Cerebral abnormalities in infants with myelomeningocele

MRI analysis of neurodevelopmental anatomy in myelomeningocele: prenatal vs postnatal repair

OBJECTIVE

Compared with postnatal repair, prenatal myelomeningocele (MMC) repair is associated with improved motor function and decreased need for cerebrospinal fluid (CSF) diversion. It is unknown how prenatal surgery alters neuroanatomical structures identifiable on magnetic resonance imaging (MRI). The purpose of this study was to use MRI to compare neurodevelopmental anatomy in patients undergoing fetal MMC repair compared with those undergoing postnatal repair.

METHODS

This was a retrospective review of neonates who underwent prenatal or postnatal MMC repair at our institution between 2016 and 2021. Imaging data, including prenatal ultrasound and pre- and postnatal MRI examinations, if available, were retrieved. We analyzed anatomical findings characteristically seen on MRI of the neuroaxis in patients with MMC and compared imaging findings between patients with prenatal vs postnatal MMC repair.

RESULTS

The study population included 61 patients who underwent surgical repair for MMC during the 6-year study period, of whom 25 underwent prenatal repair and 36 postnatal repair. CSF diversion was required in 24% of the prenatally repaired cohort vs 67% of the postnatally repaired cohort (P = 0.001). On postnatal MRI, a syrinx was present in 13% of the prenatally repaired cohort vs 42% in the postnatally repaired cohort (P = 0.02). Postnatal corpus callosal (CC) morphology was abnormal in 54% of the prenatally repaired cohort vs 53% of the postnatally repaired cohort (P = 0.92), while falx morphology was normal in 92% of the prenatally repaired cohort vs 34% of the postnatally repaired cohort (P < 0.001). On postnatal MRI, patients in the prenatally repaired cohort had a shorter tentorium-to-foramen-magnum distance compared with those in the postnatally repaired cohort (mean, 18.43 mm vs 22.42 mm; P = 0.01), a larger foramen magnum diameter (mean, 22.87 mm vs 18.94 mm; P < 0.001) and a smaller degree of hindbrain herniation (mean, 1.53 mm vs 8.72 mm; P < 0.001). The cerebral aqueduct was patent in 79% of the prenatally repaired cohort vs 100% of the postnatally repaired cohort on postnatal MRI (P = 0.008). Between the two cohorts, at postnatal MRI there was no significant difference in the presence of gray-matter heterotopia, presence of the septum pellucidum or size of the massa intermedia.

CONCLUSIONS

We report variations in developmental neuroanatomy in patients with MMC, including rates of CC dysgenesis, gray-matter heterotopia and additional cranial and spinal MRI findings. Compared to postnatal surgery, prenatal surgery is associated with changes to infratentorial anatomy, with minimal effect on supratentorial brain development. This information will be useful in counseling parents affected by fetal MMC and in understanding how prenatal repair of MMC affects brain development. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Intracranial volumetric evaluation in postnatally repaired myelomeningocele infants

INTRODUCTION

Most myelomeningocele (MMC) cases present with ventriculomegaly or hydrocephalus, yet a comprehensive volumetric assessment of MMC intracranial structures is lacking. This study aimed to provide baseline data on intracranial structural volumes immediately after birth in MMC infants who underwent repair surgeries after birth (postnatal repair).

METHODS

In this retrospective single-center study, we analyzed 52 MMC infants undergoing postnatal repair, utilizing head computed tomography scans at birth for volumetric assessment. Intracranial volume (ICV), lateral ventricles volume (LVV), choroid plexus volume (CPV), and posterior cranial fossa volume (PCFV) were measured. Hydrocephalus was classified into no hydrocephalus, progressive hydrocephalus, and hydrocephalus at birth. Comparative analysis employed the Wilcoxon rank-sum test. Receiver operating characteristic (ROC) analysis discriminated cases with and without ventriculoperitoneal shunt (VPS).

RESULTS

The median values were 407.50 mL for ICV, 33.18 mL for LVV, 0.67 mL for CPV, and 21.35 mL for PCFV. Thirty-seven cases (71.15%) underwent VPS. ROC analysis revealed an LVV cut-off value of 6.74 mL for discriminating cases with and without VPS. Progressive hydrocephalus showed no significant difference in ICV but significantly larger LVV compared to no hydrocephalus. Hydrocephalus at birth demonstrated statistically larger ICV and LVV compared to the other two types.

CONCLUSION

Baseline volumetric data were provided, and volumetric analysis exhibited statistical differences among three hydrocephalus types. These findings enhance our understanding of intracranial volumetric changes in MMC, facilitating more objective assessments of MMC cases.

Brain abnormalities in myelomeningocele patients

BACKGROUND

Myelomeningocele (MMC) is often related to hydrocephalus and Chiari malformation (CM) type 2; however, other brain abnormalities have been reported in this population. In order to better understand and quantify other forebrain abnormalities, we analyzed magnetic resonance imaging (MRI) of MMC patients treated in utero or postnatal.

METHODS

Between January 2014 and March 2017, 59 MMC were treated in our hospital. Thirty-seven patients (32 postnatal and 5 intrautero repair) had brain MRI and were enrolled at the study. MRI was analyzed by two experienced neuroradiologists to identify the supra and infratentorial brain abnormalities.

RESULTS

A wide range of brain abnormalities was consistently identified in MMC patients. As expected, the most common were hydrocephalus (94.5%) and CM type II (89.1%). Of note, we found high incidence of corpus callosum abnormalities (86.4%), mostly represented by dysplasia (46%).

CONCLUSIONS

The data are consistent with the concept that brain abnormalities related to MMC can be both infratentorial and supratentorial, cortical, and subcortical. More studies are needed to correlate these forebrain abnormalities to long-term functional outcome and their prognostic value for these patients.