64.2 and 80.1%, respectively), 5 years (49.4 and 60.2%, respectively), and the median (4.9 and 7.3 years, respectively). The longer-term rates predicted by the model agree closely with those reported in the literature.

CONCLUSIONS

This model gives a comprehensive view of the fate of a shunt for hydrocephalus after insertion. The advantages of this model compared with Kaplan-Meier survival curves are discussed. The model used in this study may provide useful prognostic information and aid in the early evaluation of new shunt designs and techniques.

Have we made progress in preventing shunt failure? A critical analysis

OBJECT

The goal of this study was to determine whether failure rates of hydrocephalus shunts have fallen over the years as a result of experience or technical improvements.

METHODS

A structured search was performed of the English language literature for case series reporting failure rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to analyze failure rates statistically for temporal trends. Separate models were used for children (< 17 years old) and adults.

RESULTS

In children, the shunt failure rate was 31.3% for the 1st year and 4.5% per year thereafter. There were no significant changes in either rate over time. Although 1st-year failure rates in adults have fallen slightly over time, late failure rates have risen.

CONCLUSIONS

Progress in preventing shunt failures has not been made over the last several decades. Any improvements made in shunt materials or insertion techniques have been overshadowed by biological and other factors.

Pediatric gravitational shunts: initial results from a prospective study

OBJECT

The authors' goal in this paper was to evaluate prospectively the efficacy and safety of a new pediatric gravitational shunt to determine whether it warrants inclusion in a randomized, controlled trial with other shunts.

METHODS

A total of 55 children between the ages of 0 and 6 years (median age 0.5 years, average age 4+/-6 years) underwent primary shunt implantation; all received the Miethke Paedi-GAV. The follow-up period ranged between 12 and 77 months (mean 47+/-21 months). The primary end point of the study was the first shunt failure necessitating revision. The 1- and 2-year shunt survival rates were 75 and 68%, respectively. The average failure-free shunt survival duration was 1423 +/- 641 days. Based on imaging findings, no slitlike ventricles occurred. The complication rate was 33%, and the median time to shunt failure was 45 days. Underdrainage occurred in one child (1.8%) and overdrainage in two children (3.6%).

CONCLUSIONS

These preliminary results prove the Miethke Paedi-GAV to be a safe and effective pediatric shunt worthy of inclusion in a randomized comparison with other shunts in the pediatric population.

Evidence that congenital hydrocephalus is a precursor to idiopathic normal pressure hydrocephalus in only a subset of patients

OBJECTIVE

To identify the proportion of patients in a large idiopathic normal pressure hydrocephalus (INPH) cohort with large head circumference (HC) who presumably have congenital hydrocephalus that has not become clinically apparent until late in life.

METHODS

HC was measured in 158 patients diagnosed with communicating INPH and assigned to HC centile range adjusted for height and sex. The proportion of patients with INPH and HC above the 97th, 90th or 50th centiles was compared with the proportion expected in a normal population.

RESULTS

The proportion of patients with HC >90th centile was significantly larger than would be expected in a normal distribution (19.6% vs 10%, p = 0.0001), as was the proportion of patients with HC >97th centile (8.9% vs 3%, p = 0.0001). The relative association between INPH and HC >97th centile was nearly tripled (relative association 2.95; CI 1.36 to 6.41), but the relative association between INPH and HC >50th centile was not significantly higher than predicted (relative association 1.13; CI 0.95 to 1.34).

CONCLUSION

A significantly larger proportion of elderly adults with INPH have a HC greater than the 90th or 97th centile than predicted by population norms, supporting the concept that compensated congenital hydrocephalus that does not become symptomatic until late in life is one aetiology of INPH, but is not responsible for all INPH. The mechanism that leads to the development of INPH in most patients remains elusive.

Siphon regulatory devices: their role in the treatment of hydrocephalus

OBJECT

The management of hydrocephalus can be challenging because of the unique cerebrospinal fluid (CSF) dynamics in each patient. Various shunt systems have been developed for the treatment of hydrocephalus. One of the main issues surrounding these systems is overshunting due to siphoning. In this paper the authors discuss the pathophysiology of CSF siphoning as well as the various devices used to treat this problem. The pros and cons of each device are discussed, as are the key differences among them. Future concepts are also introduced with an emphasis on upcoming device designs.

METHODS

The authors performed a literature review of articles addressing CSF dynamics, shunting, and regulatory devices. The literature consisted of original research articles, company literature on each device, and patent information. A number of siphon regulatory devices have been developed over the past two decades. Each device has a distinct design, requiring specific techniques of implantation for optimal function.

CONCLUSIONS

For the past two decades, a variety of siphon regulatory devices have been used to help deal with CSF siphoning. With the increasing mobility of the population, every neurosurgeon will be seeing patients with older and newer devices. Familiarity with the various devices will assist in the evaluation and care of these patients.