The pressure-volume index (PVI) technique was used to measure neural axis compliance, cerebrospinal fluid (CSF) formation (If), and CSF absorption (Ro) in 23 children and 7 adults, all free from intracranial masses, who were undergoing diagnostic or therapeutic procedures. Using bolus manipulation of CSF, If was 0.36 +/- 0.08 ml/min and Ro was 2.8 +/- 0.8 mm Hg/ml/min in both adults and children. PVI, as a measure of neural axis compliance or volume buffering capacity, was 25.9 +/- 3.7 ml for the adults. Measured PVI in the children varied from 8.2 to 30.1 ml but correlated well (r = 0.93) with predicted PVI based on estimates of intracranial and spinal volumes obtained from external measurements. This study provides normal reference data in humans for assessing CSF hydrodynamics and neural axis compliance using the PVI technique in pathological settings.

BACKGROUNDANDPURPOSE Neurologic morbidity remains high in neonates with perinatal hypoxic-ischemic injury despite therapeutic hypothermia. DTI provides qualitative and quantitative information about the microstructure of the brain, and a near-infrared spectroscopy index can assess cerebrovascular autoregulation. We hypothesized that lower ADC values would correlate with worse autoregulatory function. MATERIALSANDMETHODS Thirty-one neonates with hypoxic-ischemic injury were enrolled. ADC scalars were measured in 27 neonates (age range, 4–15 days) in the anterior and posterior centrum semiovale, basal ganglia, thalamus, posterior limb of the internal capsule, pons, and middle cerebellar peduncle on MRI obtained after completion of therapeutic hypothermia. The blood pressure range of each neonate with the most robust autoregulation was identified by using a near-infrared spectroscopy index. Autoregulatory function was measured by blood pressure deviation below the range with optimal autoregulation. RESULTS In neonates who had MRI on day of life ≥10, lower ADC scalars in the posterior centrum semiovale (r = −0.87, P = .003, n = 9) and the posterior limb of the internal capsule (r = −0.68, P = .04, n = 9) correlated with blood pressure deviation below the range with optimal autoregulation during hypothermia. Lower ADC scalars in the basal ganglia correlated with worse autoregulation during rewarming (r = −0.71, P = .05, n = 8). CONCLUSIONS Blood pressure deviation from the optimal autoregulatory range may be an early biomarker of injury in the posterior centrum semiovale, posterior limb of the internal capsule, and basal ganglia. Optimizing blood pressure to support autoregulation may decrease the risk of brain injury in cooled neonates with hypoxic-ischemic injury.

Children with PAs with an MIB-1 LI of more than 2.0 have a shortened PFS. PAs that are completely resected and are located in the cerebellum have a prolonged PFS. This initial study suggests that the MIB-1 LI identifies a more aggressive subset of PAs. Further work should focus on elucidating features of pilocytic astocytomas that will identify prospectively children at risk for progression.

Purpose: Chronic venous hypertension due to jugular foramen stenosis has been proposed as an etiology for the hydrocephalus and tonsillar herniation seen in some patients with complex craniosynostosis. We report the use of MR venography (MRV) to evaluate venous outflow obstruction in this clinical setting. Materials and Methods: We studied 17 patients, (ages 4 months to 34 years; mean 7.3 years) with complex craniosynostosis; 8 patients with Crouzon’s syndrome, 2 with Apert’s, 1 with Pfeiffer’s and 6 patients without an eponymous classification. MR imaging included routine imaging sequences and axial 2D TOF MRV. Patterns of venous drainage and the presence of hydrocephalus and tonsillar herniation were noted. Results: Jugular vein obstruction was seen in 12/17 patients; in 5/8 patients with Crouzon’s, 1/2 with Apert’s, the single patient with Pfeiffer’s and 5/6 patients with nonsyndromic craniosynostosis. The predominant collateral drainage was via the posterior condylar veins. Nine of 12 (75%) of the patients with abnormal MRV had hydrocephalus; 3/8 patients with Crouzon’s, 1/2 patients with Apert’s, and 5/6 nonsyndromic patients. Two patients had hydrocephalus with normal MRV. Ten patients had tonsillar herniation, which was associated with shunted hydrocephalus in 7/10 patients, and hydrocephalus seen prior to shunt placement in 3/9. Nine of 10 patients with tonsillar herniation had an abnormal MRV, while 1 patient had a normal MRV. Venous pressures measured in 1 patient showed an 8-mm-Hg differential across the skull base. Conclusions: The posterior condylar veins appear pivotal in maintaining venous drainage when the jugular bulbs are occluded. Although the association between venous outflow obstruction, hydrocephalus and tonsillar herniation is intriguing, evidence of venous outflow obstruction by MRV may not be indicative of significant intracranial venous hypertension.