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

Arterial spin-labeled (ASL) perfusion in children with Sturge-Weber syndrome: a retrospective cross-sectional study

PURPOSE

Sturge-Weber syndrome (SWS) is a developmental disorder with venous hypertension and associated tissue responses including pial angiomatosis, cortical calcifications, and cerebral atrophy. Arterial spin-labeled (ASL) perfusion is an advanced MR sequence which can assess perfusion, without the need for contrast. We systematically evaluated the potential benefits of using ASL in Sturge-Weber syndrome, to determine the extent of intracranial perfusion abnormality and stage of disease, relevant for prognostication and surgical planning.

METHODS

Two pediatric neuroradiologists retrospectively evaluated ASL perfusion imaging of 31 children with confirmed SWS and recorded the presence of hyper-perfusion, hypo-perfusion, or normal perfusion. The presence and distribution of ASL abnormality were compared against the presence and side of atrophy/calcification and pial angiomatosis on standard MR sequences.

RESULTS

Thirty-one children (52% female, median age 16.7 months) with SWS had ASL imaging. Seven (23%) had hyper-perfusion, 15 (48%) had hypo-perfusion, and 9 (29%) had no perfusion abnormalities. ASL perfusion abnormality matched the location of SWS findings on conventional imaging in 86% (19/22). ASL demonstrated statistically significant increased perfusion in the early stage of the disease and decreased perfusion when there was atrophy. The parietal lobe was involved in 86% of cases.

CONCLUSION

ASL perfusion imaging is an advanced technique which may contribute to earlier diagnosis and more accurate prognostication of Sturge-Weber syndrome, helping guide management and potential surgical planning.

Spontaneous Resolution of Drug-Resistant Epilepsy in Patients with Sturge-Weber Syndrome

Introduction: Sturge-Weber syndrome (SWS) is often associated with drug resistant epilepsy. The literature is unclear as to how often these patients can be weaned off of antiepileptic drugs (AEDs) to become seizure-free. Case Description: We describe two patients with SWS. After initial treatment with various AEDs, breakthrough seizures still occurred. However, after periods with no seizure activity, they were weaned off of their medications. They have been off for 4 and 3 years and seizure-free for 13 and 12 years, respectively. No surgical procedure was necessary. Conclusion: We hypothesize that spontaneous involution or pathological disconnection of the vascular malformations might underly the patients’ recovery. The initial aggressive therapy, close follow-up, choice of AEDs, or natural evolution of the disease may have played a role in their recovery. Therefore, in patients with SWS and lesional structural epilepsy, medication freedom is possible and invasive management options including surgery should be discussed carefully.

Arterial Spin-Labeling Perfusion Imaging in the Early Stage of Sturge-Weber Syndrome

BACKGROUND AND PURPOSE

Sturge-Weber syndrome is a rare congenital neuro-oculo-cutaneous disorder. Although the principal mechanism of Sturge-Weber syndrome is characterized by a leptomeningeal vascular malformation, few data regarding perfusion abnormalities of the brain parenchyma are available. Therefore, the aim of this study was to assess the diagnostic performance of arterial spin-labeling perfusion imaging in the early stage of Sturge-Weber syndrome before 1 year of age until 3.5 years of age. We hypothesized that a leptomeningeal vascular malformation has very early hypoperfusion compared with controls with healthy brains.

MATERIALS AND METHODS

We compared the CBF using arterial spin-labeling perfusion imaging performed at 3T MR imaging in the brain parenchymal regions juxtaposing the leptomeningeal vascular malformation in patients with Sturge-Weber syndrome (n = 16; 3.5 years of age or younger) with the corresponding areas in age-matched controls with healthy brains (n = 58). The analysis was performed following two complementary methods: a whole-brain voxel-based analysis and a visual ROI analysis focused on brain territory of the leptomeningeal vascular malformation.

RESULTS

Whole-brain voxel-based comparison revealed a significant unilateral decrease in CBF localized in the affected cortices of patients with Sturge-Weber syndrome (P < .001). CBF values within the ROIs in patients with Sturge-Weber syndrome were lower than those in controls (in the whole cohort: median, 25 mL/100g/min, versus 44 mL/100g/min; P < .001). This finding was also observed in the group younger than 1 year of age, emphasizing the high sensitivity of arterial spin-labeling in this age window in which the diagnosis is difficult.

CONCLUSIONS

Arterial spin-labeling perfusion imaging in the early stage of Sturge-Weber syndrome can help to diagnose the disease by depicting a cortical hypoperfusion juxtaposing the leptomeningeal vascular malformation.

A review of the natural history of Sturge-Weber syndrome through adulthood

BACKGROUND

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder caused by a somatic mutation in the GNAQ gene, leading to capillary venous malformations with neurological, ocular, and cutaneous abnormalities. Descriptions of adult and elderly patients with SWS are scarce compared to those of neonates or children.

METHODS

We reviewed clinical, neuro-radiological and electroencephalographical findings of adult patients diagnosed with SWS, treated in our tertiary center for rare epilepsies.

RESULTS

Ten adult patients were identified with a median age of 48 years at inclusion. All patients had seizures, with features of temporal lobe involvement for five patients. One patient presented typical drug-resistant mesial temporal seizures with ipsilateral hippocampal sclerosis and leptomeningeal enhancement, and was treated surgically. Other patients presented typical neurological and brain imaging features found in SWS. One patient without visible leptomeningeal angioma or brain calcifications presented neurological symptoms (tonic-clonic generalized seizures) for the first time at the age of 56. Two of the oldest patients in our cohort with supratentorial leptomeningeal angioma displayed contralateral cerebellar atrophy, consistent with crossed cerebellar diaschisis. Over 70 years of follow-up data were available for one patient whose epilepsy started at the age of 6 months, offering a vast overview of the course of SWS, in particular the onset of dementia and contralateral micro-bleeds in relation to the leptomeningeal angioma.

CONCLUSION

The long follow-up of our cohort allows for a description of the course of SWS and a characterization of uncommon neurological features in adult and elderly patients.

Focal lesionectomy as surgical treatment of epilepsy in patients with Sturge-Weber syndrome: a case-based systematic review and meta-analysis

OBJECTIVE

Sturge-Weber syndrome (SWS) is a rare neurocutaneous disorder presenting mostly with a facial port-wine stain and leptomeningeal angiomatosis. More than 85% of the patients are affected by epilepsy by the age of 2 years. Seizure and symptom control is the focus of SWS treatment, since no causal therapy exists yet. For pharmacologically intractable epilepsy, surgery is a treatment option. The aim of this systematic review and meta-analysis was to provide an overview of the literature regarding lesionectomy in SWS with a focus on seizure outcome, complications, and motor and cognitive development.

METHODS

The PubMed and Embase databases were searched using a systematic search strategy to identify studies on SWS from their inception until 2021. Two independent researchers assessed the studies for inclusion and quality. Outcome measures were seizure outcome, postoperative complications, and motor and cognitive development. Thereafter, a systematic review was conducted, and a meta-analysis was performed for all included cohort studies. Risk of bias was assessed using the Newcastle-Ottawa Scale. Forest plots have been generated for all outcomes; risk ratio was used for pooled outcomes. A p value < 0.05 was considered as statistically significant.

RESULTS

After removal of duplicates, the authors screened 439 articles, of which 9 articles with 150 patients were included. Our case and 5 case reports and 4 retrospective cohort studies were included for systematic review. The latter 4 studies qualified for the meta-analysis. In these 4 articles, 144 patients received surgical treatment: 81 (56%) underwent focal lesionectomy and 63 (44%) hemispherectomy. Pooled outcome analysis for postoperative favorable seizure outcome showed a nonsignificant difference between lesionectomy and hemispherectomy (69.2% vs 87.3%; RR 0.73, 95% CI 0.50–1.08; t = −2.56, p = 0.08). Lesionectomy showed a significantly lower rate for developmental delay and postoperative hemiparesis in comparison with hemispherectomy (29.8% vs 76.3%; RR 0.41, 95% CI 0.28–0.59; z = −4.77, p < 0.0001 and 18.1% vs 100%; RR 0.11, 95% CI 0.06–0.21; z = −6.58, p < 0.0001, respectively).

CONCLUSIONS

Based on the limited literature available, lesionectomy leads to a nonsignificant lower seizure control rate, while postoperative developmental or motor deficits are significantly lower compared with hemispherectomy. Therefore, focal lesionectomy remains a valid alternative to hemispherectomy in SWS with a clearly localized epileptogenic area; however, individual case-based decisions in a specialized multidisciplinary team are of paramount importance.

Cerebral venous collaterals: A new fort for fighting ischemic stroke?

Stroke therapy has entered a new era highlighted by the use of endovascular therapy in addition to intravenous thrombolysis. However, the efficacy of current therapeutic regimens might be reduced by their associated adverse events. For example, over-reperfusion and futile recanalization may lead to large infarct, brain swelling, hemorrhagic complication and neurological deterioration. The traditional pathophysiological understanding on ischemic stroke can hardly address these occurrences. Accumulating evidence suggests that a functional cerebral venous drainage, the major blood reservoir and drainage system in brain, may be as critical as arterial infusion for stroke evolution and clinical sequelae. Further exploration of the multi-faceted function of cerebral venous system may add new implications for stroke outcome prediction and future therapeutic decision-making. In this review, we emphasize the anatomical and functional characteristics of the cerebral venous system and illustrate its necessity in facilitating the arterial infusion and maintaining the cerebral perfusion in the pathological stroke content. We then summarize the recent critical clinical studies that underscore the associations between cerebral venous collateral and outcome of ischemic stroke with advanced imaging techniques. A novel three-level venous system classification is proposed to demonstrate the distinct characteristics of venous collaterals in the setting of ischemic stroke. Finally, we discuss the current directions for assessment of cerebral venous collaterals and provide future challenges and opportunities for therapeutic strategies in the light of these new concepts.

Reliability and Clinical Correlation of Transcranial Doppler Ultrasound in Sturge-Weber Syndrome

BACKGROUND

The reproducibility of transcranial Doppler (TCD) ultrasound measurements in Sturge-Weber syndrome (SWS) and TCD's ability to predict neurological progression is unknown.

METHODS

In 14 individuals with SWS, TCD measured mean flow velocity, pulsatility index, peak systolic velocity, and end-diastolic velocity in the middle, posterior, and anterior cerebral arteries of the affected and unaffected hemisphere. TCD was performed either once (n = 5) or twice in one day (n = 9). We assessed the reproducibility of the measurements performed twice on the same day on subjects and compared the TCD measurements to previously published age-matched controls. Clinically obtained neuroimaging was scored for extent and severity of SWS brain involvement. Patients were prospectively assigned SWS neuroscores.

RESULTS

Middle cerebral artery velocity (r = 0.79, P = 0.04, n = 7), posterior cerebral artery velocity (r = 0.90, P = 0.04, n = 5), and anterior cerebral artery pulsatility index (r = 0.82, P = 0.02, n = 7) were reproducible TCD measurements comparing same-day percent side-to-side differences. In subjects with SWS, affected and unaffected mean peak systolic velocity and end-diastolic velocity in the middle, posterior, and anterior cerebral arteries were globally lower compared with age-matched control subjects. Subjects with the lowest affected middle cerebral artery velocity had the greatest worsening in the total neurological score between time 1 and 2 (r = -0.73, P = 0.04, n = 8) and the most severe magnetic resonance imaging involvement of the affected frontal lobe (r = -0.82, P = 0.007, n = 9).

CONCLUSIONS

TCD may be a reliable measure with potential clinical value, indicating that blood flow may be globally decreased in SWS patients with unilateral brain involvement.

Epileptogenesis in neurocutaneous disorders with focus in Sturge Weber syndrome

Epilepsy is a major morbidity in Sturge Weber syndrome, a segmental vascular neurocutaneous disorder classically associated with facial angiomas, glaucoma, and leptomeningeal capillary-venous type vascular malformations. The extent of the latter correlates with neurological outcome. Post-zygotic mosaicism for the activating mutation p.R183Q of the GNAQ gene has been identified as the major cause.  GNAQ encodes for an alpha subunit of a heterotrimeric G protein critical to blood vessel development. The earlier the timing of the mutation in development, the more severe the involvement, e.g. from isolated port-wine stains to the full syndrome. The strongest predictors of adverse outcomes are MRI and the presence of angiomas involving any part of the forehead, delineated inferiorly from the outer canthus of the eye to the top of the ear, and including the upper eyelid.  The neurological course may be progressive and the typical constellation of symptoms is focal onset seizures, hemiparesis, headache, stroke-like episodes, behavior problems, intellectual disability, and visual field deficits. Antiseizure medications are effective in about half of patients. The presence of localized seizures, focal neurological deficits, and drug resistant epilepsy indicate epilepsy surgical evaluation. Earlier seizure onset, i.e. before six months of age, is associated with a more severe course with significant residual deficits. Factors contributing to epileptogenesis include decreased brain tissue perfusion due to abnormal venous drainage, anoxic injury contributing to cerebral calcification, breakdown of the blood-brain barrier, and the presence of developmental cortical malformations. Pre-symptomatic prophylactic treatment may be a future option to modify the course of the disease including the associated epileptogenesis.

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.

Neuroimaging of phakomatoses: overview and advances

The phakomatoses are disorders characterized by multiple hamartomas and other congenital malformations affecting mainly the skin and the central and peripheral nervous systems. Many affected individuals have an increased genetic susceptibility to develop malignancies. Imaging is central in the diagnosis of many of the phakomatoses, and MRI is used as a screening tool in many children with known neurocutaneous disorders. This manuscript addresses the three most common (neurofibromatosis type 1, tuberous sclerosis complex, Sturge-Weber syndrome) and focuses on pathophysiological and radiologic insights that have emerged in the last few years.

New vascular classification of port-wine stains: improving prediction of Sturge-Weber risk

BACKGROUND

Facial port-wine stains (PWSs) are usually isolated findings; however, when associated with cerebral and ocular vascular malformations they form part of the classical triad of Sturge-Weber syndrome (SWS).

OBJECTIVES

To evaluate the associations between the phenotype of facial PWS and the diagnosis of SWS in a cohort with a high rate of SWS.

METHODS

Records were reviewed of all 192 children with a facial PWS seen in 2011-13. Adverse outcome measures were clinical (seizures, abnormal neurodevelopment, glaucoma) and radiological [abnormal magnetic resonance imaging (MRI)], modelled by multivariate logistic regression.

RESULTS

The best predictor of adverse outcomes was a PWS involving any part of the forehead, delineated at its inferior border by a line joining the outer canthus of the eye to the top of the ear, and including the upper eyelid. This involves all three divisions of the trigeminal nerve, but corresponds well to the embryonic vascular development of the face. Bilateral distribution was not an independently significant phenotypic feature. Abnormal MRI was a better predictor of all clinical adverse outcome measures than PWS distribution; however, for practical reasons guidelines based on clinical phenotype are proposed.

CONCLUSIONS

Facial PWS distribution appears to follow the embryonic vasculature of the face, rather than the trigeminal nerve. We propose that children with a PWS on any part of the 'forehead' should have an urgent ophthalmology review and a brain MRI. A prospective study has been established to test the validity of these guidelines.

Patterns and pathways of calcification in the developing brain

AIM

To determine specific cell types and pathways involved in calcification of the developing brain.

METHOD

We examined the detailed histopathology of samples from 28 autopsied brains aged from 22 weeks' gestation to 14 years. The samples were selected because they showed calcification associated with a range of different diseases. Samples were examined with routine stains as well as stains to show calcification and specific markers for endothelium and macrophages.

RESULTS

Our observations indicate that calcification develops via two main pathways: dystrophic and vascular. Dystrophic calcification results from membrane disruption and uncontrolled calcium entry into necrotic (dead) cells in ischaemia and infections. Vascular calcification appears to be initiated in protein globules, sometimes intracellular, but outside the endothelium of small vessels. One case with mutation of the occludin gene, implicating impaired endothelial integrity, showed this pattern, but identical vascular calcification was seen in other conditions, including Sturge-Weber syndrome. Another form of vascular calcification involved the adventitia of arteries; the endothelium was always spared.

INTERPRETATION

Calcification in the developing brain that is not associated with tissue necrosis is initiated in cells associated with blood vessels. Calcium incrustation of blood vessels imposes rigidity, reduced vascular compliance, and altered permeability. This would explain associated atrophy, gliosis, and (in the developing brain) malformations of the cortex. Our findings suggest that pericytes initiate non-dystrophic brain calcification, but further studies are needed to explore this possibility.

Polymicrogyria: pathology, fetal origins and mechanisms

Polymicrogyria (PMG) is a complex cortical malformation which has so far defied any mechanistic or genetic explanation. Adopting a broad definition of an abnormally folded or festooned cerebral cortical neuronal ribbon, this review addresses the literature on PMG and the mechanisms of its development, as derived from the neuropathological study of many cases of human PMG, a large proportion in fetal life. This reveals the several processes which appear to be involved in the early stages of formation of polymicrogyric cortex. The most consistent feature of developing PMG is disruption of the brain surface with pial defects, over-migration of cells, thickening and reduplication of the pial collagen layers and increased leptomeningeal vascularity. Evidence from animal models is consistent with our observations and supports the notion that disturbance in the formation of the leptomeninges or loss of their normal signalling functions are potent contributors to cortical malformation. Other mechanisms which may lead to PMG include premature folding of the neuronal band, abnormal fusion of adjacent gyri and laminar necrosis of the developing cortex. The observation of PMG in association with other and better understood forms of brain malformation, such as cobblestone cortex, suggests mechanistic pathways for some forms of PMG. The role of altered physical properties of the thickened leptomeninges in exerting mechanical constraints on the developing cortex is also considered.