Newborns and preterm infants at term equivalent age: A semi-quantitative assessment of cerebral maturity.

BACKGROUND AND PURPOSE: Currently available MRI scoring systems of cerebral maturation in term and preterm infant at term equivalent age do not include the changes of transient fetal compartments that persist to term age. We studied the visibility and the pattern of these structures in healthy term newborns compared to preterm infants at term equivalent age in order to investigate if they can be included in a new MRI score system. We hypothesized that transient fetal compartments are different in both groups, and that these differences can be characterized using the clinical T2-weighted MRIs. MATERIALS AND METHODS: Using 3T MRI T2-weighted brain sequences of 21 full-term and 41 preterm infants (< 32 weeks), scanned at term equivalent age, 3 raters independently scored the maturation level of 3 transient fetal compartments: the periventricular crossroads, von Monakow segments of the white matter, and the subplate compartment. These 3 new items were included in a scoring system along with validated parameters of brain maturation (germinal matrix, bands of migration, subarachnoid space and quality of gyrification). A cumulative maturity score was calculated separately for both groups of newborns by adding together each item. More mature were the brain structures, higher was the cumulative maturity score. RESULTS: Cumulative maturity score distinguished full-term from preterm infants (mean score 41/60 ± 1.4 versus 37/60 ± 2.5 points, p < 0.001), with an increase of 0.5 points for each supplemental gestational week at birth (r = 0.5, 95% CI 0.5 - 0.85). While a majority of transient fetal compartments were less mature in preterm group at term equivalent age, von Monakow segments of the white matter and subplate compartment presented a more advanced maturational stage in the preterm group compared to the term group. No subject had all scored items in the most mature state. Except a slight intra-rater agreement for von Monakow segment II, inter- and intra-rater agreements were moderate to excellent indicating the potential of the developed scoring system in routine clinical practice. CONCLUSION: Brain transient fetal structures can be assessed on regular T2-weighted MRI in newborns. Their appearance differs between term and preterm babies. However our results suggest a more complex situation, with both delayed and accelerated maturation pattern in preterm infants. It remains to be determined if these differences could be biomarkers of the future neurodevelopment of preterm infants.

Transplantation of Adipose Tissue-Derived Stem Cells into Brain Through Cerebrospinal Fluid in Rat Models: Protocol Development and Initial Outcome Data.

BACKGROUND: Cell therapy is an important strategy for the treatment of incurable diseases including those that occur in the Central Nervous System (CNS). Among different strategies, the method of delivering or transplantation of cells into the brain has shown significant effects on regeneration. In this study, a new protocol has been developed for the transplantation of adipose tissuederived stem cells into the brain through Cerebrospinal Fluid (CSF) in rat models. METHODS: For this purpose, a wide range of ages (7-30 days old) of male neonates of Wistar rats was used. Moreover, human adipose tissue was obtained from a superficial layer of abdomen through liposuction surgery. The size of the inserted part of needle to access middle cranial fossa and subarachnoid space in animals with an average weight of 10-80 g was determined. In addition, to confirm the entrance of needle into the subarachnoid space, CSF was aspirated slowly and then injection was done within two minutes. RESULTS: The findings showed the presence of transplanted human Adipose-Derived Stem Cells (hADSC) in the cerebellum and basal ganglia following three days and also after two months that confirmed the entrance of transplanted cells into the cerebrospinal fluid and migration of them into the brain tissue. All the animals survived after the transplantation process, with the lowest side effects compared to the available conventional methods. CONCLUSION: It can be concluded that the cells could be efficiently transplanted into CSF through subarachnoid space by injection via superior orbital fissure with a minimally invasive technique.

Development and organization of the human brain tissue compartments across the lifespan using diffusion tensor imaging.

We used a diffusion tensor imaging-based whole-brain tissue segmentation to characterize age-related changes in (a) whole-brain grey matter, white matter, and cerebrospinal fluid relative to intracranial volume and (b) the corresponding brain tissue microstructure using measures of diffusion tensor anisotropy and mean diffusivity. The sample, a healthy cohort of 119 right-handed males and females aged 7-68 years. Our results demonstrate that white matter and grey matter volumes and their corresponding diffusion tensor anisotropy and mean diffusivity follow nonlinear trajectories with advancing age. In contrast, cerebrospinal fluid volume increases linearly with age.

When is enlargement of the subarachnoid spaces not benign? A genetic perspective.

Enlargement of the subarachnoid spaces is occasionally encountered during neuroimaging of children. This enlargement is generally regarded as a nonpathologic process that resolves uneventfully. However, there are several genetic disorders in which enlargement of the subarachnoid spaces can be an early sign, or the feature of an associated syndrome, that may aid in the underlying diagnosis. Recognizing subarachnoid space enlargement in these circumstances requires an understanding of the normal physiology of the subarachnoid space at different time points in a child's neurodevelopment. This article reviews the events shaping the subarachnoid space, both during normal physiologic maturation and in specific genetic disorders.

Fetal head biometry assessed by fetal magnetic resonance imaging following in utero myelomeningocele repair.

OBJECTIVE: To examine the impact of fetal myelomeningocele (MMC) repair on fetal head biometry and cerebrospinal fluid (CSF) spaces assessed by magnetic resonance imaging (MR) studies. STUDY DESIGN: Axial measurements of intracranial structures were taken at defined anatomical landmarks. Pre- and postnatal head biometry data and CSF spaces obtained from in utero repaired MMC fetuses (n = 22) were compared to the pre- and postnatal measurements of MMC patients that underwent standard neurosurgical MMC repair after birth (n = 16) and a cohort of age-matched control patients (prenatal, n = 52; postnatal, n = 9). RESULTS: In fetuses with MMC, initial MR scans showed an almost complete absence of supratentorial and posterior fossa CSF spaces. No differences in postnatal CSF spaces were found between controls and prenatally repaired MMC newborns. In fetuses with postnatal MMC repair, CSF spaces remained significantly reduced (p < 0.0001). The mean ventricular diameter (VD) increase in the postnatal repaired MMC group was significantly higher compared to the mean percentage of VD increase in the fetal repaired MMC group (6.4 vs. 4.2 mm; p = 0.02). Pre- and postnatal brain thickness measurements were significantly reduced in both MMC populations compared to age-matched normal values (p < 0.0001). In contrast to postnatally repaired patients, in utero repair fetuses showed significant reversal of hindbrain herniation and normalization of the posterior fossa CSF spaces. CONCLUSION: Mid-gestational repair of MMC promotes normalization of extra-axial CSF spaces. Due to progressive ventriculomegaly, brain thickness remains decreased in both prenatal repaired and age-matched non-repaired MMC patients when compared to age-matched normal values. Restoration of CSF volume in the posterior fossa after in utero repair is indicative of reversal of hindbrain herniation.

The structure and development of avian lumbosacral specializations of the vertebral canal and the spinal cord with special reference to a possible function as a sense organ of equilibrium.

The avian lumbosacral vertebral column and spinal cord show a number of specializations which have recently been interpreted as a sense organ of equilibrium. This sense organ is thought to support balanced walking on the ground. Although most of the peculiar structures have been described previously, there was a need to reevaluate the specializations with regard to the possible function as a sense organ. Specializations were studied in detail in the adult pigeon. The development of the system was studied both in the pigeon (semiprecocial at hatching) and in the chicken (precocial). Specializations in the vertebral canal consist of a considerable enlargement, which is not due to an increase in the size of the spinal nervous tissue, but to a large glycogen body embedded in a dorsal rhomboid sinus. The dorsal wall of the vertebral canal shows segmented bilateral dorsal grooves, which are covered by the meninges towards the lumen of the vertebral canal leaving openings in the midline and laterally. This results in a system of lumbosacral canals which look and may function similar to the semicircular canals in the inner ear. Laterally these canals open above ventrolateral protrusions or accessory lobes of the spinal cord which contain neurons. There are large subarachnoidal cerebrospinal fluid spaces, lateral and ventral to the accessory lobes. Movement of this fluid is thought to stimulate the lobes mechanically. As to the development of avian lumbosacral specializations, main attention was given to the organization of the lobes and the adjacent fluid spaces including the dorsal canals. In the pigeon the system is far from being adult-like at hatching but maturates rapidly after hatching. In the chicken the system looks already adult-like at hatching. The implications derived from the structural findings are discussed with regard to a possible function of the lumbosacral specializations as a sense organ of equilibrium. The adult-like organization in the newly hatched chickens, which walk around immediately after hatching, supports the assumed function as a sense organ involved in the control of locomotion on the ground.

Measurement of the subarachnoid space by ultrasound in preterm infants.

BACKGROUND: Measurements of the subarachnoid space during routine cranial sonography may provide an indirect method of monitoring brain growth in preterm infants. METHODS: The width of the subarachnoid space was measured on coronal views during head sonography. Initial scans (within five days of birth) were compared with follow up scans. RESULTS: A total of 361 scans were performed on 201 preterm infants. The mean width of the subarachnoid space was < 3.5 mm for 95% of initial scans. It was slightly larger in neonates born closer to term, the equivalent of an increase of 0.02 mm/gestational week (95% confidence interval 0 to 0.10 mm) for initial scans. When the scans of all infants, born at 24-36 gestational weeks who were 36 weeks corrected gestational age were compared, the mean (SD) subarachnoid space was 60% larger for follow up scans than for initial scans: 3.2 (1.38) v 1.95 (1.35) mm (p = 0.002) or the equivalent of a mean increase of 0.20 mm/week (95% confidence interval 0.15 to 0.30 mm) for follow up scans. At 36 weeks corrected gestational age, mean head circumference was not different between those having initial or follow up scans (33.0 (2.0) v 32.2 (1.9) cm; p = 0.31). CONCLUSION: The mean subarachnoid space is normally < 3.5 mm in preterm infants. The difference between initial and follow up scans suggests reduced brain growth in extrauterine preterm babies.

Developmental morphology of the subarachnoid space and contiguous structures in the mouse.

Development of pia-arachnoidal membranes in the mouse occurs in four stages: the first (prenatal days 10-13) follows closure of the neural tube and is a period of initial vascularization of the developing telencephalon; the second (prenatal days 14-16) is a period of delineation during which the limits of the subarachnoid space are defined; the third (prenatal day 17 to birth) is a period of ensheathment of pia-arachnoidal blood vessels; and the fourth (birth to postnatal day 21) includes addition of smooth muscle to larger vessels, the appearance of macrophages in the subarachnoid space, and a general increase in extracellular collagenous and elastic fibers. The mesenchyme over the telencephalic surface in the 10-day fetus has a typically large extracellular space. By the 13th fetal day cerebrospinal fluid begins to seep into and replace it. The mesenchymal extracellular compartment is reduced peripherally, resulting in a compacted pia-arachnoidal tissue which limits the peripheral extent of the subarachnoid space. By the 21st postnatal day a subarachnoid space typical of the adult animal has been established.