Complications in Ventricular Cerebrospinal Fluid Shunting

Protective effect of rifampicin and clindamycin impregnated devices against Staphylococcus spp. infection after cerebrospinal fluid diversion procedures

Background

Infection is a major complication of cerebrospinal fluid shunting procedures. The present report assesses the efficacy of such catheters in both shunts and external ventricular drains (EVDs) against infection and particularly against Staphylococcus spp. infection.

Methods

All shunt and EVD procedures performed by means of antibiotic-impregnated catheters (AICs) and non-AICs during the period of study were registered. In cases of shunt procedures, a minimal follow-up of 90 days was considered, as well as de novo insertion and catheter revisions. Single valve revisions were not included. In cases of EVD procedures, those catheters removed before the fifth post-insertion day were not included. A total of 119 cerebrospinal fluid shunting procedures performed with AICs were studied in comparison with 112 procedures performed by means of non-AICs.

Results

Antibiotic-impregnated catheters were associated with a significant decrease in both overall and staphylococcal infection (p = 0.030 and p = 0.045, respectively). The number needed to treat for AICs was 8 to prevent one infection and 14 to prevent one staphylococcal infection. When comparing with shunts, the use of EVDs was associated with a 37-fold increased likelihood of infection.

Conclusions

Antibiotic-impregnated catheters are a safe and helpful tool to reduce CSF shunting device-related infections.

Linezolid treatment of shunt-related cerebrospinal fluid infections in children

OBJECT

The emergence of multidrug-resistant bacteria as a cause of ventriculoperitoneal (VP) shunt infection is a disconcerting phenomenon that often requires the use of alternative antimicrobial agents due to resistance against commonly used medications. Linezolid, a member of a new class of antimicrobial agents, has good activity against virtually all important gram-positive pathogens, including multidrug-resistant gram-positive pathogens. The object of this article is to report a single-center experience with linezolid treatment in 6 young patients with VP shunt infections caused by drug-resistant strains.

METHODS

The authors reviewed the records of 6 pediatric patients who developed VP shunt infection and in whom initial antimicrobial treatment regimens, including vancomycin, either failed or were associated with vancomycin-resistant enterococcus. All 6 patients were treated at their hospital between July 1, 2008, and June 29, 2009. The patients' demographic and clinical characteristics, underlying diseases, clinical manifestations, laboratory results, and various treatment modalities used before linezolid therapy were evaluated.

RESULTS

The 6 patients included were 2 boys and 4 girls with a mean (+/- SD) age of 11.83 +/- 12 months (range 4-36 months). Five patients had acquired an infection within 4 months (mean 7.50 +/- 13.51 months, range 1-35 months) after shunt insertion. Four patients were treated with external ventricular drainage. Two patients' parents refused to allow shunt removal and placement of an external ventricular drain. The CSF was clear of bacterial growth within a mean of 3.67 +/- 1.36 days (range 2-6 days) after initiation of linezolid treatment. The mean duration of linezolid treatment was 18.17 +/- 3.31 days (range 14-21 days). Microbiological clearance of CSF and clinical cure were achieved in all patients. No laboratory or clinical side effects were observed during the treatment period. The mean length of hospital stay was 22.8 +/- 4.96 days (range 17-28 days).

CONCLUSIONS

Linezolid could be an appropriate treatment alternative in children with ventriculostomy-related CSF infections caused by drug-resistant strains, including cases in which shunt removal is not an option. Well-designed prospective studies providing additional information on linezolid levels in plasma and CSF are necessary to confirm the authors' observations.

Hospital costs associated with shunt infections in patients receiving antibiotic-impregnated shunt catheters versus standard shunt catheters

BACKGROUND

The average hospital cost for shunt infection treatment is $50,000, making it the most financially costly implant-related infection in the United States. We set out to determine whether introduction of antibiotic-impregnated shunts (AISs) in our practice has decreased the incidence of shunt infection or decreased infection-related hospital costs at our institution.

METHODS

Clinical and hospital billing records of pediatric patients undergoing cerebrospinal fluid (CSF) shunt insertion at a single institution from April 2001 to December 2006 were retrospectively reviewed. Eighteen months before October 2002, all CSF shunts included standard, non-AIS catheters. During the 4 years after October 2002, all CSF shunts included AIS catheters. Patients were followed at least 18 months after surgery.

RESULTS

A total of 406 pediatric patients underwent 608 shunt placement procedures (400 AISs, 208 non-AISs). Of patients with non-AIS catheters, 25 (12%) experienced shunt infection, whereas only 13 patients (3.2%) with AIS catheters experienced shunt infection during follow-up (P < .001). The total hospital cost to treat 25 non-AIS shunt infections over the first 18 months was $1,234,928. The total hospital cost to treat 13 AIS shunt infections over the past 4 years was $606,328. The mean hospital cost per shunt infection was similar for infected AIS and non-AIS catheters ($46,640 vs. $49,397). However, the infection-related hospital cost per 100 patients shunted was markedly lower in the AIS cohort than in the non-AIS cohort ($151,582 vs. $593,715).

DISCUSSION

The introduction of AIS catheters in our institutional practice reduced the incidence of shunt infection and resulted in significant hospital cost savings. AIS systems are efficient and cost-effective instruments to prevent perioperative colonization of CSF shunt components.

Rifampin combination therapy for nonmycobacterial infections

The increasing emergence of antimicrobial-resistant organisms, especially methicillin-resistant Staphylococcus aureus (MRSA), has resulted in the increased use of rifampin combination therapy. The data supporting rifampin combination therapy in nonmycobacterial infections are limited by a lack of significantly controlled clinical studies. Therefore, its current use is based upon in vitro or in vivo data or retrospective case series, all with major limitations. A prominent observation from this review is that rifampin combination therapy appears to have improved treatment outcomes in cases in which there is a low organism burden, such as biofilm infections, but is less effective when effective surgery to obtain source control is not performed. The clinical data support rifampin combination therapy for the treatment of prosthetic joint infections due to methicillin-sensitive S. aureus (MSSA) after extensive debridement and for the treatment of prosthetic heart valve infections due to coagulase-negative staphylococci. Importantly, rifampin-vancomycin combination therapy has not shown any benefit over vancomycin monotherapy against MRSA infections either clinically or experimentally. Rifampin combination therapy with daptomycin, fusidic acid, and linezolid needs further exploration for these severe MRSA infections. Lastly, an assessment of the risk-benefits is needed before the addition of rifampin to other antimicrobials is considered to avoid drug interactions or other drug toxicities.

Intraabdominal complications secondary to ventriculoperitoneal shunts: CT findings and review of the literature

OBJECTIVE

The purpose of our study was to evaluate the abdominopelvic CT findings of various intraabdominal complications secondary to ventriculoperitoneal shunts for hydrocephalus and to review the literature.

MATERIALS AND METHODS

The CT images of 70 patients (33 men and 37 women; mean age, 48.5 years) who underwent ventriculoperitoneal shunt placement and abdominopelvic CT because of shunt-related abdominal symptoms were reviewed retrospectively. CT images were analyzed with regard to the location of the shunting catheter tip; site, size, wall, and septa of localized fluid collection; peritoneal thickening; omentomesentery infiltration; abscess; bowel perforation; abdominal wall infiltration; and thickening of the catheter track wall.

RESULTS

The mean period between the last ventriculoperitoneal shunting operation and CT was 11 months (range, 1 week to 115 months), and the mean number of ventriculoperitoneal shunting operations undergone was 1.4 (range, 1-6). A total of 76 ventriculoperitoneal shunting catheters were introduced in 70 patients: 64 patients had a unilateral catheter inserted and six patients had bilateral catheters inserted. Sixteen patients (22.9%) were pathologically diagnosed with ventriculoperitoneal shunt-related complications: 11 cases (15.7%) of shunt infection, six cases (8.6%) of CSF pseudocyst, four cases (5.7%) of abdominal abscess, three cases (4.3%) of infected fluid collection, and one case (1.4%) of bowel perforation. Microorganisms were cultured from the tip of the shunting catheter or peritoneal fluid in 11 patients (15.7%).

CONCLUSION

On abdominopelvic CT, various intraabdominal complications secondary to ventriculoperitoneal shunt were shown, of which, shunt infection was the most common, followed by CSF pseudocyst, abscess, and infected fluid collection.

RADIONUCLIDE SHUNT PATENCY STUDY FOR EVALUATION OF SUSPECTED VENTRICULOPERITONEAL SHUNT MALFUNCTION IN ADULTS WITH NORMAL PRESSURE HYDROCEPHALUS

OBJECTIVE

Shunt patency studies are performed to determine whether shunt revision surgery is needed in malfunctioned ventriculoperitoneal shunt. The aim of our study was to develop a simple diagnostic algorithm in the diagnostic workup and identify factors associated with improvement after revision surgery.

METHODS

A retrospective review of patients with confirmed shunt obstruction who underwent a revision surgery and were followed for 6 to 12 months was performed. A simpler algorithm to identify shunt obstruction was created and compared with the 4-variable algorithm.

RESULTS

Of the 63 patients in whom shunt obstruction was suspected, 39 were diagnosed with complete or partial obstruction. Thirty-seven patients underwent shunt revision surgery that included removal of shunt (n = 2), conversion to a ventriculoatrial shunt (n = 8), and relocation of the distal end of the catheter into a different part of the peritoneal cavity (n = 27). Improvements were seen in 63.3% (n = 19) of patients evaluated at 6 months and 63.6% (n = 14) of patients evaluated at 12 months. The positive predictive value of the study was 80%. A simpler 1-variable algorithm using T1/2 (half-time) could correctly classify 86.9% of patients with shunt obstruction, compared with a 4-variable algorithm that correctly classified 80% of patients.

CONCLUSION

Shunt patency studies are very useful for evaluation of shunt patency. Their results can be interpreted using a single-variable (T1/2) algorithm. Patients most likely to respond to a revision surgery are those who had a good response to original placement of a ventriculoperitoneal shunt.

An experimental in-vivo canine model for adult shunt infection

Background

Detailed human studies of the mechanisms and development of shunt infection in real time are not possible, and we have developed a canine hydrocephalus model to overcome this. The intention of this pilot study was to show that the canine hydrocephalus model could be shunted using conventional "human" shunts, and that a shunt infection could be established so that further studies could then be planned.

Methods

Hydrocephalus was induced in seven dogs (Canis familiaris) by fourth ventricle obstruction. Four weeks later they were shunted using a Hakim Precision valve. Four of the dogs received shunts whose ventricular catheter had been inoculated with Staphylococcus epidermidis, and three were uninoculated controls. Four weeks after shunting the dogs were sacrificed and necropsy was performed. Removed shunts and tissue samples were examined microbiologically and isolates were subjected to detailed identification and genomic comparison.

Results

All the dogs remained well after shunting. Examination of removed shunt components revealed S. epidermidis in the brain and throughout the shunt system in the four inoculated animals, but in two of these Staphylococcus intermedius was also found. S. intermedius was also isolated from all three "negative" controls. There were slight differences between S. intermedius strains suggesting endogenous infection rather than cross- infection from a point source.

Conclusion

Shunt infection was established in the canine model, and had the experiment been extended beyond four weeks the typical microbiological, pathological and clinical features might have appeared. The occurrence of unplanned shunt infections in control animals due to canine normal skin flora reflects human clinical experience and underlines the usual source of bacteria causing shunt infection.

Antimicrobial suture wound closure for cerebrospinal fluid shunt surgery: a prospective, double-blinded, randomized controlled trial

OBJECT

Implantation of cerebrospinal fluid (CSF) shunting devices is associated with a 5-15% risk of infection as cited in contemporary pediatric neurosurgical literature. Shunt infections typically require complete removal of the device and prolonged antibiotic treatment followed by shunt replacement. Moreover, shunt infections are commonly associated with prolonged hospital stays, potential comorbidity, and the increased risk of neurological compromise due to ventriculitis or surgical complications. The authors prospectively evaluated the incidence of CSF shunt infection following shunt procedures performed using either antimicrobial suture (AMS) or conventional suture.

METHODS

In a single-center, prospective, double-blinded, randomized controlled trial, the authors enrolled 61 patients, among whom 84 CSF shunt procedures were performed over 21 months. Randomization to the study (AMS) or control (placebo) group was stratified to minimize the effect of known shunt infection risk factors on the findings. Antibacterial shunt components were not used. The primary outcome measure was the incidence of shunt infection within 6 months of surgery.

RESULTS

The shunt infection rate in the study group was 2 (4.3%) of 46 procedures and 8 (21%) of 38 procedures in the control group (p = 0.038). There were no statistically significant differences in shunt infection risk factors between the groups (procedure type and time, age < 6 months, weight < 4 kg, recent history of shunt infection). No suture-related adverse events were reported in either group.

CONCLUSIONS

These results support the suggestion that the use of AMS for CSF shunt surgery wound closure is safe, effective, and may be associated with a reduced risk of postoperative shunt infection. A larger randomized controlled trial is needed to confirm this association.

Hydrothorax: transdiaphragmatic migration of a ventriculoperitoneal shunt catheter

Symptomatic hydrothorax following ventriculoperitoneal shunt insertion is a very rare complication. The patient was a 5-month-old child known to have had shunted congenital hydrocephalus two months before. He presented to the emergency room in respiratory distress. Chest X-ray and computerized tomography images confirmed left hydrothorax and showed transdiaphragmatic migration of the tip of the peritoneal catheter to the thoracic cavity. After the catheter had been shortened and replaced to the peritoneal cavity, the patient's symptoms abated.

Prolonged exposure to antibiotic-impregnated shunt catheters does not increase incidence of late shunt infections

OBJECTIVE

Antibiotic-impregnated shunt (AIS) systems have been designed to prevent the colonization of shunt components by skin flora that occurs at surgery. Although such systems may decrease the incidence of early shunt infections (those occurring within 6 months of shunt placement), it is unclear if such exposure to prolonged antibiotics leads to an increased incidence or virulence of late shunt infections (those occurring later than 6 months after shunt placement). In this study, the authors evaluate the incidence of late shunt infection after the introduction of an AIS system in a pediatric hydrocephalus population.

MATERIALS AND METHODS

We prospectively reviewed all pediatric patients undergoing antibiotic-impregnated CSF shunt insertion or shunt revision operations at our institution for the 33 month period between October 1, 2002 and June 31, 2005. All shunt-related complications, including shunt infection, were evaluated in those patients with later than 6 months of follow-up.

RESULTS

A total of 153 pediatric patients (between 1 and 21 years of age) underwent 262 shunting procedures involving the use of antibiotic-impregnated catheters. All patients were followed-up for later than 6 months with a mean follow-up of 21.7 months (range 13-46 months). Ten patients (3.82%) experienced an early shunt infection within the 6-month follow-up period. No patients experienced a late shunt infection.

CONCLUSION

Although concern exists that AIS systems may delay shunt infections or even increase the rate or virulence of such infections, introduction of such catheters into a pediatric hydrocephalus cohort does not significantly increase incidence of late CSF shunt infection compared to historic controls.

Factors contributing to the medical costs of cerebrospinal fluid shunt infection treatment in pediatric patients with standard shunt components compared with those in patients with antibiotic-impregnated components

Object

Antibiotic-impregnated shunt (AIS) systems may decrease the incidence of cerebrospinal fluid (CSF) shunt infections. However, there is a reluctance to use AIS components because of their increased cost. In the present study the authors evaluated factors contributing to the medical costs associated with the treatment of CSF shunt infections in a hydrocephalic pediatric population, those implanted with AIS systems compared with those implanted with standard shunt systems.

Methods

The authors retrospectively reviewed data obtained in all pediatric patients who had undergone CSF shunt insertion at their institution over a 3-year period. All patients were followed up for 12 months after surgery. The independent association between AIS catheter use and subsequent shunt infection was assessed by performing a multivariate proportional hazards regression analysis. Factors contributing to the medical costs associated with shunt infection were evaluated.

Results

Two hundred eleven pediatric patients underwent 353 shunting procedures. Two hundred eight shunts (59%) were placed with nonimpregnated catheters and 145 shunts (41%) were placed with AIS catheters. Twenty-five patients (12%) with non-AIS catheters experienced shunt infection, whereas only two patients (1.4%) with AIS catheters had a shunt infection within the 6-month follow-up period (p < 0.01). Among infected patients, infected patients with standard shunt components had a longer average hospital stay, more inpatient complications related to infection treatment, and more multiple organism infections and multiple antibiotic regimens, compared with those with AIS components.

Conclusions

Although individual AIS components are more expensive than standard ones, factors contributing to medical costs are fewer in pediatric patients with infected shunts when the components are antibiotic-impregnated rather than standard.

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.

Two-stage treatment of a tectal ganglioglioma: Endoscopic third ventriculostomy followed by surgical resection

Tumours of the quadrigeminal plate in adults are usually benign. Nevertheless, obstructive hydrocephalus due to compression of the Sylvian aqueduct is an almost invariable early finding. Whether or not direct excision is undertaken, temporary or permanent treatment of the hydrocephalus is warranted. Endoscopic third ventriculostomy is an alternative to insertion of a shunt and provides both acute and long-term relief of hydrocephalus-related symptoms. We chose a two-stage approach for treating a tectal ganglioglioma in an adult: endoscopic third ventriculostomy followed by surgical excision. The advantages and disadvantages of each therapeutic strategy are discussed.

Prophylactic antibiotics in pediatric shunt surgery

INTRODUCTION

The optimal antibiotic prophylaxis for pediatric shunt-related procedures is not clear. There is much inconsistency among different medical centers. This paper summarizes and analyzes the various prophylactic antibiotic regiments used for shunt-related surgeries at different pediatric neurosurgery centers in the world.

MATERIALS AND METHODS

A survey questionnaire was distributed through the Pediatric Neurosurgery list-server (an e-mail-based special interest group in pediatric neurosurgery). Forty-five completed questionnaires were received, one per medical center, primarily from pediatric neurosurgeons with the following geographic breakdown: 25 from North America, 13 from Europe, and 7 from Asia and other countries. All centers routinely administered prophylactic antibiotics for shunt-related procedures. The drugs of choice were first-generation cephalosporins (23), second-generation cephalosporins (10), naficillin/oxacillin (4), vancomycin (3), clindamycin (1), amoxicillin (1), and mixed protocols in three centers. The initial drug administration ("first dose") was: in the department before transfer to operating room (5), upon arrival to operating room (11), at induction of anesthesia (13), and at initial skin incision (16). The duration of antibiotic dosage also varied: single dose (13), 24-h administration (26), 48-h administration (2), and longer than 48 h in four centers.

RESULTS AND DISCUSSION

Two general tendencies were noted, common to the majority of participating centers. There was a general trend to modify antibiotic treatment protocol in "high-risk" populations. The second common theme noted in more than half of responding centers was the use of long-term antibiotic treatment for externalized devices (such as externalized shunts, external ventricular drains or lumbar drains), usually till the device was in place.

Persistent and intractable ventriculitis due to retained ventricular catheters

It is generally recommended that, in cases of difficulty in removing a ventricular catheter during a shunt revision, it is best left alone to avoid intraventricular haemorrhage. Retained ventricular catheters (RVCs) are usually safe, although in the presence of ventriculitis they may become colonized by organisms and become a source of persistent or recurrent infection. The authors present a case of persistent and intractable ventriculitis due to an old retained ventricular catheter. A 23-year-old female, who had a RVC and a functioning shunt, was admitted for a suspected blocked shunt. At surgery the shunt was found to be infected and external drainage was instituted. Over the next 4 months, she developed intractable and persistent staphylococcal ventriculitis, despite undergoing 10 further surgical procedures, and appropriate intravenous and intrathecal antibiotic therapy. She responded rapidly only after surgical removal of the old RVC via a craniotomy. The staphylococcus cultured from the RVC had an identical antibiogram to the organism responsible for the intractable ventriculitis. This case emphasizes the point that, although RVC are generally considered safe, removal becomes imperative in the presence of concurrent CSF infection that fails to respond quickly to intrathecal antibiotic therapy.

Pericallosal artery pseudoaneurysm secondary to endoscopic-assisted ventriculoperitoneal shunt placement. Case report

Complications following cerebrospinal fluid (CSF) diversion procedures are protean. The formation of pseudoaneurysms after the placement of a ventricular catheter as part of a CSF diversion procedure is presumably quite rare. The authors report the case of a child in whom a pericallosal artery pseudoaneurysm developed following the endoscopic insertion of a ventricular catheter as part of a ventriculoperitoneal shunt placement procedure. Significant intraventricular bleeding signaled vascular injury. Angiography revealed a right pericallosal artery pseudoaneurysm. The patient subsequently underwent surgical trapping of his pseudoaneurysm and physical therapy for left leg monoparesis. This appears to be the first reported case of pseudoaneurysm formation following the placement of a ventricular catheter for a CSF diversion procedure. This case underlines a rare but serious risk involved with the routine placement of CSF shunts.

Conservative Management of Patients with Cerebrospinal Fluid Shunt Infections

OBJECTIVE:

In patients with cerebrospinal fluid (CSF) shunt infection, removal of the shunt and antibiotic administration is the current standard of care. In 1986, we developed a protocol for the conservative management of patients with infected but functioning shunts. Treatment was based on the administration of a combination of intraventricular and systemic antibiotics. Intraventricular antibiotics were instilled via a separate access device. The purpose of this report is to describe our experience with this therapeutic intervention.

METHODS:

An observational study of all patients treated for CSF shunt infection between 1986 and 2003 was undertaken. Cure was defined by sterile CSF after completion of therapy and sterile shunt components at next revision or long-term freedom from recurrent infection (follow-up period, 6–88 mo).

RESULTS:

In total, 43 of 122 patients with CSF shunt infections were treated conservatively according to our protocol. Overall, 84% of these patients were cured, with a 92% success rate for patients with infections caused by bacteria other than Staphylococcus aureus. This included 30 coagulase-negative staphylococcal infections, of which two were treatment failures. We abandoned conservative treatment of patients with Staphylococcus aureus infections after early experience demonstrated that the success rate (four treatment failures in seven patients) was markedly lower than that for other pathogens. During the treatment and follow-up periods, there were three deaths, two of which were unrelated to shunt infection; treatment failure could not be completely excluded in the remaining patient. There was no toxicity related to intraventricular antibiotic administration. The incidence of shunt blockage among patients who were treated conservatively was not significantly different from that among a large cohort of patients with uninfected shunts. Ten patients received part of their courses of treatment as outpatients.

CONCLUSION:

The success rate of conservative management of patients with CSF shunt infections caused by coagulase-negative staphylococci is comparable with those in the published literature for patients treated conventionally. This form of management avoids surgical intervention, with its attendant risks, and is safe.

Polymerase Chain Reaction for the Rapid Detection of Cerebrospinal Fluid Shunt or Ventriculostomy Infections

OBJECTIVE:

Infection after cerebrospinal fluid (CSF) shunts or ventriculostomies is a common complication associated with significant morbidity and mortality. Polymerase chain reaction (PCR) is a powerful molecular technique that allows rapid and precise amplification of bacterial deoxyribonucleic acid (DNA) and has proven a powerful tool in the detection of a wide variety of clinically important infectious diseases. We analyzed specimens of CSF derived from ventriculoperitoneal shunts or external ventricular drains by using both conventional cultures and PCR and report herein our preliminary results.

METHODS:

We selected 86 CSF samples from adult patients who underwent either shunt tap or routine surveillance cultures of their ventriculostomy. These specimens were chosen from a larger group of 300 specimens that were routinely collected (many serially) in our clinical practice. They were chosen because clinical suspicion of infection was increased because of either patient signs and symptoms (fever, stiff neck, lethargy, worsening neurological examination) or preliminary laboratory analysis of CSF data (increased white blood cell count, increased protein level, decreased glucose). We considered this subgroup optimal to efficiently initiate our investigation of the correlation of PCR and culture results. CSF was increased by using standard culture techniques and by using PCR. Samples of CSF that were to undergo PCR had DNA extracted, purified, and amplified for 16S rRNA using primers 16S-Forward and 16S-Reverse of conserved sequence regions of all bacteria. DNA was PCR-amplified for 30 cycles. One microliter of the first PCR product was subjected to nested PCR using primers specific for gram-positive and gram-negative bacteria. Samples were also subjected to PCR amplification for specific detection of Propionibacterium acnes, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus using specific primers for 16S rRNA Propionibacterium, nuclease gene of Staphylococcus, and Mec gene of methicillin-resistant Staphylococcus aureus.

RESULTS:

For 18 of 86 specimens (21%), both the culture and PCR were positive. For 30 of 86 specimens (35%), both the PCR and culture results were negative. For 42 of 86 specimens (49%), cultures were negative and PCR was positive. There were no positive culture results with negative PCR results. Most negative culture/positive PCR cases occurred after prolonged intravenous antibiotics. Of the 56 PCR-positive specimens, 30 were positive for Propionibacterium acnes, whereas 40 were positive for Staphylococcus aureus. Of the Staphylococcus aureus-positive specimens, two were positive for methicillin resistant-Staphylococcus aureus. Among the 56 PCR-positive specimens, 30 were positive for both Propionibacterium acnes and Staphylococcus aureus; gram-negative organisms were not detected by any method in these specimens.

CONCLUSION:

These preliminary data suggest that PCR is a highly sensitive, rapid, and potentially promising modality for the detection and treatment of CSF shunt ventriculostomy infection.

Endoscopic third ventriculostomy for hydrocephalus associated with tectal gliomas

Object

Tectal gliomas are a distinct form of pediatric brainstem tumor that present in patients with symptoms related to increased intracranial pressure due to obstructive hydrocephalus. The natural history of these lesions is often uniquely indolent. Thus, initial surgical therapies are directed at treatment of hydrocephalus, usually with ventricular shunt placement. Recently, third ventriculostomy has been used in patients with tectal gliomas, both as an initial procedure and after shunt failures. In this report the authors review their experience with the treatment of hydrocephalus in patients with tectal gliomas.

Methods

The authors reviewed 31 consecutive cases of tectal gliomas and compared the success rates of ventricular shunt placement with the success rates of endoscopic third ventriculostomy (ETV). Shunt placement procedures were associated with a significant number of malfunctions, and most patients required shunt revisions. The ETV procedure was attempted both as an initial treatment and after shunt malfunction. Overall, ETV was attempted in 18 patients and was performed successfully in all cases. At the time of follow-up evaluation, 16 patients (89%) were shunt free.

Conclusions

The authors found that ETV could be performed with good long-term success both as an initial treatment and after shunt failure. Overall, ETV was found to be superior to ventricular shunt placement in the management of hydrocephalus associated with tectal gliomas.

Cerebrospinal fluid shunt infections in children

Infections of cerebrospinal fluid shunts continue to be a substantial source of mortality and morbidity in children with hydrocephalus. Although several therapeutic modalities are currently used for the treatment of shunt infections, there are no clear guidelines for treatment. The purpose of this study was to determine the common pathogens of cerebrospinal fluid shunt infections and evaluate the success of our management. Thirty-five children treated for ventriculoperitoneal shunt infections over the past 9 years were reviewed. The management protocol consisted of the removal of the infected shunt, the application of ventricular taps or reservoir placement, intraventricular antibiotic treatment, and the placement of a new shunt when cerebrospinal fluid sterility was achieved. Four patients were treated with antibiotics alone. Most episodes occurred within 4 months of shunt placement. The most common causative microorganism identified was Staphylococcus epidermidis, followed by S. aureus, and S. warneri. Three patients died from complications of shunt infections, 2 patients had a recurrent shunt infection, while the remaining 29 patients remained free from shunt-related complications. In agreement with the evidence published in the literature, our findings suggest that the above management protocol is effective for the treatment of cerebrospinal fluid shunt infections.

Abdominal pseudocyst: predisposing factors and treatment algorithm

Abdominal pseudocyst (APC) is an uncommon complication of ventriculoperitoneal shunts. Various predisposing factors have been attributed to it, including the presence of infection and multiple shunt revisions. We reviewed the records of shunt revisions performed over a 20-year period. During that time, 64 cases of APC were found in 36 patients. The records were then reviewed for the presence of infection, history of necrotizing enterocolitis, prior abdominal surgery, and treatment performed. Of the cases of APC, 46 were primary and 18 were recurrent. A history of prior abdominal surgery other than shunt revision was found in 47% of patients and a history of necrotizing enterocolitis was found in 19% of patients. The average number of prior shunt revisions was 4.1 per patient. Shunt infection as defined by positive cultures of either cerebrospinal fluid or abdominal fluid was present in only 23% of cases of APC. A history of prior shunt infection was present in 30% of patients. Infection was treated by shunt removal, external ventricular drainage, and appropriate antibiotics. After the infection was cleared or if no infection was present, treatment consisted of: (1) repositioning the distal catheter into the peritoneum, (2) repositioning the distal catheter into the pleural space, the atrium, or the gallbladder, (3) exploratory laparotomy with lysis of adhesions and repositioning the peritoneal catheter, (4) APC aspiration only, or (5) shunt removal or disconnection. Because of the complexity of APC management, we analyzed the outcomes of our cases and outlined an algorithm to simplify this process.

Ventriculoperitoneal shunt of continuous flow vs valvular shunt for treatment of hydrocephalus in adults

BACKGROUND

Shunting for hydrocephalus is the neurosurgical procedure most frequently associated with long-term complications. We developed an alternative to valvular shunts based on a simple shunt procedure whose functioning depends on a peritoneal catheter with a highly precise cross-sectional internal diameter of 0.51 mm. Preliminary studies have shown that the shunt of continuous flow (SCF) is superior to valvular shunts for the treatment of hydrocephalus in adults. Here, we show the long-term performance of the SCF in adult patients with hydrocephalus secondary to a comprehensive variety of neurological disorders.

METHODS

In a 5-year period, ventriculoperitoneal shunting was performed on 307 patients with hydrocephalus; 114 of them were treated with the SCF and 193 controls were treated with a conventional valvular shunt. Patients were followed from 1 to 5 years after surgery; endpoint observation was considered at surgical reintervention because of shunt failure.

RESULTS

At the end of the observation period (44 +/- 17 months), the failure rate of the shunting device was 14% for the SCF and 46% for controls (P < .0002). Shunt endurance was 88% in patients with SCF and 60% in controls. Along the study, signs of overdrainage developed in 40% of patients treated with valvular shunt, but they were not observed in patients with SCF.

CONCLUSIONS

The design of the SCF was calculated according to the mean rates of cerebrospinal fluid production; it takes simultaneous advantage of the intraventricular pressure and the siphon effect and complies with the principle of uninterrupted flow, maintaining a fair equilibrium that prevents under- and overdrainage. The SCF is a simple, inexpensive, and effective treatment for hydrocephalus in adults.

Continuous-flow shunt for treatment of hydrocephalus due to lesions of the posterior fossa

OBJECT

Management of hydrocephalus caused by expansive lesions of the posterior fossa is complicated by two main drawbacks of shunt devices: sudden decompression and overdrainage. The ventriculoperitoneal (VP) continuous-flow (CF) shunt is characterized by a peritoneal catheter with an internal diameter of 0.51 mm that promotes continuous drainage of cerebrospinal fluid (CSF) at its production rate. The authors have previously demonstrated in adult patients with hydrocephalus that sudden decompression and overdrainage are absent when this shunt is used; here they report the findings of a prospective study in which the goal was to test the performance of this shunt in patients with severe hydrocephalus due to lesions of the posterior fossa.

METHODS

During a 5-year period, 103 patients with severe hydrocephalus caused by lesions of the posterior fossa were treated by placement of a VP shunt. In 53 of these patients (control group) a shunt and valve system was surgically implanted and in 50 patients a CF shunt was implanted. All patients were followed up for a minimum of 2 years after surgery. Shunt revision or change was necessary in 21 patients (40%) with conventional shunts and in four patients (8%) with the CF shunt (p < 0.003). Signs of overdrainage were observed in 18 patients (34%) in the control group, four of whom had ascending transtentorial herniation; this complication was not seen in patients with the CF shunt.

CONCLUSIONS

The CF shunt had a low rate of dysfunction and an absence of complications caused by overdrainage, which were frequently associated with the control shunts. The hydrodynamic properties of the CF shunt make it effective, even in severe cases of hydrocephalus caused by lesions of the posterior fossa.

Neck mass after catheterization of a neck vein in a child with ventriculoperitoneal shunt

There have been many reports on various mechanical complications after shunt operations in children with hydrocephalus such as catheter fracture, obstruction, disconnection, dislocation and so on. However, there are no previous reports regarding subcutaneous mass formation due to cerebrospinal fluid (CSF) pseudocyst from direct puncture injury. The authors report with a review of the literature a case of a child with ventriculoperitoneal shunt who developed a neck mass after catheterization of the neck vein. The authors also advocate that percutaneous procedures in the vicinity of shunts be avoided whenever possible to prevent the possibility of CSF leakage resulting in pseudocyst formation.

Percutaneous gastrostomy in patients with a ventriculoperitoneal shunt: case series and review

BACKGROUND

There are few data on the safety of PEG in patients with a ventriculoperitoneal shunt.

METHODS

Medical records for patients seen in 3 tertiary care, university-affiliated hospitals between January 1, 1991, and January 1, 1999, were reviewed.

OBSERVATIONS

Six patients underwent PEG after ventriculoperitoneal shunt placement during the study period. There was no immediate complication. One patient died of pneumonia 2 months after PEG insertion. There was no instance of shunt malfunction, intra-abdominal complication, or wound infection in the study group. There was no long-term complication, with either the ventriculoperitoneal shunt or the PEG.

CONCLUSIONS

Although the number of cases was small, PEG placement with prophylactic administration of antibiotics appears to be safe in patients with a pre-existing ventriculoperitoneal shunt.

Evaluation of an antibiotic-impregnated shunt system for the treatment of hydrocephalus

Object. Staphylococcus species are the most common organisms responsible for infection following implantable cerebrospinal fluid (CSF) diversionary procedures. The role of an antibiotic-impregnated shunt (AIS) system in the prevention of shunt infection has remained unclear because no human clinical trial has been reported on thus far. In this study, the authors assess an AIS system with respect to its prevention of shunt infection.

Methods. Patients were prospectively randomized into groups to evaluate the efficacy of an AIS system against an identical control shunt system. The data accrued were subjected to a detailed statistical analysis. Logistic regression analysis was performed to determine the independent association between outcome and predictor variables. Shunt function analysis was also performed to compare the average time to infection between the two groups.

One hundred ten patients were recruited; 60 received control shunt systems and 50 received AIS systems. Thirteen shunt infections were recorded (10 in the control group and three in the AIS group). Nine (69%) of 13 infections occurred within 2 months after shunt implantation (eight of 10 in the control group and one of three in the AIS group). Apart from one patient in whom no organism was identified, a total of 14 organisms (12 patients) were cultured from either the CSF (nine) or the shunt apparatus (three). Staphylococcus species accounted for the majority of shunt infections (83%): all 10 control shunts were found to have a positive culture of staphylococci, whereas none of the AISs had any staphylococci (p = 0.038).

Conclusions. The AIS afforded antistaphylococcal protection, especially during the early postoperative period when most shunt infections are known to occur and throughout the follow-up period (median 9 months). The AIS system represents another important tool to enable the neurosurgeon to prevent shunt infections.

Brain abscess--an unusual complication of ventriculo-peritoneal shunt

The authors report a case of a 10-year-old boy, who was operated for a craniopharyngioma with hydrocephalus. He succumbed to delayed development of brain abscess and its consequence, secondary to incompletely treated shunt tract infection. This unfortunate complication developed, despite the fact that conventional steps (removal of VP shunt and intravenous antibiotics) recommended for the treatment of VP shunt infection were adopted. The pathogenesis, management and review of literature of this extremely rare clinical entity is presented.

Alzheimer's disease, normal-pressure hydrocephalus, and senescent changes in CSF circulatory physiology: a hypothesis

There is evidence that production and turnover of CSF help to clear toxic molecules such as amyloid-beta peptide (Abeta) from the interstitial-fluid space of the brain to the bloodstream. Two changes in CSF circulatory physiology have been noted as part of ageing: first, a trend towards lower CSF production, hence a decrease in CSF turnover; and second, greater resistance to CSF outflow. Our hypothesis is that, all else being equal, the initially dominant physiological change determines whether CSF circulatory failure manifests as Alzheimer's disease (AD) or as normal-pressure hydrocephalus (NPH). If CSF production failure predominates, AD develops. However, if resistance to CSF outflow predominates, NPH results. Once either disease process takes hold, the risk of the other disorder may rise. In AD, increased deposition of Abeta in the meninges leads to greater resistance to CSF outflow. In NPH, raised CSF pressure causes lower CSF production and less clearance of Abeta. The disorders may ultimately converge in vulnerable individuals, resulting in a hybrid as has been observed in several clinical series. We postulate a new nosological entity of CSF circulatory failure, with features of AD and NPH. NPH-AD may cover an important subset of patients who carry the diagnosis of either AD or NPH.

Stretching and breaking characteristics of cerebrospinal fluid shunt tubing

OBJECT

Cerebrospinal fluid (CSF) shunt system malfunction due to silastic tubing fracture necessitates revision surgery in shunt-dependent individuals. The goal of this study was to examine the mechanical stretching and breaking characteristics of new and used CSF shunt tubing catheters to determine if any inherent physical properties predispose the tubing to fracture.

METHODS

Fifty-millimeter segments of new and retrieved (used) CSF shunt tubing were stretched to 120 mm in a hydraulic press to determine modulus values (modulus = stress/strain) and to measure permanent tubing deformation imparted by the applied stress and strain. Similar 50-mm tubing segments were also stretched in an electromechanical material testing system until fracture occurred; the force and strain needed to break the tubing was recorded at the time of failure. The results demonstrate that shunt tubing with a greater cross-sectional area requires greater force to fracture, and that catheters become weaker the longer they are implanted. Barium-impregnated shunt tubing, compared with translucent tubing. appears to require less applied stress and strain to break and may fracture more easily in vivo. The variety of modulus values obtained for the new catheters tested indicates that the various companies may be using materials of different quality in tubing manufacture.

CONCLUSIONS

A CSF shunt catheter design that incorporates tubing with a greater cross-sectional area may lead to fewer fractures of indwelling catheters and a reduction in shunt revision surgery.

Treatment of cerebrospinal fluid shunt infections: a decision analysis

BACKGROUND

Cerebrospinal fluid shunts transfer cerebrospinal fluid (CSF) from the lateral ventricles in the brain to the peritoneum (ventriculoperitoneal shunt) or the right atrium (ventriculoatrial shunt) via subcutaneous Silastic tubing. As with any implanted foreign body, infection is a serious complication. Although there are several therapeutic modalities currently used for the treatment of shunt infections, controversy remains as to which is best given that there has been only one randomized trial comparing their effectiveness.

OBJECTIVE

To determine which treatment modality is most effective by using decision analysis to compare three approaches with regard to cure rate, morbidity and mortality.

METHODS

We constructed a decision tree to map out the different treatment modalities and assigned probability values obtained from previously published studies. A utility value was assigned to each treatment outcome, ranging from 0 to 1.0, with a higher score indicating a more favorable outcome. Calculations were performed using Decision Analysis TreeAge computer software.

RESULTS

The removal of an infected shunt with establishment of external ventricular drainage or ventricular taps and administration of antibiotics leads to the highest expected value, 0.86. Removal of an infected shunt followed by immediate replacement and administration of antibiotics is less effective, with an expected value of 0.76. The use of antibiotics alone results in the lowest expected value, 0.61. Sensitivity analysis showed the above findings to be robust with respect to clinically relevant changes for the baseline probabilities and utility values.

CONCLUSION

A protocol of shunt removal, external ventricular drainage placement or ventricular taps and antibiotics, followed by creation of a new shunt when CSF sterility is achieved, is the most effective method of treatment for CSF shunt infection.

Ruptured cerebral pseudoaneurysm caused by the removal of a ventricular catheter. Case report

A rare case of cerebral pseudoaneurysm located at the internal carotid artery (ICA) was caused by the removal of a ventricular catheter in an infant. This 4-month-old girl underwent ventriculoperitoneal shunt revision, during which the old ventricular catheter was removed from the posterior horn of the left lateral ventricle, but the choroid plexus was pulled out by the tip of the catheter. Intraventricular hemorrhage (IVH) and subarachnoid hemorrhage were observed postoperatively. Magnetic resonance (MR) angiography performed on the 12th postoperative day revealed ICA stenosis and aneurysm formation at the C1 portion of the left ICA. Contrast-enhanced computerized tomography (CT) scans obtained on the 21st postoperative day revealed recurrent IVH and enlargement of the lesion. The patient underwent surgery for treatment of the aneurysm. Operative findings revealed a pseudoaneurysm arising from the left ICA at the proximal end of the anterior choroidal artery (AChA). The aneurysm was removed and the wall of the ICA was reconstructed. Postoperative three-dimensional CT scanning and MR angiography demonstrated disappearance of the aneurysm and preservation of the ICA. The patient was discharged without additional neurological deficits. Many complications, including IVH, are associated with removal of a ventricular catheter. This case shows that pseudoaneurysm formation can occur in a remote region due to avulsion of the AChA from the ICA. In most circumstances a ventricular catheter can be removed without difficulty. However, precision and caution should be exercised when removing a ventricular catheter.

Characterization of a model of hydrocephalus in transgenic mice

OBJECT

The purpose of this study was to elucidate the pathophysiological characteristics of hydrocephalus in a new transgenic model of mice created to overproduce the cytokine transforming growth factor-beta1 (TGFbeta1) in the central nervous system (CNS).

METHODS

Galbreath and colleagues generated transgenic mice that overexpressed TGFbeta1 in the CNS in an effort to examine the role of this cytokine in the response of astrocytes to injury. Unexpectedly, the animals developed severe hydrocephalus and died. The authors have perpetuated this transgenic colony to serve as a model of congenital hydrocephalus, breeding asymptomatic carrier males that are heterozygous for the transgene with wild-type females. One hundred twelve (49.6%) of 226 mice developed clinical manifestations of hydrocephalus, characterized by dorsal doming of the calvaria, spasticity, limb tremors, ataxia, and, ultimately, death. The presence of the TGFbeta1 transgene was determined by performing polymerase chain reaction (PCR) analysis of sample tail slices. Animals with the hydrocephalic phenotype consistently carried the transgene, although some animals with the transgene did not develop hydrocephalus. Animals without the transgene did not develop hydrocephalus. Alterations in brain structure were characterized using magnetic resonance (MR) imaging, gross and light microscopic analysis, and immunocytochemical studies. Magnetic resonance imaging readily distinguished hydrocephalic animals from nonhydrocephalic controls and demonstrated an obstruction at the outlets of the fourth ventricle. Gross and light microscopic examination confirmed the MR findings. The results of immunofluorescent staining of brain tissue slices revealed the presence of the TGFbeta1 cytokine and its receptor preferentially in the meninges and subarachnoid space in both hydrocephalic and control mice. Reverse transcriptase-PCR analysis demonstrated tissue-specific expression of the TGFbeta1, gene in the brains of transgenic mice, and enzyme-linked immunosorbent assay confirmed overexpression of the TGFbeta1 cytokine in brain, cerebrospinal fluid, and plasma.

CONCLUSIONS

The transgenic murine model provides a reproducible representation of congenital hydrocephalus. The authors hypothesize that overexpression of TGFbeta1 in the CNS causes hydrocephalus by altering the environment of the extracellular matrix and interfering with the circulation of cerebrospinal fluid. A model of hydrocephalus in which the genetic basis is known should be useful for evaluating hypotheses regarding the pathogenesis of this disorder and should also help in the search for new treatment strategies.

Meningitis in pediatric cancer patients: a review of forty cases from a single institution

BACKGROUND

Although the clinical features of bacterial meningitis in adult cancer patients and in healthy children have been described, no previous large series has described the clinical features of meningitis in pediatric cancer patients. We performed a retrospective review of bacterial or fungal meningitis in pediatric cancer patients to determine its clinical presentation, microbiology and outcome.

METHOD

We reviewed the medical records of all patients younger than 18 years old with a diagnoses of any malignancy and bacterial or fungal meningitis at Children's Hospital and Regional Medical Center in Seattle, WA, from January, 1981, to June, 1998.

RESULTS

During the study period there were 40 cases of bacterial or fungal meningitis in 36 pediatric cancer patients. Most patients (65%) had recent neurosurgery, a central nervous system device or cerebrospinal fluid leak. Neutropenia was present in 30% of patients. Fever and altered mental status were the most consistent signs at presentation. In addition at least one additional symptom or sign of meningitis (headache, neck pain or rigidity, seizures or photophobia) was present in 77% of cases. Staphylococcus aureus and Streptococcus pneumoniae were the most common microbiologic isolates. The five patients with fatal outcome were neutropenic. Neutropenia and seizures within 2 days of presentation were associated with long neurologic sequelae.

CONCLUSIONS

Meningitis in pediatric cancer patients was associated with significant morbidity and mortality. Pediatric cancer patients with meningitis had clinical features and microbiology distinctly different from those of adult cancer patients and normal children with meningitis.

Unusual complication--VP shunt coming out per rectum and brain abscess

VP shunt is the most common pediatric neurosurgical procedure. It has been shown to result in variety of complications, which may have devastating consequences. Discussed below is one of the rare complications and the strategy to manage it successfully.

Cerebral ventricular shunts

Cerebral ventricular shunts are siphoning devices used to treat hydrocephalus. They are placed within cerebral ventricles and peripheral cavities such as the ventricular atrium or peritoneal cavity. Complications include obstruction of cerebral spinal fluid (malfunction) and infection. Morbidity and mortality rates are high when shunt malfunction and infection are not treated emergently. This report summarizes the physical examination of patients with ventricular shunts, reviews the type of shunts commonly used, discusses shunt malfunctions (causing overshunting or undershunting of cerebrospinal fluid) and infections, and makes recommendations concerning empiric antibiotic therapy for shunt infection. The technique of tapping a shunt is presented for management of patients with elevated intracranial pressure that does not respond to non-invasive maneuvers to lower the pressure.

Fiberoptic delivery of laser energy to remove occlusions from ventricular shunts: technical report

OBJECTIVES

Shunts frequently require surgical replacement because occlusions block the ventricular tubing. We have examined the hypothesis that a surgical laser coupled to an optical fiber can deliver sufficient energy to disrupt the occlusion in situ and thus afford a less invasive method of repair.

METHODS

Choroid plexus tissue found in shunts explanted from patients, model tissues such as polyacrylamide gel, and animal tissues inserted into shunts were examined. Occlusions were fragmented by pulsed laser energy of 2.09-microm wavelength and 300-microsecond duration delivered via a flexible optical fiber several meters in length. The methods and conditions were similar to those likely to be used for preclinical in vivo studies.

RESULTS

Short-lived vapor bubbles generated at the fiber tip disrupted occlusions within the shunt and expelled tissue blocking the inflow holes. Energy requirements to disrupt and remove occlusions in vitro were determined. Laser pulse energies and exposure thresholds that cause intentional damage to shunts also were determined.

CONCLUSION

Laser energies needed to disrupt occlusions were below the energy needed to damage the shunt components. Our results show that a strategy using surgical lasers and optical fibers is feasible and suggest that the procedure could be used to repair blocked shunts without requiring surgical replacement.

Pediatric neurosurgical disease

The most common, primary referrals to a pediatric neurosurgeon's office are the evaluation and management of the child with a large head (to rule out hydrocephalus and other space occupying lesions) a mishappen head (to rule out various forms of craniosynostosis), or some form of congenital spinal abnormality (spinal dysraphism). The authors discuss the pathogenesis and clinical features of these disorders, provide a framework for diagnostic evaluation and referral, and discuss the various treatment options available for each.

Posthemorrhagic hydrocephalus and brain injury in the preterm infant: dilemmas in diagnosis and management

Advances in neonatal critical care have reduced the incidence of intraventricular hemorrhage (IVH) in the newborn. Paradoxically, however, the prevalence of the complications of IVH including posthemorrhagic hydrocephalus (PHHC) has increased. By virtue of its association with long-term neurodevelopmental disability, posthemorrhagic hydrocephalus is an ominous diagnosis in the premature infant. Animal models have demonstrated that ventricular distention may cause direct cerebral parenchymal injury. Evidence for secondary parenchymal injury in the premature infant with PHHC is by necessity indirect. The precise impact of secondary parenchymal injury on the overall neurological outcome of premature infants with PHHC remains unclear in large part because of the vulnerability of the immature brain to other forms of injury (e.g., periventricular leukomalacia) that may be difficult to distinguish from injury due to distention. Furthermore, parenchymal injury due to PVL may cause ventricular enlargement that does not benefit from CSF diversion. Because these primary and secondary mechanisms of injury may operate concurrently, the precise or dominant cause of ventricular enlargement is often difficult to establish with certainty in the neonatal period. These diagnostic dilemmas have in turn impeded the development and evaluation of therapies specifically aimed at reversing ventricular distention and preventing secondary parenchymal injury. This article focuses on the current dilemmas in diagnosis and management of this potentially reversible form of injury as well as on potential future strategies for its prevention.

Increased risk of distal ventriculoperitoneal shunt obstruction associated with slit valves or distal slits in the peritoneal catheter

The authors describe a relationship between the presence of distal shunt catheter side-wall slits and distal catheter obstruction in a single-surgeon series of ventriculoperitoneal (VP) shunt revisions. Between 1985 and 1996, 168 operations for VP shunt revision were performed by the senior author (J.W.C.) in 71 patients. Indications for shunt revision included obstruction in 140 operations; overdrainage or underdrainage requiring a change of valve in 17 operations; inadequate length of distal shunt tubing resulting in the distal end no longer reaching the peritoneum in five operations; the ventricular catheter in the wrong ventricle or space, requiring repositioning in five operations; and a disconnected or broken shunt in one operation. Of the 140 instances of shunt obstruction, the blockage occurred at the ventricular end in 108 instances (77.1%), the peritoneal end in 17 (12.1%), the ventricular and the peritoneal end in 14 (10%), and in the valve mechanism (not including distal slit valves) in one (0.8%). Thus, the peritoneal end was obstructed in 31 (22.1%) of 140 cases of shunt malfunction. In every case in which the peritoneal end was obstructed, some form of distal slit was found: either a distal slit valve in an otherwise closed catheter or slits in the side of an open catheter. No instances were found of distal peritoneal catheter obstruction when the peritoneal catheter was a simple open-ended tube with no accompanying side slits (0 of 55). It is concluded that side slits in the distal peritoneal catheters of VP shunts are associated with a greater incidence of distal shunt obstruction.