2570
Extracranial space in healthy infants: an age-related study based on MRI anatomical images1Baoji Center Hospital, baoji, China, 2Baoji Center Hospital, Baoji, China, 3GE Healthcare, Beijing, China
Synopsis
To date, there is no consensus exists on diagnostic criteria for pathological external hydrocephalus in infants and young children. In this study, extracerebral space of 212 healthy subjects were measured on different anatomical slices and their age correlation were analyzed. The results demonstrated that extra cerebral space measured both on axial and coronal plane features similar age-related change. The results of this study may be a valuable reference in diagnosis of external hydrocephalus.
Introduction
External hydrocephalus (EH) is a special type of hydrocephalus. It is defined as rapid enlargement of the head circumference in infants without intracranial pressure increase, accompanied by enlargement of the corresponding extracranial space, with or without ventricles. Mild enlargement can lead to poor prognosis. Therefore, the precise distinction between benign and pathological widening of the extra cerebral space is of great clinical significance. At present, there is no consensus exists on diagnostic criteria for pathological external hydrocephalus in infants and young children. Benign enlargement of extracerebral space may be misdiagnosed as pathological external hydrocephalus. In this report, six typical distance markers for extra cerebral space were measured in a cohort of healthy infants. By studying the age-related distribution of these distance markers, we hope to identify the pattern of extracerebral space underline the brain development for healthy infants. With the hypothesis that the distance markers for pathological external hydrocephalus would be classified outside of aforementioned pattern, our results could also be provided as a basis for differentiating benign from pathological enlargement of extracerebral space in clinical practices.Methods
The Institutional Review Board approved this study and all the written informed consents were obtained from parents of infants and children. 212 healthy infants without any neurological impairment were included. The ages of the subjects ranged from 0 to 36 months with a median age of 8 months. All subjects underwent magnetic resonance (MR) examination on a 3.0T MRI scanner (Discovery 750W; GE Medical system, Milwaukee, WI)) equipted with an 8-channel brain coil. The scan protocols include a 3D coronal plane volumetric T1 weighted fast spoiled gradient echo imaging (3D FSPGR) and a 2D axial plane T2 weighted fast spin echo sequence. The 3D FSPGR volumetric data was normalized and co-registered to T2 images to form a set of T1 axial images. Three distance markers, including distance between longitudinal fissure (m1), distance from bilateral superior sagittal sinus to cerebral cortex (m2) and distance from bilateral skull to cerebral cortex (m3) were measured at the interventricular foramen level[1] on coronal T1 images (Figure 1). The other three distance markers are measured both on T1 and T2 axial images, including width of the left/right anterior frontal space (m4-L-T1, m4-R-T1, m4-L-T2, m4-R-T2), the width of left/right anterior temporal space (m5-L-T1, m5-R-T1, m5-L-T2, m5-R-T2) and the width of the longitudinal fissure (m6-T1, m6-T2). Every marker was measured 2 times, and the average value was calculated and analyzed by SPSS 17.0. The scatter data points were used to fit the regression curve. All statistical results were statistically significant in terms of P<0.05.Result
All distance markers measured in our study have demonstrated similar pattern in terms of age-related changes. Distance markers increased markedly during the first 4-6 month ages, and then decrease in the following 6-11 month ages. The declining trend stabilize gradually afterwards. Scatter data points and fitted curve versus month ages for are illustrated in Figure (2-3).Discussion
Most previous study measured the extracranial space through distance markers solely on axis plane or coronal plane. Our results indicated that although they seem to have similar trends, they do differ from on another. Thus direct extracranial space volume measurements may provide more comprehensive information. Our results have shown that there are two distinct changes in the extracerebral space measured at coronal and axial positions with month age. The extracerebral space increases with age, turn to downwards after reaching the first turning point, after the second turning point, the extracerebral space seems no longer changes significantly, for example, after age of 2.Acknowledgements
No acknowledgement found.References
1.Zahl SM, Egge A, Helseth E, et al. Benign external hydrocephalus: a review, with emphasis on management[J]. Neurosurg Rev. 2011,34(4): 417-432.
2.Whitehead MT, Lee B, McCarron A, et al. Reduced subarachnoid fluid diffusion in enlarged subarachnoid spaces of infancy[J]. Neuroradiol J.2017,30(5):418-424.
3.Pettit RE, Kilroy AW, Allen JH. Macrocephaly with head growth parallel to normal growth pattern: neurological, developmental, and computerized tomography findings in full-term infants[J]. Arch Neurol. 1980,37(8):518–521.
4.Kumar R, Singhal N, Mahapatra AK. Traumatic subdural effusions in children following minor head injury[J]. Childs Nerv Syst. 2008,24(12):1391–1396.
5.Sun M, Yuan W, Hertzler DA, et al. Diffusion tensor imaging findings in young children with benign external hydrocephalus differ from the normal population[J]. Childs Nerv Syst. 2012,28(2): 199-208.
6.Marino MA,Morabito R,Vinci S, et al. Benign external hydrocephalus in infants. A single centre experience and literature review[J]. Neuroradiol J. 2014,27(2):245-250.
Figures
