Reversal Of Hindbrain Herniation Research Articles

The significance of hindbrain herniation reversal following prenatal repair of neural tube defects.

The aim of this study was to determine whether reversal of hindbrain herniation (HBH) on MRI following prenatal repair of neural tube defects (NTDs) is associated with reduced rates of ventriculoperitoneal (VP) shunt placement or endoscopic third ventriculostomy (ETV) within the 1st year of life. This is a secondary analysis of prospectively collected data from all patients who had prenatal open repair of a fetal NTD at a single tertiary care center between 2012 and 2020. Patients were offered surgery according to inclusion criteria from the Management of Myelomeningocele Study (MOMS). Patients were excluded if they were lost to follow-up, did not undergo postnatal MRI, or underwent postnatal MRI without a report assessing hindbrain status. Patients with HBH reversal were compared with those without HBH reversal. The primary outcome assessed was surgical CSF diversion (i.e., VP shunt or ETV) within the first 12 months of life. Secondary outcomes included CSF leakage, repair dehiscence, CSF diversion prior to discharge from the neonatal intensive care unit (NICU), and composite neonatal morbidity. Demographic, prenatal sonographic, and operative characteristics as well as outcomes were assessed using standard univariate statistical methods. Multivariate logistic regression models were fit to assess for independent contributions to the primary and secondary outcomes. Following exclusions, 78 patients were available for analysis. Of these patients, 38 (48.7%) had HBH reversal and 40 (51.3%) had persistent HBH on postnatal MRI. Baseline demographic and preoperative ultrasound characteristics were similar between groups. The primary outcome of CSF diversion within the 1st year of life was similar between the two groups (42.1% vs 57.5%, p = 0.17). All secondary outcomes were also similar between groups. Patients who had occurrence of the primary outcome had greater presurgical lateral ventricle width than those who did not (16.1 vs 12.1 mm, p = 0.02) when HBH was reversed, but not when HBH was persistent (12.5 vs 10.7 mm, p = 0.49). In multivariate analysis, presurgical lateral ventricle width was associated with increased rates of CSF diversion before 12 months of life (adjusted OR 1.18, 95% CI 1.03-1.35) and CSF diversion prior to NICU discharge (adjusted OR 1.18, 95% CI 1.02-1.37). HBH reversal was not associated with decreased rates of CSF diversion in this cohort. Predictive accuracy of the anticipated benefits of prenatal NTD repair may not be augmented by the observation of HBH reversal on MRI.

Neuroprotection is improved by watertightness of fetal spina bifida repair in the sheep model.

A contributing factor to unsuccessful prenatal spina bifida aperta (SBA) repair via an open approach may be incomplete neurosurgical repair causing persistent in-utero leakage of cerebrospinal fluid (CSF) and exposure of the fetal spinal cord to amniotic fluid. We aimed to investigate the neurostructural and neurofunctional efficacy of watertight prenatal SBA repair in a validated SBA fetal lamb model. A well-powered superiority study was conducted in the validated SBA fetal lamb model (n = 7 per group). The outcomes of lambs which underwent watertight or non-watertight multilayer repair through an open approach were compared to those of unrepaired SBA lambs (historical controls) at delivery (term = 145 days). At ∼75 days, fetal lambs underwent standardized induction of lumbar SBA. At ∼100 days, they were assigned to an either watertight or non-watertight layered repair group based on an intraoperative watertightness test using subcutaneous fluorescein injection. At 1-2 days postnatally, as primary outcome, we assessed reversal of hindbrain herniation using magnetic resonance imaging (MRI). Secondary proxies of neuroprotection were: absence of CSF leakage at the repair site; hindlimb motor function based on joint-movement score, locomotor grade and Motor Evoked Potential (MEP); four-score neuroprotection scale, encompassing live birth, complete hindbrain herniation reversal, absence of CSF leakage and joint-movement score ≥ 9/15; and brain and spinal cord histology and immunohistochemistry. As the watertightness test cannot be used clinically due to its invasiveness, we developed a potential surrogate intraoperative three-score skin-repair-quality scale based on visual assessment of the quality of the skin repair (suture inter-run distance ≤ 3 mm, absence of tear and absence of ischemia), with high quality defined by a score ≥ 2/3 and low quality by a score < 2/3, and assessed its relationship with improved outcome. Compared with unrepaired lambs, lambs with watertight repair achieved a high level of neuroprotection (neuroprotection score of 4/4 in 5/7 vs 0/7 lambs) as evidenced by: a significant 100% (vs 14%) reversal of hindbrain herniation on MRI; low CSF leakage (14% vs 100%); better hindlimb motor function, with higher joint-movement score, locomotor grade and MEP area under the curve and peak-to-peak amplitude; higher neuronal density in the hippocampus and corpus callosum; and higher reactive astrogliosis at the SBA lesion epicenter. Conversely, lambs with non-watertight SBA repair did not achieve the same level of neuroprotection (score of 4/4 in 1/7 lambs) compared with unrepaired lambs, with: a non-significant 86% (vs 14%) reversal of hindbrain herniation; high CSF leakage (43% vs 100%); no improvement in motor function; low brain neuron count in both the hippocampus and corpus callosum; and small spinal astroglial cell area at the epicenter. Both watertight layered repair and high (≥ 2/3) intraoperative skin-repair-quality score were associated with improved outcome, but the watertightness test and skin-repair-quality scale could not be used interchangeably due to result discrepancies. Watertight layered fetal SBA repair is neuroprotective since it improves brain and spinal-cord structure and function in the fetal lamb model. This translational research has important clinical implications. A neurosurgical technique that achieves watertightness should be adopted in all fetal centers to improve neuroprotection. Future clinical studies could assess whether a high skin-repair-quality score (≥ 2/3) correlates with neuroprotection. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

The significance of hindbrain herniation reversal following prenatal surgery for fetal neural tube defects

Reversal of hindbrain herniation (RHH) on postnatal MRI is often observed after prenatal repair of neural tube defects (NTD). We sought to determine whether RHH is associated with early pediatric outcomes.

Pseudomeningocele after in utero repair of myelomeningocele as an early sign of hypertensive hydrocephalus – a case report and review of the literature

Background Myelomenigocele (MMC) is the most common congenital defect of the spine. The Management of Myelomeningocele study (MOMS trial) demonstrated that the prenatal repair decreased shunt implant, reversal of hindbrain herniation and better neurologic function compared to postnatal repair. Several ultrasound findings can predict the risk of postnatal hydrocephalus after intrauterine MMC repair. This report shows a prenatal pseudomenigocele after intrauterine correction of MMC as an early sign of hydrocephalus.&#x0D; Method A 34-year-old female G2P1 with a prenatal diagnosis of MMC with anatomical level L4 and ventricular enlargement was submitted to open surgery intrauterine repair. Follow up ultrasound showed regression of the lemon sign, partial regression of hindbrain herniation and a progressive increase in the wound with local bulging characterizing a pseudomingocele. In the postnatal period, after correction of the pseudomenigocele, the neonate showed signs of hipertensive hydrocephalus. After ventriculoperitoneal shunt, the patient was discharged.&#x0D; Conclusion Presence of pseudomeningocele prenatally after in utero repair of MMC may represent an early sign of hypertensive hydrocephalus.

Impact of the size of the lesion in prenatal neural tube defect repair on imaging, neurosurgical and motor outcomes: a retrospective cohort study.

(1) To compare brain findings between large and non-large neural tube defect (NTD); (2) to evaluate the impact of large lesion on the surgical parameters; (3) to study any associations between the size of the lesions and brain findings 6weeks postoperatively and neurological short-term outcomes. Retrospective cohort study. Texas Children's Hospital, between 2011 and 2018. Patients who underwent prenatal NTD repair. Large lesion was defined when the lesion's surface was >75th centile of our cohorts' lesions. Time of referral: ventriculomegaly and anatomical level of the lesion; surgery: duration and need for relaxing incisions. 6weeks postoperative: hindbrain herniation (HBH) and ventriculomegaly. After delivery: dehiscence, need for hydrocephalus treatment and motor function. A total of 99 patients were included, 25 of whom presented with large lesions. Type of lesion and ventriculomegaly were comparable between individuals with large and non-large lesions. Individuals with large lesions were associated with increased need for relaxing incisions by 5.4 times (95% CI 1.3-23.2, P=0.02). Six weeks postoperatively, having a large lesion decreased by ten times the likelihood of having a postoperative reversal of HBH (odds ratio=0.1, 95% CI 0.1-0.4, P<0.01). At birth, larger lesions increased the risk for repair dehiscence by 6.1 times (95% CI 1.6-22.5, P<0.01) and the risk of dehiscence or leakage of cerebrospinal fluid at birth by 5.5 times (95% CI 1.6-18.9, P<0.01). Prenatal repair of patients with large NTD presents a lower proportion of HBH reversal 6weeks after the surgery, a higher risk of dehiscence and a higher need for postnatal repair. Evaluation of the size of fetal NTD can predict adverse neurological outcomes after prenatal NTD repair.

Learning curves of open and endoscopic fetal spina bifida closure: systematic review and meta-analysis.

The Management of Myelomeningocele Study (MOMS) trial demonstrated the safety and efficacy of open fetal surgery for spina bifida aperta (SBA). Recently developed alternative techniques may reduce maternal risks without compromising the fetal neuroprotective effects. The aim of this systematic review was to assess the learning curve (LC) of different fetal SBA closure techniques. MEDLINE, Web of Science, EMBASE, Scopus and Cochrane databases and the gray literature were searched to identify relevant articles on fetal surgery for SBA, without language restriction, published between January 1980 and October 2018. Identified studies were reviewed systematically and those reporting all consecutive procedures and with postnatal follow-up ≥ 12 months were selected. Studies were included only if they reported outcome variables necessary to measure the LC, as defined by fetal safety and efficacy. Two authors independently retrieved data, assessed the quality of the studies and categorized observations into blocks of 30 patients. For meta-analysis, data were pooled using a random-effects model when heterogeneous. To measure the LC, we used two complementary methods. In the group-splitting method, competency was defined when the procedure provided results comparable to those in the MOMS trial for 12 outcome variables representing the immediate surgical outcome, short-term neonatal neuroprotection and long-term neuroprotection at ≥ 12 months of age. Then, when raw patient data were available, we performed cumulative sum analysis based on a composite binary outcome defining successful surgery. The composite outcome combined four clinically relevant variables for safety (absence of extreme preterm delivery < 30 weeks, absence of fetal death ≤ 7 days after surgery) and efficacy (reversal of hindbrain herniation and absence of any neonatal treatment of dehiscence or cerebrospinal fluid leakage at the closure site). Of 6024 search results, 17 (0.3%) studies were included, all of which had low, moderate or unclear risk of bias. Fetal SBA closure was performed using standard hysterotomy (11 studies), mini-hysterotomy (one study) or fetoscopy by either exteriorized-uterus single-layer closure (one study), percutaneous single-layer closure (three studies) or percutaneous two-layer closure (one study). Only outcomes for standard hysterotomy could be meta-analyzed. Overall, outcomes improved significantly with experience. Competency was reached after 35 consecutive cases for standard hysterotomy and was predicted to be achieved after ≥ 57 cases for mini-hysterotomy and ≥ 56 for percutaneous two-layer fetoscopy. For percutaneous and exteriorized-uterus single-layer fetoscopy, competency was not reached in the 81 and 28 cases available for analysis, respectively, and LC prediction analysis could not be performed. The number of cases operated is correlated with the outcome of fetal SBA closure, and the number of operated cases required to reach competency ranges from 35 for standard hysterotomy to ≥ 56-57 for minimally invasive modifications. Our observations provide important information for institutions looking to establish a new fetal center, develop a new fetal surgery technique or train their team, and inform referring clinicians, potential patients and third parties. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Minimally invasive fetal surgery for myelomeningocele: preliminary report from a single center.

Recent trials have shown the safety and benefits of fetoscopic treatment of myelomeningocele (MMC). The authors' aim was to report their preliminary results of prenatal fetoscopic treatment of MMC using a biocellulose patch, focusing on neurological outcomes, fetal and maternal complications, neonatal CSF leakage, postnatal hydrocephalus, and radiological outcomes. Preoperative assessment included clinical examination, ultrasound imaging, and MRI of the fetus. Patients underwent purely fetoscopic in utero MMC repair, followed by postoperative in utero and postnatal MRI. All participants received multidisciplinary follow-up. Five pregnant women carrying fetuses affected by MMC signed informed consent for the fetoscopic treatment of the defect. The mean MMC size was 30.4 mm (range 19-49 mm). Defect locations were L1 (2 cases), L5 (2 cases), and L4 (1 case). Hindbrain herniation and ventriculomegaly were documented in all cases. The mean gestational age at surgery was 28.2 weeks (range 27.8-28.8 weeks). Fetoscopic repair was performed in all cases. The mean gestational age at delivery was 33.9 weeks (range 29.3-37.4 weeks). After surgery, reversal of hindbrain herniation was documented in all cases. Three newborns developed signs of hydrocephalus requiring CSF diversion. Neurological outcomes in terms of motor level were favorable in all cases, but a premature newborn died due to CSF infection and sepsis. The authors' preliminary results suggest that fetoscopic treatment of MMC is feasible, reproducible, and safe for mothers and their babies. Neurological outcomes were favorable and similar to those in the available literature. As known, prematurity was the greatest complication.

Long-term neuroimaging and neurological outcome of fetal spina bifida aperta after postnatal surgical repair.

Parents faced with the choice between postnatal management and prenatal surgery for spina bifida need to have up-to-date information on the expected outcomes. The aim of this study was to report the long-term physical and neurological outcomes of infants with prenatally diagnosed isolated spina bifida that underwent postnatal surgical repair and were managed by a multidisciplinary team from a large tertiary center. This was a retrospective cohort study of all cases of fetal spina bifida managed in a tertiary unit between October 1999 and January 2018. All cases of fetal spina bifida from the local health region were routinely referred to the tertiary unit for further perinatal management. Details on surgical procedures and neonatal neurological outcomes were obtained from institutional case records. Ambulatory status, bladder and bowel continence and neurodevelopment were assessed at a minimum of 3 years. During the study period, 241 pregnancies with isolated spina bifida were seen in the unit. Of these, 84 (34.9%) women opted to continue with the pregnancy after multidisciplinary counseling by clinicians. Sixty-seven infants underwent postnatal repair of spina bifida aperta and were included in the analysis. After birth, hindbrain herniation was observed in 91.5% of infants with only seven requiring surgical decompression. Ventriculoperitoneal shunt placement was needed in 64.2% of infants, while normal cognitive development or mild impairment was demonstrated in 85.4% of cases with data for this outcome available, at a mean age of 8 years. Cumulatively, 40% of infants were walking independently or using minor support, and normal or mild impairment of bladder and bowel function was reported in 45.5% and 44.4% of infants, respectively. Neurodevelopmental and neurological outcomes between prenatal and postnatal repair are similar. As with fetal surgery, conventional postnatal surgery is associated with the reversal of hindbrain herniation. Similarly, postnatal ventriculoperitoneal shunt placement appears to be required mainly in fetuses without evidence of significant fetal ventriculomegaly. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Perinatal outcomes after open fetal surgery for myelomeningocele repair: a retrospective cohort study.

ObjectiveDescribe outcomes of open fetal surgery for myelomeningocele (MMC) repair in two Brazilian hospitals and the impact of surgical experience on outcome.DesignRetrospective cohort study.SettingSao Paulo, Brazil.Population237 pregnant women carrying a fetus with an open spinal defect.MethodsSurgical details, and maternal and fetal outcomes collected from all patients.Main outcome measuresAnalysis of surgical and perinatal outcome parameters.ResultsTotal surgical time was 119 ± 7.6 minutes. Preterm labour occurred in 24.2%, premature rupture of membranes in 26.7%, placental abruption in 0.8%, need for a blood transfusion at delivery in 2.1%, and dehiscence at the repair site in 2.5%. Reversal of hindbrain herniation at birth occurred in 71.4%. There were no maternal deaths or severe maternal morbidities. The failure rate with the patient anaesthetised was 0.42% and perinatal mortality was 2.1% (three intrauterine demises and two neonatal deaths). Comparing results from our study in the first 3 years with the last 3 years demonstrated improvement in the total surgical time (121.2 ± 6.4 versus 118.5 ± 8.2 minutes, P = 0.005) and an increase in reversal of hindbrain herniation at birth (64.0 versus 77.1%, P = 0.042).ConclusionOur open fetal surgical approach for MMC was effective and results were comparable to past studies. Improvements in surgical performance and perinatal outcome increased as the surgical team became more familiar with the procedure.FundingThe study was funded solely by institutional funds.Tweetable abstractBrazilian experience of in utero open surgery for myelomeningocele repair.

Safety and efficacy of fetal surgery techniques to close a spina bifida defect in the fetal lamb model: A systematic review.

To determine the safety and efficacy of different neurosurgical techniques for closure of spina bifida (SB) in the fetal lamb model. Systematic review of studies reporting on fetal lambs undergoing induction and closure of SB compared with non-operated normal lambs (negative controls) and/or lambs not undergoing closure of the defect (positive controls). Primary outcomes were (1) survival at birth (safety) and/or (2) presence of Somatosensory Evoked Potentials on hind limbs and/or improvement in quantitative histological spinal cord findings and/or reversal of hindbrain herniation (efficacy). Out of 1311, 36 full-text articles were eligible. Nineteen were included for quality assessment. Due to high bias, only 2 adequately powered studies were included in the final analysis. An open approach using a 2-layer closure (muscle flap or acellular-dermal-matrix patch plus skin) was the only safe (patch+skin) and effective (both techniques) technique for prenatal closure in this animal model. No comparable level of evidence was identified for other techniques. The experimental literature on prenatal SB closure underscores the lack of standardization. At present, there is animal experimental evidence that a 2-layer closure by hysterotomy is safe and effective. This technique is currently clinically used in a subset of patients. As new clinical techniques are introduced, it would seem logic to preclinically validate them against this experimental standard.

Complete tissue coverage achieved by scaffold-based tissue engineering in the fetal sheep model of Myelomeningocele

Myelomeningocele (MMC) is the most severe form of spina bifida, one of the most common congenital anomalies. Although open fetal surgical repair of the MMC defect has been shown to result in improved outcomes, a less invasive approach applicable earlier in gestation than the current open surgical approach between 19 and 26 weeks of gestation is desirable for further improvement of neurological symptoms, as well as reduction of maternal and fetal risks. We previously reported the therapeutic potential of a scaffold-based tissue engineering approach in a fetal rat MMC model. The objective of this study was to confirm the long-term efficacy of this approach in the surgically created fetal sheep MMC model. Gelatin-based or gelatin/collagen hybrid sponges were prepared with and without basic fibroblast growth factor (bFGF) incorporation. The defect was covered by a sponge and secured by a supporting sheet with adhesive at 100 days of gestation or the gelatin/collagen hybrid with bFGF was secured with adhesive without the sheet. Although sheets were found detached at term (140 days' gestation), both gelatin-based and gelatin/collagen hybrid sponges had integrated within the newly formed granulation tissue, resulting in complete coverage of the MMC defect. The release of bFGF from sponges resulted in enhanced formation of granulation tissue and epithelialization. There was also evidence of improved preservation of the spinal cord with less associated damage on histological analysis and reversal of hindbrain herniation. These experiments provide important proof-of-principle evidence of the efficacy of scaffold-based tissue engineered coverage for the prenatal treatment of MMC.

In utero repair of spina bifida.

Open spina bifida or myelomeningocele (MMC) is the most common congenital malformation of the central nervous system compatible with long-term survival and is associated with significant lifelong disabilities. Postnatal care of MMC involves covering the exposed spinal cord, infection prevention, and ventricular shunting for hydrocephalus. The aim of postnatal MMC surgery is not to reverse or prevent the neurologic injury seen in MMC, but to palliate. The neurologic defects result from primary incomplete neurulation and secondary chronic in utero damage to the exposed neural elements through mechanical and chemical trauma-the two-hit hypothesis. With the ability to accurately diagnose spina bifida prenatally and the concept of the two-hit hypothesis, in utero repair to decrease exposure and alter the antenatal course of neurologic destruction was conceived. Through animal models and human pilot studies, the feasibility of fetal spina bifida repair was demonstrated. Subsequently, the prospective randomized multicenter Management of Myelomeningocele Study (MOMS trial) revealed a decreased need for shunting, reversal of hindbrain herniation, and preservation of neurologic function, making in utero repair an accepted care alternative for select women carrying a fetus with spina bifida. This article will highlight the background and rationale for in utero repair, and the progression to becoming an alternative standard of care. The future directions of fetal spina bifida repair will also be addressed.

OP06.06: Reversal of hindbrain herniation within a few days after minimally‐invasive fetoscopic surgery for spina bifida indicates the desired water‐tight closure of the lesion

a drop in saturation to 90% despite an FiO2 of 0.8. These values immediately normalized after adjusting the insufflation pressure. Fetal demise was observed after four procedures but could not be attributed to PACI (three fetuses did not tolerate anesthesia, one fetus died from placental hemorrhage). Conclusions: In this still small clinical series, PACI was well tolerated by pregnant women and her fetuses during fetoscopic surgery for spina bifida aperta. Careful monitoring and adjustments of insufflation pressure at all times may aid in avoiding undesired maternal hemodynamic events.

Fetal myelomeningocele: Natural history, pathophysiology, and in-utero intervention

Myelomeningocele (MMC) is a common birth defect that is associated with significant lifelong morbidity. Little progress has been made in the postnatal surgical management of the child with spina bifida. Postnatal surgery is aimed at covering the exposed spinal cord, preventing infection, and treating hydrocephalus with a ventricular shunt. In-utero repair of open spina bifida is now performed in selected patients and presents an additional therapeutic alternative for expectant mothers carrying a fetus with MMC. It is estimated that about 400 fetal operations have now been performed for MMC worldwide. Despite this large experience, the technique remains of unproven benefit. Preliminary results suggest that fetal surgery results in reversal of hindbrain herniation (the Chiari II malformation), a decrease in shunt-dependent hydrocephalus, and possibly improvement in leg function, but these findings might be explained by selection bias and changing management indications. A randomized prospective trial (the MOMS trial) is currently being conducted by three centers in the USA, and is estimated to be completed in 2010. Further research is needed to better understand the pathophysiology of MMC, the ideal timing and technique of repair, and the long-term impact of in-utero intervention.

Reversal of Hindbrain Herniation after Maternal-fetal Surgery for Myelomeningocele Subsequently Impacts on Brain Stem Function

The aim of our study was to delineate whether the reversal of hindbrain herniation (HH) following fetal myelomeningocele (fMMC) closure subsequently reduces the incidence and severity of HH-associated brainstem dysfunction (BSD). Prior to the NIH-sponsored Management of Myelomeningocele Study (MOMS) trial, 54 children underwent fMMC closure at our institution. Forty-eight (89%) families participated in a structured survey focusing on HH-associated BSD (e.g., apnea, neurogenic dysphagia [ND], gastro-esophageal reflux disease [GERD], neuro-ophthalmologic disturbances [NOD]). Median age at follow-up was 72 months (range: 46-98). Fifty-percent required shunting. HH-related symptoms were completely absent in 15 (63%) non-shunted and 10 (42%) shunted children (P=0.15). No HH-related death occurred and none developed severe persistent cyanotic apnea. ND was reported in 2 (8%) non-shunted and 9 (38%) shunted infants (P=0.03). Mild GERD (medically managed) developed in 2 (8%) without and 6 (25%) with shunt placement (P=0.24). NOD was found in 6 (25%) and 13 (54%) of non-shunted and shunted children, respectively (P=0.07). The majority of fMMC children developed no or only mild BSD at follow-up. Our data support the hypothesis that neurodevelopmental deficits associated with MMC are at least partially acquired and that reversal of HH following fMMC surgery may help to reduce the incidence and severity of BSD.

553: Reversal of hindbrain herniation after maternal-fetal surgery for myelomeningocele subsequently improves brain stem function

553: Reversal of hindbrain herniation after maternal-fetal surgery for myelomeningocele subsequently improves brain stem function

Correction of cerebrospinal fluid levels and brain growth demonstrated by serial fetal magnetic resonance imaging following

DEMONSTRATED BY SERIAL FETAL MAGNETIC RESONANCE IMAGING FOLLOWING ENRICO DANZER, MARK P. JOHNSON, MICHAEL BEBBINGTON, R. DOUGLAS WILSON, LARISSA BILANIUK, ERIN SIMON, ALAN FLAKE, LESLIE SUTTON, N. SCOTT ADZICK, Children’s Hospital of Philadelphia, Center for Fetal Diagnosis & Treatment, Philadelphia, Pennsylvania, Children’s Hospital of Philadelphia, Department of Radiology, Philadelphia, Pennsylvania, Children’s Hospital of Philadelphia, Pediatric Neurosurgery, Philadelphia, Pennsylvania OBJECTIVE: Physiological levels of cerebrospinal fluid (CSF) may influence brain growth and maturation during fetal development. Fetuses with myelomeningocele (MMC) have diminished extra-axial CSF levels and altered brain growth. We evaluated extra-axial CSF levels and brain growth following fetal MMC repair by serial assessment of brain morphometry using ultrafast MRI. STUDY DESIGN: Axial measurements were taken at defined anatomical landmarks and in utero repaired MMC fetuses (n = 35) were compared to cohorts of age-matched control fetuses (prenatal = 18, postnatal = 9) and MMC fetuses that underwent postnatal repair (prenatal = 9, postnatal = 22). The brain/ventricular ratio was calculated as transverse diameter of the brain at the level of the atria divided by mean ventricular diameter. RESULTS: In fetuses with MMC, initial MRI scans showed significant cerebellar herniation and almost complete absence of extra-axial and posterior fossa CSF. In utero repair fetuses showed significant reversal of hindbrain herniation. In fetuses with postnatal MMC repair, CSF levels remained low. No differences in postnatal extra-axial CSF levels were found between normal and in utero MMC repaired newborns. The mean increase in ventricular diameter after fetal MMC repair was 33.9% compared to 71.6% in the cohorts of MMC fetuses that underwent postnatal repair. The mean mantle-thickness at the level of atria increased by 28.5 mm (141.8%) in the fetal repair group, by 32.1mm (191.5%) in the control group and by 24 mm (105.3%) in the postnatal repair group cohorts. The mean increase in brain/ventricular ratio after fetal repair was 36.8%, in normal controls 53.1% and 10.4% in postnatal repaired MMC cohorts. CONCLUSION: Midgestational MMC repair results in reestablishment of the extra-axial CSF space. Normalization of CSF volume in the posterior fossa reflects reversal of hindbrain herniation. Increases in mantle thickness and brain/ ventricular ratio suggest increased brain growth in fetuses following in utero repair.

Anaesthesia for fetal surgery.

*Department of Anesthesia, Children’s Hospital, Harvard Medical School, Boston, MA,**Department of Anesthesiology and Critical Care, The Children’s Hospital of Philadelphia,University of Pennsylvania School of Medicine, Philadelphia and †Department of Anesthesia andCritical Care, The Hospital of the University of Pennsylvania, University of Pennsylvania Schoolof Medicine, Philadelphia, PA, USA