Impact of tethered cord release on symptoms of Chiari II malformation in children born with a myelomeningocele

Abnormal prenatal brain development in Chiari II malformation

Introduction

The Chiari II is a relatively common birth defect that is associated with open spinal abnormalities and is characterized by caudal migration of the posterior fossa contents through the foramen magnum. The pathophysiology of Chiari II is not entirely known, and the neurobiological substrate beyond posterior fossa findings remains unexplored. We aimed to identify brain regions altered in Chiari II fetuses between 17 and 26 GW.

Methods

We used in vivo structural T2-weighted MRIs of 31 fetuses (6 controls and 25 cases with Chiari II).

Results

The results of our study indicated altered development of diencephalon and proliferative zones (ventricular and subventricular zones) in fetuses with a Chiari II malformation compared to controls. Specifically, fetuses with Chiari II showed significantly smaller volumes of the diencephalon and significantly larger volumes of lateral ventricles and proliferative zones.

Discussion

We conclude that regional brain development should be taken into consideration when evaluating prenatal brain development in fetuses with Chiari II.

The incidence and effect of tethered cord release for tethered cord syndrome in patients with myelomeningocele: a population-based study

OBJECTIVE

The goal of this study was to establish an incidence and assess the effect of tethered cord release for tethered cord syndrome in patients with myelomeningocele.

METHODS

The study population was based on the Western Denmark Myelomeningocele Database, which contains all patients born with myelomeningocele in western Denmark since 1970. The study population was cross-referenced in 2015 with a database for surgical procedures containing all surgical procedures performed in the central Denmark region since 1996. Patients alive between 1996 and 2015 were identified. Incidences was calculated and presented for year of age. File reviews were conducted for all patients who underwent the procedure. Follow-up was divided into short-term and long-term follow-up.

RESULTS

One hundred sixty-six patients were alive during various time periods between 1996 and 2015. Of these, 45 patients underwent the procedure. Seven underwent reoperation. The median age for the procedure was 12 years and the highest incidence was found at 15 years of age. Incidence was bimodal with highest incidence in children and adolescents. The most common indications were progressive spine deformity (40%), deteriorating ambulation (38%), and deteriorating neurogenic bladder and/or bowel dysfunction (32%). The mean short-term follow-up was 4.7 months and the mean long-term follow-up was 72.6 months. Postoperatively, the majority had improved (27%) or stabilized (27%) at short-term follow-up. At long-term follow-up, most patients were stable (27%) or had deteriorated (24%). For both follow-up terms there was a loss of approximately one-third of all patients. Complications occurred in 17% of the procedures.

CONCLUSIONS

In this population-based study, tethered cord release has the highest incidence in children and adolescents. The beneficial effect of the procedure seems to be short term. Due to the uncertainty of a long-term effect of the procedure in patients with myelomeningocele and the registered complications, the authors suggest that this surgical indication should be reserved for well-selected patients.

Risk factors, presentation and outcome of meningomyelocele repair

Objective:

To determine the risk factors, presentation and outcome of meningomyelocele repair

Methods:

We reviewed 150 cases operated for meningomyelocele (MMC) at Jinnah Postgraduate Medical Centre Karachi between May 2015 and May 2018. Data of infants operated for MMC repair was extracted including socioeconomic status, maternal folate intake during pregnancy, head circumference, location and width of the defect, accompanying bladder and limb anomalies and treatments administered. Patients were followed up for a mean period of six months.

Results:

A total of 150 children were evaluated, out of which there were 83(55.3%) males and 67(44.7%) females. All belonged to low socio economic group and prenatal maternal folate intake as risk factor was positive in 103(68.7%) cases. Mean head circumference was 37.4 cm (range, 30.7 to 50 cm). Based on their location, 83(55%) of the defects were lumbosacral, 38(25.4%) were lumbar, 16(10.7%) were thoraco lumbar, 10(6.7%) were thoracic and three (2%) were cervical. Mean size of the meningomyelocele sac was 4.3 cm×5.6 cm (range, 1cm×2 cm to 11cm×8.4cm) and 21(14%) of the babies had a skin defect requiring flap. According to accompanying anomalies, 98(65.3%) of the babies had hydrocephalus, 13(9%) had club foot, four (2.7%) had diastematomyelia and three (2%) had tethered cord. Eighty seven (58%) patients had neurological deficit pre operatively and eight (5.4%) patients with normal power deteriorated after surgery out of which five (3.3%) developed paraplegia and three (2%) developed paraparesis. CSF leak was the major complication encountered in 16(11%) followed by meningitis in seven (5%), while the overall mortality was four (2.6%).

Conclusion:

The practice of periconceptional folic acid supplementation is essential to reduce the prevalence of neural tube defects (NTDs) in the developing world. Improved maternal nutrition with access to quality antenatal care is vital to decrease the prevalence and health burden.

Twenty years' experience with myelomeningocele management at a single institution: lessons learned

OBJECTIVE

The authors reviewed 20 years' experience with the surgical management of open myelomeningocele in a well-defined retrospective cohort from a single large academic medical center. Their goal was to define the characteristics of a modern cohort of children with myelomeningocele to allow for evidence-based decision-making for the treatment of these patients.

METHODS

After IRB approval was obtained, the authors queried an operative database maintained by the Department of Neurological Surgery at Children's Hospital of Pittsburgh for patients who underwent closure of a myelomeningocele between 1995 and 2015. They identified 153 infants, and a retrospective chart review was performed.

RESULTS

Eighty-eight percent of the patients required placement of a ventriculoperitoneal shunt, and 15% of these patients acquired shunt-related infections. Eighteen percent of patients underwent Chiari malformation type II (CM-II) decompression. Sixteen percent of patients underwent a tethered cord release. Three percent of patients died within the 1st year of life. Predictors of an early demise included poor Apgar scores, large head circumference, and need for early CM-II decompression. Functional motor outcome was slightly better than predicted by anatomical level of defect.

CONCLUSIONS

Myelomeningoceles represent a severe birth defect with life-threatening complications. The authors provide long-term follow-up data and insight into factors that contribute to early death.

Prenatal diagnosis of spina bifida: from intracranial translucency to intrauterine surgery

Accurate and timely prenatal diagnosis of spina bifida (SB) is a major goal of modern antenatal care. Prenatal screening for open SB should be first performed at the time of routine first-trimester ultrasound by examining the posterior fossa for obliteration or non-visualization of the fourth ventricle ("intracranial translucency") and cisterna magna. The second step of screening is the second-trimester anatomy scan, at which time the features of the Chiari type II malformation should be looked for, including ventriculomegaly, scalloping of the frontal bones ("lemon" sign), and backward and caudal displacement of the cerebellar vermis with obliteration of the cisterna magna ("banana" sign). In cases with positive findings, evaluation must include a focused examination of the spine for defects. In cases of closed SB and SB occulta, the cranial and posterior fossa features will not be present as they are not associated with leaking of spinal fluid and resultant hindbrain herniation, highlighting the fact that the spine should be examined thoroughly whenever possible during the second-trimester scan. In tertiary fetal medicine centers, two-dimensional and three-dimensional ultrasound allows an accurate determination of the location, type, extent, and upper level of the spinal defect as well as the presence of associated anomalies. Fetal magnetic resonance imaging should be restricted to candidates for intrauterine surgery as part of the preoperative protocol.

Spinal level of myelomeningocele lesion as a contributing factor in posterior fossa volume, intracranial cerebellar volume, and cerebellar ectopia

OBJECT

McLone and Knepper's unified theory of Chiari malformation Type II (CM-II) describes how the loss of CSF via the open posterior neuropore fails to create adequate distending pressure for the developing rhomboencephalic vesicle. The authors of the present article describe the relationship between the posterior fossa volume and intracranial cerebellar volume as being related to the distance from the obex of the fourth ventricle to the myelomeningocele lesion using a common mathematical model, the Hagen-Poiseuille law.

METHODS

All newborns who required closure of a myelomeningocele at the authors' institution between 2008 and 2011 and who were between 4 weeks premature and 2 months, corrected gestational age, at the time of MRI were included in this study. Volumes and measurements were obtained from axial and sagittal T2-weighted MR images of the brain and spine.

RESULTS

A total of 56 newborn infants met the inclusion criteria. There was a direct linear relationship between both posterior fossa volume and cerebellar volume and the spinal level of the myelomeningocele lesion (p = 0.0012 and p = 0.0041, respectively). There was a negative linear relationship between the cerebellar descent, the spinal level of the lesion, and posterior fossa volume and cerebellar volume. These relationships strengthen in patients with no syringomyelia and are not significant in those groups with syringomyelia. The results of a 1-way ANOVA for the 3 groups did not reach significance.

CONCLUSIONS

Using a linear equation derived from the Hagen-Poiseuille law that describes pressure in the fourth ventricle as being directly related to the length of the central canal from the obex to the myelomeningocele lesion, the authors were able to explain the directly observed linear relation between posterior fossa volume, intracranial cerebellar volume, and cerebellar descent to the level of the spinal lesion. As this model assumes a uniform radius of the central canal they were able to validate this model when they observed a strengthening in relationships in the no syringomyelia group and statistically insignificant correlations in the groups with syringomyelia. They therefore propose that the spinal level of the lesion is one of the major determinants of posterior fossa volume, intracranial cerebellar volume, and cerebellar ectopia.