Classification and management of the slit ventricle syndrome

Vaulting further: cranial vault expansion for craniocerebral disproportion without primary craniosynostosis

PURPOSE

Treatment of subjects with refractory idiopathic intracranial hypertension (IIH) or shunted hydrocephalus with chronic shunt complications is challenging. What is the role for cranial vault expansion, particularly utilizing posterior vault distraction osteogenesis (PVDO), in these cases? This study assesses medium-term efficacy of cranial vault expansion in this unique patient population.

METHODS

A retrospective review was conducted of patients who underwent cranial vault expansion from 2008 to 2023 at the Children's Hospital of Philadelphia. Subjects who did not have a diagnosis of primary craniosynostosis were included in the study. Demographic information, medical history, and perioperative details were collected from medical records. Primary outcomes were the rate of CSF diversion procedures and resolution of presenting signs and symptoms. Secondary outcomes were perioperative and 90-day complications and reoperation requirement.

RESULTS

Among 13 included subjects, nine (69.2%) patients had a primary diagnosis of shunted hydrocephalus and 4 (30.8%) patients had IIH. Twelve (92.3%) subjects underwent posterior vault distraction osteogenesis (PVDO) and one (7.7%) underwent posterior vault remodeling (PVR). All 4 patients with IIH demonstrated symptomatic improvement following PVDO, including resolution of headaches, vomiting, and/or papilledema. Among 9 patients with shunted hydrocephalus, CSF diversion requirement decreased from 2.7 ± 1.6 procedures per year preoperatively to 1.2 ± 1.8 per year following cranial vault expansion (p = 0.030). The mean postoperative follow-up was 4.1 ± 2.1 years and four (30.8%) patients experienced complications within 90 days of surgery, including infection (n = 2), CSF leak (n = 1), and elevated ICP requiring lumbar puncture (n = 1). Four (30.8%) patients underwent repeat cranial vault expansion for recurrence of ICP-related symptoms. At most recent follow-up, 7 of 9 patients with shunted hydrocephalus demonstrated symptomatic improvement.

CONCLUSION

Cranial vault expansion reduced intracranial hypertension-related symptomology as well as the rate of CSF diversion-related procedures in patients with refractory IIH and shunted hydrocephalus without craniosynostosis, and should be considered in those who have significant shunt morbidity.

Effectiveness of subtemporal decompression for the management of slit ventricle syndrome

OBJECTIVES

To assess the effectiveness of subtemporal decompression in the management of slit ventricle syndrome.

METHODS

We conducted a retrospective review of all patients with slit ventricle syndrome (SVS) who underwent subtemporal decompression (STD) at our centre between 2010 and 2021. Cases were identified using the hospital database. Medical records for each patient were reviewed, including operative and radiological reports.

RESULTS

Fifteen patients underwent STD for the management of SVS. Median age at time of STD was 9.18 years. Aetiology of hydrocephalus consisted of spinal dysraphism (5), idiopathic (4), post-infectious (1), post-haemorrhagic (3), secondary to tumour (1), and craniofacial anomalies (1). Median age at first shunt insertion was 3.4 months. Median pre-operative period assessed, from initial shunt insertion to STD, was 4.54 (interquartile range [IQR] 3.12-10.47) years. Twelve patients underwent ≥1 shunt revision prior to STD. All patients had a diagnosis of SVS at time of STD. Presenting symptoms, for the admission in which STD was performed, included nausea (9), vomiting (8), lethargy (8), headache (12), irritability (5), and visual disturbances (6). One third underwent shunt revision at the time of STD. Two patients developed post-operative complications requiring further surgery (meningitis requiring shunt revision: 1; wound debridement: 1). Three patients developed uncomplicated post-operative pyrexia, which was managed with antibiotics. Median duration of post-operative follow-up was 5.4 (IQR 1.73-8.54) years. Eleven patients underwent ≥1 shunt related procedure following STD. Wilcoxon signed-rank test demonstrated a significant difference in number of shunt related procedures before (median = 5, IQR 1-8) and after (median = 3, IQR 0-5) STD (Z = -2.083, p = .037). All patients reported subjective symptom improvement post-operatively. Thirteen patients experienced symptom recurrence at a median duration of 10 months post-operatively.

CONCLUSIONS

STD was associated with a reduction in the amount of shunt related procedures required in this group of patients with SVS. Further study is required to confirm this association.

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.

Incidental and Clinical Significance of Slit Ventricles in Fixed Pressure Valves

INTRODUCTION

Slit ventricle syndrome (SVS) is a recognized delayed complication of cerebrospinal fluid (CSF) shunting in children. It had been linked to the use of low-pressure shunts and considered an argument for the use of programmable valves. In this study, we aim to assess the rate of SVS in children that were shunted using fixed-pressure valves.

METHODOLOGY

This study is a retrospective cohort study that occurred in King Abdulaziz Medical City, Jeddah, which reviews 100 patients with a median age of 15.5 months that were shunted by using fixed pressure valves during the period from 2010 to 2018. Fixed low-pressure valves were used in 69% of patients, while fixed medium-pressure valves were used in 31% of patients. SVS was defined by the presence of slit-like ventricles (fronto-occipital [F-O] horns ratio was ≤ 0.2 on any post-shunt CT scan) and the occurrence of slit-like ventricle-related symptoms (chronic headache, nausea, vomiting, and altered conscious level_ in the absence of other causes of shunt malfunction.

RESULTS

The overall SVS rate in the cohort was 6%. Nine children had slit-like ventricles, but only six of them were symptomatic. Relatively higher SVS rates were observed in younger male children, obstructive hydrocephalus, and medium-pressure valves. Slit-like ventricle-related symptoms in the absence of a slit-like ventricle were reported in 24 out of 91 (26%) patients. A total of 42 patients underwent shunt revisions for other complications. All SVS patients were treated conservatively. There was a temporal fluctuation in the F-O horns ratio and in some patients with SVS their F-O horns ratio returned to normal at further follow-up without intervention.

CONCLUSIONS

The overall SVS rate following the use of fixed-pressure CSF valves in children is low and managed conservatively. Not all patients with slit-like ventricles are symptomatic and the radiological appearance of SVS may improve on further follow-up without intervention. Fixed pressure valves remain an acceptable device in the treatment of hydrocephalus in children.

Slit ventricle syndrome: Historical considerations, diagnosis, pathophysiology, and treatment review

After the introduction of shunt treatment for the management of childhood hydrocephalus, a wide variety of complications related to this treatment modality have been recognized. The entity of slit ventricle syndrome (alternatively, symptomatic ventricular coaptation) is one of them, is frequently encountered in the pediatric population and its symptom complex resembles that of shunt failure. We conducted research on PubMed^®, MEDLINE^®, and Web of Science^®, using the keywords: “slit ventricles,” “slit ventricle syndrome,” “SVS” and “ventricular coaptation.” The aim of our review was to trace the advances made through the past decades, concerning our knowledge about the clinical characteristics, pathophysiology, and treatment options of this entity. The discrepancy among researchers about the offending etiology and the optimum treatment algorithm of this entity, as well as the necessity of an updated concept regarding shunt over drainage is analyzed. The multiple treatment modalities proposed and pathophysiologic mechanisms implicated for the treatment of slit ventricle syndrome illustrate the complexity of this entity. Consequently, the issue requires more detailed evaluation. In this review, we comment on all the main facets related to shunt over drainage and the resultant slit ventricle syndrome.

Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model

Although shunt overdrainage is a well-known complication in hydrocephalus management, the problem has been underestimated. Current literature suggests that the topic requires more examination. An insight into this condition is limited by a lack of universally agreed-upon diagnostic criteria, heterogeneity of published series, the multitude of different management options and misunderstanding of relationships among pathophysiological mechanisms involved. We carried out a review of the literature on clinical, radiological, intracranial pressure (ICP), pathophysiological and treatment concepts to finally propose an integrative model. Active prophylaxis and management are proposed according to this model based on determination of pathophysiological mechanisms and predisposing factors behind each individual case. As pathophysiology is progressively multifactorial, prevention of siphoning with gravitational valves or antisiphon devices is mandatory to avoid or minimize further complications. Shunt optimization or transferal and neuroendoscopy may be recommended when ventricular collapse and cerebrospinal fluid isolation appear. Cranial expansion may be useful in congenital or acquired craniocerebral disproportion and shunting the subarachnoid space in communicating venous hydrocephalus and idiopathic intracranial hypertension.

In vitro performance of six combinations of adjustable differential pressure valves and fixed anti-siphon devices with and without vertical motion

OBJECTIVE

Adjustable differential pressure (DP) valves in combination with fixed anti-siphon devices are currently a popular combination in counteracting the effects of cerebrospinal fluid overdrainage following implantation of a ventriculoperitoneal shunt system. The study examined the flow performance of three DP valves in successive combination with an anti-siphon device in an in vitro shunt laboratory with and without vertical motion.

METHODS

We analyzed three DP valves (Codman Hakim Medos programmable valve [HM], Codman CertasPlus [CP], and Miethke proGAV [PG], in combination with either Codman SiphonGuard [SG] or Miethke ShuntAssistant [SA]), resulting in the evaluation of six different valve combinations. Defined DP conditions between 4 and 40 cm H₂O within a simulated shunt system were generated and the specific flow characteristics were measured. In addition, combinations with SA, which is a gravity-dependent valve, were measured in defined spatial positions (90°, 60°). All device combinations were tested during vertical motion with movement frequencies of 2, 3, and 4 Hz.

RESULTS

All valve combinations effectively counteracted the siphon effect in relation to the chosen DP. Angulation-related flow changes were similar in the three combinations of DP valve and SA in the 60° and 90° position. In CP-SA and PG-SA, repeated vertical movement at 2, 3, and 4 Hz led to significant increase in flow, whereas in HM-SA, constant increase was seen at 4 Hz only (flow change at 4Hz, DP 40 cm H₂O: PG (opening pressure 4 cm H₂O) 90°: 0.95 ml/min, 60°: 0.71 ml/min; HM (opening pressure 4 cm H₂O) 90°: 0.66 ml/min, 60°: 0.41 ml/min; CP (PL 2) 90°: 0.94 ml/min, 60°: 0.79 ml/min; p < 0.01); however, HM-SA showed relevant motion-induced flow already at low DPs (0.85 ml/min, DP 4 cm H₂O). In combinations of DP valve with SG, increase of flow was far less pronounced and even led to significant reduction of flow in certain constellations. Maximum overall flow increase was 0.46 ± 0.04 ml/min with a HM (opening pressure 12 cm H₂O) at 2 Hz and a DP of 10 cm H₂O, whereas maximum flow decrease was 1.12 ± 0.08 with a PG (opening pressure 4 cm H₂O) at 3 Hz and a DP of 10 cmH₂O.

CONCLUSION

In an experimental setup, all valve combinations effectively counteracted the siphon effect in the vertical position according to their added resistance. Motion-induced increased flow was consistently demonstrated in combinations of DP valve and SA. The combination of HM and SA especially showed relevant motion-induced flow already at low DPs. In combinations of DP and SG, the pattern of the motion induced flow was more inconsistent and motion even led to significant flow reduction, predominantly at DPs of 10 and 20 cmH₂O.

Novel Endoscopic Technique for Inserting a Sheath into a Slit Ventricle: The Water-Slide Technique

BACKGROUND

The efficacy and safety of endoscopic procedures for slit ventricle syndrome (SVS) have been presented in recent studies. However, inserting a sheath into a target ventricle is essential in the beginning of endoscopic procedures for SVS, and this maneuver is challenging owing to the quite narrow ventricular space. We report a novel flexible endoscopic technique, the water-slide technique, that can effectively guide a sheath into a slit ventricle without the use of other adjunctive devices, such as a neuronavigation system and an ultrasound machine.

METHODS

Ten endoscopic procedures using the water-slide technique were performed in 9 patients with SVS. All patients had undergone ventriculoperitoneal shunt placement. Using the technique, the sheath was first placed on the flexible endoscope. The endoscope was then inserted into the lateral ventricle along the tract around the pre-existing ventricular catheter with irrigation of artificial cerebrospinal fluid via the working channel of the endoscope. After the endoscope reached the ventricle, the sheath was inserted into the ventricle along the endoscope. The endoscope was then used as a stylet. The endoscopic procedure was performed afterward. Continuous irrigation of artificial cerebrospinal fluid via the working channel is important when using this technique.

RESULTS

In all cases, the sheath was successfully introduced to the slit ventricle without the use of adjunctive devices. There were no postoperative complications correlated with the maneuver.

CONCLUSIONS

This novel endoscopic technique is effective and safe for inserting a sheath into a target ventricle in the management of SVS.

Upward ballooning of the third ventricle floor in a patient with slit ventricle syndrome: A unique magnetic resonance imaging finding

Slit ventricle syndrome (SVS) is a well-known chronic complication of ventriculoperitoneal shunt (VPS) placement. In this report, we describe a unique anatomical change that we observed on the magnetic resonance (MR) images of the brain acquired from a patient with SVS. The patient was a 40-year-old woman who had undergone VPS placement at 3 months of age. A computed tomography scan of her brain revealed a slit-like ventricle. In addition, an MR image of her brain revealed upward ballooning of the third ventricle floor, which returned to normal after a lumbar puncture. This anatomical change resulted from the pressure gradient between the intra- and extraventricular spaces. We believe our findings will further our understanding of the pathogenesis of SVS. Moreover, we hope our findings will help clinicians to select endoscopic third ventriculostomy as the primary surgical approach in patients with this particular SVS pathogenesis in order to avoid complications.

The "steppingstone" phenomenon: a new endoscopic finding in slit-ventricle syndrome

Slit-ventricle syndrome (SVS) seems to encompass various pathophysiological abnormalities, including overdrainage of cerebrospinal fluid (CSF) and craniocerebral disproportion after extracranial CSF shunt placement. These pathologies result in small ventricle morphologically, and the ventricular catheter is obstructed by the collapsed ventricular walls. Patients with intermittent headaches, small ventricles on neuroimaging, and slow refill of the shunt reservoir are diagnosed with SVS. In this report, we present a case of SVS treated endoscopically. We detected bulges in a zigzag line on the ventricular walls according to side holes of the ventricular tube, and named them "steppingstone" phenomenon. It is a curious finding which directly shows that the intermittent obstruction of the ventricular tube occurs in patients with SVS. No previous articles have reported this phenomenon, and it indicates adequate treatment for SVS should be provided.

In vitro performance of the fixed and adjustable gravity-assisted unit with and without motion-evidence of motion-induced flow

BACKGROUND

Anti-siphon devices and gravitational-assisted valves have been introduced to counteract the effects of overdrainage after implantation of a shunt system. The study examined the flow performance of two gravitational-assisted valves (shunt assistant - SA and programmable shunt assistant - proSA, Miethke & Co. KG, Potsdam, Germany) in an in vitro shunt laboratory with and without motion.

METHODS

An in vitro laboratory setup was used to model the cerebrospinal fluid (CSF) drainage conditions similar to a ventriculo-peritoneal shunt and to test the SA (resistance of +20 cmH2O in 90°) and proSA (adjustable resistance of 0 to +40 cmH2O in 90°). The differential pressure (DP) through the simulated shunt and tested valve was adjusted between 0 and 60 cmH2O by combinations of different inflow pressures (40, 30, 20, 10, and 0 cmH2O) and the hydrostatic negative outflow pressure (0, -20, and -40 cmH2O) in several differing device positions (0°, 30°, 60°, and 90°). In addition, the two devices were tested under vertical motion with movement frequencies of 2, 3, and 4 Hz.

RESULTS

Both gravity-assisted units effectively counteract the hydrostatic effect in relation to the chosen differential pressure. The setting the proSA resulted in flow reductions in the 90° position according to the chosen resistance of the device. Angulation-related flow changes were similar in the two devices in 30-90° position, however, in the 0-30° position, a higher flow is seen in the proSA. Repeated vertical movement significantly increased flow through both devices. While with the proSA a 2-Hz motion was not able to induce additional flow (0.006 ± 0.05 ml/min), 3- and 4-Hz motion significantly induced higher flow values (3 Hz: +0.56 ± 0.12 ml/min, 4 Hz: +0.54 ± 0.04 ml/min). The flow through the SA was not induced by vertical movements at a low DP of 10 cmH2O at all frequencies, but at DPs of 30 cmH2O and higher, all frequencies significantly induced higher flow values (2 Hz: +0.36 ± 0.14 ml/min, 3 Hz: +0.32 ± 0.08 ml/min, 4 Hz: +0.28 ± 0.09 ml/min).

CONCLUSIONS

In a static setup, both tested valves effectively counteracted the hydrostatic effect according to their adjusted or predefined resistance in vertical position. Motion-induced increased flow was demonstrated for both devices with different patterns of flow depending on applied DP and setting of the respective valve. The documented increased drainage should be considered when selecting appropriate valves and settings in very active patients.

The truth and coherence behind the concept of overdrainage of cerebrospinal fluid in hydrocephalic patients

INTRODUCTION

Overdrainage, siphoning, and slit-ventricle syndrome are well-documented complications of shunting in hydrocephalic patients. Despite the prevalence of these conditions, their mechanisms are still not fully understood. In this paper, the authors trace the concept of overdrainage and the related phenomena of siphoning and slit-ventricle syndrome.

PURPOSE

To provide a historical overview of overdrainage and to reignite discussion of a topic that has been settled.

METHODS AND RESULTS

A medical literature search and review were performed via Google Scholar. Of 565 publications, 3 primary papers were identified and a timeline was developed demonstrating the convergence of the aforementioned concepts. From the primary papers, 25 relevant publications were selected and further analyzed searching for hypothesis, evidence, and conclusions.

CONCLUSION

Overdrainage, siphoning, and slit-ventricle syndrome are associated concepts that have converged into a pathophysiological theory where siphoning of CSF leads to overdrainage, which is then hypothesized to cause slit-ventricle syndrome in a small subset of patients. Our data suggests that while there have been numerous reports regarding overdrainage and its consequences, the evidence is not as robust as currently presumed and this subject requires prospective exploration.

Craniocerebral disproportion: a topical review and proposal toward a new definition, diagnosis, and treatment protocol

INTRODUCTION

At some point in their lives, patients previously shunted for hydrocephalus may experience chronic, debilitating headaches, despite the fact that their shunts are functioning properly. Previously published reports have suggested that a subset of these patients may be suffering from an iatrogenic craniocerebral disproportion (CCD) and, therefore, may benefit from procedures that expand the available intracranial space. A unified definition of this disorder, however, is lacking.

DISCUSSION

Here, the authors chart the history (including historical terminology) of CCD, review its incidence, describe its signs, symptoms, and associated radiologic findings, and expound upon its pathophysiology. Next, a concise clinical definition of CCD based on the temporal correlation of headaches with the appearance of plateau waves on intracranial pressure (ICP) monitoring is proposed. The authors conclude with a discussion of the various therapeutic strategies employed previously to treat this disorder and present their individualized treatment strategy based upon the simultaneous utilization of ICP monitors and gradual external cranial vault expansion.

Effect of electromagnetic navigated ventriculoperitoneal shunt placement on failure rates

OBJECTIVE

To evaluate the effect of electromagnetic (EM) navigation system on ventriculoperitoneal (VP) shunt failure rate through comparing the result of standard shunt placement.

METHODS

All patients undergoing VP shunt from October 2007 to September 2010 were included in this retrospective study. The first group received shunt surgery using EM navigation. The second group had catheters inserted using manual method with anatomical landmark. The relationship between proximal catheter position and shunt revision rate was evaluated using postoperative computed tomography by a 3-point scale. 1) Grade I; optimal position free-floating in cerebrospinal fluid, 2) Grade II; touching choroid or ventricular wall, 3) Grade III; tip within parenchyma.

RESULTS

A total of 72 patients were participated, 27 with EM navigated shunts and 45 with standard shunts. Grade I was found in 25 patients from group 1 and 32 patients from group 2. Only 2 patients without use of navigation belonged to grade III. Proximal obstruction took place 7% in grade I, 15% in grade II and 100% in grade III. Shunt revision occurred in 11% of group 1 and 31% of group 2. Compared in terms of proximal catheter position, there was growing trend of revision rate according to increase of grade on each group. Although infection rate was similar between both groups, the result had no statistical meaning (p=0.905, chi-square test).

CONCLUSION

The use of EM navigation in routine shunt surgery can eliminate poor shunt placement resulting in a dramatic reduction in failure rates.

New and improved ways to treat hydrocephalus: Pursuit of a smart shunt

The most common treatment for hydrocephalus is placement of a cerebrospinal fluid shunt to supplement or replace lost drainage capacity. Shunts are life-saving devices but are notorious for high failure rates, difficulty of diagnosing failure, and limited control options. Shunt designs have changed little since their introduction in 1950s, and the few changes introduced have had little to no impact on these long-standing problems. For decades, the community has envisioned a “smart shunt” that could provide advanced control, diagnostics, and communication based on implanted sensors, feedback control, and telemetry. The most emphasized contribution of smart shunts is the potential for advanced control algorithms, such as weaning from shunt dependency and personalized control. With sensor-based control comes the opportunity to provide data to the physician on patient condition and shunt function, perhaps even by a smart phone. An often ignored but highly valuable contribution would be designs that correct the high failure rates of existing shunts. Despite the long history and increasing development activity in the past decade, patients are yet to see a commercialized smart shunt. Most smart shunt development focuses on concepts or on isolated technical features, but successful smart shunt designs will be a balance between technical feasibility, economic viability, and acceptable regulatory risk. Here, we present the status of this effort and a framework for understanding the challenges and opportunities that will guide introduction of smart shunts into patient care.

Stereotactic versus endoscopic surgery in periventricular lesions

OBJECT

Endoscopic and stereotactic surgery have gained widespread acceptance as minimally invasive tools for the diagnosis of intracerebral pathologies. We investigated the specific advantages and disadvantages of each technique in the assessment of periventricular lesions.

METHOD

This study included a retrospective series of 70 patients with periventricular lesions. Endoscopic surgery was performed in 17 patients (mean age, 37 years; range, 4 months-78 years) and stereotactic biopsy in 55 patients (mean age, 63 years; range, 23-80 years), including two patients who underwent both procedures.

RESULTS

Hydrocephalus was present in 13/17 patients in the endoscopic group (77%) and in 11/55 patients in the stereotactic group (20%). Diagnosis was achieved in all patients in the endoscopic group and in all but one patient in the stereotactic group, in whom histological diagnosis was obtained by endoscopic biopsy during a second operation. In the endoscopic group, additional procedures performed included ventriculostomy (2/17), cyst fenestration (3/17), endoscopic shunt revision (3/17) and placement of Rickham reservoirs or external cerebrospinal fluid drains (6/17). Adverse events occurred in one patient after endoscopy (chronic subdural hematoma) and in two patients after stereotactic surgery (one mild hemiparesis and one transitory paresis of the contralateral leg).

CONCLUSIONS

Endoscopic and stereotactic surgery have distinct advantages and disadvantages in approaching periventricular lesions. The advantages of endoscopy encompass the possibility to perform additional surgical procedures during the same session (e.g. tumour reduction, third ventriculostomy, fenestration of a cyst). The visual control reduces the hazard of injury to anatomical structures and allows for a better control of bleeding although there is a considerable blind-out in such situations. The advantages of stereotactic surgery include a smaller approach and precise planning of the trajectory. It is usually performed under local anaesthesia. Both methods provide a safe and efficient therapeutic option in periventricular lesions with low surgical-related morbidity.

Prevention of ventricular catheter obstruction and slit ventricle syndrome by the prophylactic use of the Integra antisiphon device in shunt therapy for pediatric hypertensive hydrocephalus: a 25-year follow-up study

OBJECT

This 25-year follow-up study was performed on 120 children with hypertensive hydrocephalus to evaluate the influence of the early prophylactic implantation of the Integra antisiphon device (ASD, Integra Neurosciences Ltd.) on the rate of proximal shunt obstructions and the frequency of symptomatic slit ventricle syndrome (SVS). The adaptability of the ASD to growth, proper positioning of the ASD as a necessity for its successful performance, and the 3 phases of SVS development are discussed.

METHOD

Since 1978, the ASD has consistently been implanted either at the time of primary shunt insertion (66 neonates, mean follow-up 11 years) or during revisions of preexisting shunts (54 children, mean follow-up 11.8 years). The complication rate among the 54 children before ASD implantation (mean follow-up 8.3 years) was compared with that among all 120 patients once an ASD had been inserted. Shunt complications were documented as ventricular catheter, distal catheter, and infectious complications.

RESULTS

The study revealed a significant long-term reduction in ventricular catheter obstructions and hospitalizations due to intermittent intracranial hypertension symptoms (symptomatic SVS) after both primary and secondary ASD implantation. Data in the study suggest that the high rate of ventricular catheter obstruction in pediatric shunt therapy is caused by hydrostatic suction induced by differential-pressure valve shunts during mobilization of the patient and that the development of a SVS can be traced back to this constant suction, which causes chronic CSF overdrainage and ventricular noncompliance. Recurrent ventricular catheter obstruction and SVS can be prevented by prophylactic supplementation of every shunt system with an ASD.

CONCLUSIONS

To inhibit chronic hydrostatic suction, to prevent overdrainage and proximal shunt obstruction, and to avoid SVS and thus improve the patient's quality of life, the prophylactic implantation of an ASD in every pediatric hydrocephalus shunt is recommended.

Experiences with a gravity-assisted valve in hydrocephalic children. Clinical article

OBJECT

Over the past decade, a gravity-assisted valve (GAV) has become a standard device in many European pediatric hydrocephalus centers. Because past comparative clinical outcome studies on valve design have not included any GAV, the authors in this trial evaluated the early results of GAV applications in a pediatric population.

METHODS

For a minimum of 2 years the authors monitored 169 of 182 hydrocephalic children who received a pediatric GAV at their first CSF shunt insertion (61.5%) or as a substitute for any differential pressure valve (38.5%) at 1 of 7 European pediatric hydrocephalus centers. Outcomes were categorized as valve survival (primary outcome) or shunt survival (secondary outcome). The end point was defined as valve explantation.

RESULTS

Within a follow-up period of 2 years, the valve remained functional in 130 (76.9%) of 169 patients. One hundred eight of these patients (63.9%) had an uncomplicated clinical course without any subsequent surgery, and 22 (13%) were submitted to a valve-preserving catheter revision without any further complications during the follow-up period. Thirty-nine patients (23.1%) reached an end point of valve explantation: 13 valve failures from infection (7.7%), 8 (4.7%) from overdrainage, and 18 (10.6%) from underdrainage.

CONCLUSIONS

Compared with nongravitational shunt designs, a GAV does not substantially affect the early complication rate. Valve-preserving shunt revisions do not increase the risk of subsequent valve failure and therefore should not be defined as an end point in studies on valve design. A significant impact of any well-established valve design on the early complication rate in shunt surgery is not supported by any current data; therefore, this correlation should be dismissed. As overdrainage-related complications have been shown to occur late, the presumed advantages of a pediatric GAV remain to be shown in a long-term study.

The use of noninvasive electromagnetic neuronavigation for slit ventricle syndrome and complex hydrocephalus in a pediatric population

OBJECT

The aim of this study was to prospectively evaluate the use of noninvasive electromagnetic neuronavigation in children, in particular its use in complex hydrocephalus and slit ventricle syndrome.

METHODS

Prospective data was collected from all pediatric patients undergoing insertion of ventriculoperitoneal shunts using electromagnetic frameless neuronavigation from January 2006 to November 2007.

RESULTS

Twenty-three patients fulfilled the study criteria. All ventricles were cannulated on the first pass. There were no immediate or early postprocedural complications. All but 1 patient had resolution of symptoms (mainly chronic headache) on follow-up (median 7 months, range 1-17 months). The proximal revision rate was 9% (2 of 23 patients). One patient required distal catheter revision. Infection occurred in 1 patient.

CONCLUSIONS

Electromagnetic neuronavigation using a frameless and pinless system is especially suited for pediatric patients. The authors hypothesize that successful placement of ventricular catheters will reduce morbidity and improve shunt longevity.

[Cerebral fluid edema: a rare complication of ventriculoperitoneal shunt]

Physiopathologic knowledge of hydrocephalus allows progress in the conception of modern shunts. With better controlled surgical techniques, shunting has revolutionized the prognosis of hydrocephalus. However, peritoneal or atrial shunting is not harmless, as illustrated by the large number of reported complications. We describe here an unusual complication of ventriculoperitoneal shunt dysfunction revealed by focal cerebral edema in a 60-year-old patient. Preoperative cerebral CT scan showed the focal brain edema with diffusion of cerebrospinal fluid around the trajectory of the ventricular catheter. Abdominal CT scan demonstrated distal shunt dysfunction. Clinical and radiological outcome was good after surgical revision of the shunt, confirming the diagnosis.

Shunts vs endoscopic third ventriculostomy in infants: are there different types and/or rates of complications? A review

INTRODUCTION

The decision-making process when we compare endoscopic third ventriculostomy (ETV) with shunts as surgical options for the treatment of hydrocephalus in infants is conditioned by the incidence of specific and shared complications of the two surgical procedures.

REVIEW

Our literature review shows that the advantages of ETV in terms of complications are almost all related to two factors: (a) the avoidance of a foreign body implantation and (b) the establishment of a 'physiological' cerebrospinal fluid (CSF) circulation. Both these kinds of achievements are particularly important in infants because of the relative high rate of some intraoperative (i.e. abdominal) and late (secondary craniosynostosis, slit-ventricle syndrome) shunt complications in this specific subset of patients. On the other side, the main factor which is claimed against ETV is the relatively high risk of immediate mortality and neurological complications. Clinical manifestations of neurological structure damage seem to be more frequent in infants, probably due to the more relevant effect of parenchymal and vascular damage in this age group; however, both the immediate mortality and neurological damage risk of ETV procedures should be weighted against the long-term mortality and the late neurological damage which is not infrequently described as a consequence of shunt malfunction and proximal shunt revision procedures. Infections are possible in both ETV and extrathecal CSF procedures, especially in infants. However, the incidence of infective complications is significantly lower in case of ETV (1-5% vs 1-20%). Moreover, different from shunting procedures, infections in children with third ventriculostomy have a more benign course, being generally controlled by antibiotic treatment alone.

Reexpandability of the ventricular system of hydrocephalic children in the event of shunt occlusion

INTRODUCTION

To estimate intracranial volume-buffering capacity in the event of shunt occlusion, the reexpandabilty of the lateral ventricles and clinical manifestations were examined in shunt-dependent hydrocephalic children.

MATERIAL AND METHODS

This retrospective study was performed in 38 children who displayed acute deterioration due to spontaneous shunt obstruction. At the time of shunt obstruction, patients with small lateral ventricles [small ventricle (SV) group: Evans' index <or=35, n=13] showed significantly more rapid deterioration into lethargy after onset than those with large lateral ventricles [lateral ventricle (LV) group: Evans' index >0.35, n=25]. All patients in the SV group were 3 years or older at the time of shunt obstruction or had a long period (5.2 years) between initial shunting and shunt occlusion. Their Evans' index was less than 0.33 prior to shunt obstruction.

CONCLUSIONS

While a shunt is functioning, the factors predictive of reduced ventricular reexpandability include (1) a lateral ventricular size smaller than 0.33 on the Evans' index and (2) either an age of more than 3 years in children who have undergone initial shunting at less than 1 year of age or over 5 years of the period after initial shunting.

Failure of cerebrospinal fluid shunts: part II: overdrainage, loculation, and abdominal complications

Complications from cerebrospinal fluid shunts are common and can present with a variety of signs and symptoms. In this second part of a two-part review, shunt overdrainage, loculation of the ventricular system in patients with shunts, and abdominal complications related to ventriculoperitoneal shunts are discussed. Familiarity with these types of shunt failure is essential for neurologists and pediatricians because they are often the first to evaluate and triage these children.

Endoscopic third ventriculostomy in the treatment of shunt-related over-drainage: Preliminary experience with a new approach how to render ventricles navigable

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is increasingly used for the treatment of shunt-related complications in hydrocephalic patients, particularly if the etiology of the underlying hydrocephalus is of obstructive nature.

PURPOSE

Due to the slit-like configuration of the ventricles, ventricular dilatation must be achieved prior to ETV in patients with problems due to over-drainage. This has been accomplished by ligating or explanting the shunt. Here we present an alternative procedure using a gravitational antisiphon device.

MATERIALS AND METHODS

In two patients with over-drainage due to shunted occlusive hydrocephalus ventricles were dilated by integrating an antisiphon device (Miethke ShuntAssistant, Aesculap AG, Tuttlingen, Germany) into their shunt systems. The resistance of the antisiphon device, which is available in configurations from 10 to 35 cm H2O was chosen 10 cm H2O higher than necessary to prevent siphoning in the individual patient.

RESULTS

Both patients gradually recovered from their over-drainage symptoms and the ventricles enlarged enough to allow access with an endoscope. Using a standard procedure, ETV was performed 7 days and 1 month later, respectively. In the same operative session the shunts were occluded. Shunts were removed within 6 weeks after ETV. During follow-up of more than 3 years, both patients remained free of symptoms.

CONCLUSION

The incorporation of an antisiphon device with resistance level selected 10 cm H2O higher than needed to prevent anti-siphoning into a pre-existing shunt system in patients suffering from shunt-related over-drainage is a safe and effective technique to render ventricles large enough to allow endoscopic access for ETV.

Pediatric hydrocephalus: current management

Hydrocephalus is a common problem in pediatric neurology and neurosurgery. The key to the diagnosis of hydrocephalus is the clinical or radiographic progression over time. Most children who have hydrocephalus require ventriculoperitoneal shunts, but the complications of shunting remain distressingly common. Using current endoscopic techniques, a small proportion of patients can be treated without ventriculoperitoneal shunts. The population of pediatric patients who have had hydrocephalic shunts is maturing; these young adults now face issues related to independent living, pregnancy, and long-term care of their hydrocephalus.

In vivo intracranial pressure dynamics in patients with hydrocephalus treated by shunt placement

OBJECT

With the commercial availability of a variety of shunt systems, there is considerable controversy over the choice of the most appropriate shunt valve for each individual with hydrocephalus. Although the performance characteristics of all shunt systems are well documented in the laboratory setting, there is little description of the in vivo dynamics of intracranial pressure (ICP) after implantation of commonly used shunt systems in humans. The authors coupled telemonitoring devices to several different shunt systems to measure the performance characteristics of these valve systems with respect to intraventricular pressure (IVP) at increments of head elevation.

METHODS

Twenty-five patients with different shunt systems and three control patients without shunts were studied for IVP at 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 90 degrees of head elevation, and the resultant curves were analyzed for the best-fit regression coefficient. For purposes of analysis the authors grouped shunt valve systems by design characteristics into three groups: differential-pressure valves (r = -0.321 +/- 0.061; 11 patients), nonsiphoning systems (r = -0.158 +/- 0.027; 10 patients), and flow-regulated valves (r = -0.16 +/- 0.056; four patients); there were three control patients without shunts (r = -0.112 +/- 0.037).

CONCLUSIONS

The authors found that differential-pressure valves always caused ICP to drop to 0 by 30 degrees of head elevation, whereas all other valve systems caused a more gradual drop in ICP, more consistent with pressures observed in the control patients without shunts. Not surprisingly, the differential-pressure valve group was found to have a significant difference in mean regression coefficient when compared with those in whom nonsiphoning shunts (p < 0.023) or no shunts were placed (p < 0.049). These data provide a basis for evaluating shunt valve performance and for predicting valve appropriateness in patients in whom characteristics such as pressure and flow dynamics are weighed in the choice of a specific valve for implantation.

Subtemporal decompression: the treatment of noncompliant ventricle syndrome

OBJECTIVE

To explore the effects of subtemporal decompression (STD) on the frequency of shunt revision and attendances with symptoms of raised intracranial pressure secondary to slit ventricle syndrome and slit ventricle-like syndrome. A renaming of these syndromes as noncompliant ventricle syndrome is suggested.

METHOD

A retrospective review of the notes of all patients at our institution having STD from 1984 to 1997 was conducted.

RESULTS

Twenty-eight patients underwent STD (age range, 4-31 yr). Thirty-two STD procedures were performed. The mean follow-up duration after STD was 5.3 years (range, 0-12 yr). The number of shunt revisions before STD was 128 (mean, 4.6 revisions; range, 0-30 revisions) and after STD was 28 (mean, 1.0 revision; range, 0-7 revisions). The number of attendances before STD was 213 (mean, 6.7 attendances; range, 1-31 attendances) and after STD was 57 (mean, 1.8 attendances; range, 0-10 attendances). Among 15 patients for whom there was sufficient clinical data, 7 revisions were required during the 3 years before STD and 22 during the 3 years after STD. There were 53 admissions during the 3 years before STD and 11 during the 3 years after STD.

CONCLUSION

Although the overall incidence of shunt revision decreases, there is an early increase in the frequency of revision after STD. The number of admissions of patients with raised intracranial pressure symptoms reduces after STD, and we think that this is a more important factor in the consideration of this procedure than the number of recent revisions. We explore these arguments in this article.

Risks in using siphon-reducing devices in adult patients with normal-pressure hydrocephalus: bench test investigations with Delta valves

To elucidate the reason for malfunction of Delta valves in patients with normal-pressure hydrocephalus, the authors applied a new concept of the bench test and simulated intracranial pressure (ICP) to measure the resultant flow with a complete shunt system. Subcutaneous pressure on the valve, valve implantation site, and postural hydrostatic differential-pressure changes were simulated in this bench test designed for adult patients with normal-pressure hydrocephalus. Subcutaneous pressure ranged within 6.4 +/- 0.09 cm H2O (mean +/- standard deviation) on the 7th day after the implantation of the valve in rats. A linear correlation between valve closing pressures and the external pressure was observed: gradual increase of the latter resulted in an approximately equal rise in the closing pressure. Closing pressure ranged within the physiological variation of ICP (10 +/- 5 cm H2O) in the supine position. In the erect position it was higher than the physiological variation (+5 to -5 cm H2O) when the valve was placed at the level of the foramen of Monro and lower when placed at the level of the clavicle. This observation indicates that the subcutaneous pressure around the Delta valve significantly affects its closing pressure. An excessive reduction of flow or a functional obstruction occurs when the patient with a Delta valve implanted at the foramen of Monro assumes an erect posture. The authors conclude that Delta valves are not recommended for implantation at the level of the foramen of Monro in patients with normal-pressure hydrocephalus because of the risk of underdrainage. The mastoid process or clavicle may be the alternative levels for its implantation to prevent underdrainage; however, the possibility of shunt malfunction should be kept in mind because subcutaneous pressure is variable among patients and that might affect the performance characteristics of these valves.

Experiences with flow-regulated shunts (Orbis-Sigma valves) in cases of difficulty in managing hydrocephalus in children

Due to an increasing number of shunt complications with conventional valves, we performed a study of 80 flow-regulated Orbis-Sigma valves implanted in 47 children who had had repeated complications with conventional valves and 33 children receiving their first shunt. The results were encouraging. During the first 5 years after implantation, the probability of absence of any kind of surgical intervention to the valve system was 57% and the probability satisfactory function of the valve itself was 70%. The most frequent complication was underdrainage of CSF, especially in children under the age of 1 year. No cases of CSF overdrainage occurred in this series. The Orbis-Sigma valve appears especially useful for patients unable to tolerate the anti-siphon device, and for patients over 1 year old receiving their first valve for hydrocephalus of non-tumoral and non-haemorrhagic origin.

Effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal shunts

The present study was performed to investigate the effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal (VP) shunts. The series included 35 hydrocephalic patients and five individuals without hydrocephalus who were used as controls. The hydrocephalic patients were divided into three groups: 15 patients who received VP shunts with a differential-pressure valve (DP group); 11 who received VP shunts with a variable-resistance valve (VR group), and 13 hydrocephalic patients (Hyd group) who had not received shunts (four underwent VP shunts later). The cerebral blood flow (CBF) of patients in the supine and upright positions was measured by technetium-99m hexamethylpropylenamine oxide (HMPAO) single-photon emission computerized tomography in each patient, using the subtraction technique. Cerebral perfusion pressure (CPP) was taken as the difference between the mean arterial blood pressure and ventricular fluid pressure, both referenced to the level of the foramen of Mono. The patients' heads were elevated stepwise from supine to upright. Percent changes of the mean CBF in the upright position (% delta mCBFupr) were 24.9% +/- 4.3% (mean +/- standard error of the mean) in the DP group, 6.2% +/- 2.7% in the VR group, 3.5% +/- 2.6% in the Hyd group, and 4.5% +/- 2.2% in the control group. Patients in the DP group showed a pathological increase in CPP with head elevation, whereas those in the Hyd and VR groups showed a physiological decrease in CPP. Three patients with differential-pressure valves, whose % delta mCBFupr was markedly high, developed low-intracranial pressure syndrome. In conclusion, shunted patients with a DP valve showed pathological intracranial hemodynamics in the upright position. This pathological hemodynamic stress in patients with long-standing differential-pressure valve implantation may induce pathological changes in the brain such as subependymal gliosis.

Cerebrospinal fluid edema associated with shunt obstruction

The authors report four hydrocephalic children with cerebrospinal fluid (CSF) edema extending along the ventricular catheter of an obstructed CSF shunt. Three of the patients exhibited massive CSF edema along the ventricular catheter, yet they manifested neither ventricular enlargement nor apparent periventricular CSF edema despite increased intraventricular pressure. These findings suggested ventricular tautness. The remaining patient, who had dilated ventricles with periventricular CSF edema, displayed CSF edema in a limited area along the ventricular catheter. Replacement of the obstructed peritoneal catheter of the shunt resulted in rapid improvement of the edema in all patients. In the three patients with massive CSF edema, however, a small lesion remained in the subcortical white matter along the ventricular catheter as demonstrated by computerized tomography and/or magnetic resonance imaging 3 to 5 years after shunt revision. It is concluded that shunt obstruction may result in massive CSF edema along the ventricular catheter in hydrocephalic children who have ventricular tautness after installation of the shunt causing irreversible although usually asymptomatic damage to the affected area of the brain.

The Delta Valve: a physiologic shunt system

PS Medical has advanced the state-of-the-art in hydrocephalus valve technology with the introduction of the Delta Valve. The Delta Valve is designed upon the premise that the shunted patient should have intracranial pressure (ICP) maintenance within a normal range regardless of cerebrospinal fluid (CSF) flow rate or body position. All previous valves have performance characteristics that are greatly influenced by the negative hydrostatic pressure caused by the gravitational effect on the vertical water column in the distal catheter. This negative pressure influence is non-physiologic and contributes directly to overdrainage that can cause slit ventricles, subdural hematoma, and proximal catheter occlusions. The Delta Valve is the only valve that maintains a near-constant pressure gradient regardless of flow rate or patient posture. It automatically adjusts for increasing negative pressures in the distal catheter by proportionally increasing its resistance to flow, thus nullifying the adverse effects of the hydrostatic force on intracranial pressures. The result is a shunt system that provides for CSF drainage while allowing the patient's normal physiologic conditions to control ICP. The early use of the Delta Valve in the treatment of hydrocephalus may reduce the incidence of the dramatic complications associated with overdrainage.

Is the slit ventricle syndrome always a slit ventricle syndrome?

The term 'slit ventricle syndrome' (SVS) refers to the occurrence of headache, vomiting, and possibly some degree of consciousness impairment in shunted hydrocephalic children in whom slit-like ventricles are seen on computerized tomography (CT) scan examination. The syndrome has been typically observed in older hydrocephalic children operated on in early infancy, even though it has also been observed occasionally in young children and adults. The clinical characteristics of the SVS, the results of the laboratory investigations and the therapeutic measures utilized in the various cases described in the literature differ so widely as to suggest that different clinical conditions are actually being described. In some cases, the diagnosis of SVS should be avoided and substituted by a correct diagnosis of CSF shunt malfunction or of disturbances unrelated to the CSF shunting therapy, e.g., childhood migraine.

Hydrocephalus: slit ventricles, shunt obstructions, and third ventricle shunts: a clinical study

In a retrospective 5 year study of patients with ventricle shunts for hydrocephalus (N = 88), studies were developed on slit ventricles in teenagers and in young adults. These studies presented here are (1) time to slit ventricles from first shunt and average upright ICP associated (N = 24); (2) upright ICP in asymptomatic long-term ventricle shunt patients without slit ventricles (N = 21), (3) clinical course of patients with uncorrected slit ventricles and lateral ventricles or third ventricle shunts (N = 31), (4) resolution of slit ventricles by Zero ICP Shunt with normal upright ICP (N = 28), (5) no resolution of slit or large ventricles in shunted patients with normal upright ICP (N = 23), and (6) unreliability of CT ventricle size (slit or enlarged) after normal upright ICP achieved (N = 28; 23). Surprisingly, slit ventricle patients with the ventricular catheter in collapsed lateral ventricles develop shunt obstruction within 20 months (21/31; 71%; 10/31 29%) patients with ventricle catheters incidentally in the third ventricle did not obstruct during the 4 1/2 year follow-up.

Hydrocephalus: overdrainage by ventricular shunts. A review and recommendations

Selected literature review of the clinical course of patients with ventricular shunts for hydrocephalus shows that the effects of cerebrospinal fluid overdrainage are subdural hematoma, craniosynostosis, slit ventricle syndrome, and low intracranial pressure syndrome. These occur sequentially at different age groups, but approximate averages of incidence and time of occurrence after first shunt reveal an overall incidence of 10%-12% for at least one of these appearing at 6.5 years after shunting. The basic etiology, diagnosis, and variety of treatment modalities available are reviewed, including the need for shunt closing intracranial pressure control. Included is a hydrocephalus program designed to minimize the need for long-term extracranial shunts and to maximize therapeutic intracranial procedures for hydrocephalus.

Slit ventricle syndrome after cyst-peritoneal shunting for the treatment of intracranial arachnoid cyst

Serious complications following installation of a cyst-peritoneal shunt in an 8-year-old boy with asymptomatic arachnoid cyst in the middle cranial fossa are reported. Highly elevated intracranial pressure without association of ventriculomegaly seen in this patient indicates slit ventricle syndrome caused by malfunction of the cyst-peritoneal shunt. This phenomenon is worth recognizing as a possible consequence of cyst-peritoneal shunting for the treatment of intracranial arachnoid cyst.

The incidence and management of the slit ventricle syndrome

The incidence of slit ventricles of shunt treated hydrocephalic children was evaluated in a follow up study of 141 patients. Slit like ventricles on computer tomography was seen in 75 patients (53%). 52 patients (37%) suffered from clinical symptoms corresponding with overdrainage of cerebrospinal fluid. Those 52 patients with the "Slit Ventricle Syndrome" (SLVS) were treated by changing the valve to one with a higher opening pressure and/or adding an antisiphon device (ASD) to the shunt. 22 patients, initially treated by changing the opening pressure of the valve, needed the ASD later. Altogether 74 episodes of the SLVS were treated. The ASD proved reliable for the management of the SLVS. Normalization of ventricular size occurred in 54% of patients. whereas only in 15% treated without the ASD. Reduction of paroxysmal activity on EEG was seen in 70% of patients treated with the ASD, whereas only in 23% of patients treated without the ASD. Clinical relief of symptoms occurred in every patient, and ventricular catheter obstructions could be avoided, even if the ventricular size remained slit-like on CT.

Age-dependent changes of cerebral ventricular size. Part I: Review of intracranial fluid collections

The age distributions of communicating hydrocephalus (CH), pseudotumour cerebri (PC) slit-ventricle syndrome (SVS), and chronic subdural haematomas (CSH) were reviewed in the medical literature. An age-related incidence was found: CH and CSH predominated in neonates less than 2 years and adults older than 55 years, while PC and SVS occurred mainly in older children and young adults. The latter two patient groups seem to show a greater resistance to ventricular dilatation in the presence of decreased CSF absorption. This may be related to larger volume and state of maturity of the cerebrum. On the other hand, neonates and the elderly more readily develop enlarged ventricles, in association with impairment of CSF absorption, or subdural fluid collections. Factors including status of cranial sutures, cerebral atrophy, cerebral water content, degree of cerebral myelination, and glial cell composition, may contribute to the age-related incidence of the four disorders investigated. Similarly, the development of ventriculomegaly may depend upon cerebral elastic properties besides the pri mary disturbance of CSF dynamics. The authors postulate that the size of cerebral ventricles in disorders of the cerebrospinal fluid (CSF) absorption is related to the elastic properties and volume of the brain. Furthermore, cerebral volume and elastic properties may also contribute to the age distribution of chronic subdural haematomas (CSH).