Chronic Pediatric Headache as a Manifestation of Shunt Over-Drainage and Slit Ventricle Syndrome in Patients Harboring a Cerebrospinal Fluid Diversion System: A Narrative Literature Review.

The main subject of the current review is a specific subtype of headache, which is related to shunt over-drainage and slit ventricle syndrome, in pediatric patients harboring an implanted shunt device for the management of hydrocephalus. This clinical entity, along with its impairment regarding the quality of life of the affected individuals, is generally underestimated. This is partly due to the absence of universally agreed-upon diagnostic criteria, as well as due to a misunderstanding of the interactions among the implicated pathophysiological mechanisms. A lot of attempts have been performed to propose an integrative model, aiming at the determination of all the offending mechanisms of the shunt over-drainage syndrome, as well as the determination of all the clinical characteristics and related symptomatology that accompany these secondary headaches. This subcategory of headache, named postural dependent headache, can be associated with nausea, vomiting, and/or radiological signs of slim ventricles and/or subdural collections. The ultimate goal of our review is to draw clinicians' attention, especially that of those that are managing pediatric patients with permanent, long-standing, ventriculoperitoneal, or, less commonly, ventriculoatrial shunts. We attempted to elucidate all clinical and neurological characteristics that are inherently related to this type of headache, as well as to highlight the current management options. This specific subgroup of patients may eventually suffer from severe, intractable headaches, which may negatively impair their quality of daily living. In the absence of any other clinical condition that could be incriminated as the cause of the headache, shunt over-drainage should not be overlooked. On the contrary, it should be seriously taken into consideration, and its management should be added to the therapeutic armamentarium of such cases, which are difficult to be handled.

Bifrontal-Parietal Ratio: A Novel Risk Factor for Cerebrospinal Fluid Overdrainage after Ventriculoperitoneal Shunting.

Objective This study aimed to examine potential risk factors associated with cerebrospinal fluid overdrainage after ventriculoperitoneal (VP) shunting. Materials and Methods We retrospectively examined the medical records of hydrocephalus patients who underwent VP shunting at a single institution between January 2011 and December 2017 and had a minimum 3-year follow-up. Variables studied included age, gender, hydrocephalus etiology, symptoms, shunt valve, ventricular catheter entry point, and neurosurgical history, including history of external ventricular drainage. Radiographic variables included Evans index, bicaudate index, callosal angle, measurements of frontal lobe thickness, and bifrontal-parietal ratio. Results Among the 182 study patients, 11 experienced overdrainage. Age, gender, etiology, symptoms, and surgical history did not significantly differ between patients who experienced overdrainage and those who did not. Evans index, bicaudate index, and callosal angle did not significantly differ between the groups. Measurements of frontal lobe thickness and bifrontal--parietal ratio were significantly lower in the overdrainage group. Conclusion Bifrontal-parietal ratio may be useful to predict overdrainage after VP shunt surgery.

Prospective evaluation of flow-regulated valves for idiopathic normal pressure hydrocephalus: 1-year results.

OBJECTIVE: Overdrainage and frequent reprogramming are common problems with programmable valves after ventriculoperitoneal shunt surgery for idiopathic normal pressure hydrocephalus (iNPH). Non-adjustable, flow-regulated valves offer a potential solution to these problems, but there is limited data on their efficacy. This study will evaluate neurological improvement and overdrainage rates within one year of treatment with a flow-regulated valve. PATIENTS AND METHODS: This prospective study analyzes 45 iNPH patients (median age: 73 years) treated with a flow-regulated valve. Clinical evaluations were performed at baseline, postoperatively, and at 3, 6, and 12 months after surgery. The primary efficacy endpoint was improvement of at least 5 points on the iNPH grading scale at follow-up. The safety endpoint was radiographic evidence of overdrainage. RESULTS: All patients presented with gait disturbance, 35 (78 %) had cognitive impairment, and 35 (78 %) had urinary incontinence. The median duration of symptoms was 24 months. The total iNPH score improved in 33/41 (81 %) at 3 months, in 29/34 (85 %) at 6 months, and in 22/29 (64 %) at 12 months. Overall, 40/45 (89 %) patients had a significant improvement on the iNPH scale. Secondary worsening of symptoms after initial improvement was observed in 5 (11 %) patients. Overdrainage occurred in one patient (2 %) requiring surgical evacuation. CONCLUSION: Treatment of iNPH patients with flow-regulated valves resulted in a good neurological outcome with minimal rates of overdrainage. These results are encouraging and justify the clinical use of these valve types.

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.

Venous congestive encephalopathy secondary to arteriovenous fistula aggravated by cerebrospinal fluid shunt.

We present a unique clinical case of venous congestive encephalopathy in the context of a cerebral arteriovenous fistula with clinical worsening secondary to valvular overdrainage. ICP monitoring, the different pressure settings of the programable CSF shunt and the detailed clinical description that is carried out offer us enough data to understand that this case provides important pathophysiological knowledge to a little-known disease.

Practical Aspects of Nuclear Medicine Ventriculoperitoneal Shunt Evaluation.

The radionuclide ventriculoperitoneal shunt evaluation study is a simple test that involves injecting a small volume of radionuclide into the shunt reservoir and then observing its disappearance using dynamic γ-camera imaging. Although it seems simple, there are several potential pitfalls that can result in a misinterpreted or uninterpretable study. This paper is a detailed description of how to avoid the pitfalls and also how to interpret the results.

Programmable (proSA®) vs. fixed (SHUNTASSISTANT®) gravitational valves in pediatric patients with hydrocephalus: a 16-year retrospective single-center comparative study with biomechanical analysis.

PURPOSE: In pediatric hydrocephalus (HC) treatment, programmable gravitational valves offer greater flexibility to manage overdrainage during children's growth. However, it remains unclear whether these devices provide better outcomes rather than their precursors. The study assessed the benefit from programmability of gravitational valve, i.e., programmable-SHUNTASSISTANT (proSA®) vs. SHUNTASSISTANT® (SA®). METHODS: Clinical records and imaging of pediatric patients with hydrocephalus of non-tumoral etiology treated with fixed (SA®) or programmable (proSA®) gravitational valves between January 2006 and January 2022 were analyzed in a retrospective single-center study. Valve survival was compared in relation to age and etiology. Lately explanted valves received biomechanical analysis. RESULTS: A total of 391 gravitational valves (254 SA® and 137 proSA®) were inserted in 244 patients (n = 134 males). One hundred thirty-three SA® (52.4%) and 67 proSA® (48.9%) were explanted during a follow-up of 81.1 ± 46.3 months. Valve survival rate at 1 and 5 years with proSA® was 87.6% and 60.6% compared to 81.9% and 58.7% with SA®, with mean survival time 56.4 ± 35.01 and 51.4 ± 43.0 months, respectively (P = 0.245). Age < 2 years at implantation correlated with significantly lower valve survival rates (P < 0.001), while HC etiology showed no significant impact. Overdrainage alone accounted for more SA® revisions (39.8% vs. 3.1%, P < 0.001), while dysfunctions of the adjustment system represented the first cause of valve replacement in proSA® cohort (45.3%). The biomechanical analysis performed on 41 proSA® and 31 SA® showed deposits on the valve's internal surface in 97.6% and 90.3% of cases. CONCLUSION: Our comparative study between proSA® and SA® valves in pediatric HC demonstrated that both valves showed similar survival rates, regardless of etiology but only with young age at implantation. The programmability may be beneficial in preventing sequelae of chronic overdrainage but does not reduce need for valve revision and proSA® valve should be considered in selected cases in growing children older than 2 years.

Sinking bone flap due to overdrainage of a ventriculoperitoneal shunt. A case report and review of the literature / Hundimiento de colgajo óseo por sobredrenaje de una derivación ventriculoperitoneal. Caso clínico y revisión de la literatura

The widespread use of decompressive craniectomy and subsequent cranioplasty has led to a better understanding of its complications. However, cases of a sunken bone flap have hardly ever been described. We present the eighth case reported up to date and perform a review of the literature of this sporadic complication. A 40-year-old Caucasian male suffered a traumatic brain injury that required a decompressive craniectomy. One month after initial trauma autologous cranioplasty was performed. A ventriculoperitoneal shunt was also placed. Neurological status progressively improved but his therapist noted cognitive status decline 8 months later. Follow-up computed tomography showed a progressive sinking bone flap. The patient underwent bone flap removal and a custom-made calcium phosphate-based implant was inserted, leading to symptoms resolution. Bone resorption has been described as the main cause of sinking bone flap following cranioplasty. This entity may manifest with symptoms of overdrainage in patients with cerebrospinal fluid shunt devices (AU)

El uso extendido de la craniectomía descompresiva y la consiguiente craneoplastia ha propiciado un mejor conocimiento de sus complicaciones. Sin embargo, esporádicamente se han descrito casos de hundimiento del colgajo óseo. Describimos el octavo caso descrito hasta la fecha y realizamos una revisión de la literatura de esta infrecuente complicación. Un varón de 40 años sufrió un traumatismo craneoencefálico que requirió craniectomía descompresiva. Un mes después se sometió a la reposición de su colgajo óseo, junto con la implantación de una derivación ventriculoperitoneal. Presentó mejoría neurológica progresiva que se frenó y empeoró ocho meses después. La tomografía computarizada de control mostró hundimiento progresivo del colgajo óseo. El paciente se sometió a la retirada del colgajo óseo y cranioplastia con implante a medida, con resolución de los síntomas. La resorción ósea se ha descrito como la principal causa del hundimiento del colgajo óseo tras cranioplastia. Sin embargo, esta entidad puede manifestarse como síntomas de sobredrenaje en pacientes con derivación de líquido cefalorraquídeo (AU)

Effect of antisiphon devices on ventriculoperitoneal shunt drainage dynamics in growing children.

OBJECTIVE: Infants and small children face changing boundary conditions when treated with a ventriculoperitoneal shunt (VPS) for hydrocephalus. There are no systematic data describing shunt drainage behavior and changes over time in a growing child. Using a child-adapted patient simulator, the authors investigated the drainage behaviors of fixed differential pressure (DP) valves and adjustable valves with devices for preventing overdrainage in children of different ages. METHODS: Three miniNAV DP valves with a 10-cm H2O medium-pressure setting (MN10) and three adjustable proGAV2.0 valves with a 25-cm H2O gravitational unit (GU) at low 5-cm H2O opening pressure (PG5) and medium 10-cm H2O opening pressure (PG10) settings were each investigated with a hardware-in-the-loop test bed. This test bed consisted of a posture motion mechanism and two pressure compartments that mimicked intracranial and abdominal pressures and was used to test the VPS under realistic in vitro conditions. Body orientation and length were physically set according to the child's age. The software simulated the physiological situations of children aged 1, 5, and 10 years. All valves were tested according to these specifications, with 5 runs for 1 hour each in the horizontal, vertical, and horizontal positions. Intracranial pressure (ICP) and VPS flow were measured, and the respective cerebrospinal fluid volume changes and ICP set value were computed. RESULTS: The drainage parameters increased with age in all valves in the vertical position, with that of MN10 being pronounced in the 1-year-old simulation. The GU values in PG5 and PG10 substantially reduced drainage compared with MN10. PG10 prevented drainage in the 1-year-old and 5-year-old setups, but there was some drainage at physiological ICP in the 10-year-old setup. In contrast, MN10 produced the largest decreases in ICP across all ages and positions, and overdrainage resulted in insufficient ICP recovery in the subsequent horizontal position. ICP levels were mostly constant with PG10 at all ages. CONCLUSIONS: This study shows that unprotected DP valves may lead to overdrainage in infants, whereas low-pressure GU valves can prevent overdrainage through 5 years and medium-pressure GU valves admit physiological ICP through at least 10 years. Therefore, devices for preventing overdrainage should be included in the first implanted shunt, and opening pressure should be adjusted as the child grows.

Sinking bone flap due to overdrainage of a ventriculoperitoneal shunt. A case report and review of the literature.

The widespread use of decompressive craniectomy and subsequent cranioplasty has led to a better understanding of its complications. However, cases of a sunken bone flap have hardly ever been described. We present the eighth case reported up to date and perform a review of the literature of this sporadic complication. A 40-year-old Caucasian male suffered a traumatic brain injury that required a decompressive craniectomy. One month after initial trauma autologous cranioplasty was performed. A ventriculoperitoneal shunt was also placed. Neurological status progressively improved but his therapist noted cognitive status decline 8 months later. Follow-up computed tomography showed a progressive sinking bone flap. The patient underwent bone flap removal and a custom-made calcium phosphate-based implant was inserted, leading to symptoms resolution. Bone resorption has been described as the main cause of sinking bone flap following cranioplasty. This entity may manifest with symptoms of overdrainage in patients with cerebrospinal fluid shunt devices.

How to define CSF overdrainage: a systematic literature review.

PURPOSE: Overdrainage (OD) is one of the most frequent complications related to drainage of the cerebrospinal fluid (CSF). It is mostly associated with valve-bearing shunt systems but should probably be considered as a risk factor in any type of CSF diversion procedure. There is extreme variation in the reported incidence of OD due to the lack of consensus on defining criteria and an unclear perception of the pathophysiology. Hence, OD is probably underreported and underestimated. The objective of this paper was to establish a definition of OD, based on a systematic review of the literature. METHODS: A systematic search was conducted in MEDLNE and EMBASE. Studies providing a definition or a description of diagnostic findings related to OD in ventriculoperitoneal shunt treated hydrocephalus were included. Non-English titles, abstracts and manuscripts were excluded. Extracted descriptions were graded into five groups (class I-V studies) based on how precise the terminology used to describe OD was. Class I studies were included for further analysis and characteristics of OD were extracted. The quality of included descriptions was assessed by a clinical expert panel. RESULTS: A total of 1309 studies were screened, 190 were graded into groups, and 22, which provided specific definitions or descriptions of OD, were graded as class I studies. We extracted 32 different characteristics consistent with OD (e.g., clinical symptoms, radiological signs, and syndromes). CONCLUSION: There was an overall agreement that CSF overdrainage following implantation of a ventriculoperitoneal shunt in a mixed pediatric and adult population is characterized as a persistent condition with clinically manifestations as postural dependent headache, nausea, and vomiting and/or radiological signs of slim ventricles and/or subdural collections.

A case of recurrent flight-induced cerebrospinal fluid shunt overdrainage.

Shunted patients often complain of headaches after flights. The effect of air travel on shunt systems is unknown. We describe the case of a patient with longstanding hydrocephalus, who suffered flight-induced clinical deterioration and shunt overdrainage in two independent occasions. The patient, clinically stable for 1.5 and 5 years before each episode, reported severe headaches starting during the descent stages of the air travel. On both occasions, brain MRI imaging demonstrated pronounced ventricular size reduction. This case suggests that flight-induced shunt overdrainage can occur and should be suspected in patients with prolonged headaches and/or clinical deterioration triggered by air travel.

Acquired Chiari type I malformation: a late and misunderstood supratentorial over-drainage complication.

PURPOSE: Acquired Chiari I malformation is an uncommon but possible late complication of supratentorial shunting in children. This condition can be caused by an abnormal thickening of the cranial vault and consequent reduction of the posterior cranial fossa (PCF) volume especially in children with already a small PCF volume. The management of Acquired Chiari I malformation is very challenging, and several options have been proposed for this condition. These are aimed to expand the PCF volume both through decompression and PCF remodeling in order to relieve symptoms of acquired Chiari I malformation. A cranial vault remodeling or a standard Chiari decompression is two proposed techniques aimed to expand the PCF volume thus relieving symptoms . METHODS: We describe the case of a 16-year-old girl undergone surgical removal of sellar-suprasellar glioneuronal tumor and ventriculo-peritoneal shunting, who developed an acquired symptomatic Chiari type I malformation some years after ventricular-peritoneal shunting. For this condition, she underwent successful standard Chiari decompression with C0-C1 craniectomy and duroplasty. RESULTS: We retrospectively analyzed MRI and CT scan performed during follow-up, in order to evaluate the volume of the posterior cranial fossa and to measure the variation of skull thickness at different periods. MRI and CT scan analysis showed a progressive thickening of the calvaria, in particular of the occipital bone, leading to a progressive reduction of PCF volume with the establishment of acquired Chiari type I malformation. In this case, standard C0-C1 Chiari decompression was effective in restoring PCF volume and relieving symptoms. CONCLUSION: Acquired Chiari I malformation due to chronic overhunting could be a severe and late complication in patient undergone supratentorial shunting. These patients require careful clinical and radiological follow-up to avoid over-drainage. According to our analysis, a careful selection of pediatric patients for supratentorial shunting should be made according to pre-operative PCF volume in order to foresee higher odds of possible late complications from over-drainage.

Cerebral Venous Thrombosis Due to Overdrainage in a Patient With Normal Pressure Hydrocephalus: A Case Report.

Mechanical shunting of cerebrospinal fluid (CSF) is an effective treatment for hydrocephalus but is not exempt from complications. A 67-year-old male with a history of normal pressure hydrocephalus (NPH) and ventriculoperitoneal shunting (VPS) one year ago presented with gait disturbance and memory impairment. His head computed tomography (CT) was normal, and the shunting pressure was reduced from 110 to 70 mmH20 with gait and memory improvement. One week later, he reported persistent pressure headaches, which worsen when lying down, accompanied by nausea and vomiting. His neurological examination was notable for a short-stepped wide-based gait. Two generalized seizures were observed. CT cerebral venography revealed sinus venous thrombosis (SVT). After two days, a new CT was performed, and bilateral subdural hygromas were found. The shunting pressure was readjusted to 110 mmH20, and symptom improvement was noted. One week later, CT showed enlargement and bleeding of subdural collections. The drainage system was closed, and the patient continue to recover. The temporal association between pressure adjustment and symptom onset and the evidence of progressive subdural effusions suggest that the decrease of CSF volume by overdrainage led to an increase in cerebral blood volume and the dilatation of the venous sinus, which precipitated thrombus formation.

Cervical Myelopathy Caused by Engorged Epidural Cervical Plexus Associated with Iatrogenic Intracranial Hypotension.

Teaching Point: Iatrogenic overdrainage of cerebrospinal fluid may cause intracranial hypotension with secondary engorgement of the epidural venous plexus, resulting in potentially reversible compression radiculopathy or myelopathy.

Dural sac shrinkage signs on spinal magnetic resonance imaging indicate overdrainage after lumboperitoneal shunt for idiopathic normal pressure hydrocephalus.

Background: We previously found the usefulness of dural sac shrinkage signs (DSSSs), which are the anterior shift of the spinal cord and dura mater behind the cord, detected by magnetic resonance imaging (MRI) at the thoracic level for the diagnosis of spontaneous intracranial hypotension (IH). This is a retrospective survey on the usefulness of DSSSs for the early detection of iatrogenic IH caused by overdrainage through a lumboperitoneal shunt (LPS) for patients with idiopathic normal pressure hydrocephalus (INPH). Methods: Forty-five INPH patients had an LPS using a pressure programmable valve equipped with an anti-siphon device. Results: Nine patients complained of orthostatic headache after the LPS, indicating IH due to overdrainage, which persisted for more than a week in three patients and 2-7days in six patients. The headache was transient/ nonorthostatic in ten patients and absent in 26 patients. The DSSSs and accompanying enlargement of the venous plexus were observed in all three patients with prolonged orthostatic headaches. Only the anterior shift of the dura mater was observed in 1 (4%) among 25 patients who had short-term orthostatic headache, transient/ nonorthostatic headache, or absent headache, and underwent spinal MRI. A patient with prolonged severe orthostatic headache with both DSSSs eventually developed intracranial subdural effusion and underwent tandem valve surgery, which provided a quick improvement of symptoms. The DSSSs on thoracic MRI also disappeared promptly. Conclusion: DSSSs may serve as objective signs for the diagnosis of IH due to overdrainage through an LPS for INPH.

Shunt Over-drainage, Slit Ventricle Syndrome, Programmable Valves and Anti-Siphon Devices. A Narrative Review of a Multifactorial and Intractable Problem.

The current management strategy of hydrocephalus mainly involves the insertion of a ventriculoperitoneal shunt and is inherently related with a complication widely known as shunt over-drainage. Albeit this is a well-recognized complication, the true incidence and severity of this phenomenon remains undefined and most probably underdiagnosed, necessitating a more comprehensive pathophysiologic and therapeutic consideration. The slit ventricle syndrome is intimately related with the entity of shunt over-drainage, although who's the definition of the former is implicated by a lack of universally accepted inclusion criteria. Another point of controversy is related with the absence of widely accepted criteria that would be able to discriminate the existing differentiations between these two entities. This is reflected in the fact that there are many proposed, relevant, treatment protocols. The background for all this data is based on the uncertainty and ambiguity regarding the pathophysiological mechanisms that are implicated. Current efforts are centered on the implementation of precautionary measures, as well as on treatment of both of these entities. Currently, there are enough evidence that support the concept that prevention of siphoning via the use of gravitational valves or antisiphon devices is the most efficacious means contained in our current therapeutic armamentarium. We attempt to present an overview of this complex entity, emphasizing on the hydrodynamics of the cerebrospinal fluid circulation in conditions harboring a ventriculoperitoneal shunt, the effect of the siphoning effect and the role of programmable valves and anti-siphon devices in our effort to eliminate this phenomenon. Based on an extensive literature review and on expert opinion, we concluded that the insertion of an anti-siphon device (gravitational shunt valves) could reliably address the issue of over-drainage, when a patient assumes a vertical position. Besides that, there are ongoing prospective studies centered on the safety and efficacy of adjustable gravitational valves, whose results are of ultimate importance. It is of paramount importance to be recognized that, due to the complexity of the pathophysiology of shunted hydrocephalus, lifelong follow-up of patients with ventriculoperitoneal shunts is necessary.

The Role of Antisiphon Devices in the Prevention of Central Ventricular Catheter Obliteration for Hydrocephalus: A 15-Years Institution's Experience Retrospective Analysis.

Shunt over-drainage in patients harboring a ventriculoperitoneal shunt constitutes one of the most devastating, and difficult to manage, side effects associated with this operation. Siphoning is one of the most important contributing factors that predispose to this complication. Based on the fact that the predisposing pathophysiologic mechanism is considerably multiplicated, amelioration of that adverse condition is considerably difficult to achieve. A lot of evidence suggests that the widespread utilization of gravitational valves or antisiphon devices is of utmost importance, in order to minimize or even avoid the occurrence of such complications. The recent literature data highlight that gravity-related, long-lasting shunt over-drainage consists of a momentous factor that could be considered one of the main culprits of central shunt failure. A lot of efforts have been performed, in order to design effective means that are aimed at annihilating siphoning. Our tenet was the investigation of the usefulness of the incorporation of an extra apparatus in the shunt system, capable of eliminating the impact of the siphoning effect, based on the experience that was gained by their long-term use in our institution. A retrospective analysis was performed, based on the data that were derived from our institution's database, centered on patients to which an ASD was incorporated into their initial shunt device between 2006 and 2021. A combination of clinical, surgical, radiological findings, along with the relevant demographic characteristics of the patients were collected and analyzed. We attempted to compare the rates of shunt dysfunction, attributed to occlusion of the ventricular catheter, in a group of patients, before and after the incorporation of an anti-siphon device to all of them. A total number of 120 patients who have already been shunted due to hydrocephalus of different etiologies, were managed with the insertion of an ASD. These devices were inserted at different anatomical locations, which were located peripherally to the initially inserted valvular mechanism. The data that were collected from a subpopulation of 17 of these patients were subjected to a separate statistical analysis because they underwent a disproportionately large number of operations (i.e., >10-lifetime shunt revisions). These patients were studied separately as their medical records were complicated. The analysis of our records revealed that the secondary implementation of an ASD resulted in a decrease of the 1-year and 5-year central catheter dysfunction rates in all of our patients when compared with the relevant obstruction rates at the same time points prior to ASD insertion. According to our data, and in concordance with a lot of current literature reports, an ASD may offer a significant reduction in the obstruction rates that is related to the ventricular catheter of the shunt. These data could only be considered preliminary and need to be confirmed with prospective studies. Nevertheless, this study could be considered capable of providing supportive evidence that chronic shunt over-drainage is a crucial factor in the pathophysiology of shunt malfunction. Apart from that, it could provide pilot data that could be reviewed in order to organize further clinical and laboratory studies, aiming toward the assessment of optimal shunt valve systems that, along with ASD, resist siphoning.

Retrospective single-center historical comparative study between proGAV and proGAV2.0 for surgical revision and implant duration.

OBJECTIVE: Cerebrospinal fluid (CSF) diversion shunt systems remain to be the most common treatment for pediatric hydrocephalus. Different valve systems are used to regulate CSF diversion. Preventing complications such as occlusions, ruptures, malpositioning, and over- or underdrainage are the focus for further developments. The proGAV and proGAV2.0 valve system are compared in this retrospective study for revision-free survival and isolated valve revision paradigms. METHODS: In the first part of the study, the shunt and valve revision-free survival rates were investigated in a retrospective historical comparison design for a period of 2 years in which each valve was used as standard valve (proGAV: July 2012-June 2014; proGAV2.0: January 2015-December 2016) with subsequent 30-month follow-up period, respectively. In the second part of the study, the implant duration was calculated by detecting isolated valve (valve-only) revisions together with another valve explantation during the entire period of the first study and its follow-up period. RESULTS: Two hundred sixty-two patients (145 male and 117 female, mean age 6.2 ± 6.1 years) were included in the cohort of revision-free survival. During the 30-month follow-up period, 41 shunt revisions, including 27 valve revisions (shunt survival rate: 72.1%, valve survival rate: 81.6%) were performed in the proGAV cohort and 37 shunt revisions, including 21 valve revisions (shunt survival rate: 74.8% and valve survival rate: 85.0%) were performed in the proGAV2.0 cohort without showing statistically significant differences. In the second part of the study, 38 cases (mean age 4.0 ± 3.9 years) met the inclusion criteria of receiving a valve-only-revision. In those patients, a total of 44 proGAV and 42 proGAV2.0 were implanted and explanted during the entire study time. In those, a significantly longer implant duration was observed for proGAV (mean valve duration 961.9 ± 650.8 days) compared to proGAV2.0 (mean length of implantation period 601.4 ± 487.8 days; p = 0.004). CONCLUSION: The shunt and valve revision-free survival rates were found to be similar among the groups during 30 month follow-up. In patients who received "valve only" revisions and a subsequent explanation, the implant duration was significantly longer in the proGAV. Although the amount of patients with valve-only-revisions are small compared to the entire cohort certain patients seem to be at higher risk for repeated valve revisions.

Differential Diagnosis of Cyclic Vomiting and Periodic Headaches in a Child with Ventriculoperitoneal Shunt: Case Report of Chronic Shunt Overdrainage.

Fourteen months after the implantation of a ventriculoperitoneal shunt catheter, a six-year-old boy developed recurrent, severe headaches and vomiting every three weeks. The attacks were of such severity that hospitalizations for analgesic and antiemetic therapies and intravenous rehydration and electrolyte substitution were repeatedly required. The patient was asymptomatic between the attacks. After an extensive diagnostic workup-including repeated magnetic resonance imaging (MRI) and neurosurgical examinations-common differential diagnoses, including shunt overdrainage, were ruled out. The patient was transferred to a specialized pediatric pain clinic with suspected cyclic vomiting syndrome (CVS). Despite intensive and in part experimental prophylactic and abortive pharmacological treatment, there was no improvement in his symptoms. Consecutive MRI studies reinvestigating the initially excluded shunt overdrainage indicated an overdrainage syndrome. Subsequently, the symptoms disappeared after disconnecting the shunt catheter. This case report shows that even if a patient meets CVS case definitions, other differential diagnoses must be carefully reconsidered to avoid fixation error.