Developmental expression of the Sturge-Weber syndrome-associated genetic mutation in Gnaq: a formal test of Happle's paradominant inheritance hypothesis.

Sturge-Weber Syndrome (SWS) is a sporadic (non-inherited) syndrome characterized by capillary vascular malformations in the facial skin, leptomeninges, or the choroid. A hallmark feature is the mosaic nature of the phenotype. SWS is caused by a somatic mosaic mutation in the GNAQ gene (p.R183Q), leading to activation of the G protein, Gαq. Decades ago, Rudolf Happle hypothesized SWS as an example of "paradominant inheritance", that is, a "lethal gene (mutation) surviving by mosaicism". He predicted that the "presence of the mutation in the zygote will lead to death of the embryo at an early stage of development". We have created a mouse model for SWS using gene targeting to conditionally express the GNAQ p.R183Q mutation. We have employed two different Cre-drivers to examine the phenotypic effects of expression of this mutation at different levels and stages of development. As predicted by Happle, global, ubiquitous expression of this mutation in the blastocyst stage results in 100% embryonic death. The majority of these developing embryos show vascular defects consistent with the human vascular phenotype. By contrast, global but mosaic expression of the mutation enables a fraction of the embryos to survive, but those that survive to birth and beyond do not exhibit obvious vascular defects. These data validate Happle's paradominant inheritance hypothesis for SWS and suggest the requirement of a tight temporal and developmental window of mutation expression for the generation of the vascular phenotype. Furthermore, these engineered murine alleles provide the template for the development of a mouse model of SWS that acquires the somatic mutation during embryonic development, but permits the embryo to progress to live birth and beyond, so that postnatal phenotypes can also be investigated. These mice could then also be employed in pre-clinical studies of novel therapies.

A novel somatic mutation in GNAQ in a capillary malformation provides insight into molecular pathogenesis.

Sturge-Weber syndrome (SWS) is a sporadic, congenital, neuro-cutaneous disorder characterized by a mosaic, capillary malformation. SWS and non-syndromic capillary malformations are both caused by a somatic activating mutation in GNAQ encoding the G protein subunit alpha-q protein. The missense mutation R183Q is the sole GNAQ mutation identified thus far in 90% of SWS-associated or isolated capillary malformations. In this study, we sequenced skin biopsies of capillary malformations from 9 patients. We identified the R183Q mutation in nearly all samples, but one sample exhibited a Q209R mutation. This new mutation occurs at the same residue as the constitutively-activating Q209L mutation, commonly seen in tumors. However, Q209R is a rare variant in this gene. To compare the effect of the Q209R mutation on downstream signaling, we performed reporter assays with a GNAQ-responsive reporter co-transfected with either GNAQ WT, R183Q, Q209L, Q209R, or C9X (representing a null allele). Q209L showed the highest reporter activation, with R183Q and Q209R showing significantly lower activation. To determine whether these mutations had similar or different downstream consequences we performed RNA-seq analysis in microvascular endothelial cells (HMEC-1) electroporated with the same GNAQ variants. The R183 and Q209 missense variants caused extensive dysregulation of a broad range of transcripts compared to the WT or null allele, confirming that these are all activating mutations. However, the missense variants exhibited very few differentially expressed genes (DEGs) when compared to each other. These data suggest that these activating GNAQ mutations differ in magnitude of activation but have similar downstream effects.

Endothelial GNAQ p.R183Q Increases ANGPT2 (Angiopoietin-2) and Drives Formation of Enlarged Blood Vessels.

OBJECTIVE: Capillary malformation (CM) occurs sporadically and is associated with Sturge-Weber syndrome. The somatic mosaic mutation in GNAQ (c.548G>A, p.R183Q) is enriched in endothelial cells (ECs) in skin CM and Sturge-Weber syndrome brain CM. Our goal was to investigate how the mutant Gαq (G-protein αq subunit) alters EC signaling and disrupts capillary morphogenesis. Approach and Results: We used lentiviral constructs to express p.R183Q or wild-type GNAQ in normal human endothelial colony forming cells (EC-R183Q and EC-WT, respectively). EC-R183Q constitutively activated PLC (phospholipase C) ß3, a downstream effector of Gαq. Activated PLCß3 was also detected in human CM tissue sections. Bulk RNA sequencing analyses of mutant versus wild-type EC indicated constitutive activation of PKC (protein kinase C), NF-κB (nuclear factor kappa B) and calcineurin signaling in EC-R183Q. Increased expression of downstream targets in these pathways, ANGPT2 (angiopoietin-2) and DSCR (Down syndrome critical region protein) 1.4 were confirmed by quantitative PCR and immunostaining of human CM tissue sections. The Gαq inhibitor YM-254890 as well as siRNA targeted to PLCß3 reduced mRNA expression levels of these targets in EC-R183Q while the pan-PKC inhibitor AEB071 reduced ANGPT2 but not DSCR1.4. EC-R183Q formed enlarged blood vessels in mice, reminiscent of those found in human CM. shRNA knockdown of ANGPT2 in EC-R183Q normalized the enlarged vessels to sizes comparable those formed by EC-WT. CONCLUSIONS: Gαq-R183Q, when expressed in ECs, establishes constitutively active PLCß3 signaling that leads to increased ANGPT2 and a proangiogenic, proinflammatory phenotype. EC-R183Q are sufficient to form enlarged CM-like vessels in mice, and suppression of ANGPT2 prevents the enlargement. Our study provides the first evidence that endothelial Gαq-R183Q is causative for CM and identifies ANGPT2 as a contributor to CM vascular phenotype.

Parkes Weber syndrome associated with two somatic pathogenic variants in RASA1.

Parkes Weber syndrome is associated with autosomal dominant inheritance, caused by germline heterozygous inactivating changes in the RASA1 gene, characterized by multiple micro arteriovenous fistulas and segmental overgrowth of soft tissue and skeletal components. The focal nature and variable expressivity associated with this disease has led to the hypothesis that somatic "second hit" inactivating changes in RASA1 are necessary for disease development. We report a 2-yr-old male with extensive capillary malformation and segmental overgrowth of his lower left extremity. Ultrasound showed subcutaneous phlebectasia draining the capillary malformation; magnetic resonance imaging showed overgrowth of the extremity with prominence of fatty tissues, fatty infiltration, and enlargement of all the major muscle groups. Germline RASA1 testing was normal. Later somatic testing from affected tissue showed two pathogenic variants in RASA1 consistent with the c.934_938del, p.(Glu312Argfs*14) and the c.2925del, p.(Asn976Metfs*20) with variant allele fractions of 3.6% and 4.2%, respectively. The intrafamilial variability of Parkes Weber syndrome involving segmental overgrowth of soft tissue, endothelium, and bone is strongly suggestive of a somatic second-hit model. There are at least two reports of confirmed second somatic hits in RASA1 To our knowledge, this is the first report of an individual with two somatic pathogenic variants in the RASA1 gene in DNA from a vascular lesion.

Association of Somatic GNAQ Mutation With Capillary Malformations in a Case of Choroidal Hemangioma.

Importance: Choroidal hemangiomas are defined by a thickened choroid owing to vessel overgrowth, which may increase the intraocular pressure and lead to glaucoma. Choroidal hemangioma and glaucoma often co-occur in patients with Sturge-Weber syndrome, a rare neurocutaneous disorder characterized by capillary malformations. Objective: To determine whether the mutation found in most capillary malformations, GNAQ R183Q (c.548G>A), was present in the choroidal hemangioma of a patient with Sturge-Weber syndrome. Design, Setting, and Participant: Using laser-capture microdissection, choroidal blood vessels were isolated from paraffin-embedded tissue sections, and genomic DNA was extracted for mutational analysis. Choroidal sections were analyzed in parallel. A patient with choroidal hemangioma and Sturge-Weber syndrome who had undergone enucleation was analyzed in this study at Boston Children's Hospital. Negative controls were choroidal tissue from an eye with retinoblastoma and unaffected lung tissue; brain tissue from a different patient with Sturge-Weber syndrome served as a positive control. Infantile hemangioma was analyzed as well. Data were analyzed in 2018. Main Outcomes and Measures: The mutant allelic frequency of GNAQ R183 and GNAQ Q209L/H/P was determined by droplet digital polymerase chain reaction on isolated genomic DNA. The infantile hemangioma marker glucose transporter-1 was visualized by immunofluorescent staining of tissue sections. Results: The GNAQ R183Q mutation was present in the patient's choroidal vessels (21.1%) at a frequency similar to that found in brain tissue from a different patient with Sturge-Weber syndrome (25.1%). In contrast, choroidal vessels from a case of retinoblastoma were negative for the mutation (0.5%), as was lung tissue (0.2%). The patient's choroidal tissue was negative for the 3 GNAQ mutations associated with congenital hemangioma and for the infantile hemangioma marker glucose transporter-1. Conclusions and Relevance: The results suggest that a more accurate description for choroidal hemangioma in patients with Sturge-Weber syndrome is choroidal capillary malformation. This finding may explain why propranolol, used to treat infantile hemangiomas, has been largely ineffective in patients with choroidal hemangioma. Further studies are needed to corroborate this finding.

Metabolic correlates of cognitive function in children with unilateral Sturge-Weber syndrome: Evidence for regional functional reorganization and crowding.

To evaluate metabolic changes in the ipsi- and contralateral hemisphere in children showing a cognitive profile consistent with early reorganization of cognitive function, we evaluated the regional glucose uptake, interhemispheric metabolic connectivity, and cognitive function in children with unilateral SWS. Interictal 2-deoxy-2[18 F]fluoro-D-glucose (FDG)-PET scans of 27 children with unilateral SWS and mild epilepsy and 27 age-matched control (non-SWS children with epilepsy and normal FDG-PET) were compared using statistical parametric mapping (SPM). Regional FDG-PET abnormalities calculated as SPM(t) scores in the SWS group were correlated with cognitive function (IQ) in left- and right-hemispheric subgroups. Interhemispheric metabolic connectivity between homotopic cortical regions was also calculated. Verbal IQ was substantially (≥10 points difference) higher than non-verbal IQ in 61% of the right- and 71% of the left-hemispheric SWS group. FDG SPM(t) scores in the affected hemisphere showed strong positive correlations with IQ in the left-hemispheric, but not in right-hemispheric SWS group in several frontal, parietal, and temporal cortical regions. Significant positive interhemispheric metabolic connectivity, present in controls, was diminished in the SWS group. In addition, the left-hemispheric SWS group showed inverse metabolic interhemispheric correlations in specific parietal, temporal, and occipital regions. FDG SPM(t) scores in the same regions of the right (unaffected) hemisphere showed inverse correlations with IQ. These findings suggest that left-hemispheric lesions in SWS often result in early reorganization of verbal functions while interfering with ("crowding") their non-verbal cognitive abilities. These cognitive changes are associated with specific metabolic abnormalities in the contralateral hemisphere not directly affected by SWS.

Somatic GNAQ Mutation is Enriched in Brain Endothelial Cells in Sturge-Weber Syndrome.

BACKGROUND: Sturge-Weber syndrome (SWS) is a rare congenital neurocutaneous disorder characterized by facial and extracraniofacial capillary malformations and capillary-venule malformations in the leptomeninges. A somatic mosaic mutation in GNAQ (c.548G>A; p.R183Q) was found in SWS brain and skin capillary malformations. Our laboratory showed endothelial cells in skin capillary malformations are enriched for the GNAQ mutation. The purpose of this study is to determine whether the GNAQ mutation is also enriched in endothelial cells in affected SWS brain. METHODS: Two human SWS brain specimens were fractionated by fluorescence-activated cell sorting into hematopoietic (CD45), endothelial (CD31, VE-Cadherin, and vascular endothelial growth factor receptor 2), and perivascular (platelet-derived growth factor receptor beta) cells and cells negative for all markers. The sorted cell populations were analyzed for GNAQ p.R183Q mutation by droplet digital polymerase chain reaction. SWS patient-derived brain endothelial cells were selected by anti-CD31-coated magnetic beads and cultured in endothelial growth medium in vitro. RESULTS: The GNAQ p.R183Q mutation was present in brain endothelial cells in two SWS specimens, with mutant allelic frequencies of 34.7% and 24.0%. Cells negative for all markers also harbored the GNAQ mutation. The mutant allelic frequencies in these unidentified cells were 9.2% and 8.4%. SWS patient-derived brain endothelial cells with mutant allelic frequencies of 14.7% and 21% survived and proliferated in vitro. CONCLUSIONS: Our study provides evidence that GNAQ p.R183Q mutation is enriched in endothelial cells in SWS brain lesions and thereby reveals endothelial cells as a source of aberrant Gαq signaling. This will help to understand the pathophysiology of SWS, to discover biomarkers for predicting cerebral involvement, and to develop therapeutic targets to prevent neurological impairments in SWS.

Imaging increased glutamate in children with Sturge-Weber syndrome: Association with epilepsy severity.

BACKGROUND: Sturge-Weber syndrome (SWS) is strongly associated with epilepsy. Brain tissue studies have suggested that epileptic activity in SWS is driven by glutamatergic synaptic activity. Here, we used proton magnetic resonance spectroscopic imaging (MRSI) to test if glutamate (GLU) concentrations are increased in the affected hemisphere and if such increases are associated with severity of epilepsy in children with SWS. We also studied the metabolic correlates of MRSI abnormalities, using glucose positron emission tomography (PET) imaging. METHODS: 3T MRI and glucose PET were performed in 10 children (age: 7-78 months) with unilateral SWS and a history of epilepsy. MRSI data were acquired from the affected (ipsilateral) and non-affected (contralateral) hemispheres. GLU, N-acetyl-aspartate (NAA) and creatine (Cr) were quantified in multiple voxels; GLU/Cr and NAA/Cr ratios were calculated and compared to seizure frequency as well as glucose PET findings. RESULTS: The highest GLU/Cr ratios were found in the affected hemisphere in all children except one with severe atrophy. The maximum ipsilateral/contralateral GLU/Cr ratios ranged between 1.0 and 2.5 (mean: 1.6). Mean ipsilateral/contralateral GLU/Cr ratios were highest in the youngest children and showed a strong positive correlation with clinical seizure frequency scores assessed at the time of the scan (r=0.88, p=0.001) and also at follow-up (up to 1 year, r=0.80, p=0.009). GLU increases in the affected hemisphere coincided with areas showing current or previous increases of glucose metabolism on PET in 5 children. NAA/Cr ratios showed no association with clinical seizure frequency. CONCLUSIONS: Increased glutamate concentrations in the affected hemisphere, measured by MRSI, are common in young children with unilateral SWS and are associated with frequent seizures. The findings lend support to the role of excess glutamate in SWS-associated epilepsy.

Lymphatic abnormalities are associated with RASA1 gene mutations in mouse and man.

Mutations in gene RASA1 have been historically associated with capillary malformation-arteriovenous malformation, but sporadic reports of lymphatic involvement have yet to be investigated in detail. To investigate the impact of RASA1 mutations in the lymphatic system, we performed investigational near-infrared fluorescence lymphatic imaging and confirmatory radiographic lymphangiography in a Parkes-Weber syndrome (PKWS) patient with suspected RASA1 mutations and correlated the lymphatic abnormalities against that imaged in an inducible Rasa1 knockout mouse. Whole-exome sequencing (WES) analysis and validation by Sanger sequencing of DNA from the patient and unaffected biological parents enabled us to identify an early-frameshift deletion in RASA1 that was shared with the father, who possessed a capillary stain but otherwise no overt disease phenotype. Abnormal lymphatic vasculature was imaged in both affected and unaffected legs of the PKWS subject that transported injected indocyanine green dye to the inguinal lymph node and drained atypically into the abdomen and into dermal lymphocele-like vesicles on the groin. Dermal lymphatic hyperplasia and dilated vessels were observed in Rasa1-deficient mice, with subsequent development of chylous ascites. WES analyses did not identify potential gene modifiers that could explain the variability of penetrance between father and son. Nonetheless, we conclude that the RASA1 mutation is responsible for the aberrant lymphatic architecture and functional abnormalities, as visualized in the PKWS subject and in the animal model. Our unique method to combine investigatory near-infrared fluorescence lymphatic imaging and WES for accurate phenoptyping and unbiased genotyping allows the study of molecular mechanisms of lymphatic involvement of hemovascular disorders.

Importance of utilizing a sensitive free thyroxine assay in Sturge-Weber syndrome.

Sturge-Weber syndrome has been found to result in hypothalamic-pituitary dysfunction including central hypothyroidism. Because central hypothyroidism is more prevalent in Sturge-Weber syndrome than in the general population, we routinely evaluated thyroid function. Here we describe 5 children with Sturge-Weber syndrome on anticonvulsants and diagnosed with hypothyroidism based on thyroid function testing. All 5 patients were eventually tested utilizing the more accurate free thyroxine equilibrium dialysis assay. Results indicated that only 2 of the 5 patients, who exhibited the most severe symptoms, had true hypothyroidism. This case series demonstrates the benefits of using the free thyroxine by equilibrium dialysis when testing Sturge-Weber syndrome patients on antiepileptic medications. This testing algorithm is more cost-effective and also improves the quality of care by providing an accurate diagnosis more quickly. In addition, we propose consideration of this testing method in any patient taking anticonvulsants, most notably oxcarbazepine.

Cell proliferation and oxidative stress pathways are modified in fibroblasts from Sturge-Weber syndrome patients.

Sturge-Weber syndrome (SWS) is defined by vascular malformations of the face, eye and brain and an underlying somatic mutation has been hypothesized. We employed isobaric tags for relative and absolute quantification (iTRAQ-8plex)-based liquid chromatography interfaced with tandem mass spectrometry (LC-MS/MS) approach to identify differentially expressed proteins between port-wine-derived and normal skin-derived fibroblasts of four individuals with SWS. Proteins were identified that were significantly up- or down-regulated (i.e., ratios >1.2 or <0.8) in two or three pairs of samples (n = 31/972 quantified proteins) and their associated p values reported. Ingenuity pathway analysis (IPA) tool showed that the up-regulated proteins were associated with pathways that enhance cell proliferation; down-regulated proteins were associated with suppression of cell proliferation. The significant toxicologic list pathway in all four observations was oxidative stress mediated by Nrf2. This proteomics study highlights oxidative stress also consistent with a possible mutation in the RASA1 gene or pathway in SWS.

Increased L-[1-11 C] leucine uptake in the leptomeningeal angioma of sturge-weber syndrome: a PET study.

BACKGROUND AND PURPOSE: We used L-[1-(11) C]leucine (LEU) positron emission tomography (PET) to measure amino acid uptake in children with Sturge-Weber syndrome (SWS), and to relate amino acid uptake measures with glucose metabolism. METHODS: LEU and 2-deoxy-2[(18) F]fluoro-D-glucose (FDG) PET were performed in 7 children (age: 5 months-13 years) with unilateral SWS. Asymmetries of LEU uptake in the posterior brain region, underlying the angioma and in frontal cortex, were measured and correlated with glucose hypometabolism. Kinetic analysis of LEU uptake was performed in 4 patients. RESULTS: Increased LEU standard uptake value (SUV, mean: 15.1%) was found in the angioma region in 6 patients, and smaller increases in LEU SUV (11.5%) were seen in frontal cortex in 4 of the 6 patients, despite normal glucose metabolism in frontal regions. High LEU SUV was due to both increased tracer transport (3/4 patients) and high protein synthesis rates (2/4). FDG SUV asymmetries in the angioma region were inversely related to LEU SUV asymmetries (r=-.83, P= .042). CONCLUSIONS: Increased amino acid uptake in the angioma region and also in less affected frontal regions may provide a marker of pathological mechanisms contributing to chronic brain damage in children with SWS.

A perfusion-metabolic mismatch in Sturge-Weber syndrome: a multimodality imaging study.

OBJECTIVE: We combined perfusion weighted imaging (PWI) with 2-deoxy-2[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET) to study the relationship between regional metabolic and perfusion abnormalities and their clinical correlates in children with Sturge-Weber syndrome (SWS). METHODS: Fifteen children (age: 0.9-10 years) with unilateral SWS underwent high-resolution PWI and FDG PET prospectively. Regional (lobar) asymmetry indices (AIs) of subcortical white matter (WM) cerebral blood flow (CBF) were correlated with corresponding cortical FDG uptake asymmetries, extent of leptomeningeal vascular malformation and clinical seizure variables. RESULTS: Abnormal cortical glucose metabolism and/or subcortical WM CBF were seen in all lobes affected by vascular malformation and extended to lobes not affected by abnormal pial vessels in 6 patients. Lower CBF was associated with lower cortical glucose metabolism in the temporal, parietal and occipital lobes (p≤0.02). While decreased perfusion was associated with hypometabolism in most cases, increased regional CBF (found in 6 patients) was commonly associated with relatively mild or no hypometabolism. Ten of 24 cerebral lobes with normal glucose metabolism in the affected hemisphere showed abnormal perfusion. High seizure frequency was associated with severe parieto-occipital hypoperfusion (p≤0.03), while long duration of epilepsy was related to frontal lobe hypometabolism (p=0.015). CONCLUSIONS: Regional perfusion and cortical metabolic abnormalities can extend beyond lobes affected by leptomeningeal vascular malformations and are related to epilepsy in SWS. Despite a general correlation between perfusion and metabolism, increased WM perfusion with preserved cortical metabolism in overlying cortex is a common pattern of a perfusion/metabolic mismatch. This may represent a disease stage where cortical function is preserved while increased WM perfusion provides collateral drainage of cortex via the deep vein system.

Clinical outcomes in bilateral Sturge-Weber syndrome.

Approximately 15% of patients with Sturge-Weber syndrome demonstrate bilateral intracranial involvement, and the prognosis of these patients is considered particularly unfavorable. We reviewed the clinical and neuroimaging features of patients with Sturge-Weber syndrome and bilateral intracranial involvement. Seizure variables, the presence of hemiparesis, and the degree of developmental impairment at most recent follow-up were compared with imaging abnormalities. Of 110 Sturge-Weber syndrome patients, 14 demonstrated bilateral brain involvement, with an asymmetric pattern on glucose metabolism positron emission tomography. Although most patients manifested frequent seizures initially, associated with frontal hypometabolism on positron emission tomography, six (43%) had achieved good seizure control during follow-up. Bilateral frontal hypometabolism was associated with severe developmental impairment. Two children with bitemporal hypometabolism exhibited autistic features. Hemiparesis was associated with superior frontal (motor cortex) hypometabolism. Three patients underwent resective surgery, resulting in improved seizure control and developmental outcomes. The severity of neurologic complications and clinical course depend on the extent of cortical dysfunction in bilateral Sturge-Weber syndrome. Bilateral frontal and temporal hypometabolism is associated with poor developmental outcomes. Good seizure control and only mild/moderate developmental impairment can be achieved in about 50% of patients with bilateral Sturge-Weber syndrome, with or without resective surgery.

Transient focal cortical increase of interictal glucose metabolism in Sturge-Weber syndrome: implications for epileptogenesis.

PURPOSE: To investigate clinical correlates and longitudinal course of interictal focal cortical glucose hypermetabolism in children with Sturge-Weber syndrome (SWS). METHODS: Fluorodeoxyglucose positron emission tomography (FDG-PET) scans of 60 children (age range 3 months to 15.2 years) with Sturge-Weber syndrome and epilepsy were assessed prospectively and serially for focal hypo- or hypermetabolism. Thirty-two patients had two or more consecutive PET scans. Age, seizure variables, and the occurrence of epilepsy surgery were compared between patients with and without focal hypermetabolism. The severity of focal hypermetabolism was also assessed and correlated with seizure variables. KEY FINDINGS: Interictal cortical glucose hypermetabolism, ipsilateral to the angioma, was seen in nine patients, with the most common location in the frontal lobe. Age was lower in patients with hypermetabolism than in those without (p=0.022). In addition, time difference between the onset of first seizure and the first PET scan was much shorter in children with increased glucose metabolism than in those without (mean: 1.0 vs. 3.6 years; p=0.019). Increased metabolism was transient and switched to hypometabolism in all five children where follow-up scans were available. Focal glucose hypermetabolism occurred in 28% of children younger than the age of 2 years. Children with transient hypermetabolism had a higher rate of subsequent epilepsy surgery as compared to those without hypermetabolism (p=0.039). SIGNIFICANCE: Interictal glucose hypermetabolism in young children with SWS is most often seen within a short time before or after the onset of first clinical seizures, that is, the presumed period of epileptogenesis. Increased glucose metabolism detected by PET predicts future demise of the affected cortex based on a progressive loss of metabolism and may be an imaging marker of the most malignant cases of intractable epilepsy requiring surgery in SWS.

Magnetic resonance spectroscopic imaging detects abnormalities in normal-appearing frontal lobe of patients with Sturge-Weber syndrome.

BACKGROUND: In Sturge-Weber syndrome (SWS), structural MRI abnormalities are most common in the posterior brain regions. Frontal lobe involvement increases the risk of motor impairment. The goal of this study was to determine whether Magnetic Resonance Spectroscopic Imaging (MRSI) can improve detection of frontal lobe involvement in children with SWS. METHODS: Sixteen children (age: .9-10.4 years) with unilateral SWS underwent MRI with MRSI prospectively. N-acetyl-aspartate (NAA) and choline asymmetries in the posterior and frontal regions were measured. RESULTS: Eight children presented normal-appearing frontal lobes on conventional MRI, but 7 of them showed abnormal NAA and/or choline content in the frontal lobe of the affected hemisphere. Lower frontal lobe gray matter NAA was associated with earlier onset of seizures (r= .76; P= .04) and impaired motor function (r=-.89, P < .001). Frontal NAA asymmetry was an independent predictor of motor function in a regression analysis (P= .01) CONCLUSION: MRSI is more sensitive than conventional structural MRI for detection of frontal lobe involvement in SWS. Decreased frontal lobe NAA is an excellent predictor of motor functions. Thus, MRSI can provide complementary information for the assessment of normal-appearing brain regions, and may assist prognosis evaluation in children with SWS.

Increased visual cortex glucose metabolism contralateral to angioma in children with Sturge-Weber syndrome.

Functional reorganization after focal brain injury can lead to altered cerebral metabolism of glucose. Sturge-Weber syndrome (SWS) with unilateral involvement is a clinical model for evaluating the effects of early focal brain injury on brain metabolism and function. In this study, 2-deoxy-2[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET) was used to measure glucose metabolism in cortex and basal ganglia, both ipsilateral and contralateral to the angioma, in 17 children (eight males, nine females; age range 1y 8mo-10y 4mo; mean 5y 7mo [SD 2y 11mo]) with unilateral SWS and epilepsy. The PET findings were compared with those of a control group of 11 age-matched children (four males, seven females; age range 3y-10y 8mo; mean 6y [SD 2y 10mo]) with partial epilepsy but normal magnetic resonance imaging and PET scans. In the SWS group, visual and parietal cortex showed decreased glucose metabolism on the side of the angioma (p=0.001) but increased metabolism on the contralateral side (p=0.002). In particular, glucose metabolism was very high in contralateral visual cortex of childrenwith SWS, showing severe occipital hypometabolism on the side of the angioma. Eight children with visual field defect showed increased metabolism in the contralateral visual cortex (p=0.012). These findings indicate that early, severe unilateral cortical damage in SWS may induce increased glucose metabolism in the contralateral visual cortex, probably reflecting reorganization.

Multimodality imaging of cortical and white matter abnormalities in Sturge-Weber syndrome.

BACKGROUND AND PURPOSE: Impaired cortical venous outflow and abnormal deep venous collaterals are common in Sturge-Weber syndrome (SWS), but their relation to brain metabolism and function is poorly understood. In this study, advanced MR imaging techniques, such as susceptibility-weighted imaging (SWI) and diffusion tensor imaging (DTI), were applied in conjunction with positron-emission tomography (PET), to assess cortical and white matter structural abnormalities and their relation to cortical glucose metabolism and cognitive functions in children with unilateral SWS. MATERIALS AND METHODS: Thirteen children (age, 1.5-10.3 years) with unilateral SWS underwent MR imaging with SWI and DTI, glucose metabolism PET, and comprehensive neuropsychologic assessment prospectively. The MR imaging and PET images were coregistered and cortical regions showing decreased glucose metabolism were compared with locations of SWI signal intensity abnormalities, changes in white matter water diffusion, and cognitive functions. RESULTS: SWI detected both cortical abnormalities (n=8) and deep transmedullary veins (n=9), including those in young children with no cortical SWI signal intensity changes. These veins were often located under cortex adjacent to hypometabolic regions. DTI showed abnormal water diffusion both under hypometabolic cortex and in adjacent white matter with collateral veins. Cognitive dysfunction was associated with abnormal water diffusion in the posterior white matter. CONCLUSIONS: Transmedullary venous collaterals can be detected early by SWI and persist in white matter adjacent to damaged cortex in children with SWS. Microstructural white matter damage extends beyond cortical abnormalities and may contribute to cognitive impairment. SWI and DTI can be incorporated into clinical MR imaging acquisitions to objectively assess microstructural abnormalities at different stages of SWS.

Evolution of cortical metabolic abnormalities and their clinical correlates in Sturge-Weber syndrome.

BACKGROUND: The natural course of Sturge-Weber syndrome (SWS) is poorly understood, although neurological symptoms are often progressive. AIMS: To track longitudinal changes in brain glucose metabolism measured with positron emission tomography (PET) and their relation to clinical changes during the early course of SWS. METHODS: Fourteen children (age 3 months to 3.9 years at enrollment) with SWS and unilateral leptomeningeal angioma underwent two consecutive glucose metabolism PET scans with a mean follow-up time of 1.2 years. Longitudinal changes of the extent of cortical glucose hypometabolism on the angioma side were measured and correlated with age, clinical seizure frequency and hemiparesis. RESULTS: An increase in the size of the hypometabolic cortex was seen in 6 children, coinciding with an age-related increase in cortical glucose metabolism measured in unaffected contralateral cortex. These 6 patients were younger both at the initial (mean age 0.75 vs. 2.8 years; p<0.001) and the second scan (mean age 1.8 vs. 4.2 years; p=0.001) than those with no change in the extent of hypometabolic cortex (n=6). The area of cortical hypometabolism decreased in the two remaining children, and this was associated with resolution of an initial hemiparesis in one of them. Seizure frequency between the two scans was higher in children who showed progressive enlargement of cortical hypometabolism, as compared to those with no progression (p=0.008). CONCLUSIONS: In SWS, detrimental metabolic changes occur before 3 years of age coinciding with a sharp increase of developmentally regulated cerebral metabolic demand. Progressive hypometabolism is associated with high seizure frequency in these children. However, metabolic abnormalities may remain limited or even partially recover later in some children with well-controlled seizures. Metabolic recovery accompanied by neurological improvement suggests a window for therapeutic intervention in children with unilateral SWS.