Longitudinal comparison of pre- and postoperative diffusion tensor imaging parameters in young children with hydrocephalus

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The goal in this study was to compare the integrity of white matter before and after ventriculoperitoneal (VP) shunt insertion by evaluating the anisotropic diffusion properties with the aid of diffusion tensor (DT) imaging in young children with hydrocephalus.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors retrospectively identified 10 children with hydrocephalus who underwent both pre- and postoperative DT imaging studies. The DT imaging parameters (fractional anisotropy [FA], mean diffusivity, axial diffusivity, and radial diffusivity) were computed and compared longitudinally in the splenium and genu of the corpus callosum (gCC) and in the anterior and posterior limbs of the internal capsule (PLIC). The patients' values on DT imaging at the pre- and postshunt stages were compared with the corresponding age-matched controls as well as with a large cohort of healthy children in the database.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In the gCC, 7 of 10 children had abnormally low preoperative FA values, 6 of which normalized postoperatively. All 3 of the 10 children who had normal preoperative FA values had normal FA values postoperatively as well. In the PLIC, 7 of 10 children had abnormally high FA values, 6 of which normalized postoperatively, whereas the other one had abnormally low postoperative FA. Of the remaining 3 children, 2 had abnormally low preoperative FA values in the PLIC; this normalized in 1 patient after surgery. The other child had a normal preoperative FA value that became abnormally low postoperatively. When comparing the presurgery frequency of abnormally low, normal, and abnormally high FA values to those postsurgery, there was a statistically significant longitudinal difference in both gCC (p = 0.02) and PLIC (p = 0.002).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>In this first longitudinal DT imaging study of young children with hydrocephalus, DT imaging anisotropy yielded abnormal results in several white matter regions of the brain, and trended toward normalization following VP shunt placement.</jats:p></jats:sec>

Postshunt lateral ventricular volume, white matter integrity, and intellectual outcomes in spina bifida and hydrocephalus

“…3,15 In a longitudinal study of children with hydrocephalus, preshunt increases in FA were observed within the internal capsule, and these changes also normalized after shunting. 1 Thus, the observed patterns in DTI metrics in the present study may stem from WM alterations similar to those found in individuals with acutely enlarged ventricles due to untreated hydrocephalus.…”

“…There was also a significant effect of the number of shunt revisions (F [3,70] = 2.95, p = 0.039) but not of age (F [1,70] = 2.96, p = 0.09) on RD along the parietal pathways. Post hoc pairwise comparisons indicated that the RD (adjusted for age) along the frontal pathways in cases of 2-4 shunt revisions was significantly higher than for cases of no shunt revisions (t [44] = 2.45, p = 0.016).…”

“…However, these increases in FA normalized after insertion of a ventriculoperitoneal shunt. 1 In a whole-brain, voxel-wise analysis of heterogeneous hydrocephalus etiologies in a small sample of adults, the same pattern of FA variations was observed, but elevations in these DTI metrics persisted after shunting. 32 Elevated FA has also been identified in the subcortical gray matter of the caudate, likely because of the elevated ICP in chronic hydrocephalus.…”

DTI Values in Key White Matter Tracts from Infancy through Adolescence

“…The method is similar to the approach of Hermoye et al 8 and has also been described in our past studies. 15,24 Each region of interest was placed manually by a single investigator (W.Y. ), with the assistance of a neuroradiologist (B.V.J.)…”

Clinical benefits of diffusion tensor imaging in hydrocephalus

“…Thus, it is difficult to evaluate success after this type of operation. 1,6,9 Complicating the paradigm in these situations is the fact that, as of today, there is no reliable noninvasive method to assess intracranial pressure (ICP) and to demonstrate the pressure of the fluid on adjacent brain tissue.…”