Prenatal surgery for myelomeningocele and the need for cerebrospinal fluid shunt placement

OBJECT

The Management of Myelomeningocele Study (MOMS) was a multicenter randomized trial comparing the safety and efficacy of prenatal and postnatal closure of myelomeningocele. The trial was stopped early because of the demonstrated efficacy of prenatal surgery, and outcomes on 158 of 183 pregnancies were reported. Here, the authors update the 1-year outcomes for the complete trial, analyze the primary and related outcomes, and evaluate whether specific prerandomization risk factors are associated with prenatal surgery benefit.

METHODS

The primary outcome was a composite of fetal loss or any of the following: infant death, CSF shunt placement, or meeting the prespecified criteria for shunt placement. Primary outcome, actual shunt placement, and shunt revision rates for prenatal versus postnatal repair were compared. The shunt criteria were reassessed to determine which were most concordant with practice, and a new composite outcome was created from the primary outcome by replacing the original criteria for CSF shunt placement with the revised criteria. The authors used logistic regression to estimate whether there were interactions between the type of surgery and known prenatal risk factors (lesion level, gestational age, degree of hindbrain herniation, and ventricle size) for shunt placement, and to determine which factors were associated with shunting among those infants who underwent prenatal surgery.

RESULTS

Ninety-one women were randomized to prenatal surgery and 92 to postnatal repair. The primary outcome occurred in 73% of infants in the prenatal surgery group and in 98% in the postnatal group (p < 0.0001). Actual rates of shunt placement were only 44% and 84% in the 2 groups, respectively (p < 0.0001). The authors revised the most commonly met criterion to require overt clinical signs of increased intracranial pressure, defined as split sutures, bulging fontanelle, or sunsetting eyes, in addition to increasing head circumference or hydrocephalus. Using these modified criteria, only 3 patients in each group met criteria but did not receive a shunt. For the revised composite outcome, there was a difference between the prenatal and postnatal surgery groups: 49.5% versus 87.0% (p < 0.0001). There was also a significant reduction in the number of children who had a shunt placed and then required a revision by 1 year of age in the prenatal group (15.4% vs 40.2%, relative risk 0.38 [95% CI 0.22-0.66]). In the prenatal surgery group, 20% of those with ventricle size < 10 mm at initial screening, 45.2% with ventricle size of 10 up to 15 mm, and 79.0% with ventricle size ≥ 15 mm received a shunt, whereas in the postnatal group, 79.4%, 86.0%, and 87.5%, respectively, received a shunt (p = 0.02). Lesion level and degree of hindbrain herniation appeared to have no effect on the eventual need for shunting (p = 0.19 and p = 0.13, respectively). Similar results were obtained for the revised outcome.

CONCLUSIONS

Larger ventricles at initial screening are associated with an increased need for shunting among those undergoing fetal surgery for myelomeningocele. During prenatal counseling, care should be exercised in recommending prenatal surgery when the ventricles are 15 mm or larger because prenatal surgery does not appear to improve outcome in this group. The revised criteria may be useful as guidelines for treating hydrocephalus in this group.

Posterior odontoid process angulation in pediatric Chiari I malformation: an MRI morphometric external validation study

OBJECT Osseous anomalies of the craniocervical junction are hypothesized to precipitate the hindbrain herniation observed in Chiari I malformation (CM-I). Previous work by Tubbs et al. showed that posterior angulation of the odontoid process is more prevalent in children with CM-I than in healthy controls. The present study is an external validation of that report. The goals of our study were 3-fold: 1) to externally validate the results of Tubbs et al. in a different patient population; 2) to compare how morphometric parameters vary with age, sex, and symptomatology; and 3) to develop a correlative model for tonsillar ectopia in CM-I based on these measurements. METHODS The authors performed a retrospective review of 119 patients who underwent posterior fossa decompression with duraplasty at the Monroe Carell Jr. Children's Hospital at Vanderbilt University; 78 of these patients had imaging available for review. Demographic and clinical variables were collected. A neuroradiologist retrospectively evaluated preoperative MRI examinations in these 78 patients and recorded the following measurements: McRae line length; obex displacement length; odontoid process parameters (height, angle of retroflexion, and angle of retroversion); perpendicular distance to the basion-C2 line (pB-C2 line); length of cerebellar tonsillar ectopia; caudal extent of the cerebellar tonsils; and presence, location, and size of syringomyelia. Odontoid retroflexion grade was classified as Grade 0, > 90°; Grade I,85°-89°; Grade II, 80°-84°; and Grade III, < 80°. Age groups were defined as 0-6 years, 7-12 years, and 13-17 years at the time of surgery. Univariate and multivariate linear regression analyses, Kruskal-Wallis 1-way ANOVA, and Fisher's exact test were performed to assess the relationship between age, sex, and symptomatology with these craniometric variables. RESULTS The prevalence of posterior odontoid angulation was 81%, which is almost identical to that in the previous report (84%). With increasing age, the odontoid height (p < 0.001) and pB-C2 length (p < 0.001) increased, while the odontoid process became more posteriorly inclined (p = 0.010). The pB-C2 line was significantly longer in girls (p = 0.006). These measurements did not significantly correlate with symptomatology. Length of tonsillar ectopia in pediatric CM-I correlated with an enlarged foramen magnum (p = 0.023), increasing obex displacement (p = 0.020), and increasing odontoid retroflexion (p < 0.001). CONCLUSIONS Anomalous bony development of the craniocervical junction is a consistent feature of CM-I in children. The authors found that the population at their center was characterized by posterior angulation of the odontoid process in 81% of cases, similar to findings by Tubbs et al. (84%). The odontoid process appeared to lengthen and become more posteriorly inclined with age. Increased tonsillar ectopia was associated with more posterior odontoid angulation, a widened foramen magnum, and an inferiorly displaced obex.

Evaluating the relationship of the pB-C2 line to clinical outcomes in a 15-year single-center cohort of pediatric Chiari I malformation

OBJECT

The clinical significance of radiological measurements of the craniocervical junction in pediatric Chiari I malformation (CM-I) is yet to be fully established across the field. The authors examined their institutional experience with the pB-C2 line (drawn perpendicular to a line drawn between the basion and the posterior aspect of the C-2 vertebral body, at the most posterior extent of the odontoid process at the dural interface). The pB-C2 line is a measure of ventral canal encroachment, and its relationship with symptomatology and syringomyelia in pediatric CM-I was assessed.

METHODS

The authors performed a retrospective review of 119 patients at the Monroe Carell Jr. Children's Hospital at Vanderbilt University who underwent posterior fossa decompression with duraplasty, 78 of whom had imaging for review. A neuroradiologist retrospectively evaluated preoperative and postoperative MRI examinations performed in these 78 patients, measuring the pB-C2 line length and documenting syringomyelia. The pB-C2 line length was divided into Grade 0 (<3 mm) and Grade I (≥3 mm). Statistical analysis was performed using the t-test for continuous variables and Fisher's exact test analysis for categorical variables. Multivariate logistic and linear regression analyses were performed to assess the relationship between pB-C2 line grade and clinical variables found significant on univariate analysis, controlling for age and sex.

RESULTS

The mean patient age was 8.5 years, and the mean follow-up duration was 2.4 years. The mean pB-C2 line length was 3.5 mm (SD 2 mm), ranging from 0 to 10 mm. Overall, 65.4% of patients had a Grade I pB-C2 line. Patients with Grade I pB-C2 lines were 51% more likely to have a syrinx than those with Grade 0 pB-C2 lines (RR 1.513 [95% CI 1.024-2.90], p=0.021) and, when present, had greater syrinx reduction (3.6 mm vs 0.2 mm, p=0.002). Although there was no preoperative difference in headache incidence, postoperatively patients with Grade I pB-C2 lines were 69% more likely to have headache reduction than those with Grade 0 pB-C2 lines (RR 1.686 [95% CI 1.035-2.747], p=0.009). After controlling for age and sex, pB-C2 line grade remained an independent correlate of headache improvement and syrinx reduction.

CONCLUSIONS

Ventral canal encroachment may explain the symptomatology of select patients with CM-I. The clinical findings presented suggest that patients with Grade I pB-C lines2, with increased ventral canal obstruction, may experience a higher likelihood of syrinx reduction and headache resolution from decompressive surgery with duraplasty than those with Grade 0 pB-C2 lines.

Time to First Shunt Failure in Pediatric Patients over 1 Year Old: A 10-Year Retrospective Study

Studies comparing alternatives to ventriculoperitoneal (VP) shunting for treatment of hydrocephalus have often relied upon data from an earlier era that may not be representative of contemporary shunt survival outcomes. We sought to determine the shunt survival rate of our cohort and compare our results to previously published shunt survival and endoscopic third ventriculostomy (ETV) success rates. We identified 95 patients between 1 and 18 years of age, who underwent initial VP shunt placement between January 2001 and December 2010. Our study shows a shunt survival rate of 85% at 6 months and 79% at 2 years, for initial shunts in pediatric patients over 1 year of age in this cohort. The overall infection rate was 3%. This compares favorably with published success rates of ETV at similar time points as well as with the rate of infection. This suggests that ventricular shunting remains a viable alternative to ETV in the older child.

Cerebral regional oxygen saturation monitoring in pediatric malfunctioning shunt patients

BACKGROUND

Shunt malfunction produces increased intracranial pressure causing decreased cerebral regional perfusion and tissue O(2)sat. Cerebral regional oxygen saturation (rSO(2)) by near-infrared spectroscopy represents tissue perfusion and oxygen saturation. Cerebral rSO(2) is used to detect cerebral ischemia in pediatric clinical settings.

OBJECTIVE

The objective of the study was to determine the reliability of cerebral rSO(2) in pediatric malfunctioning shunt.

METHODS

A prospective observational study of pediatric patients presented to the pediatric emergency department was conducted. Confirmed malfunctioning shunt subjects had cerebral rSO(2) monitoring.

RESULTS

A total of 131 malfunctioning shunt subjects had cerebral rSO(2) monitoring. Patient's central trend and intrasubject variability of cerebral rSO(2) readings for left and right probe and malfunction sites (n = 131) are as follows: Intrasubject left and right rSO(2) Pearson correlation was -0.46 to 0.98 (mean ± SD, 0.35 ± 0.34; median, 0.34; interquartile range, 0.06-0.61). The correlation coefficients of 99 subjects between left and right rSO(2) was significantly different (P < .001), suggesting that intrasubjects' left and right rSO(2) are highly correlated. Sample mean difference between left and right rSO(2) were -1.7% (95% confidence interval [CI], -1.8 to -1.6; P < .001) supporting overall left lower than right. Intraclass correlation for left rSO(2) was 87.4% (95% CI, 87.2%-87.6%), and that for right rSO(2) was 83.8% (95% CI, 83.8%-84%), showing intersubject differences accounting for the variation, and relative to intersubject variation, intrasubjects readings are consistent. Intrasubjects, left and right rSO(2) highly correlate and are asymmetrical. Left and right rSO(2) are consistent in intrasubject with large rSO(2) variations in trend and variability across subjects.

CONCLUSION

This study demonstrates reliable cerebral rSO(2) readings in subjects with malfunctioning shunts, with asymmetrical cerebral rSO(2) hemispheric dynamics within subjects.

Intracranial hypertension caused by a depressed skull fracture resulting in superior sagittal sinus thrombosis in a pediatric patient: treatment with ventriculoperitoneal shunt insertion

OBJECT

Intracranial hypertension resulting from compression of the superior sagittal sinus (SSS) by an overlying depressed calvarial fracture is a rare condition. Primary surgical treatment for the symptomatic patient in this setting traditionally involves elevation of the fracture, which often carries significant associated morbidity.

METHODS

The authors report a case involving a 6-year-old boy who suffered a closed, depressed, parietooccipital fracture as the result of an unhelmeted all-terrain vehicle accident. This fracture caused compression and subsequent thrombosis of the SSS, which resulted in CSF malabsorption and progressive intracranial hypertension. Initially headache free following the injury, he had developed severe and unremitting headaches by postinjury Day 7. A CT angiography study of the head obtained at this time exhibited thrombosis of the SSS underlying the depressed calvarial fracture. Subsequent lumbar puncture demonstrated markedly elevated intrathecal pressures. Large volumes of CSF were removed, with temporary improvement in symptoms. After medical management with anticoagulation failed, the decision was made to proceed with image-guided ventriculoperitoneal shunt insertion.

RESULTS

The patient's headaches resolved immediately following the procedure, and anticoagulation therapy was reinstituted. Follow-up images obtained 4 months after the injury demonstrated evidence of resolution of the depressed fracture, with recanalization of the SSS. The anticoagulation therapy was then discontinued. To the authors' knowledge, this report is the first description of ventriculoperitoneal shunt insertion as the primary treatment of this infrequent condition.

CONCLUSIONS

This report demonstrates that select patients with this presentation can undergo CSF diversion in lieu of elevation of the depressed skull fracture-a surgical procedure shown to be associated with increased risks when the depressed fracture overlies the posterior SSS. The literature on this topic is reviewed and management of this condition is discussed.

Intrauterine Shunt for Obstructive Hydrocephalus – Still Not Ready

OBJECTIVE

To determine the safety and efficacy of ventriculoamniotic shunt placement through a hysterotomy in the second trimester of pregnancy as treatment for isolated obstructive hydrocephalus.

METHODS

Between 1999 and 2003, four pregnancies with isolated fetal obstructive hydrocephalus in the second trimester were treated at Vanderbilt University Medical Center. Preoperatively, all fetuses underwent serial ultrasonographic examinations and an ultrafast magnetic resonance imaging to confirm isolated aqueductal stenosis. A normal fetal karyotype and negative polymerase chain reaction or culture of the amniotic fluid for cytomegalovirus and toxoplasmosis were obtained. Serial enlargement of the lateral ventricles >1.5 mm/week and fetal macrocephaly were documented. Using epidural and GETA, a standard ultrasmall ventricular catheter and valve were inserted via a hysterotomy. The distal catheter, rather than being inserted into the fetal peritoneum, exited between the fetal scapulae. Patients were discharged home from the hospital, and the remainder of their prenatal care was provided by their local obstetrician. After delivery, the distal drain was converted to a ventriculoperitoneal shunt.

RESULTS

Cases were performed at 23 6/7, 25 5/7, 26 4/7, and 26 5/7 weeks. Shunts performed well during pregnancy, and were intact at delivery. Deliveries occurred at 34 1/7, 27 1/7, 28, and 32 4/7 weeks. Birthweights were 2,010, 907, 1,200, and 2,220 g. All Apgar scores were normal. Case 1 developed a neonatal shunt infection, and is now developmentally delayed, with swallowing dysfunction, hearing deficits and a poor pupillary response. Case 2 developed neonatal sepsis and is now developmentally delayed. Case 3 delivered preterm due to chorioamnionitis, and neonatal death occurred from sepsis. Case 4 is developmentally delayed.

CONCLUSIONS

Ventriculoamniotic shunt can be placed through a hysterotomy, overcoming many of the technical difficulties of earlier percutaneous shunts. However, recent developments in fetal imaging and molecular genetics have not improved case selection. Unless new breakthroughs occur, fetal shunting cannot reasonably be expected to improve perinatal outcome.

Effect of an intraoperative double-gloving strategy on the incidence of cerebrospinal fluid shunt infection

OBJECT

The purpose of this study was to determine the effect of double gloving on cerebrospinal fluid (CSF) shunt infection rates.

METHODS

Data obtained in two large groups of patients, one in which the surgical personnel wore a single pair of gloves each and the other in which the personnel wore two pairs of gloves each, were retrospectively studied. The study involved 863 patients. The overall infection rate in the single-gloved group was 15.2%, whereas it was 6.7% in the double-gloved group (p = 0.0002). Of additional interest was the marked difference between the overall shunt infection rates in younger children (< 11.3 years of age; 15.7%) and older children (> 11.3 years of age) and adults (6.7%; p < 0.00005).

CONCLUSIONS

The strategy of wearing two pairs of gloves while performing surgery appears to reduce the incidence of postoperative shunt infection by more than 50%. The incidence of shunt infection is highly age dependent. The shunt infection rate may be further reduced by carefully studying the individual variables associated with the shunt insertion procedure.

Upper level of the spina bifida defect: how good are we?

OBJECTIVE

To assess the accuracy of obstetric sonography in determining the upper level of myelomeningocele lesions.

METHODS

This was a retrospective study of 171 consecutive cases of spina bifida repaired in utero. The upper level of the lesion as determined by obstetric sonography was assigned by community physicians prior to referral in the second trimester and by the authors at Vanderbilt University Medical Center during preoperative evaluation. One hundred and eleven cases had levels established by plane-film X-ray or magnetic resonance imaging after delivery and this was regarded as the gold standard.

RESULTS

Of the 171 community examinations, only 29% identified a specific upper level of the lesion; our corresponding examinations specified the lesion level in all cases. Of the 111 cases that had upper levels of the lesion established by post-delivery imaging, corresponding levels were available for comparison from 35 of the community examinations and from 111 of the examinations performed at Vanderbilt. All three assigned levels were available for comparison in 35 cases. In 26% of cases, community-assigned levels agreed exactly with post-delivery levels, while 66% agreed within one level and 80% agreed within two levels. In 38% of cases, levels assigned at Vanderbilt agreed exactly with post-delivery levels, while 78% agreed within one level and 96% agreed within two levels. Upper levels of the lesion assigned at Vanderbilt were significantly more accurate overall compared with those assigned by community physicians (signed rank test [paired comparison], P = 0.048). However, comparison of lesion levels assigned at Vanderbilt in the first 50 vs. the last 61 cases revealed a significant learning effect (Fisher's exact test, P = 0.03). When comparison of lesion levels assigned by community physicians was restricted to the first 50 cases at Vanderbilt, accuracy was similar (n = 13; t-test, P = 0.16; rank sum test, 0.31).

CONCLUSIONS

Community physicians were successful in assigning the upper level of the spina bifida lesion only 29% of the time. When successful, the accuracy of these determinations was similar to that of the authors at Vanderbilt. A significant learning effect was demonstrated by improved accuracy over time at Vanderbilt. A concerted continuing medical education effort is indicated to improve the imaging skills of physicians in the accurate diagnosis of the severity of spina bifida in fetuses.

Intrauterine repair of spina bifida: preoperative predictors of shunt-dependent hydrocephalus

OBJECTIVE

The objective of this study was to determine which factors that are present at the time of intrauterine repair of spina bifida could predict the need for ventriculoperitoneal shunt for hydrocephalus during the first year of life.

STUDY DESIGN

One hundred seventy-eight fetuses have undergone intrauterine repair of spina bifida at Vanderbilt University Medical Center since 1997. Among these, 116 fetuses had a postnatal follow-up period of at least 12 months. The primary outcome of the study was the need for a ventriculoperitoneal shunt for hydrocephalus during the first year of life. The following variables were analyzed: maternal demographics (age, race, gravidity, and parity), gestational age at the time of surgery, ventricular size, degree of hindbrain herniation (determined by magnetic resonance imaging in 33 cases), type of defect (myelomeningocele vs myeloschisis), upper level of the lesion, presence of talipes, and intraoperative use of a lumbar drain. Statistical analysis was performed with logistic regression (to test the association of fetal and maternal factors and the need for ventriculoperitoneal shunting), 2-sample t-tests for comparison of means, and receiver operating curves with the use of the probabilities that were generated by the logistic regression for both continuous and categoric versions of the factors.

RESULTS

Sixty-one of 116 of the fetuses (54%) who underwent operation in utero required the placement of a ventriculoperitoneal shunt before the age of 1 year. The upper level of the lesion was the strongest predictor of shunt requirement (adjusted odds ratio per 1 level increase with the use of continuous variables [S1 through T10], 1.73 [95% CI, 1.22- 2.44]; adjusted odds ratio with the use of upper lesion level >or=L3 vs <L3 as a categorized variable, 5.7 [95% CI, 2.18- 14.7]), followed by gestational age at the time of surgery (adjusted odds ratio per 1 week increase with the use of continuous variables, 1.37 [95% CI, 1.06-1.77]; adjusted odds ratio with the use of gestational age <or=25 weeks vs >25 weeks as a categorized variable, 3.3 [95% CI, 1.28-8.24]), and preoperative ventricular size (adjusted odds ratio per 1 unit increase with the use of continuous variables, 1.17 [95% CI, 1.01-1.36]; adjusted odds ratio with the use of ventricular size >or=14 mm vs <14 mm as a categorized variable, 3.5 [95% CI, 1.08-11.16]). Receiver operating curves with the use of the probabilities that were generated by the logistic regression analyses for both the continuous and categoric versions of the factors were compared. The area under the curve was approximately 0.81 for both methods. Thirty-eight of 48 of the fetuses (79%) with an upper level of the lesion >or=L3 required placement of a ventriculoperitoneal shunt, although 25 of 68 of the fetuses (37%) with lesions <or=L4 did not (P < .0001). Eighty-four percent of the fetuses with a preoperative ventricular size >or=14 mm (27/32 fetuses) needed a shunt compared with 41% of the fetuses (34/81 fetuses) with smaller ventricles (P=.03). Seventy-one percent of the fetuses who underwent operation at >25 weeks of gestation also required shunt placement (37/52 fetuses); 39% of the fetuses (24/61 fetuses) who were treated <or=25 weeks of gestation did not (P=.01). Thirty-five fetuses had a lesion level <or=L4 and a ventricular size <14 mm and underwent operation at <or=25 weeks of gestation. Among these, 8 fetuses (23%) required a ventriculoperitoneal shunt during the first year of life.

CONCLUSION

This study suggests that, among fetuses who underwent operation in utero for spina bifida, fetuses with a ventricular size of <14 mm at the time of surgery, fetuses who had surgery at <or=25 weeks of gestation, and fetuses with defects that were located at <or=L4 were less likely to require ventriculoperitoneal shunting for hydrocephalus during the first year of life.

Intrauterine closure of myelomeningocele: an update

Preliminary evidence suggests that intrauterine myelomeningocele repair may benefit patients by reducing the both incidence of hydrocephalus and the severity of the Chiari malformation; however, this benefit remains unproved. Furthermore, the procedure entails substantial risks not associated with conventional therapy. A randomized controlled trial of intrauterine and conventional therapies is underway. This study should definitively establish the procedure-related risks and benefits. Regardless of the outcome, it is clear that the risks of intrauterine intervention need to be reduced before myelomeningocele, or other congenital malformations, can be effectively treated prior to birth. To that end, studies are being conducted to assess the potential advantages of applying state-of-the-art endoscopic techniques to intrauterine therapy. If benefit can be proven and risks reduced, intrauterine myelomeningocele repair has the potential to become the preferred therapy for patients suffering from this debilitating disease.

Intrauterine Myelomeningocele Repair: Effect on Short-Term Complications of Prematurity

OBJECTIVE

To determine whether short-term complications of prematurity are affected by intrauterine myelomeningocele repair.

METHODS

Medical records of the first 100 infants undergoing intrauterine myelomeningocele repair (IUMR) at the Vanderbilt University Medical Center were reviewed. Infants born at <34 weeks' gestation were identified. Two controls were identified for each IUMR infant. Controls were matched for gestational age, sex, birth weight, antenatal steroids, and mode and month of delivery. Development of respiratory distress syndrome, intraventricular hemorrhage, and chronic lung disease and days on ventilator and length of hospital stay were recorded. The results are expressed as mean values and ranges. Comparison of data between groups was performed using the Mann-Whitney U test. Categorical data were compared using the chi-square test and Fisher's exact test. p </= 0.05 was considered statistically significant.

RESULTS

One hundred infants underwent IUMR. Forty-four infants were born at <34 weeks of gestation. Complete data were available on 37 infants. Seventy-four matched controls were studied. Eleven infants from the IUMR group and 23 infants from the control group developed respiratory distress syndrome (29.7 vs. 31.1%; p = 0.8). Six infants from the IUMR group and 13 infants from the control group developed chronic lung disease (16.2 vs. 17.5%; p = 0.9). The length of stay was 28 (range 2-82) days for the IUMR group and 24 (range 1-99) days (p = 0.09) for the control group. There was also no significant difference between groups with regard to intraventricular hemorrhage and days on ventilators.

CONCLUSION

There is no difference between short-term complications of prematurity following IUMR and those associated with prematurity resulting from other causes.

Intrauterine myelomeningocele repair

Preliminary studies have suggested that IUMR reduces the incidence of shunt-dependent hydrocephalus and the severity of the Chiari malformation. An RCT is in progress to confirm these results. Future efforts will revolve around refinement of the procedure with the goal of reducing risk. Robot-assisted surgery holds the promise of achieving this goal. If it is successful. IUMR might well become the standard therapy for myelomeningocele, resulting in a significant reduction in the devastating morbidity associated with this disease.

Late gestational intrauterine myelomeningocele repair does not improve lower extremity function

OBJECTIVE

To determine whether intrauterine myelomeningocele repair performed at between 20 and 28 weeks gestation improves lower extremity function (LEF).

METHODS

Thirty-seven consecutive patients who had undergone intrauterine repair of their myelomeningocele at Vanderbilt University Medical Center had their lower extremity function and radiographic level (first defective vertebral level) compared to these same parameters in 40 controls who had undergone traditional postgestational repair of their myelomeningocele at the Children's Hospital in Birmingham, Ala., USA.

RESULTS

Of all 77 patients (controls and study group), 13 had a LEF that matched their radiographic level, 27 had a LEF that was rostral to their radiographic level, and 37 had a LEF that was caudal to their radiographic level. Further stratification revealed that for the intrauterine repaired myelomeningoceles, 11% had no difference between LEF and radiographic level, 43% had a LEF that was rostral to their radiographic level, and 46% had a LEF that was caudal to their radiographic level. For those closed in a traditional manner, LEF matched their radiographic level, was rostral to their radiographic level, and was caudal to their radiographic level in 22.5%, 27.5%, and 50% respectively. However, the overall mean differences between institutions produced a p-value of 0.2026 (paired t-test).

CONCLUSIONS

Although the current timing of intrauterine myelomeningocele repair has been found to lessen the degree of herniation of the rhombencephalon and reduce the incidence of shunt-dependent hydrocephalus, it does not statistically improve LEF. Parents should be advised of these findings prior to surgical intervention so as to focus their expectations.

The effect of intrauterine myelomeningocele repair on the incidence of shunt-dependent hydrocephalus

BACKGROUND

Intrauterine myelomeningocele repair (IUMR) was first successfully performed in 1997. Preliminary reports suggest that this procedure reduces the incidence of shunt-dependent hydrocephalus when compared to conventional postnatal therapy. However, the existing cohort of IUMR patients has not yet been systematically compared to a comparable group of conventionally treated controls.

METHODS

Patients 1 year old or greater who had undergone IUMR at either Vanderbilt University or the Children's Hospital of Philadelphia (CHOP) were compared to a group of conventionally treated historical controls treated and followed at CHOP. In order to measure any differences between the groups, patients were stratified according to the level of the myelomeningocele lesion and the gestational age at the time of IUMR.

RESULTS

One hundred and four IUMR patients were compared to 189 conventionally treated controls. IUMR resulted in statistically significant reductions in the incidence of shunt-dependent hydrocephalus at both lumbar and sacral lesion levels. When lumbar lesion levels were further stratified, from L1 to L5, it appeared that the benefit of IUMR was statistically significant only at levels below L2. Other factors with a significant impact on hydrocephalus were estimated gestational age and ventricular size at the time of surgery. In particular, statistically significant differences compared to controls were seen in the younger (< or =25 weeks) group but not in the older (>25 weeks) group.

CONCLUSIONS

IUMR appears to substantially reduce the incidence of shunt-dependent hydrocephalus when compared to conventional treatment even when lesion level is taken into account. Patients with lesions above L3 may not share in this benefit. IUMR cannot be justified in fetuses older than 25 weeks of gestation. Additional improvements might be obtained by further reducing the average age at which fetuses are operated upon. It remains to be determined whether this benefit outweighs the potential risks of intrauterine surgery.

Gestational age at intrauterine myelomeningocele repair does not influence the risk of prematurity

OBJECTIVE

To determine the effect of gestational age at the time of intrauterine myelomeningocele repair on the duration of pregnancy and the gestational age at the time of delivery.

METHODS

This study is a retrospective chart review of the maternal and neonatal medical records of all infants undergoing intrauterine myelomeningocele repair at Vanderbilt University Medical Center. Birth weight, gestational age at the time of surgery and gestational age at the time of delivery were recorded. Infants were divided into 2 groups depending on gestational age at the time of surgery, either > or = 25 weeks' gestation (group 1) or < 25 weeks (group 2). Results were expressed as medians and interquartile ranges. Statistical analysis was done using the unpaired (2-sample) t test; p values < or = 0.05 were considered significant.

RESULTS

Ninety-five infants were studied. Fifty-one infants were repaired after 25 weeks' gestation (group 1) at a median gestational age of 26.3 weeks (range 25.6-27.6). Their median gestational age at delivery was 34.4 weeks (range 32.6-35.3). Forty-four infants were repaired before 25 weeks' gestation (group 2). Surgery was done at a median gestational age of 23.6 weeks (range 22.4-24.5). The median gestational age at delivery was 34 weeks (range 31.6-35.3; p = 0.88).

CONCLUSION

Early intrauterine myelomeningocele repair before 25 week's gestation does not decrease the gestational age at delivery when compared with repair after 25 weeks.

The urodynamic profile of myelodysplasia in childhood with spinal closure during gestation

PURPOSE

Spinal dysraphism is the most common cause of neurogenic bladder dysfunction in newborns. Urodynamic findings in these patients include uninhibited bladder contractions, bladder areflexia, decreased compliance and detrusor-sphincter dyssynergia. Early urodynamic studies are recommended for spina bifida to help identify bladder characteristics that may cause a risk of upper tract deterioration. We recently evaluated a new early type of intervention involving closure of the neural tube defect during gestation in 25 patients at our institution. We hypothesize that this procedure results in decreased exposure of the spinal cord to amniotic fluid, which may improve neurological function. To date we have evaluated 16 of the 25 patients with video urodynamics. We compared the results to those in the literature on patients with myelomeningocele and without prenatal intervention.

MATERIALS AND METHODS

We performed urodynamic testing in 16 patients with a mean age of 6.5 months, including cystometrography, fluoroscopic evaluation of filling and voiding, pelvic floor electromyography and post-void residual urine measurement. In addition, we retrospectively reviewed renal ultrasound, voiding cystourethrography, catheterization need, number of urinary tract infections and medication in these cases.

RESULTS

Uninhibited detrusor contractions and an areflexic bladder were identified in 6% and 43% of patients, respectively, while 19% had decreased compliance and 75% had leak point pressure greater than 40 cm. water. Mean bladder capacity was 40 cc and 31% of patients had much lower capacity than expected for age. Previous renal ultrasound and voiding cystourethrography showed evidence of upper tract dilatation and reflux in 2 cases, respectively. Intermittent catheterization and anticholinergic therapy were required by 1 patient each and 1 had a significant urinary tract infection.

CONCLUSIONS

Urodynamic findings in this population are comparable to those previously reported in the literature in patients with spina bifida without prenatal closure of the spinal defect. The lower incidence of urinary tract infection and reflux in our study probably represents more aggressive early urological management rather than neurological improvement. These urodynamic studies were performed early in life and future evaluation may ultimately reveal improved bladder function compared with that in others with myelodysplasia. However, at this time we recommend that patients who undergo spinal cord defect closure during gestation be evaluated and treated in the same manner as those with myelomeningocele but without fetal intervention.

Fetal MRI in the evaluation of intrauterine myelomeningocele

BACKGROUND

Accurate fetal imaging is essential to the practice of maternal-fetal medicine. While ultrasonography has been the traditional mainstay of fetal imaging, its ability to resolve critical features of central nervous system (CNS) anatomy remains limited. As interest in intrauterine therapy for myelomeningocele has increased, so has the need for more accurate, noninvasive imaging of the CNS. Fetal magnetic resonance imaging (MRI) promises to fill the gap left by ultrasound.

METHODS

Thirty-seven MRI scans of fetuses previously diagnosed with myelomeningocele were reviewed by 2 neuroradiologists. The ability of fetal MRI to resolve the commonest CNS stigmata of spina bifida, and the incidence and extent of interobserver error, was assessed. In 4 cases, postnatal MRIs were also available. These were compared to the corresponding fetal studies.

RESULTS

The imaging quality with the technique used in this study was excellent, even without the use of maternal or fetal sedation. There were no complications, and the imaging times were minimal. Interobserver error was minimal with respect to the evaluation of ventricular dilatation and hindbrain herniation, but moderate in the description and location of the spinal lesion. As had previously been documented with ultrasonography, a reduction was seen in hindbrain herniation when comparing pre- and postnatal MRIs.

CONCLUSION

It is concluded that fetal MRI is an effective, noninvasive means of assessing fetal CNS anatomy. Its ability to resolve posterior fossa anatomy is superior to ultrasonography while, with respect to the evaluation of hydrocephalus and the level and nature of the spinal lesion, it may be equivalent to inferior. Inclusion of the fetal MRI into the standard diagnostic armamentarium will probably await the next major advance in speed and resolution. It is conceivable that, with further advances, MRI might supplant ultrasonography as the diagnostic tool of choice for evaluation of fetal anomalies including myelomeningocele.

Use of bipedicular advancement flaps for intrauterine closure of myeloschisis

Several groups have begun to explore the feasibility and utility of intrauterine closure of myelomeningocele. A subset of these fetuses have defects which fall into the category of myeloschisis, and therefore have inadequate skin to enable primary closure. After considerable discussion, it was decided to utilize bipedicular flaps to close these lesions. The procedure is described, and representative examples are shown. To date, 13 of 56 fetuses have required this approach for closure in utero. While this technique generally provides adequate coverage of the dural sac, the cosmetic results have been less than optimal.

Fetal surgery for myelomeningocele and the incidence of shunt-dependent hydrocephalus

CONTEXT

Intrauterine closure of exposed spinal cord tissue prevents secondary neurologic injury in animals with a surgically created spinal defect; however, whether in utero repair of myelomeningocele improves neurologic outcome in infants with spina bifida is not known.

OBJECTIVE

To determine whether intrauterine repair of myelomeningocele improves patient outcomes compared with standard care.

DESIGN

Single-institution, nonrandomized observational study conducted between January 1990 and February 1999.

SETTING

Tertiary care medical center.

PARTICIPANTS

A sample of 29 study patients with isolated fetal myelomeningocele referred for intrauterine repair that was performed between 24 and 30 gestational weeks and 23 controls matched to cases for diagnosis, level of lesion, practice parameters, and calendar time. All infants were followed up for a minimum of 6 months after delivery.

MAIN OUTCOME MEASURES

Requirement for ventriculoperitoneal shunt placement, obstetrical complications, gestational age at delivery, and birth weight for study vs control subjects.

RESULTS

The requirement for ventriculoperitoneal shunt placement for decompression of hydrocephalus was significantly decreased among study infants (59% vs 91%; P = .01). The median age at shunt placement was also older among study infants (50 vs 5 days; P = .006). This may be explained by the reduced incidence of hindbrain herniation among study infants (38% vs 95%; P<.001). Following hysterotomy, study patients had an increased risk of oligohydramnios (48% vs 4%; P = .001) and admission to the hospital for preterm uterine contractions (50% vs 9%; P = .002). The estimated gestational age at delivery was earlier for study patients (33.2 vs 37.0 weeks; P<.001), and the birth weight of study neonates was less (2171 vs 3075 g; P<.001).

CONCLUSIONS

Our study suggests that intrauterine repair of myelomeningocele decreases the incidence of hindbrain herniation and shunt-dependent hydrocephalus in infants with spina bifida, but increases the incidence of premature delivery.

The Tulipan-Bruner trocar for uterine entry during fetal surgery

OBJECTIVE

Our goal was to compare the use of a specially designed trocar for initial uterine entry with standard entry by electrocautery in creation of a hysterotomy for fetal surgery.

STUDY DESIGN

Ten consecutive patients undergoing hysterotomy for intrauterine repair of myelomeningocele were randomized to initial uterine entry with electrocautery or with the Tulipan-Bruner trocar. Timing of initial uterine entry with electrocautery began with incision into the uterine serosa and ended with incision of the chorioamnionic membranes. Timing of initial uterine entry with the Tulipan-Bruner trocar began with placement of stay sutures and ended with removal of the central introducer from the peel-away sheath. Blood loss was estimated by the primary surgeon. All of the participating surgeons judged the convenience and ease of each technique. The times required for initial uterine entry were compared with an unpaired t test. Statistical significance was set at P <.05.

RESULTS

The time required for initial uterine entry with electrocautery was 231 +/- 63 (mean +/- SD) seconds compared with 146 +/- 51 seconds with the trocar (P <.05). The total blood loss for all 10 cases was <50 mL, but the presence of blood in the wound was judged much more inconvenient when electrocautery was used. Finally, electrocautery required 2 surgical assistants in every case, whereas the trocar was readily placed with only a single assistant.

CONCLUSION

The Tulipan-Bruner trocar provides quicker, less traumatic uterine entry during creation of a hysterotomy, as compared with electrocautery.

Effect of intrauterine myelomeningocele repair on central nervous system structure and function

BACKGROUND

It has been postulated that intrauterine myelomeningocele repair might improve neurologic outcome in patients with myelomeningocele. A total of 59 such procedures have been performed at Vanderbilt University. Preliminary results suggested that the degree of hindbrain herniation is reduced by intrauterine repair. In an attempt to further quantify the possible benefits of this surgery, a subset of these patients was brought back to Vanderbilt for study.

METHODS

A group of 26 patients who had undergone intrauterine myelomeningocele repair underwent an extensive evaluation which included manual muscle testing, MR imaging and precise determination of the anatomic level of their lesions as well as multiple other tests. The results of this analysis were compared to those in 2 groups of historical controls.

RESULTS

In this group of patients intrauterine myelomeningocele repair substantially reduced the incidence of moderate to severe hindbrain herniation (4 vs. 50%). The incidence of shunt-dependent hydrocephalus was more modestly reduced (58 vs. 92%). The average level of leg function closely matched the average anatomic level of the lesion in both the fetal surgery and control groups.

CONCLUSION

The most dramatic effect of intrauterine repair appears to be on hindbrain herniation. A less dramatic, but significant, reduction in shunt-dependent hydrocephalus is also seen. Prospective patients should be cautioned not to expect improvement in leg function as the result of this surgery. The potential benefits of surgery must be carefully weighed against the potential risks of prematurity.

Intrauterine myelomeningocele repair reverses preexisting hindbrain herniation

BACKGROUND

It has been reported that intrauterine myelomeningocele repair reduces the amount of hindbrain herniation normally seen in association with the Chiari type II malformation. It is not yet known, however, whether hindbrain herniation is prevented, or whether preexisting herniation is reversed. The following study was designed to elucidate this issue.

METHODS

A series of 9 patients underwent intraoperative ultrasound examinations immediately prior to intrauterine myelomeningocele repair. These same patients were then evaluated postnatally using ultrasound and/or MRI. The degree of hindbrain herniation before and after repair was compared using a grading system devised by the authors.

RESULTS

Eight patients had clear evidence of moderate to severe hindbrain herniation on intraoperative scans while one was mild. In contrast, on postnatal studies 5 of 9 patients had no evidence of hindbrain herniation, while the other 4 had only mild herniation.

CONCLUSION

Intra-uterine myelomeningocele repair appears to reverse preexisting hindbrain herniation. It is postulated that continuous flow of cerebrospinal fluid through the neural placode is the force responsible for inducing migration of the cerebellum and brain stem downward through the foramen magnum. By interrupting that flow during gestation, intrauterine myelomeningocele repair enables the cerebellum and brain stem to resume a normal, or nearly normal, configuration.

Reduced hindbrain herniation after intrauterine myelomeningocele repair: A report of four cases

BACKGROUND

It has been theorized that fetal myelomeningocele repair may reduce ongoing intrauterine injury and perhaps allow healing and regeneration of dysplastic neural tissue. We report on the postnatal imaging studies of the first 4 patients to have undergone intrauterine myelomeningocele repair at our institution.

METHODS

Each of the 4 patients underwent postnatal sonographic and MRI. In addition, the postnatal ultrasounds of these 4 were compared to a group of retrospective controls.

RESULTS

MRI scans of the 4 experimental subjects revealed no evidence of hindbrain herniation while other stigmata of the Chiari-II malformation persisted. In comparison to the retrospective controls this absence of herniation was distinctly unusual.

CONCLUSION

Intrauterine myelomeningocele repair may reduce the degree of hindbrain herniation normally seen in patients with myelomeningocele. This raises the possibility that intrauterine repair may decrease the morbidity associated with the Chiari type-II malformation including brainstem dysfunction, hydrocephalus and syringomyelia.

Stereotactic ventriculoperitoneal shunt for idiopathic intracranial hypertension: technical note

OBJECTIVE

Lumboperitoneal shunting is the bastion of neurosurgical management for idiopathic intracranial hypertension (IIH). However, recent studies document a high failure rate for this procedure. The present study was designed to explore the feasibility of placing ventriculoperitoneal shunts under stereotactic control into patients with IIH as an alternative to lumboperitoneal shunting.

METHODS

Seven patients with IIH for whom medical management had failed underwent stereotactic implantation of ventriculoperitoneal shunts.

RESULTS

Shunt placement was successful and uncomplicated in each case. Five of seven patients experienced complete resolution of papilledema. The remaining two patients showed resolving papilledema. Six of seven patients experienced resolution of headache. The remaining patient continued to have headaches despite a radionuclide study demonstrating normal shunt function.

CONCLUSION

Our results suggest that stereotactic ventriculoperitoneal shunting may be a reasonable alternative to lumboperitoneal shunting in those patients with IIH who require surgical intervention.

Pediatric head injury

Pediatric head injury is a public health problem that exacts a high price from patients, their families and society alike. While much of the brain damage in head-injured patients occurs at the moment of impact, secondary injuries can be prevented by aggressive medical and surgical intervention. Modern imaging devices have simplified the task of diagnosing intracranial injuries. Recent advances in monitoring technology have made it easier to assess the effectiveness of medical therapy. These include intracranial pressure monitoring devices that are accurate and safe, and jugular bulb monitoring which provides a continuous, qualitative measure of cerebral blood flow. The cornerstones of treatment remain hyperventilation and osmotherapy. Despite maximal treatment, however, the mortality and morbidity associated with pediatric head injury remains high. Reduction of this mortality and morbidity will likely depend upon prevention rather than treatment.

Myelomeningocele repair in utero: a report of three cases

BACKGROUND

Evidence accumulating over the last 10 years suggests that the exposed spinal cord tissue in a myelomeningocele sustains a secondary injury as the result of prolonged exposure to the intrauterine environment. These data suggest that early closure of the myelomeningocele sac might prevent such injury and in turn improve the neurologic outcome in the affected infant.

METHODS

Three patients with fetuses carrying the ultrasonic diagnosis of myelomeningocele elected to enter a study of the feasibility of repairing myelomeningocele in utero. At approximately 28 weeks of gestation each patient underwent laparotomy and hysterotomy, thus exposing the myelomeningocele defect. The defect was closed in a routine surgical fashion, and the hysterotomy was then closed.

RESULTS

The 3 patients recovered from surgery without incident. Early premature contractions subsided, and they were discharged by the 5th postoperative day. At between 33 and 36 weeks of gestation, each infant was delivered via cesarean section. The observed neurologic deficits were within the range expected from the anatomic level of the defects. Two of the infants have not required ventriculoperitoneal shunting.

CONCLUSIONS

This limited series of patients suggests that myelomeningocele can be repaired in utero with minimal morbidity to either the mother or her fetus. A larger study will be needed to substantiate this low morbidity and to determine the extent of any neurologic benefit of early surgery.

Quantitative analysis of the toxicity of human amniotic fluid to cultured rat spinal cord

It has been proposed that the myelodysplastic components of a myelomeningocele are secondarily damaged as the result of exposure to amniotic fluid, the so-called 'two-hit' hypothesis. The critical time at which this secondary insult might occur has not been clearly defined. The present study addresses this issue by quantitatively assessing the toxic effects of human amniotic fluid of various gestational ages upon organotypic cultures of rat spinal cord. Using an assay for lactate dehydrogenase efflux to evaluate toxicity in such spinal cord cultures, we found that the amniotic fluid became toxic at approximately 34 weeks' gestation. This toxic effect of amniotic fluid appears to emerge rather suddenly. Accordingly, it seems reasonable to suggest that prevention of exposure of vulnerable spinal cord tissue to this toxicity by surgical closure of a myelomeningocele defect prior to the emergence of toxicity in amniotic fluid may prevent injury to vulnerable myelodysplastic spinal cord tissue.

Neoplastic meningitis as the presentation of occult primitive neuroectodermal tumors

Seven children and young adults initially presented with subacute meningitis and/or increased intracranial pressure. The diagnosis of neoplastic meningitis secondary to a primitive neuroectodermal neoplasm was delayed by the absence of an obvious primary tumor. The neuroradiologic appearance was that of a basimeningeal infiltrative process, complicated by communicating hydrocephalus or "pseudotumor cerebri." Myelography was important in the diagnosis of disseminated meningeal malignancy in four cases. Cerebrospinal fluid cytologic diagnosis was insensitive but ultimately confirmed in five cases. All seven patients experienced progressive disease despite neuraxis radiotherapy and intensive chemotherapy; six have died. Systemic dissemination to bone and/or peritoneum occurred in three patients while on therapy. In two, a primary parenchymal brain or spinal cord tumor could not be identified at postmortem examination. The presentation of a primitive neuroectodermal tumor as subacute meningitis without an evident primary tumor heralds an aggressive and refractory neoplasm.

Alterations in prealbumin concentration after adrenal autotransplantation for Parkinson's disease

The cerebrospinal fluid of eight patients with Parkinson's disease who underwent adrenal medullary autotransplantation was analyzed using SDS-polyacrylamide gel electrophoresis. A protein, subsequently identified as prealbumin, was noted to change in concentration over the intraoperative to 18-month postoperative time course. The qualitative changes observed on visual inspection were confirmed and quantified using laser densitometry. The concentration of prealbumin increased by an average of 90% when the intraoperative and 12-month samples were compared. This increase persisted at 18 months. The ratio of prealbumin to albumin also increased from intraoperative to 12 months by an average of 56%. This suggests that the increases in PA are the result of choroid plexus activation rather than a nonspecific breakdown of the blood-brain barrier. Given the association of prealbumin with other nervous system diseases, as well as its known ability to bind multiple substances, these findings may have important implications. Alterations in prealbumin may be responsible for the improvement seen in some patients who receive adrenal medullary autotransplants. Alternatively, prealbumin may be implicated in the pathophysiology of Parkinson's disease.

Osteoblastic meningioma of the fourth ventricle

Meningiomas of the fourth ventricle are rare neoplasms. Only meningothelial and fibroblastic subtypes, purportedly arising from the tela choroidea, have been described. In this report we describe clinical, neuroradiological and pathological findings in a 52-year-old man with mild hydrocephalus produced by a large, calcified, osteoblastic meningioma of the fourth ventricle.

Striatal grafts provide sustained protection from kainic and quinolinic acid-induced damage

Grafts of neonatal striatal tissue were placed into the striata of adult rats. When challenged immediately with intrastriatal injections of either kainic or quinolinic acid, excitotoxic damage was prevented. Thirty days later these same graft recipients received another injection of excitotoxin. The intrastriatal grafts continued to mitigate toxin-induced damage. It is hypothesized that the grafted cells not only survive, but that they may continue to elaborate some substance or substances that prevent excitotoxin-induced injury for at least 30 days. Previous investigations indicated that grafts of neonatal striatal tissue can protect the recipient striatum from kainic acid toxicity. In the following study it is demonstrated that such grafts also protect the striatum from quinolinic acid, an endogenous excitotoxin which induces kainate-like neuronal degeneration and has been implicated in the pathogenesis of Huntington's disease. It is postulated that the salutary effect of striatal grafting may be sufficiently long lasting to mitigate a chronic toxic insult. Such grafting may therefore represent a therapy for Huntington's disease and other neurodegenerative disorders in which an endogenous or exogenous toxin has been implicated as the pathogenetic agent.

Brain transplants. A new approach to the therapy of neurodegenerative disease

There is now a wealth of experimental evidence to suggest that transplantation to the brain may ameliorate a variety of neurologic and endocrine disorders. Many unanswered questions remain. Chief among these questions are the duration of any salutary effects and the potential long-term risks to the host CNS. Answers to these questions will only come with carefully controlled long-term clinical studies. Given the high incidence and devastating nature of many of these diseases, such studies will have enormous scientific and social impact. Regardless of the outcome, there is the potential for a greater understanding of the pathologic mechanisms underlying neurodegenerative diseases and, thus, the possibility that definitive therapies will be found as a result.

Neonatal striatal grafts prevent lethal syndrome produced by bilateral intrastriatal injection of kainic acid

It is reported that unilateral grafts of neonatal striatal tissue protect the recipient from the lethal aphagia and adipsia produced by bilateral intrastriatal injection of 10 nmol of kainic acid in rats. It is shown that neither adult striatum nor neonatal tissue from other sites have the same lifesaving effect and that the salutary effect of the graft is dependent upon graft survival. Grafts from a histoincompatible donor are apparently rejected, leading to the death of the recipient. Cyclosporine inhibits rejection thereby enabling recipient survival. It is postulated that the graft exerts a neurohumoral influence that protects the striatum from the toxic effect of kainate.