Association of Early MRI Characteristics With Subsequent Epilepsy and Neurodevelopmental Outcomes in Children With Tuberous Sclerosis Complex

BACKGROUND AND OBJECTIVE

Multiple factors have been found to contribute to the high risk of epilepsy in infants with Tuberous Sclerosis Complex (TSC), including evolution of EEG abnormalities, TSC gene mutation and MRI characteristics. The aim of the present prospective multi-center study was to: 1) identify early MRI biomarkers of epilepsy in infants with TSC aged < 6 months and before seizure onset, and 2) associate these MRI biomarkers with neurodevelopmental outcomes at 2 years of age. The study was part of the EPISTOP project.

METHODS

We evaluated brain MRIs performed in infants with TSC younger than 6 months of age. We used harmonized MRI-protocols across centers and children were monitored closely with neuropsychological evaluation, and serial video EEG. MRI characteristics defined as tubers, radial migration lines, white matter abnormalities, cysts, calcifications, subependymal nodules (SEN) and subependymal giant cell astrocytoma (SEGA) were visually evaluated and lesions were detected semi-automatically. Lesion to brain volume ratios were calculated and associated with epilepsy and neurodevelopmental outcomes at two years.

RESULTS

Lesions were assessed on MRIs from 77 TSC infants, 62 MRIs were sufficient for volume analysis. The presence of tubers and higher tuber-brain ratios were associated with the development of clinical seizures, independently of TSC gene mutation and preventive treatment. Furthermore, higher tuber-brain ratios were associated with lower cognitive and motor development quotients at two years, independently of TSC gene mutation and presence of epilepsy.

DISCUSSION

In infants with TSC, there is a significant association between characteristic TSC lesions detected on early brain MRI and development of clinical seizures, as well as neurodevelopmental outcomes in the first two years of life. According to our results, early brain MRI findings may guide clinical care for young children with TSC.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that in infants with TSC, there is a significant association between characteristic TSC lesions on early brain MRI and the development of clinical seizures and neurodevelopmental outcomes in the first two years of life.

The epileptogenic zone in children with tuberous sclerosis complex is characterized by prominent features of focal cortical dysplasia

OBJECTIVE

Patients with tuberous sclerosis complex (TSC) present with drug-resistant epilepsy in about 60% of cases, and evaluation for epilepsy surgery may be warranted. Correct delineation of the epileptogenic zone (EZ) among multiple dysplastic lesions on MRI represents a challenging step in pre-surgical evaluation.

METHODS

Two experienced neuroradiologists evaluated pre- and post-surgical MRIs of 28 epilepsy surgery patients with TSC, assessing characteristics of tubers, cysts, calcifications, and focal cortical dysplasia (FCD)-resembling lesions. Utilizing multiple metrics, we compared MRI features of the EZ-defined as the resected area in TSC patients who achieved seizure-freedom 2 years after epilepsy surgery-with features of other brain areas. Using combinatorial analysis, we identified combinations of dysplastic features that are most frequently observed in the epileptogenic zone in TSC patients.

RESULTS

All TSC-associated dysplastic features were more frequently observed in the EZ than in other brain areas (increased cortical thickness, gray-white matter blurring, transmantle sign, calcifications, and tubers; Kendal's tau 0.35, 0.25, 0.27, 0.26, and 0.23, respectively; P value <.001 in all). No single feature could reliably and independently indicate the EZ in all patients. Conversely, the EZ was indicated by the presence of the combination of three of the following features: tubers, transmantle sign, increased cortical thickness, calcifications, and the largest FCD-affected area. Out of these, the largest FCD-affected area emerged as the most reliable indicator of the EZ, combined either with calcifications or tubers.

SIGNIFICANCE

The epileptogenic zone in TSC patients harbors multiple dysplastic features, consistent with focal cortical dysplasia. A specific combination of these features can indicate the EZ and aid in pre-surgical MRI evaluation in epilepsy surgery candidates with TSC.

Fetal Brain Magnetic Resonance Imaging Findings Predict Neurodevelopment in Children with Tuberous Sclerosis Complex

OBJECTIVE

To correlate fetal brain magnetic resonance imaging (MRI) findings with epilepsy characteristics and neurodevelopment at 2 years of age in children with tuberous sclerosis complex (TSC) to improve prenatal counseling.

STUDY DESIGN

This retrospective cohort study was performed in a collaboration between centers of the EPISTOP consortium. We included children with definite TSC, fetal MRIs, and available follow-up data at 2 years of age. A pediatric neuroradiologist masked to the patient's clinical characteristics evaluated all fetal MRIs. MRIs were categorized for each of the 10 brain lobes as score 0: no (sub)cortical lesions or doubt; score 1: a single small lesion; score 2: more than one small lesion or at least one large lesion (>5 mm). Neurologic manifestations were correlated to lesion sum scores.

RESULTS

Forty-one children were included. Median gestational age at MRI was 33.3 weeks; (sub)cortical lesions were detected in 97.6%. Mean lesion sum score was 4.5. At 2 years, 58.5% of patients had epilepsy and 22% had drug-resistant epilepsy. Cognitive, language, and motor development were delayed in 38%, 81%, and 50% of patients, respectively. Autism spectrum disorder (ASD) was diagnosed in 20.5%. Fetal MRI lesion sum scores were significantly associated with cognitive and motor development, and with ASD diagnosis, but not with epilepsy characteristics.

CONCLUSIONS

Fetal cerebral lesion scores correlate with neurodevelopment and ASD at 2 years in children with TSC.

TSC2 pathogenic variants are predictive of severe clinical manifestations in TSC infants: results of the EPISTOP study

PURPOSE

To perform comprehensive genotyping of TSC1 and TSC2 in a cohort of 94 infants with tuberous sclerosis complex (TSC) and correlate with clinical manifestations.

METHODS

Infants were enrolled at age <4 months, and subject to intensive clinical monitoring including electroencephalography (EEG), brain magnetic resonance imaging (MRI), and neuropsychological assessment. Targeted massively parallel sequencing (MPS), genome sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used for variant detection in TSC1/TSC2.

RESULTS

Pathogenic variants in TSC1 or TSC2 were identified in 93 of 94 (99%) subjects, with 23 in TSC1 and 70 in TSC2. Nine (10%) subjects had mosaicism. Eight of 24 clinical features assessed at age 2 years were significantly less frequent in those with TSC1 versus TSC2 variants including cortical tubers, hypomelanotic macules, facial angiofibroma, renal cysts, drug-resistant epilepsy, developmental delay, subependymal giant cell astrocytoma, and median seizure-free survival. Additionally, quantitative brain MRI analysis showed a marked difference in tuber and subependymal nodule/giant cell astrocytoma volume for TSC1 versus TSC2.

CONCLUSION

TSC2 pathogenic variants are associated with a more severe clinical phenotype than mosaic TSC2 or TSC1 variants in TSC infants. Early assessment of gene variant status and mosaicism might have benefit for clinical management in infants and young children with TSC.

Counselling in tuberous sclerosis complex: A survey on content and satisfaction in the Netherlands

BACKGROUND

Tuberous sclerosis complex (TSC) is a highly variable condition and its clinical features cannot reliably be predicted from the genotype. Counselling of parents of a child with TSC is challenging because of the variability of the condition and the changing outlook due to new treatment options. This study explored current counselling strategies in TSC in the Netherlands, with the aim of developing a recommendation for counselling.

METHOD

We performed a nationwide survey using digital questionnaires. Questionnaires were sent to parents of children diagnosed with TSC, and to medical doctors involved in counselling, both no more than ten years prior to the study. Questions focused on general information about the child with TSC, medical doctors involved in counselling, type of information provided, mode of providing information, and recommendations for improvement of counselling.

RESULTS

Parents of 34 children diagnosed with TSC (7 prenatally) and 18 medical doctors from different departments responded to the questionnaires. Almost all parents were informed on the neurological and cardiac symptoms of TSC, other symptoms were mentioned less often. Satisfaction on counselling was higher when more information on the variability of TSC was provided, preferentially during a clinical visit, when emotional support was provided, and when parents were notified of the TSC patient society.

CONCLUSIONS

Information on the variability in expression and quality of life is highly demanded by (expecting) parents of a child with TSC. Furthermore, reference should be made to institutions such as the support organisation for patients and social services for questions and support.

Novel Histopathological Patterns in Cortical Tubers of Epilepsy Surgery Patients with Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is a genetic hamartoma syndrome frequently associated with severe intractable epilepsy. In some TSC patients epilepsy surgery is a promising treatment option provided that the epileptogenic zone can be precisely delineated. TSC brain lesions (cortical tubers) contain dysmorphic neurons, brightly eosinophilic giant cells and white matter alterations in various proportions. However, a histological classification system has not been established for tubers. Therefore, the aim of this study was to define distinct histological patterns within tubers based on semi-automated histological quantification and to find clinically significant correlations. In total, we studied 28 cortical tubers and seven samples of perituberal cortex from 28 TSC patients who had undergone epilepsy surgery. We assessed mammalian target of rapamycin complex 1 (mTORC1) activation, the numbers of giant cells, dysmorphic neurons, neurons, and oligodendrocytes, and calcification, gliosis, angiogenesis, inflammation, and myelin content. Three distinct histological profiles emerged based on the proportion of calcifications, dysmorphic neurons and giant cells designated types A, B, and C. In the latter two types we were able to subsequently associate them with specific features on presurgical MRI. Therefore, these histopathological patterns provide consistent criteria for improved definition of the clinico-pathological features of cortical tubers identified by MRI and provide a basis for further exploration of the functional and molecular features of cortical tubers in TSC.

[A woman with a postoperative lumbar swelling]

A 65-year-old woman had developed a large lumbar swelling in a period of four weeks following lumbar laminectomy. An MRI-scan revealed a large fluid collection, which had formed from the spinal canal. The diagnosis 'liquorcele', a rare complication of spine surgery, was established.