Anne M. Comi

Dynamic MR perfusion and proton MR spectroscopic imaging in Sturge-Weber syndrome: correlation with neurological symptoms.

To investigate physiological alterations in Sturge‐Weber syndrome (SWS) using MR perfusion imaging (PWI) and proton spectroscopic imaging (MRSI), and their association with neurological status.

Neurogenesis and neuronal commitment following ischemia in a new mouse model for neonatal stroke

Stroke in the neonatal brain is an important cause of neurologic morbidity. To characterize the dynamics of neural progenitor cell proliferation and maturation after survival delays in the neonatal brain following ischemia, we utilized unilateral carotid ligation alone to produce infarcts in postnatal day 12 CD1 mice. We investigated the neurogenesis derived from the sub-ventricular zone and the sub-granular zone of the dentate gyrus subsequent to injury. Newly produced cells were labeled by bromodeoxyuridine at approximately 1 week (P18-20) after the insult by 5 i.p. injections (each 50 mg/kg). Subsequent migration and differentiation of the newborn cells was investigated at postnatal day 40 by immunohistochemistry for molecular neuronal and glial cell-lineage markers and BrdU incorporation. Cresyl violet stain demonstrated massive loss of neurons in the ipsilateral septal hippocampus in the CA3 and CA1 regions associated with atrophy. Total counts of new cells were significantly lowered not only in the ipsilateral injured but also the contralateral uninjured hippocampi and correlated with the lesion induced atrophy. Bilateral percent neuronal commitments in the dentate gyri however, were not significantly different from control. New cell densities in the neocortex and striatum increased bilaterally after neonatal stroke. The predominantly non-neuronal commitment of the SVZ-derived new cells was similar to the percentage of non-neuronal commitment in controls. In conclusion, neurogenesis occurring at 1 week after neonatal ischemia in the model maintained cell-lineage commitment patterns similar to sham controls. However, the total number of hippocampal SGZ-derived new neurons was reduced bilaterally; in contrast, the SVZ-derived neurogenesis was amplified.

Chronic brain injury and behavioral impairments in a mouse model of term neonatal strokes.

Stroke in term neonates remains a significant cause of long-term neurological morbidity. This study was designed to assess the relationships between ischemic stroke induced by permanent unilateral carotid ligation in P12 CD1 mice and the structural and functional outcomes in the young mice as a consequence. After P12 ischemic strokes, mice were behaviorally tested using accelerated rotorod, spontaneous alternation on a T-maze, open-field, and cylinder tests between P33 and P39. Brain injury was scored by histology at P40 with cresyl violet-stained coronal sections and computerized quantification of the ischemic injury. The ligation-injured mice were not different from controls on cylinder testing for asymmetric use of their forelimb, or on rotorod measures. In the spontaneous alternation task, however, injured mice demonstrated significantly lower rates of alternation indicating a deficit in working memory. Open-field testing repeated on two consecutive days revealed that the ligated mice were less active than the controls and that they failed to habituate to the open field environment between sessions indicating a learning deficit. Overall, our results demonstrate that ischemia induced by our neonatal stroke model produces behavioral deficits that are consistent with the brain injury.

Central Hypothyroidism and Sturge- Weber Syndrome

Sturge-Weber syndrome is a rare disorder manifesting with a facial port-wine birthmark and a vascular malformation of the brain. Infants and children present with seizures and stroke-like episodes with focal neurologic deficits. Our previous investigations revealed that growth-hormone deficiency occurs with an increased prevalence in Sturge-Weber syndrome, presumably secondary to involvement of the hypothalamic-pituitary axis. We have continued to screen for hormonal abnormalities in patients with Sturge-Weber syndrome, specifically those from our multidisciplinary center for patients with this condition. We describe 2 children out of 83 (2.4%) with Sturge-Weber syndrome and brain involvement who were evaluated at our center and diagnosed with central hypothyroidism, based on clinical signs and laboratory findings. This prevalence is much higher than that of central hypothyroidism in the general population. Although it is well-known that anticonvulsants can lead to abnormalities in thyroid function tests, including central hypothyroidism, patients with Sturge-Weber syndrome carry the additional risk of developing hypothalamic-pituitary dysfunction, secondary to their central nervous system dysfunction. Therefore, it is important that patients with Sturge-Weber syndrome undergo routine thyroid-function testing, especially in the face of any clinical manifestations.

Pluripotent possibilities: Human umbilical cord blood cell treatment after neonatal brain injury

Perinatal hypoxic-ischemic brain injury and stroke in the developing brain remain important causes of chronic neurologic morbidity. Emerging data suggest that transplantation of umbilical cord blood-derived stem cells may have therapeutic potential for neuroregeneration and improved functional outcome. The pluripotent capacity of stem cells from the human umbilical cord blood provides simultaneous targeting of multiple neuropathologic events initiated by a hypoxic-ischemic insult. Their high regenerative potential and naïve immunologic phenotype makes them a preferable choice for transplantation. A multiplicity of transplantation protocols have been studied with a variety of brain injury models; however, only a few have been conducted on immature animals. Biological recipient characteristics, such as age and sex, appear to differentially modulate responses of the animals to the transplanted cord blood stem cells. Survival, migration, and function of the transplanted cells have also been studied and reveal insights into the mechanisms of cord blood stem cell effects. Data from preclinical studies have informed current clinical safety trials of human cord blood in neonates, and further work is needed to continue progress in this field.

Increased choroidal thickness in patients with Sturge-Weber syndrome.

IMPORTANCE With the recent development of enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT), it is now possible to measure choroidal thickness in patients with Sturge-Weber syndrome and detect abnormalities that are not visible as part of the fundus examination. OBSERVATIONS We were successful in imaging at least 1 eye in 12 individuals with Sturge-Weber syndrome using enhanced depth imaging SD-OCT. Eyes were defined as affected if they manifested at least one of the following: darkened choroid, glaucomatous optic nerve damage, or conjunctival hyperemia. None of the participants had a clinically visible choroidal hemangioma. The affected eyes had over twice the choroidal thickness of the unaffected eyes (mean [SD], 697 [337] μm vs 331 [94] μm; P = .004, determined by use of an unpaired t test). For the 6 unilaterally affected participants who had both eyes imaged, the choroidal thickness was greater in the affected eyes than in the unaffected eyes of 5 participants (mean [SD], 672 [311] μm vs 329 [88] μm; P = .01, determined by use of a paired t test). CONCLUSIONS AND RELEVANCE The advent of enhanced depth imaging SD-OCT has allowed us to quantify choroidal thickness in the posterior pole, even in eyes with a markedly thickened choroid, such as those found in individuals with Sturge-Weber syndrome. Spectral-domain OCT has a much higher resolution (5-10 μm) than B-scan ultrasonography (150 μm) and can be used to distinguish between the retina and the choroid. Furthermore, enhanced depth imaging SD-OCT can detect choroidal thickness in eyes without clinically apparent choroidal abnormalities.

Impact of age and strain on ischemic brain injury and seizures after carotid ligation in immature mice.

Stroke is an important cause of neurologic injury in the neonatal period and frequently results in lifelong neurologic impairments. We reported previously that unilateral carotid ligation on postnatal day (P)12 in CD1 mice causes acute behavioral seizures and unilateral brain injury and provides a model for neonatal stroke in human infants. In the present study we confirmed that behavioral seizures observed after ligation on P12 in the CD1 strain are associated with rhythmic ictal discharges that show temporal progression on electrocorticograms. We also examined the effects of carotid ligation performed at different ages in CD1 mice or performed in the C57Bl/6 strain. The right common carotid was ligated at P7, P10, P12 or P21 in CD1 mice or at P12 in C57Bl/6 mice. Littermate controls received sham surgery. Seizures were rated for 4 h after surgery; brain injury was scored one week later. In a separate group of P12 CD1 mice, electrocorticographic activity was recorded continuously for 4 h after carotid ligation or sham surgery. Brain injury and cumulative seizure score varied significantly with age (p < 0.001) and strain (p < 0.001). In CD1 mice, injury was greatest after ligation on P10 to P12 and seizure score was maximal at P12. Seizure scores were significantly correlated with injury after ligation on P10 or P12. C57Bl/6 mice, like C3Heb/FeJ mice examined previously, were much less vulnerable to seizures and injury than CD1 mice after ligation on P12. This study demonstrates that carotid ligation in the CD1 mouse on P12 causes acute electrographic rhythmic discharges that correlate with behavioral seizures. We also found that the age at which ligation is performed and genetic strain have a strong influence on the severity of injury.

Neonatal Stroke in Mice Causes Long-Term Changes in Neuronal Notch-2 Expression That May Contribute to Prolonged Injury

Background and Purpose— Notch receptors (1–4) are membrane proteins that, on ligand stilumation, release their cytoplasmic domains to serve as transcription factors. Notch-2 promotes proliferation both during development and cancer, but its role in response to ischemic injury is less well understood. The purpose of this study was to understand whether Notch-2 is induced after neonatal stroke and to investigate its functional relevance. Methods— P12 CD1 mice were subjected to permanent unilateral (right-sided) double ligation of the common carotid artery. Results— Neonatal ischemia induces a progressive brain injury with prolonged apoptosis and Notch-2 up-regulation. Notch-2 expression was induced shortly after injury in hippocampal areas with elevated c-fos activation and increased cell death. Long-term induction of Notch-2 also occurred in CA1 and CA3 in and around areas of cell death, and had a distinct pattern of expression as compared to Notch-1. In vitro oxygen glucose deprivation treatment showed a similar increase in Notch-2 in apoptotic cells. In vitro gain of function experiments, using an active form of Notch-2, show that Notch-2 induction is neurotoxic to a comparable extent as oxygen glucose deprivation treatment. Conclusions— These results suggest that Notch-2 up-regulation after neonatal ischemia is detrimental to neuronal survival.

Neuropsychological Features and Risk Factors in Children With Sturge-Weber Syndrome: Four Case Reports

Sturge-Weber Syndrome (SWS) is a rare neurocutaneous disorder involving facial capillary malformation (port-wine birthmark) and vascular malformation of the brain that is frequently associated with epilepsy, stroke-like episodes, cognitive deficits, motor impairment, and/or visual field cut. The four cases presented here (ages 8–9, two females) illustrate the broad range of physiologic involvement and associated neuropsychological functioning in SWS, and argue against the idea of a “typical” SWS neuropsychological presentation. Rather, we highlight a preliminary collection of disease status/severity factors thought to impact neuropsychological presentation in SWS, including degree of cortical involvement (unilateral versus bilateral; posterior only versus posterior/anterior), age at time of seizure onset, extent of seizure control, history of stroke-like episodes, and magnitude of neurologic decline/deficit. We discuss the need for broad-based assessment in this medical population, as various impairment combinations (e.g., perceptual, language, executive) create unique presentations as well as the need for individualized intervention.

Functional integration of new neurons into hippocampal networks and poststroke comorbidities following neonatal stroke in mice.

Stroke in the developing brain is an important cause of chronic neurological morbidities including neurobehavioral dysfunction and epilepsy. Here, we describe a mouse model of neonatal stroke resulting from unilateral carotid ligation that results in acute seizures, long-term hyperactivity, spontaneous lateralized circling behavior, impaired cognitive function, and epilepsy. Exploration-dependent induction of the immediate early gene Arc (activity-regulated cytoskeleton associated protein) in hippocampal neurons was examined in the general population of neurons versus neurons that were generated approximately 1 week after the ischemic insult and labeled with bromodeoxyuridine. Although Arc was inducible in a network-specific manner after severe neonatal stroke, it was impaired, not only in the ipsilateral injured but also in the contralateral uninjured hippocampi when examined 6 months after the neonatal stroke. Severity of both the stroke injury and the acquired poststroke epilepsy negatively correlated with Arc induction and new neuron integration into functional circuits in the injured hippocampi.