Function of parietal and frontal shunts in childhood hydrocephalus

Results of endoscopic third ventriculostomy

ETV is emerging as the treatment of choice for aqueductal stenosis caused by anatomic, inflammatory, and selected neoplastic etiologies. The technique has also proven useful in the pathologic diagnosis and treatment of these conditions. Long-term results of this procedure and comparison to standard shunting procedures are necessary to define indications for patients with pathologic findings in the intermediate response groups. Development of new studies for pre-operative assessment of CSF absorptive capacity and quantitative postoperative measures of ventriculostomy function would be invaluable additions to our ability to assess candidates for this procedure and their eventual outcome. Further study and technical refinements will, no doubt, lead to many more potential uses for these procedures in the treatment of hydrocephalus and its associated etiologies. The challenge for neuro-surgeons will be to define the operative indications and outcomes, while refining techniques for safely performing these useful procedures.

Cerebral fluid edema: an unusual complication of ventriculoperitoneal shunts

INTRODUCTION

A case of accumulation of CSF into the brain parenchyma simulating a brain tumor, secondary to an obstructed ventriculoperitoneal shunt, is presented. Until now, only seven cases of this rare complication have been described.

CASE REPORT

Magnetic resonance showed an expansive, low-density intracranial lesion on the right frontal and parietal lobe. This mass was biopsied, but no tumor was found and the diagnosis was brain edema.

CONCLUSION

The mistake in the diagnosis was due to the clinical symptoms and to the MR images.

Comparison of revision rates following endoscopically versus nonendoscopically placed ventricular shunt catheters

BACKGROUND

Endoscopic placement of ventriculoperitoneal (VP) shunt catheters in pediatric patients has been increasingly used in an attempt to minimize the unacceptably high rates of revision. Although this procedure carries an increased expense, there is currently no evidence to support an improved long-term outcome. This paper compares the rates of revision following ventricular catheter placement for shunted hydrocephalus with and without the use of endoscopy.

METHODS

We retrospectively reviewed the records of all pediatric patients who had undergone shunt placement for hydrocephalus between April 1992 and February 1998. All shunts placed before March 1995 were performed without the endoscope; all subsequent shunts were placed endoscopically. The independent effect of endoscopic versus nonendoscopic shunt placement on subsequent shunt failure was analyzed via multivariate proportional hazards regression model. Multiple logistic regression analyses were used to determine the independent effect of endoscopic placement on subsequent etiology of failure (infection, proximal obstruction, distal malfunction) in the 511 failing shunts.

RESULTS

There were 447 pediatric patients who underwent a total of 965 shunt placements or revisions. Six hundred and five (63%) catheters were placed with the use of the endoscope. Three hundred and sixty (37.3%) were placed without the use of the endoscope. Neuroendoscopy did not independently affect the risk of subsequent shunt failure [Hazard Ratio (95% Confidence Interval) = 1.08 (0.84-1.41)]. Endoscopic placement independently decreased the odds [Odds Ratio (95% Confidence Interval) = 0.56 (0.32-0.93)] of proximal obstruction, increased the odds of distal malfunction [1.52 (1.02-2.72)], and was not associated with infection [1.42 (0.78-2.61)].

CONCLUSIONS

Endoscopic assisted ventricular catheter placement decreased the odds of proximal obstruction but failed to improve overall shunt survival in this 6 year experience.

Risk factors for pediatric ventriculoperitoneal shunt infection and predictors of infectious pathogens

Identification of risk factors for shunt infection and predictors of infectious pathogens may improve current methods to prevent and treat shunt infections. We reviewed data on 820 consecutive ventriculoperitoneal (VP) shunt placement procedures in 442 pediatric patients at our institution during 1992-1998. Ninety-two shunts (11%) developed infection a median of 19 days (interquartile range, 11-35 days) after insertion. Premature birth (relative risk [RR], 4.81; 95% confidence interval [CI], 2.19-10.87), previous shunt infection (RR, 3.83; 95% CI, 2.40-6.13), and intraoperative use of the neuroendoscope (RR, 1.58; 95% CI, 1.01-2.50) were independent risk factors for shunt infection. The bacterial organisms early after shunt surgery (<14 days) were the same as those late after shunt surgery (>14 days). As determined by an analysis of the 92 infected shunts, hospital stay of >3 days at the time of shunt insertion (odds ratio [OR], 5.27; 95% CI, 1.15-25.3) and prior Staphylococcus aureus shunt infection (OR, 5.91; 95% CI, 1.35-25.9) independently increased the odds that S. aureus was the causal pathogen.

Pediatric neuroanesthesia. Hydrocephalus

Hydrocephalus, one of the most common adult and pediatric neurosurgical disorders, is an abnormal accumulation of cerebrospinal fluid in the ventricular system as a result of obstruction to the flow of cerebrospinal fluid. Causes of hydrocephalus include congenital obstruction, hemorrhage, infection, cysts and tumors, and associated neural tube deformities (i.e., myelomeningocele, Arnold-Chiari malformation). Treatment of hydrocephalus involves surgical implantation of shunt systems to drain the cerebrospinal fluid. Anesthetic considerations involve attention to the possibility of increased intracranial pressure and prevention of aspiration through rapid-sequence intravenous induction and modest hyperventilation until the ventricles have been decompressed.

Intraoperative fiber-optic endoscopy for ventricular catheter insertion

OBJECTIVE

Ventricular catheter placement is a common neurosurgical procedure often resulting in inaccurate intraventricular positioning. We conducted a comparison of the accuracy of endoscopic and conventional ventricular catheter placement in adults.

METHODS

A retrospective analysis of data was performed on 37 consecutive patients undergoing ventriculo-peritoneal shunt (VPS) insertion with endoscopy and 40 randomly selected, unmatched patients undergoing VPS insertion without endoscopy, for the treatment of hydrocephalus of varied etiology. A grading system for catheter tip position was developed consisting of five intraventricular zones, V1 -V5, and three intraparenchymal zones, A, B, C. Zones V1 for the frontal approaches and V1 or V2 for the occipital approaches were the optimal catheter tip locations. Postoperative scans of each patient were used to grade the accuracy of ventricular catheter placement.

RESULTS

Seventy-six percent of all endoscopic ventricular catheters were in zone V1 and 100% were within zones V1-V3. No endoscopically inserted catheters were observed in zones V4, V5 or intraparenchymally. Thirty-eight percent of the conventionally placed catheters were in zone V1, 53% in zones V1-3 and 15% intraparenchymally. There was a statistically significant difference in the percentage of catheters in optimal location versus in any other location, favoring endoscopic guidance (p<0.001).

CONCLUSION

We conclude that endoscopic ventricular catheter placement provides improved positioning accuracy than conventional techniques.

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.

A randomized, controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus. Hakim-Medos Investigator Group

OBJECTIVE

A multicenter prospective randomized controlled study was performed to assess the safety and efficacy of a Codman Hakim programmable shunt valve (Codman/Johnson & Johnson, Raynham, MA) versus a conventional valve system of the surgeon's choice for the treatment of patients with hydrocephalus.

METHODS

Enrollment was stratified on the basis of whether the patient was undergoing initial shunt insertion or revision of an existing valve system at study entry. Study end points were: 1) valve explantation, and 2) shunt failure (surgical intervention for any component of the shunt). A total of 377 patients were enrolled onto the study, with 235 undergoing first shunt insertion (119 experimental, 116 control) and 142 undergoing revisions (75 experimental, 67 control).

RESULTS

During a follow-up interval of 104 weeks after the first implantation on-study, explantation of the valve was required in 62 (32%) of 194 experimental valves, compared with 71 (39%) of 183 control valves. Two-year survival rates of the original shunt without revision of any component were 52% (62 of 119) and 50% (58 of 116) in experimental and control patients, respectively, who underwent initial shunt insertion, and 43% (32 of 75) and 43% (29 of 67) in experimental and control patients, respectively, who underwent replacement of an existing valve. No statistically significant difference was observed between experimental and control patients in the survival of either the valve or the overall shunt system. Control of hydrocephalus as assessed symptomatically and by imaging was comparable in the two treatment groups. Although problems related to inability to achieve the desired pressure setting were reported in 22 experimental valves, in all but four instances no additional programming was attempted because the patients were functioning well clinically. The most common reasons cited for valve explantation and shunt revision were infection (9.8% frequency in the overall cohort) and proximal shunt malfunction, which occurred with comparable frequency in the experimental and control groups.

CONCLUSION

Safety and efficacy of the Codman Hakim programmable shunt valve is comparable to conventional valves in the overall population of patients with hydrocephalus. However, the current study was not designed to assess the efficacy of programmable versus conventional valves in the management of individual hydrocephalus problems, and it had insufficient statistical power to support such comparisons. This study provides a rationale for examining whether the theoretical advantages of a programmable valve for managing challenging hydrocephalus problems can translate into meaningful improvements in shunt and valve survival.

Change in ventricular size and effect of ventricular catheter placement in pediatric patients with shunted hydrocephalus

OBJECTIVE

The multicenter, randomized pediatric cerebrospinal fluid shunt valve design trial found no difference in the rate of shunt failure between a standard valve, a siphon-reducing valve (Delta; Medtronic PS Medical, Goleta, CA), and a flow-limiting valve (Orbis Sigma; Cordis, Miami, FL); however, the valves were expected to have different effects on ultimate ventricular size. Also, the catheter position or local environment of the ventricular catheter tip might have affected shunt failure. Therefore, we performed a post hoc analysis to understand what factors, other than valve design, affected shunt failure and to identify strategies that might be developed to reduce shunt failure.

METHODS

Ventricular size was measured at as many as six different intervals, using a modified Evans' ratio (with incorporation of the frontal and occipital dimensions), in 344 patients. Ventricular catheter location was defined as being in the frontal horn, occipital horn, body of the lateral ventricle, third ventricle, embedded in brain, or unknown. The ventricular catheter tip was described as surrounded by cerebrospinal fluid, touching brain, or surrounded by brain parenchyma within the ventricle (slit ventricle). Repeated measures analysis of variance for unbalanced data was used to analyze ventricular size. A Cox model (with incorporation of time-dependent covariates) was used to evaluate the contribution of age, etiology, shunt design, ventricular size, ventricular catheter location, and environment among the cases.

RESULTS

Ventricular volume decreased in an exponential fashion, forming a plateau at 14 months, and was similar for the three valves (P = 0.4). Frontal and occipital ventricular catheter tip locations were associated with a reduced risk of shunt failure (hazard ratios, 0.60 [P = 0.02] and 0.45 [P = 0.001], respectively). Ventricular catheter tips surrounded by cerebrospinal fluid or touching the brain were associated with a reduced risk of failure (hazard ratios, 0.21 and 0.33, respectively; P = 0.0001). Patients with myelomeningocele or large ventricles had increased risk of malfunction (hazard ratios, 1.78 [P = 0.006] and 2.33 [P = 0.03], respectively).

CONCLUSION

Decline of ventricular size over time is not affected by these different shunt valve designs. This suggests that the mechanical models of hydrocephalus on which the designs were based are inadequate. Ventricular catheter tip location and ventricular catheter environment are important. Techniques to accurately place ventricular catheters and new valve designs that effectively control ventricular size might reduce shunt malfunction.

Outcome data and analysis in pediatric neurosurgery

OBJECTIVE

The purpose of this study was to analyze the outcomes of five commonly performed pediatric neurosurgical operations: 1) initial shunt insertion; 2) first shunt revision; 3) craniotomy for brain tumor; 4) correction of sagittal synostosis; and 5) release of tethered cords. A second purpose was to analyze the neurological outcome data after tethered cord releases.

METHODS

Morbidity and mortality records, patient charts, and operative records were reviewed to determine length of hospitalization and, for each disorder, the pertinent outcomes such as duration of shunt function and incidence of infection or neurological morbidity.

RESULTS

Many outcome data were expected, such as a high long-term shunt function rate after primary shunt insertion (65% at 5 yr), a low mortality rate (1%) and permanent morbidity rate (10%) after craniotomy for brain tumor, and a low frequency of transfusion (20%) for sagittal synostosis operations. The outcomes among the three neurosurgeons varied more than expected, e.g., the duration of hospitalization after sagittal reconstructions ranged from 3.1 to 5.8 days; the frequency of infections of primary shunt revisions ranged from 0 to 15%; and the neurological morbidity after tethered cord releases ranged from 0 to 12%, with all neurological morbidity occurring in patients undergoing their second or third tether release.

CONCLUSION

The data may serve as a basis for outcome comparisons for these procedures. Outcome data allow us to analyze factors to improve patient care, but outcome analysis is complex.

Epilepsy in shunt-treated hydrocephalus

Although epilepsy is commonly associated with shunt-treated hydrocephalus, its relation to the shunting procedure and the criteria identifying postoperative epilepsy remain controversial. Of 283 patients shunted at Würzburg University Hospital over a 24-year period (1970 to 1994), 182 were followed up for a minimum of 1 year after shunt insertion and entered the study. The data were analyzed retrospectively in 1995 and 1996. Epilepsy was analyzed in relation to the etiology of hydrocephalus, functional status, time and site of shunt insertion, onset of seizures and seizure type, EEG changes, sex, shunt systems, and shunt revisions. Of the 182 patients studied, 37 (20%) developed epilepsy. The incidence of epilepsy varied according to the etiology of hydrocephalus: posthemorrhagic (5%), postinfectious (4%), connatal/miscellaneous/unknown (3%), myelomeningocele (2%), tumor/arachnoidal cyst/aqueduct stenosis (0%). Early shunting and poor functional status was associated with a higher risk for epilepsy. Epilepsy was not influenced by sex, shunt systems, or number of shunt revisions. Twenty-two (12%) of 182 patients developed epilepsy (generalized N=13, focal N=9) after intracranial shunting. Focal EEG abnormalities (N=16) were located mainly at the anatomical site of the shunt (N=14), but only three patients (2%) presented with focal seizures contralateral and focal EEG abnormalities ipsilateral to the site of the shunt. The presence of epilepsy was determined by the etiology of hydrocephalus rather than by surgical intervention. The incidence of postoperative epilepsy (12%) was low. Onset of epilepsy, clinical presentation of seizures, and EEG changes did not appear to be valid criteria for identifying shunt-related epilepsy. Thus, epilepsy as a complication of intracranial shunting might be overestimated in the literature.

Targeted studies as a learning tool in outcomes assessment

Authors discuss the need for increased analytical skills in the current medical environment and suggest a method which combines the use of targeted studies and Internet communication as part of graduate medical education. Advantages of such a program include involvement of the private sector in clinical outcome studies, improvements in the design of clinical studies and publications and the early development of skills in interpreting and evaluating literature. A further goal would be the development of an understanding of the principles underlying, to the extent that it is possible, unbiased assessment of one's own clinical practices.

Comparative study of two customary cerebrospinal fluid shunting systems in early childhood hydrocephalus

The validity of clinical studies on shunt-treated hydrocephalic patients is often hindered by inhomogeneity of the patient population examined, technical devices used, or by other specific factors. In an effort to introduce a homogeneous clinical study on hydrocephalic patients 66 hydrocephalic newborns and infants have been treated exclusively with CORDIS Orbis-Sigma Valve (OSV) System (CORDIS Corporation, Miami, USA) in 1990-1995. The results are compared with an equivalent group of 53 children treated with CODMAN Holter Valve (HV) System (CODMAN Inc., Randolph, USA) during a similar 5-year-period (e.g., 1986-1991). Searching for different reasons of shunt insufficiency in both groups demonstrates a more than double risk of shunt complication for ventriculo-atrial HV treated patients (VA-HV) in comparison with those treated ventriculo-peritoneally with OSV System (VP-OSV): 4.22 versus 1.98 mean surgical procedures per person. The different revision and survival rates are discussed and specific problems are mentioned.

Rationale and methodology of the multicenter pediatric cerebrospinal fluid shunt design trial. Pediatric Hydrocephalus Treatment Evaluation Group

Cerebrospinal fluid shunt failure remains a common and at times overwhelming problem in pediatric patients with hydrocephalus. Two new shunt valve designs, the Orbis-Sigma (Cordis Corporation, Miami, Florida) and the Delta valve (PS Medical, Goletta, California), have flow/pressure characteristics dramatically different from those of standard differential pressure valves which have been used for over three decades. Both new designs reduce the siphoning effect in the upright position, and have been reported to reduce shunt failure rates in uncontrolled series, allegedly due to reduction in shunt overdrainage. Most mechanical shunt failure in the first 2 years after implantation is due to proximal shunt obstruction, overdrainage, and loculated ventricles. By reducing the incidence of slit ventricles associated with standard valves, both new designs could be envisioned as reducing the early mechanical complications. The improved results with both new valves could, however, also be to a large extent due to other confounding effects of shunt surgery, including patient selection, surgical technique, and specific configuration of the components of the shunt other than the valve. There are also theoretical reasons why these valve designs might be worse than their predecessors, including the narrow orifice and high resistance of the Orbis-Sigma, and the flexible membrane of the siphon control portion of the Delta valve, which may increase the ventricular pressure in the upright position or become blocked by encasing scar tissue. For this reason a randomized trial is required to determine efficacy, and a standard differential pressure valve is required as the control design. A significant reduction in early shunt failure would dramatically improve the morbidity and mortality of pediatric hydrocephalic patients, as well as providing substantial savings to the health care system. Failure to determine any difference would focus attention on other issues surrounding shunt surgery, such as patient characteristics or surgical technique.

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.

A guide to placement of parietooccipital ventricular catheters. Technical note

Accurate placement of parietooccipital ventricular catheters can be difficult and frustrating. To minimize the morbidity of the procedure and lengthen the duration of shunt function, the catheter tip should lie in the ipsilateral frontal horn. The authors describe a posterior ventricular guide (PVG) for placement of parietooccipital catheters that operates by mechanically coupling the posterior burr hole to the anterior target point. In a series of 38 patients who underwent ventriculoperitoneal shunting with the assistance of the guide, postoperative computerized tomography (CT) scanning revealed that 35 (92.0%) had accurate catheter placement. In comparison, a retrospective review of free-hand posterior catheter placement revealed good catheter position in only 22 of 43 patients (51.1%). The use of the guide added less than 5 minutes to the entire procedure, and there were no complications related to its use. The PVG is a simple and useful tool that aids in the placement of parietooccipital ventricular catheters.

Time-related patterns of ventricular shunt failure

Proximal obstruction is reported to be the most common cause of ventriculoperitoneal (VP) shunt failure, suggesting that imperfect ventricular catheter placement and inadequate valve mechanisms are major causes. This study retrospectively examined patterns of shunt failure in 128 consecutive patients with symptoms of shunt malfunction over a 2-year period. Factors analyzed included site of failure, time from shunt placement or last revision to failure, age of patient at time of failure, infections, and primary etiology of the hydrocephalus. One hundred of these patients required revisions; 14 revisions were due to infections. In this series there was a higher incidence of distal (43%) than of proximal (35%) failure. The difference was not statistically significant when the overall series was considered; however, when factoring time to failure as a variable, marked differences were noted regardless of the underlying cause of hydrocephalus or the age of the patient. Of the 49 patients needing a shunt revision or replacement within 2 years of the previous operation, 50% had proximal malfunction, 14% distal, and 10% had malfunctions attributable directly to the valve itself. Also, 12 of the 14 infections occurred during this time interval. In sharp contrast, of the 51 patients having shunt failure from 2 to more than 12 years after the previous procedure, 72% had distal malfunction, 21% proximal, and only 6% had a faulty valve or infection. This difference between time to failure for proximal versus distal failures was statistically significant (P < 0.00001 for both Student's t-test and non-parametric Mann-Whitney U-test).(ABSTRACT TRUNCATED AT 250 WORDS)

Brain oedema induced by ventricular puncture. A study by magnetic resonance on a series of forty-one normal-pressure hydrocephalic patients

After ventricular catheterization magnetic resonance (MR) imaging very often demonstrates a focal area of high signal along the drain track which corresponds to parenchymal oedema. This high signal seemed to be more pronounced when the frontal area was catheterized than when the junctional parieto-temporo-occipital parenchyma (or trigonal area) was catheterized. In order to confirm this impression, we prospectively studied 41 consecutive patients with normal-pressure hydrocephalus in whom both of these brain regions were catheterized for intracranial pressure monitoring. Each patient was evaluated by serial MR. The extent of the MR hypersignal induced by both catheterizations was computed from digitized MR masks. The extent of the MR high signal area was significantly greater when the frontal area was catheterized compared to the trigonal area suggesting that the frontal area could be more prone to injury.

Ventriculoscope-guided ventriculoperitoneal shunt and shunt revision. Technical note

A new small, flexible fiberoptic ventriculoscope for the accurate positioning of a ventricular catheter tip has been developed. The technique for ventriculoscope-guided ventriculoperitoneal shunt and shunt revision is described. The ventricular catheter can easily be positioned away from the choroid plexus. Choroid plexus adhering to the shunt tube can be coagulated during shunt revision. This procedure can thus prevent an obstruction of the ventricular catheter by an adherent choroid plexus.

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.

CT measurement of the ventricular catheter length in shunt surgery

When inserting a ventricular shunt, the length of the ventricular catheter is a deciding factor in the avoidance of complications. The author has devised a standardized method of determining this length which has been shown to achieve consistently successful results. It is determined from the CT scan scout film of the individual patient with hydrocephalus. The length is half the distance between the external auditory meatus and the mid-point of the coronal suture of the skull. The catheter is inserted by the frontal approach and is directed perpendicular to the skull, aiming at the inner canthus of the ipsilateral eye. The burrhole is located in the same parasagittal plane as the pupil either in front of or behind the coronal suture. The catheter tip has been demonstrated by repeated follow-up CT scans to lie just anterior to the foramen of Monro. This method was used in 175 patients and it proved to be highly successful.

Short-term response of brain tissue to cerebrospinal fluid shunts in vivo and in vitro

The purpose of the studies was to determine how gross physical characteristics of cerebrospinal fluid (CSF) shunts and the cellular proliferative response to shunts contribute to shunt obstruction. Ventricular catheters with round holes, slots, and flanges were implanted into the lateral ventricles of rabbits for 4 weeks. All shunt designs were subject to ingrowth of tissue from the ventricle wall or choroid plexus. There were no qualitative or quantitative differences between normal and hydrocephalic rabbits. Astroglial cells from newborn mice were cultured on shunt catheters for 2 or 4 weeks. The growth of these cells was poor, probably because the cells cannot attach well to the silicone rubber substrate. Contact between the shunt catheter and vascularized brain tissue is the most important factor in the genesis of shunt obstruction.

Traumatic brain edema induced by ventricular puncture. A study by magnetic resonance imaging

Magnetic resonance imaging demonstrates after ventricular catheterization a focal brain hypersignal corresponding to a parenchymal edema along the drain track. In the course of our daily clinical activity, this hypersignal extension seemed more pronounced when catheterizing the frontal area than the junctional parieto-temporo-occipital parenchyma (or trigonal area). In order to confirm this impression, we prospectively studied ten consecutive patients with normal pressure hydrocephalus in whom both of these brain regions were successively catheterized first by a frontal puncture for intracranial pressure monitoring and then by a trigonal one for a ventricular shunt. Each patient was evaluated by serial magnetic resonance imaging. The extension of the hypersignal induced by both catheterizations was estimated on a scale of five grades (0 to 4) of hypersignal extension. A statistically significant more important hypersignal extension was demonstrated at the level of frontal area when compared to the trigonal one. We discuss the likely underlying mechanisms of this phenomenon.

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.

Avulsion of choroid plexus during revision of ventricular shunting: its high incidence and predictive value on computed tomography scan

Over a 2-year period, 5 of 10 patients with revision of ventricular shunting were complicated by intraventricular and/or intracerebral hemorrhage due to avulsion of the choroid plexus. Retrospective analysis of computed tomography scans prior to the revision disclosed the presence of an intraventricular or periventricular mass adjoining the ventricular catheter in four of the five patients. Histologic findings of the soft tissue at the tip of the removed catheter were compatible with the choroid plexus accompanied by granulation tissue. The risk factors useful for detecting the possible occurrence of this complication are discussed.

Scintigraphic study of cerebrospinal fluid shunts

This paper deals with experience gained in the study of patency of different types of shunt. Results of subsequent surgery are considered. Findings of 79 scintigraphic studies with radiotechnetium on 68 patients are presented. The method is simple, quick, easy to reproduce and means only moderate radiation load for the patient. Results obtained suggest that this study is a reliable diagnostic tool which can be used in a routine way.