Tuberous sclerosis complex with an unruptured intracranial aneurysm: manifestations of contiguous gene syndrome

Brachial and subclavian arteries aneurysms due to tuberous sclerosis complex mechanisms - case report and literature review

INTRODUCTION

Tuberous sclerosis complex (TSC) is a rare autosomal dominant condition characterized by cutaneous, cerebral, and other multiorgan involvement. Aneurysms due to TSC pathogenic mechanism are rarely present, mainly aortic, renal, or intracranial and very few associated with peripheral circulation. A TSC patient, aged 31 years, who developed brachial and subclavian arteries aneurysms is presented. The question of a random association of the aneurysms with TSC versus aneurysms within pathogenic released mammalian target of rapamycin (mTOR) pathway effect was raised.

CASE PRESENTATION

Patient's file, available from the age of six months, was analyzed for demonstration of the TSC diagnosis. Patient was examined, and cerebral magnetic resonance imaging (MRI) was repeated. Surgery and angiographic reports and images were reviewed. Pathology of the aneurysmal wall available from surgery was reexamined and special stainings and immunohistochemistry markers were applied. Genetic characterization of the patient was performed. Definite TSC was diagnosed based on major criteria [ungual fibromas, shagreen patch, cortical tubers, subependymal nodules (SENs), subependymal giant cell astrocytoma (SEGA)], minor criteria (confetti skin lesions, dental enamel pits, gingival fibromas), genetic result showing heterozygous variant in exon 8 of TSC1 gene (c.733C>T-p.Arg245*). Pathology analysis revealed markedly thickened aneurysmal wall due to smooth muscle cells (SMCs) proliferation in media and neoformation vessels with similar characteristics in the aneurysmal wall.

DISCUSSIONS AND CONCLUSIONS

This is a rare case with aneurysms related to TSC, with an exceptional peripheral localization. Pathology exam is the key investigation in demonstrating the TSC-related pathogenic mechanism. A literature review showed 73 TSC cases presenting aneurysms published until now.

Intracranial aneurysms in patients with tuberous sclerosis complex: a systematic review

OBJECTIVE

Tuberous sclerosis complex (TSC) is a rare multisystem genetic disease. Arterial wall developmental disorders, such as aneurysms, in association with TSC have been well described for extracranial vasculature. The characteristics of intracranial aneurysms (IAs) in TSC have not previously been addressed in the literature. This systematic review was performed to identify and assess the distinct characteristics of IAs in patients with TSC.

METHODS

The authors searched PubMed, Scopus, and Web of Science for publications describing cases of TSC and IA reported before August 7, 2018. They also report 2 cases of IAs in TSC patients treated at their own institution.

RESULTS

Thirty-three TSC patients with a total of 42 IAs were included in this review. Three individuals presented with subarachnoid hemorrhage. The IAs were large or giant in 57.1% and fusiform in 45.2% of the cases. Most of the IAs (61.9%, 26 of 42) originated from the internal carotid artery. There was a higher prevalence of pediatric cases (66.7%) and male patients (63.6%, 21 of 32 individuals with known sex) among the collected series.

CONCLUSIONS

TSC patients with IAs are characterized with a higher proportion of large/giant and fusiform IAs and young age, suggesting rapid aneurysmal growth. Furthermore, there is a distinct location pattern of IAs and an inverse sex ratio than in the healthy population. Large population-based patient registers are required to improve the understanding of epidemiology and pathophysiology of IA formation in TSC.

Genetic basis of intracranial aneurysm formation and rupture: clinical implications in the postgenomic era

OBJECTIVE

Despite the prevalence and impact of intracranial aneurysms (IAs), the molecular basis of their pathogenesis remains largely unknown. Moreover, there is a dearth of clinically validated biomarkers to efficiently screen patients with IAs and prognosticate risk for rupture. The aim of this study was to survey the literature to systematically identify the spectrum of genetic aberrations that have been identified in IA formation and risk of rupture.

METHODS

A literature search was performed using the Medical Subject Headings (MeSH) system of databases including PubMed, EMBASE, and Google Scholar. Relevant studies that reported on genetic analyses of IAs, rupture risk, and long-term outcomes were included in the qualitative analysis.

RESULTS

A total of 114 studies were reviewed and 65 were included in the qualitative synthesis. There are several well-established mendelian syndromes that confer risk to IAs, with variable frequency. Linkage analyses, genome-wide association studies, candidate gene studies, and exome sequencing identify several recurrent polymorphic variants at candidate loci, and genes associated with the risk of aneurysm formation and rupture, including ANRIL (CDKN2B-AS1, 9p21), ARGHEF17 (11q13), ELN (7q11), SERPINA3 (14q32), and SOX17 (8q11). In addition, polymorphisms in eNOS/NOS3 (7q36) may serve as predictive markers for outcomes following intracranial aneurysm rupture. Genetic aberrations identified to date converge on posited molecular mechanisms involved in vascular remodeling, with strong implications for an associated immune-mediated inflammatory response.

CONCLUSIONS

Comprehensive studies of IA formation and rupture have identified candidate risk variants and loci; however, further genome-wide analyses are needed to identify high-confidence genetic aberrations. The literature supports a role for several risk loci in aneurysm formation and rupture with putative candidate genes. A thorough understanding of the genetic basis governing risk of IA development and the resultant aneurysmal subarachnoid hemorrhage may aid in screening, clinical management, and risk stratification of these patients, and it may also enable identification of putative mechanisms for future drug development.

TSC2/PKD1 contiguous gene syndrome, with emphasis on a case with an atypical mild polycystic kidney phenotype and a novel genetic variant

About 80% of patients with tuberous sclerosis complex (TSC) present renal involvement, usually as angiomyolipomas followed by cystic disease. An early diagnosis of polycystic kidney disease (PKD) in such patients is frequently related to the TSC2/PKD1 contiguous gene syndrome (PKDTS). Molecular confirmation of PKDTS is important for a prompt diagnosis, which can be complicated by the phenotypic heterogeneity of PKD and the absence of a clear phenotype-genotype correlation. Herein, we report three PKDTS pediatric patients. The case 3 did not present a classic PKDTS phenotype, having only one observable cyst on renal ultrasound at age 4 and multiple small cysts on magnetic resonance imaging at age 15. In this patient, chromosomal microarray analysis showed a gross deletion of 230.8kb that involved TSC2, PKD1 and 13 other protein-coding genes, plus a heterozygous duplication of a previously undescribed copy number variant of 242.9kb that involved six protein-coding genes, including SSTR5, in the 16p13.3 region. Given the observations that the case 3 presented the mildest renal phenotype, harbored three copies of SSTR5, and the reported inhibition of cystogenesis (specially in liver) observed with somatostatin analogs in some patients with autosomal dominant PKD, it can be hypothesized that other genetic factors as the gene dosage of SSTR5 may influence the PKD phenotype and the progression of the disease; however, future work is needed to examine this possibility.

A Review of the Genetics of Intracranial Berry Aneurysms and Implications for Genetic Counseling

Here we review the current understanding of the genetic architecture of intracranial berry aneurysms (IBA) to aid in the genetic counseling of patients at risk for this condition. The familial subtype of IBA, familial intracranial aneurysms (FIA), is associated with increased frequency of IBA, increased risk of rupture, and increased morbidity and mortality after rupture. Family history is the strongest predictor for the development of IBA. However, a genetic test is not yet available to assess risk within a family. Studies using linkage analysis, genome-wide association, and next-generation sequencing have found several candidate loci and genes associated with disease onset, but have not conclusively implicated a single gene. In addition to family history, a separate or concurrent diagnosis of autosomal dominant polycystic kidney disease is a strong genetic risk factor for IBA formation. We also discuss the relative risk for developing IBA in several Mendelian syndromes including vascular Ehlers-Danlos syndrome, Marfan syndrome, Neurofibromatosis Type I, and Loeys-Dietz syndrome.

Imaging features of tuberous sclerosis complex with autosomal-dominant polycystic kidney disease: a contiguous gene syndrome

BACKGROUND

Genes for tuberous sclerosis complex (TSC) type 2 and autosomal-dominant polycystic kidney disease (ADPKD) type 1 are both encoded over a short segment of chromosome 16. When deletions involve both genes, an entity known as the TSC2/ADPKD1 contiguous gene syndrome, variable phenotypes of TSC and ADPKD are exhibited. This syndrome has not been reviewed in the radiology literature. Unlike renal cysts in TSC, cystic disease in TSC2/ADPKD1 contiguous gene syndrome results in hypertension and renal failure. A radiologist might demonstrate polycystic kidney disease before the patient develops other stigmata of TSC. Conversely, in patients with known TSC, enlarged and polycystic kidneys should signal the possibility of the TSC2/ADPKD1 contiguous gene syndrome and not simply TSC. Distinguishing these diagnoses has implications in prognosis, treatment and genetic counseling.

OBJECTIVE

To describe the clinical and imaging findings of tuberous sclerosis complex and polycystic kidney disease in seven pediatric patients.

MATERIALS AND METHODS

We retrospectively reviewed renal and brain imaging of children and young adults with genetically proven or high clinical suspicion for TSC2/ADPKD1 contiguous gene syndrome.

RESULTS

We included seven pediatric patients from two referral institutions. Ages ranged from birth to 21 years over the course of imaging. The mean follow-up period was 9 years 8 months (4 years 6 months to 20 years 6 months). No child progressed to end-stage renal disease during this period. Three patients were initially imaged for stigmata of TSC, three for abdominal distension and one for elevated serum creatinine concentration. All patients developed enlarged, polycystic kidneys. The latest available imaging studies demonstrated that in 12 of the 14 kidneys 50% or more of the parenchyma was ultimately replaced by >15 cysts, resulting in significant cortical thinning. The largest cysts in each kidney ranged from 2.4 cm to 9.3 cm. Echogenic lesions were present in 13 of the 14 kidneys, in keeping with angiomyolipomas (ranging from 0.4 cm to 7.8 cm). Compared to the latest imaging studies, the initial studies only demonstrated 64% of kidneys to be borderline or enlarged; the majority had 10 or more cysts and 0-5 echogenic foci in each kidney, measuring 0.8 cm maximally, which were possible angiomyolipomas. Increased cortical echogenicity was observed in eight kidneys, and decreased corticomedullary differentiation was demonstrated in six kidneys. Cortical thinning varied with size and number of cysts.

CONCLUSION

The sonographic renal findings in TSC2/ADPKD1 contiguous gene syndrome progress over time and demonstrate a specific pattern of renal disease different from typical tuberous sclerosis complex. There are multiple cysts at presentation and there is progressive enlargement of the kidneys and of the renal cysts. Because clinical or imaging findings of TSC may not manifest in the young child, the radiologist can be the first to suggest a diagnosis of TSC2/ADPKD1 contiguous gene syndrome and recommend thorough skin examination and imaging in search of TSC findings. The radiologist should be able to suggest the diagnosis of TSC2/ADPKD1 contiguous gene syndrome in children with TSC who have large cysts occupying a large portion of an enlarged kidney. This should not be dismissed as renal cystic disease of TSC or as ADPKD because the diagnosis of TSC2/ADPKD1 contiguous gene syndrome has implications for patient management and prognosis.

Intracranial arteriopathy in tuberous sclerosis complex

Arterial aneurysms, mostly aortic and intracranial, have been occasionally reported in patients with tuberous sclerosis complex. Brain magnetic resonance imaging reports of 404 patients with definite and 16 patients with either probable or possible tuberous sclerosis complex were revised for intracranial aneurysms. Among these patients, brain images of 220 patients with definite and 16 with probable or possible tuberous sclerosis complex were reviewed. Intracranial aneurysms were reported in 3 of 404 patients with a definite diagnosis (0.74%) (general population: 0.35%), including 2 children. A fourth intracranial aneurysm was found in a patient with probable tuberous sclerosis complex, who did not have tubers or subependymal nodules but had clinical manifestations related to neural crest derivatives, including lymphangioleiomyomatosis and extrarenal angiomyolipomas. The authors hypothesize that neural crest dysfunction can have a major role in intracranial arteriopathy in tuberous sclerosis complex, as smooth muscle cells in the forebrain vessels are of neural crest origin.

Coil embolization of an intracranial aneurysm in an infant with tuberous sclerosis complex: A case report and literature review

BACKGROUND

Tuberous sclerosis (TS) is a multiorgan neurocutaneous syndrome. Vascular manifestations are often extracranial. There is a paucity of cases involving TS combined with intracranial aneurysms reported in the literature. As a result, treatment has not been well described.

CASE DESCRIPTION

We report the case of a 13-month-old female infant with a prior diagnosis of TS that was found to have new onset of left eye ptosis, anisocoria, and papillary mydriasis indicative of left third cranial nerve palsy. A magnetic resonance angiogram (MRA) of the brain revealed a left internal carotid artery (ICA) aneurysm. Endovascular embolization was determined to be the best option for treatment. After a successful balloon test occlusion with neuromonitoring, the left internal carotid artery was sacrificed via coil embolization.

CONCLUSIONS

This is only the third case report of endovascular coil embolization of an intracranial aneurysm in an infant with TS. We report no complications during the procedure, and the patient was discharged with resolving left third cranial nerve palsy. Neither surgical nor endovascular outcomes have been well described in the literature. Follow-up on this patient will be useful for establishing protocols of treatment.

Intracranial aneurysms in children aged under 15 years: review of 59 consecutive children with 75 aneurysms

OBJECTIVE

The objective was to review the clinical aspects and therapeutic strategies in a series of aneurysmal vasculopathies seen in children 15 years or under.

METHODS

From our dedicated neurovascular databank of patients, we reviewed 59 consecutive children who had 75 separate lesions.

RESULTS

The children were divided into four age groups: below 2 years (22%), 2-5 years (24%), 6-10 years (24%) and 11-15 years (30%). Thirty-three children had dissecting aneurysms, 2 had chronic post-traumatic aneurysms, 8 had infectious aneurysms and 16 had saccular lesions. Twenty-seven percent of the lesions were in the posterior circulation, and 21% developed on the middle cerebral artery. Most dissecting lesions were encountered in the vertebrobasilar system, while saccular lesions were present mostly in the anterior circulation. Half of all cases presented with haemorrhage. Haemorrhage in patients below 2 years of age was due to dissecting aneurysms, while saccular aneurysms were responsible for haemorrhage in patients above 5 years of age. Five children had familial disease and 9 presented with multiple aneurysms. Forty-eight children were referred to us for treatment. Thirty-two underwent surgical (21.9%), endovascular (62.8%) or combined (9.3%) treatment. Eleven patients were treated conservatively and in 5 patients the aneurysms had spontaneously thrombosed at admission. Overall, complete or partial spontaneous thrombosis was seen in 10 patients (16.9%). Dissecting aneurysms were frequent in children of all ages with either associated thrombosis or arterial tear with repeated acute haemorrhage and poor outcome. Two types of dissection seem identifiable despite the small number of cases collected: acute segmental arterial tear without thrombosis, acute subarachnoid haemorrhage (SAH) and recurrence before 5 years; and subacute focal dissection with partial thrombosis (or mural haematoma), rare SAH and no early recurrence. The former would require aggressive management whereas the latter often do not require interventional approaches. The mortality in our series of aneurysms is low in the treated group (10.42%). The overall tolerance to haemorrhage seems better than in adults, as already stressed in the literature.

CONCLUSION

The multiple etiologies encountered confirm the heterogenous nature of "aneurysms". The variety of treatments used suggests the need to categorise aneurysms into subgroups in sufficient numbers to fully appreciate the behavior of the lesions and make the appropriate therapeutic decisions.