A longitudinal study of shunt function in 360 patients with hydrocephalus

Efficacy of endoscopic third ventriculostomy in old aged patients with normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a chronic disorder caused by interrupted CSF absorption or flow. Generally, shunt placement is first option for NPH treatment. Due to complications of ventriculo-peritoneal (VP) shunt placement, endoscopic third ventriculostomy (ETV) can be considered as an alternative treatment option. Here we report the efficacy of ETV especially in old aged patients with normal pressure hydrocephalus. Total 21 old aged patients with communicating hydrocephalus with opening pressure, measured via lumbar puncture, less than 20cm H₂O underwent ETV. 15 patients had primary/idiopathic NPH and 6 patients had secondary NPH. All patients were studied with a MRI to observe the flow void at aqueduct and the fourth ventricle outflow. And all of them underwent ETV. In a group with peak velocity was higher than 5cm/s, nine patients (75%) were evaluated was 'favorable' and three of them (25%) was scored 'poor'. In another group with peak velocity less than 5cm/s, three of them were scored 'poor' and two of them were scored 'stable'. None of them was evaluated as 'favorable'. We also evaluated the outcomes according to etiology: 12 patients (80% of the patients with primary NPH) were evaluated with 'favorable' after ETV treatment. Two patients (13.3%) were as 'stable'. And one patient was as 'poor' evaluated. Five patients (83.3%) among patients with secondary NPH were as 'poor' evaluated and one of them was stable and no patient was as 'favorable' evaluated. 4 patients, which was as 'poor' evaluated in the group with the secondary NPH, underwent additional VP shunt implantation. Overall, the outcomes of the group with the idiopathic NPH after ETV treatment were more favorable than of the group with the secondary NPH. Our study suggest that ETV can be effective for selected elderly patients with primary/idiopathic NPH, when they satisfy criteria including positive aqueduct flow void on T2 Sagittal MRI and the aqueductal peak velocity, which is greater than 5cm/s on cine MRI.

Development of hydrocephalus and classical hypothesis of cerebrospinal fluid hydrodynamics: facts and illusions

According to the classical hypothesis of the cerebrospinal fluid (CSF) hydrodynamics, CSF is produced inside the brain ventricles, than it circulates like a slow river toward the cortical subarachnoid space, and finally it is absorbed into the venous sinuses. Some pathological conditions, primarily hydrocephalus, have also been interpreted based on this hypothesis. The development of hydrocephalus is explained as an imbalance between CSF formation and absorption, where more CSF is formed than is absorbed, which results in an abnormal increase in the CSF volume inside the cranial CSF spaces. It is believed that the reason for the imbalance is the obstruction of the CSF pathways between the site of CSF formation and the site of its absorption, which diminishes or prevents CSF outflow from the cranium. In spite of the general acceptance of the classical hypothesis, there are a considerable number of experimental results that do not support such a hypothesis and the generally accepted pathophysiology of hydrocephalus. A recently proposed new working hypothesis suggests that osmotic and hydrostatic forces at the central nervous system microvessels are crucial for the regulation of interstial fluid and CSF volume which constitute a functional unit. Based on that hypothesis, the generally accepted mechanisms of hydrocephalus development are not plausible. Therefore, the recent understanding of the correlation between CSF physiology and the development of hydrocephalus has been thoroughly presented, analyzed and evaluated, and new insights into hydrocephalus etiopathology have been proposed, which are in accordance with the experimental data and the new working hypothesis.

Shunt dependence: myths and facts

INTRODUCTION

Chronically shunted patients are believed to be unable to have a shunt-free life. Nevertheless, sometimes shunt removal is possible after an endoscopic third ventriculostomy, even after long periods of cerebral spinal fluid diversion.

RESULTS AND DISCUSSION

We perform a literature review that leads to a discussion of this subject in the light of the current medical knowledge.

A mathematical model of survival in a newly inserted ventricular shunt

OBJECT

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Frameless stereotactic ventricular shunt placement for idiopathic intracranial hypertension

INTRODUCTION

Cerebrospinal fluid (CSF) shunting effectively reverses symptoms of idiopathic intracranial hypertension (IIH). Lumboperitoneal (LP) shunts have traditionally been used in patients with IIH due to a frequently undersized ventricular system. However, the advent of image-guided stereotaxis has enabled effective ventricular catheter placement in patients with IIH. We describe the first large series of frameless stereotactic ventriculoperitoneal (VP) shunting for patients with slit ventricles and IIH.

METHODS

We describe the frameless stereotactic VP shunting technique for IIH in 32 procedures. Outcomes following shunt placement, time to shunt failure, and etiology of shunt failure are reported.

RESULTS

A total of 21 patients underwent 32 ventricular shunting procedures (20 VP, 10 ventriculoatrial, 2 ventriculopleural). One hundred percent of shunts were successfully placed into slit ventricles, all requiring only one pass of the catheter under stereotactic guidance to achieve the desired location and CSF flow. There were no procedure-related complications and each ventricular catheter showed rapid egress of CSF. All (100%) patients experienced significant improvement of headache immediately after shunting. Ten percent of ventricular shunts failed at 3 months after insertion, 20% failed by 6 months, 50% failed by 12 months, and 60% failed by 24 months. Shunt revision was due to distal obstruction in 67%, overdrainage in 20%, and distal catheter migration or CSF leak in 6.5%. There were no shunt revisions due to proximal catheter obstruction or shunt infection.

CONCLUSIONS

In our experience treating patients with IIH, frameless stereotactic ventricular CSF shunts were extremely effective at treating IIH-associated intractable headache, and continued to provide relief in nearly half of patients 2 years after shunting without many of the shunt-related complications that are seen with LP shunts. Placing ventricular shunts using image-guided stereotaxis in patients with IIH despite the absence of ventriculomegaly is an effective, safe treatment option.

Endoscopic third ventriculostomy for shunt dysfunction in occlusive hydrocephalus: long-term follow up and review

OBJECT

Endoscopic third ventriculostomy (ETV) is the treatment of choice for occlusive (noncommunicating) hydrocephalus. Nevertheless, its routine use in patients who have previously undergone shunt placement is still not generally accepted. The authors' aim was to investigate the long-term effects of ETV in a group of prospectively chosen patients.

METHODS

Patients who underwent ETV and had previously undergone shunt placement for occlusive hydrocephalus were followed prospectively for at least 3 years (range 36-103 months, mean 63.6 months). Nine female and eight male patients ranging from 8 to 54 years of age (mean 32 years) had undergone shunt placement 0.7 to 23.5 years (mean 8.1 years) before ETV. Fifteen patients were admitted with underdrainage and two with overdrainage. In six cases, ETV was performed as an emergency operation. The origin of hydrocephalus was aqueductal stenosis in 12 cases and aqueductal compression by a tumor in two cases. Three patients suffered from a fourth ventricle outlet syndrome, and in two patients an additional malresorptive component was suspected. Thirteen patients underwent ETV with shunt removal and insertion of an external drain in one session. The drain served as a safety measure; it could be opened if raised intracranial pressure or ventricular dilation was observed on postoperative imaging studies. In the other four patients the shunt was initially ligated and then removed during a second operation. Fourteen patients (82%) have remained shunt free. The other three patients, including the two with an additional malresorptive component, needed shunt reimplantation 3 days, 2 weeks, or 7 months after ETV.

CONCLUSIONS

Use of ETV is safe and effective for the treatment for shunt dysfunction in patients with obstructive hydrocephalus.

Risk factors for repeated cerebrospinal shunt failures in pediatric patients with hydrocephalus

OBJECT

Repeated cerebrospinal fluid (CSF) shunt failures in pediatric patients are common, and they are a significant cause of morbidity and, occasionally, of death. To date, the risk factors for repeated failure have not been established. By performing survival analysis for repeated events, the authors examined the effects of patient characteristics, shunt hardware, and surgical details in a large cohort of patients.

METHODS

During a 10-year period all pediatric patients with hydrocephalus requiring CSF diversion procedures were included in a prospective single-institution observational study. Patient characteristics were defined as age, gender, weight, head circumference, American Society of Anesthesiology class, and cause of hydrocephalus. Surgical details included whether the procedure was performed on an emergency or nonemergency basis, use of antibiotic agents, concurrent surgical procedures, and duration of the surgical procedure. Details on shunt hardware included: the type of shunt, the valve system, whether the shunt system included multiple or complex components, the type of distal catheter, the site of the shunt, and the side on which the shunt was placed. Repeated shunt failures were assessed using multivariable time-to-event analysis (by using the Cox regression model). Conditional models (as established by Prentice, et al.) were formulated for gap times (that is, times between successive shunt failures). There were 1183 shunt failures in 839 patients. Failure time from the first shunt procedure was an important predictor for the second and third episodes of failure, thus establishing an association between the times to failure within individual patients. An age younger than 40 weeks gestation at the time of the first shunt implantation carried a hazard ratio (HR) of 2.49 (95% confidence interval [CI] 1.68-3.68) for the first failure, which remained high for subsequent episodes of failure. An age from 40 weeks gestation to 1 year (at the time of the initial surgery) also proved to be an important predictor of first shunt malfunctions (HR 1.77, 95% CI 1.29-2.44). The cause of hydrocephalus was significantly associated with the risk of initial failure and, to a lesser extent, later failures. Concurrent other surgical procedures were associated with an increased risk of failure.

CONCLUSIONS

The patient's age at the time of initial shunt placement and the time interval since previous surgical revision are important predictors of repeated shunt failures in the multivariable model. Even after adjusting for age at first shunt insertion as well as the cause of hydrocephalus, there is significant association between repeated failure times for individual patients.

Risk factors for repeated cerebrospinal shunt failures in pediatric patients with hydrocephalus

Repeated cerebrospinal fluid (CSF) shunt failures in pediatric patients who have undergone neurosurgical procedures are common, and they are a significant cause of morbidity and occasionally mortality. To date, the risk factors for repeated failure have not been established. By performing survival analysis for repeated events, the authors examined the effects of patient characteristics, shunt hardware, and surgical details in a large cohort of patients.

During a 10-year period all pediatric patients with hydrocephalus requiring CSF diversionary procedures were included in a prospective single-institution observational study. Patient characteristics were defined as age, gender, weight, head circumference; American Society of Anesthesiology class, and the cause of hydrocephalus. Surgical details included whether the procedure was performed on an emergency or nonemergency basis, use of antibiotics, concurrent other surgical procedures, and the duration of surgical procedure. Details on shunt hardware included the type of shunt, the valve system, whether the shunt system included multiple or complex components, the type of distal catheter, site of the shunt, and side on which the shunt was placed.

Repeated shunt failures were assessed with multivariable time-to-event analysis (using the Cox regression model). Conditional models (as established by Prentice, et al.) were formulated for gap times (that is, times between successive shunt failures).

There were 1183 shunt failures in 839 patients. Failure time from the first shunt procedure was an important predictor for the second and third episodes of failures, thus establishing an association between the times to failure within individual patients. Age of less than 40 weeks gestation at time of the first shunt implantion carried a hazard ratio (HR) of 2.49 (95% confidence interval [CI] 1.68-3.68) for the first failure and remained high for subsequent episodes of failure. Age of 40 weeks to 1 year (at the time of the initial surgery) also proved to be an important predictor of first shunt malfunctions (HR 1.77, 95% CI 1.29-2.44). The cause of hydrocephalus was significantly associated with the risk of initial failure and, to a lesser extent, later failures. Concurrent other surgical procedures were associated with an increased risk of failure.

The patient's age at the time of initial shunt placement and the time interval since previous surgical revision are important predictors of repeated shunt failures in the multivariable model. Even after adjusting for age at first shunt insertion as well as the cause of hydrocephalus there is significant association between repeated failure times for individual patients.

Hydrocephalus: obliterated perimesencephalic cisterns and the danger of sudden death

OBJECTIVE

We reported a possible risk factor which could identify patients with chronic hydrocephalus who are risk for sudden death.

METHODS

A retrospective review of medical records and computed tomographic (CT) scans was conducted on three patients with chronic hydrocephalus who suffered acute cardiorespiratory arrest without those signs which are normally associated with a progressive worsening of hydrocephalus.

RESULTS

All three of these patients were awake and communicative shortly before the life threatening or terminal event. All had experienced some recent worsening of neurologic signs or symptoms, but none had shown a progressive impairment of consciousness or major neurologic decline ordinarily associated with life threatening elevation of intracranial pressure. Absence of the perimesencephalic cisterns on head CT scans done prior to or just after the life threatening event was the only new radiologic finding common to all these patients.

CONCLUSIONS

The absence of the perimesencephalic cisterns in an awake and alert patient with severe hydrocephalus indicates that the patient may be at risk for neurogenic cardiorespiratory failure. In such cases, (especially when there has been a recent, albeit mild, change in neurologic signs or symptoms), the neurologist should urge emergency ventriculostomy or shunting for the hydrocephalus.

Biportal endoscopic management of third ventricle tumors in patients with occlusive hydrocephalus: technical note

OBJECTIVE

To present the feasibility and advantages of the biportal endoscopic management of posterior third ventricle tumors. As a result of recent developments in neuroendoscopy, classical third ventriculostomy has become a standard single burr hole procedure and a real alternative to shunting in the treatment of occlusive hydrocephalus. In patients with third ventricle tumors occluding the aqueduct, the acute development of hydrocephalus may often precede debilitating focal symptoms and signs. Forty percent of those tumors are radiosensitive, rendering craniotomy unnecessary. The goal of primary management is the alleviation of raised intracranial pressure and determination of the histological nature of the tumor. Cerebrospinal fluid shunting and the performance of a computed tomography- or magnetic resonance imaging-guided biopsy are generally suggested as the methods of choice.

METHODS

Three patients with posterior third ventricle tumors and acute hydrocephalus were treated in one session by computed tomography-guided endoscopic third ventriculostomy and endoscopic tumor biopsy was performed by means of two rigid ventriculoscopes.

RESULTS

Ventriculostomy was performed in three patients, and tumor biopsy was performed in two patients. The maximum 40-minute operation did not involve mortality or morbidity. Histological findings were established in all patients. In two patients with malignant infiltrative tumors, postoperative radiotherapy was used; in one patient with a small cavernoma, no further measures were taken. At the 6-month follow-up, flow-sensitive magnetic resonance imaging confirmed ventriculostomy patency in all patients.

CONCLUSION

The biportal endoscopic approach allowed independent visual control of both procedures, safe passages of the ventriculoscopes via the narrow foramen of Monro, and facile control of the intracranial pressure in the ventricles via the available four irrigation channels during the performance of tumor biopsy and fenestration of the floor of the third ventricle. In selected patients with infiltrating posterior third ventricle tumors, this procedure and postoperative radiotherapy may be an alternative to direct surgery or to shunting and performance of image-guided biopsy.

The treatment of hydrocephalus: a brief guide to shunt selection

The placement of a cerebrospinal fluid shunt system is a procedure that most neurosurgeons feel comfortable performing. The procedure is fraught with many pitfalls and the choices of equipment are staggering. We review the recent literature on shunt systems. We describe the newer shunt systems and procedures and identify possible roles for them in shunt procedures by the neurosurgeon in practice.

Indicators of hypoxia in cerebrospinal fluid of hydrocephalic children with suspected shunt malfunction

We used high performance liquid chromatography to determine the concentration of purine metabolites in the cerebrospinal fluid of three hydrocephalic children with a history of shunt malfunction. Hypoxanthine and xanthine levels were high in comparison with controls. We consider these purines to be valuable indicators of disturbance of neuronal metabolism following the sustained rise in intracranial pressure caused by shunt valve malfunction.

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.

Infection of cerebrospinal fluid shunts in infants: a study of etiological factors

The aim of this study was to find reasons for the high incidence of cerebrospinal fluid shunt infections seen in neonates. Four-hundred sixty-six consecutive shunt operations were analyzed retrospectively in 294 children, and 60 children were studied prospectively by quantitative sampling of skin bacteria before surgery and by sampling open wounds, shunt catheters, surgical gloves, and airborne bacteria. In total, 110 strains of coagulase-negative Staphylococcus isolated from the skin of 53 children before surgery were then tested for bacterial adherence. Retrospectively, the infection rate for infants younger than 6 months old was 15.7% (28 of 178 procedures), compared with 5.6% (16 of 288 procedures) for older children (p = 0.0005). Of all infections, 67% were due to coagulase-negative Staphylococcus. Age was the only major factor influencing the infection rate. Three of the 60 children studied prospectively developed postoperative shunt infections. All were younger than 6 months and all had high skin bacterial densities before surgery. Contamination during surgery was generally low, but correlated with the preoperative skin bacterial density. Strains of coagulase-negative Staphylococcus with high bacterial adherence were more commonly found in neonates than in older children. High skin bacterial density in neonates before surgery was a risk factor for infection in this study. These results also suggest that there is selection of more virulent strains of coagulase-negative Staphylococcus on the skin of neonates. Prevention of shunt infections in this high-risk group could be facilitated by the reduction of skin bacterial density before surgery using chlorhexidine shampoos and by the elimination of contamination by skin bacteria during surgery using packs soaked in an antiseptic agent to isolate wound edges and glove-changing before handling the shunt.

Stereotactic third ventriculostomy in patients with nontumoral adolescent/adult onset aqueductal stenosis and symptomatic hydrocephalus

Sixteen consecutive patients with obstructive hydrocephalus due to nontumoral aqueductal stenosis of adolescent or adult onset underwent computerized tomography-guided stereotactic third ventriculostomy. Computer-assisted angiographic target-point cross-registration was used in surgical planning to reduce morbidity. The procedure was used as primary treatment in five previously unshunted patients and in 11 patients who had previously received shunts and who presented when their shunts became obstructed (five patients), became infected (five patients), or required multiple revisions (one patient). At the time of third ventriculostomy, shunt hardware was removed in patients with infected shunts and the distal element of the shunt was ligated in all patients with obstructed shunts except one, who later required repeat third ventriculostomy; the distal shunt was ligated at that time. Follow-up data (range 1 to 5 years, mean 3 1/2 years, after surgery) showed that only one of the 16 patients had undergone a shunting procedure after the third ventriculostomy. The other 15 patients are asymptomatic and shunt-independent. In previously shunt-dependent patients, the peripheral subarachnoid space and cerebrospinal fluid absorption mechanism remained patent in spite of shunts placed earlier. Therefore, in patients with obstructive hydrocephalus due to aqueductal stenosis of adolescent or adult onset, stereotactic third ventriculostomy should be seriously considered as primary surgical management in previously unshunted patients and in shunt-dependent patients with obstructed or infected shunts.

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.

A new approach in the treatment of hydrocephalus

To date, most patients suffering from hydrocephalus have been treated by insertion of differential-pressure valves that have fairly constant resistance. Since intracranial pressure (ICP) is a variable parameter (depending on such factors as patient's position and rapid eye movement sleep) and since cerebrospinal fluid (CSF) secretion is almost constant, it may be assumed that some shunt complications are related to too much or too little CSF drainage. The authors suggest a new approach to treating hydrocephalus, the aim of which is to provide CSF drainage at or below the CSF secretion rate within a physiological ICP range. This concept has led the authors to develop a three-stage valve system. The first stage consists of a medium-pressure low-resistance valve that operates as a conventional differential-pressure valve until the flow through the shunt reaches a mean value of 20 ml/hr. A second stage consists of a variable-resistance flow regulator that maintains flow between 20 and 30 ml/hr at differential pressures of 80 to 350 mm H2O. The third stage is a safety device that operates at differential pressures above 350 mm H2O (inducing a rapid increase in CSF flow rate) and therefore prevents hyper-elevated ICP. An in vitro study is described that demonstrates the capability of this system to maintain flow rates close to CSF production under a range of pressures similar to those observed under various human physiological and postural conditions. Promising clinical results in 19 patients shunted with this valve are summarized.

Danish experience with the one-piece shunt. A long-term follow-up

A review of the efficacy and complications of the simple one-piece ventriculoperitoneal shunt is given, based on a consecutive series of 61 children with nontumorous hydrocephalus. Control of the hydrocephalic state was satisfactory but was, however, complicated by a rather high frequency of slit ventricles and subdural effusions. No significant increase in the complication rate was observed among premature babies. The infection rate was low (3%) and no visceral perforations were observed. The one-piece shunt can be recommended, especially for smaller children with hydrocephalus.

Influence of prognosis on decisions regarding the care of newborns with myelodysplasia

Treatment of newborns with myelodysplasia (meningomyelocele and related disorders) continues to be a controversial subject. We have used a consistent plan of care and have employed the same prognostic criteria over the period from 1965 to 1982 to address the needs of 212 affected newborns. A good prognosis and early surgical care were given to 42 per cent of 53 newborns during the period 1965 to 1970, to 58 per cent of 65 newborns from 1971 to 1976, and to 71 per cent of 94 newborns from 1977 to 1982. Of the newborns with an initially poor prognosis, 19 per cent of 31 received early surgery between 1965 and 1970, as compared with 33 per cent of 27 between 1971 and 1976 and 52 per cent of 27 between 1977 and 1982. Life-table analyses of survival in the three periods revealed significant improvement over time in the survival of newborns receiving early surgical care, regardless of the initial prognosis (log-rank statistic = 8.240, P = 0.016) and in comparison to recipients of supportive care alone (log-rank statistic = 5.975, P = 0.05). We conclude that early surgery permits the survival of an increasing percentage of patients with myelodysplasia.