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Marina Pitsika, Jack Fletcher, Ian C. Coulter, and Christopher J. A. Cowie

OBJECTIVE

Perioperative management of hydrocephalus in children with posterior fossa tumors (PFTs) remains challenging. The modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) has been previously described as a useful tool in predicting which children are at higher risk for permanent hydrocephalus following PFT resection and can be used in guiding treatment. The aim of this study was to externally validate this predictive model.

METHODS

A retrospective review of the children treated in a single unit was conducted, recording all of the mCPPRH parameters (age, preoperative radiological diagnosis, presence of moderate/severe hydrocephalus, transependymal edema, and metastatic disease at the time of diagnosis), the need for a CSF diversion procedure at 6 months, time to surgery, and management of hydrocephalus. A receiver operating characteristic (ROC) curve was plotted using the mCPPRH, age, Evans index (EI), and frontooccipital horn ratio (FOHR), and an area under the curve (AUC) was calculated. A point-biserial correlation was run to determine the relationship between time to surgery, the insertion of an external ventricular drain (EVD), or initial EVD clamping and the development of postoperative persistent hydrocephalus.

RESULTS

From a total of 75 patients (mean age 6.99 years, 62.7% male) who were included in the study, 8 (10.7%) required permanent CSF diversion following PFT resection. The AUC of the ROC curve was 0.618 for the mCPPRH (p = 0.18, SE 0.088, 95% CI 0.446–0.791), 0.633 for age (p = 0.26, SE 0.119, 95% CI 0.4–0.867), 0.604 for the EI (p = 0.34, SE 0.11, 95% CI 0.389–0.818), and 0.663 for the FOHR (p = 0.17, SE 0.121, 95% CI 0.427–0.9). A significant positive correlation between EVD insertion (r = 0.239, p = 0.03) and insertion of a ventriculoperitoneal shunt was found. A negative correlation between the postoperative clamping of the EVD (r = −0.158, p = 0.4) and the time to PFT surgery (r = −0.06, p = 0.6) did not reach statistical significance.

CONCLUSIONS

The implementation of the mCPPRH score failed to reliably predict which children would require permanent CSF diversion following PFT resection when applied to this cohort. Clinical judgment remains the mainstay of choosing the perioperative treatment of hydrocephalus.

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Farideh Nejat, Soheil Naderi, and Mostafa El Khashab

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Lyla E. Hampton, Jack M. Fletcher, Paul T. Cirino, Susan Blaser, Larry A. Kramer, James Drake, and Maureen Dennis

Object

The effect of hydrocephalus status on neuropsychological outcomes in children with spina bifida (SB) has not been carefully evaluated. The authors hypothesized a stepwise progression of outcomes related to hydrocephalus status (shunt-treated, arrested, or no hydrocephalus) and that motor, spatial, and executive function tasks would be more sensitive to hydrocephalus status than vocabulary and reading tasks.

Methods

Two hundred eight children (mean age 11.2 years) with SB were grouped according to hydrocephalus status: shunt-treated hydrocephalus (166 children), arrested hydrocephalus (18 children), and no hydrocephalus (24 children). Sixty-one typically developing children were included as a control group (mean age 12.05 years). All children were tested across neuropsychological content domains, including verbal and nonverbal IQ, reading and mathematical achievement, explicit memory, visuospatial function, executive function, and motor skills.

Results

There was a stepwise progression of outcomes. Averaging across tasks, performance scores of children with SB and no hydrocephalus (mean standard score 92.60) were higher than those of children with SB and arrested hydrocephalus (mean standard score 86.86), and scores of children in the latter group were higher than those of children with SB and shunt-treated hydrocephalus (mean standard score 82.30). All 3 groups scored lower than the control group (mean standard score 105.94). Fine motor tasks best differentiated the arrested-hydrocephalus and shunt-treated groups. Verbal and executive function tasks, often associated with socioeconomic status, best differentiated the group of children with SB and no hydrocephalus from the control group.

Conclusions

With the exception of fine motor skills and small differences in memory and spatial domains, children with SB and arrested or shunt-treated hydrocephalus have similar neuropsychological profiles. Performance of all 3 groups of children with SB was below that of the control group, which also reflects the lower socioeconomic status of the children with SB.

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Khader M. Hasan, Ambika Sankar, Christopher Halphen, Larry A. Kramer, Linda Ewing-Cobbs, Maureen Dennis, and Jack M. Fletcher

Object

Patients with spina bifida (SB) have variable intellectual outcomes. The authors used diffusion tensor (DT) imaging to quantify whole-brain volumes of gray matter, white matter, and cerebrospinal fluid (CSF), and perform regional quantitative microstructural assessments of gray matter nuclei and white matter tracts in relation to intellectual outcomes in patients with SB.

Methods

Twenty-nine children with myelomeningoceles and 20 age- and sex-matched children with normal neural tube development underwent MR imaging with DT image acquisition and assessments of intelligence. The DT imaging–derived metrics were the fractional anisotropy (FA), axial (parallel), and transverse (perpendicular) diffusivities. These metrics were also used to segment the brain into white matter, gray matter, and CSF. A region-of-interest analysis was conducted of the white and gray matter structures implicated in hydrocephalus.

Results

The amount of whole-brain gray matter was decreased in patients with SB, with a corresponding increase in CSF (p < 0.0001). Regional transverse diffusivity in the caudate nucleus was decreased (p < 0.0001), and the corresponding FA was increased (p < 0.0001), suggesting reduced dendritic branching and connectivity. Fractional anisotropy in the posterior limb of the internal capsule increased in the myelomeningocele group (p = 0.02), suggesting elimination of some divergent fascicles; in contrast, the FA in several white matter structures (such as the corpus callosum genu [p < 0.001] and arcuate fasciculus) was reduced, suggesting disruption of myelination. Diffusion tensor imaging–metrics involving gray matter volume and the caudate nucleus, but not other structures, predicted variations in IQ (r = 0.37–0.50; p < 0.05).

Conclusions

Diffusion tensor imaging–derived metrics provide noninvasive neuronal surrogate markers of the pathogenesis of SB and predict variations in general intellectual outcomes in children with this condition.

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Panagiotis G. Simos, Eduardo M. Castillo, Jack M. Fletcher, David J. Francis, Fernando Maestu, Joshua I. Breier, William W. Maggio, and Andrew C. Papanicolaou

Object. There are conflicting claims in the functional imaging literature concerning whether different languages are represented by distinct brain mechanisms in individuals who are proficient in more than one language. This interesting theoretical issue has practical implications when functional imaging methods are used for presurgical language mapping. To address this issue the authors compared the location and extent of receptive language cortex specific to English and Spanish in neurologically intact bilingual volunteers by using magnetic source imaging.

Methods. Areas of the cortex that were specialized for receptive language functions were identified separately for each language in 11 healthy adults who were bilingual in English and Spanish. The authors performed exactly the same procedures used routinely for presurgical receptive language mapping. In each bilingual individual, the receptive language—specific map always encompassed the posterior portion of the superior temporal gyrus. In every case, however, substantial differences in the receptive language maps were also observed for the two languages, regardless of whether each participant's first language was English or Spanish.

Conclusions. Although the reasons for such differences and their ultimate significance in identifying the cerebral mechanisms of language are subject to continuing investigation, their presence is noteworthy and has practical implications for the surgical management of patients with lesions in the temporal and parietal regions of the dominant hemisphere.

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Victoria J. Williams, Jenifer Juranek, Karla K. Stuebing, Paul T. Cirino, Maureen Dennis, Robin M. Bowman, Susan Blaser, Larry A. Kramer, and Jack M. Fletcher

OBJECT

No previous reports exist that have evaluated the relationships of white matter (WM) integrity with the number of shunt revisions, ventricular volume after shunting, and cognition in medically stable children who have spina bifida and hydrocephalus (SBH). The authors hypothesized that enlarged ventricles and a greater number of shunt revisions decrease WM integrity in children.

METHODS

In total, 80 children (mean age 13.7 years) who had SBH underwent MRI and IQ testing. Probabilistic diffusion tractography was performed to determine mean diffusion tensor imaging (DTI) metrics along the frontal and parietal tectocortical pathways. The DTI metrics were evaluated for significant correlation with a composite IQ measure and with the total number of shunt revisions and the total lateral ventricular volume obtained through semiautomated parcellation of T1-weighted MRI scans.

RESULTS

An enlargement in total lateral ventricle volume and an increase in the number of shunt revisions were both associated with higher fractional anisotropy (FA) and with lower radial diffusivity (RD) along both frontal and parietal tectocortical pathways. Children who had not undergone a shunt revision had on average a greater lateral ventricle volume and higher FA and lower RD along frontal and parietal pathways than those who had undergone multiple shunt revisions. The mean DTI metrics along parietal pathways predicted IQ scores, but intellectual ability was not significantly correlated with ventricular volume or with the number of lifetime shunt revisions.

CONCLUSIONS

Significant changes in DTI metrics were observed as a function of ventricular volume. An increased lateral ventricle volume was associated with elevated FA and decreased RD. Given that the participants were medically stable at the time of the MRI examination, the results suggested that those who have enlarged ventricles show a DTI pattern consistent with axonal compression due to increased intracranial pressure (ICP) in attenuated hydrocephalus. Although limited by a cross-sectional design, the study's findings suggest that DTI metrics may serve as sensitive indicators for chronic, mild hydrocephalus in the absence of overt clinical symptoms due to increased ICP. Having enlarged ventricles and undergoing multiple shunt revisions did not affect intellectual ability in children with SBH.

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Jack M. Fletcher, Kim Copeland, Jon A. Frederick, Susan E. Blaser, Larry A. Kramer, Hope Northrup, H. Julia Hannay, Michael E. Brandt, David J. Francis, Grace Villarreal, James M. Drake, John P. Laurent, Irene Townsend, Susan Inwood, Amy Boudousquie, and Maureen Dennis

Object. The aim of this study was to evaluate whether the level of a spinal lesion is associated with variations in anomalous brain development and neurobehavioral outcomes in children suffering from the meningomyelocele form of spina bifida and hydrocephalus (SBM-H).

Methods. Two hundred sixty-eight children with SBM-H were divided into upper (T-12 and above; 82 patients) and lower (L-1 and below; 186 patients) lesion-level groups. Magnetic resonance images were qualitatively coded by radiologists and quantitatively segmented for cerebrum and cerebellum volumes. Psychometric assessments of handedness, intelligence, academic skills, and adaptive behavior were compared between lesion-level groups and also used to determine the number of children who met research-based criteria for mental retardation, attention deficit hyperactivity disorder, and learning disabilities.

The magnetic resonance images obtained in children with upper-level spinal lesions demonstrated more qualitative abnormalities in the midbrain and tectum, pons, and splenium, although not in the cerebellum, compared with images obtained in children with lower-level spinal lesions. Upper-level lesions were also associated with reductions in cerebrum and cerebellum volumes, lower scores on measures of intelligence, academic skills, and adaptive behavior, and with a higher frequency of individuals meeting the criteria for mental retardation. Hispanic children (who were also more economically disadvantaged) were more likely to have upper-level lesions and poorer neurobehavioral outcomes, but lesion-level effects were generally independent of ethnicity.

Conclusions. A higher level of spinal lesion in SBM-H is a marker for more severe anomalous brain development, which is in turn associated with poorer neurobehavioral outcomes in a wide variety of domains that determine levels of independent functioning for these children at home and school.