Epilepsy in the setting of neurocutaneous syndromes

Partial epilepsy: A pictorial review of 3 TESLA magnetic resonance imaging features

Epilepsy is a disease with serious consequences for patients and society. In many cases seizures are sufficiently disabling to justify surgical evaluation. In this context, Magnetic Resonance Imaging (MRI) is one of the most valuable tools for the preoperative localization of epileptogenic foci. Because these lesions show a large variety of presentations (including subtle imaging characteristics), their analysis requires careful and systematic interpretation of MRI data. Several studies have shown that 3 Tesla (T) MRI provides a better image quality than 1.5 T MRI regarding the detection and characterization of structural lesions, indicating that high-field-strength imaging should be considered for patients with intractable epilepsy who might benefit from surgery. Likewise, advanced MRI postprocessing and quantitative analysis techniques such as thickness and volume measurements of cortical gray matter have emerged and in the near future, these techniques will routinely enable more precise evaluations of such patients. Finally, the familiarity with radiologic findings of the potential epileptogenic substrates in association with combined use of higher field strengths (3 T, 7 T, and greater) and new quantitative analytical post-processing techniques will lead to improvements regarding the clinical imaging of these patients. We present a pictorial review of the major pathologies related to partial epilepsy, highlighting the key findings of 3 T MRI.

Epidermal nevus syndrome

Epidermal nevus syndrome (ENS) is an inclusive term for a heterogeneous group of congenital disorders characterized by the presence of epidermal nevi associated with systemic involvement. These disorders, as are all primary neurocutaneous syndromes, are neurocristopathies. The epidermal nevi that follow the lines of Blaschko and most systemic anomalies in skeletal, ocular, cardiovascular, endocrine, and orodental tissues, as well as lipomas, are due to defective neural crest. The most important and frequent anomaly in the brain in all forms of epidermal nevus syndromes (ENSs) is hemimegalencephaly (HME). This malformation often is not recognized, despite being the principal cause of neurological manifestations in ENSs. They consist mainly of epilepsy and developmental delay or intellectual disability. The onset of epilepsy in ENS usually is in early infancy, often as infantile spasms. Several syndromic forms have been delineated. I propose the term "Heide's syndrome" for those distinctive cases with the typical triad of hemifacial epidermal nevus, ipsilateral facial lipoma, and hemimegalencephaly. Most ENSs are sporadic. The mechanism is thought to be genetic mosaicism with a lethal autosomal dominant gene. Specific genetic mutations (PTEN, FGFR3, PIK3CA, and AKT1) have been documented in some patients. The large number of contributors for over more than a century and a half to the description of these disorders precludes the use of new author eponyms.

Neurofibromatosis type 1 and infantile spasms

BACKGROUND

There is no agreement on the prevalence, natural history and outcome of infantile spasms (IS) in neurofibromatosis type 1 (NF1). By contrast, its prevalence and outcome are well characterised in the setting of other neurocutaneous disorders (e.g. tuberous sclerosis).

MATERIALS AND METHODS

The aim of the present study was to try to establish a genotype-phenotype correlation in IS in the setting of NF1. A retrospective (years 1990-2000) and prospective (years 2000-2006) study in three paediatric centres in Italy were taken as referral populations for: (1) children with NF1 and (2) neurological problems in childhood.

RESULTS

Ten NF1 patients have had IS. The calculated population-based: (1) prevalence of IS in NF1 (0.76%) was higher than the reported frequency of IS in the general population (0.02-0.05%) and (2) frequency of NF1 in the IS series in two out of three centres (0.62-0.90%) was lower than the estimated frequencies in the literature (1.5-3.0%). Patients had psychomotor delay preceding the spasms (50%), symmetrical spasms (50%), typical (80%) and modified (20%) hypsarrhythmia and foci of spikes and waves and a good response to corticosteroid treatment (50%). Outcome was good in 30%. Imaging revealed high-signal foci in atypical locations (sub-cortical and central brain regions). Deoxyribonucleic acid analysis revealed three novel NF1 gene mutations without genotype-phenotype correlation.

CONCLUSION

Even though the combination of IS and NF1 does not seem to be coincidental, it is certainly an unusual event in NF1--rarer than in other neurocutaneous disorders. Spasms in NF1 are not associated with specific genetic defects.

Infantile spasms in the setting of Sturge-Weber syndrome

INTRODUCTION

The prevalence and outcome of the most frequent type of epilepsy in infancy-infantile spasms (IS)-are well characterized in the setting of most neurocutaneous disorders. By contrast, still there is no study describing the natural history of IS in the setting of Sturge-Weber syndrome (SWS).

MATERIALS AND METHODS

Two patients with SWS and IS were identified in our series and five in the literature. The aim of study is to evaluate the clinical, electroencephalographic (EEG) and imaging features of our cases and to compare our cases with those described in the literature. IS in the setting of SWS is an uncommon but possible event (2/19 patients seen over 13 years in our institutions).

RESULTS

We confirmed the correlation between IS and severity of SWS cutaneous and neural (extension of leptomeningeal capillary malformation) phenotype. IS in SWS seems to be atypical both from a clinical viewpoint (they are asymmetric) and from a laboratory viewpoint (EEG is not classically hypsarrhythmic).

[Familial clinical manifestation in patients with neuromesoectodermic defect]

We relate the association of two distinct cases of neuromesoectodermosis occurred in a family, one manifested as neurofibromatosis type 1 and the other as tuberous sclerosis. The two anomalies at cousins, caused by different genetic mutations and transmitted by autosomal dominant inheritance, suggest a possible relation between them. Also, clinical manifestations are described, their consequences and the diagnostic criteria of both illnesses, emphasizing the importance of the precocious diagnosis.

Epilepsy in neurofibromatosis 1

Neurofibromatosis 1 is the most common neurocutaneous disease. Neurologic manifestations are mainly represented by tumors such as optic gliomas, focal areas of high T2-weighted signal known as unidentified bright objects, and mental retardation or learning disabilities. The prevalence of seizures has been reported to range from 3.8 to 6%. In the present study, we evaluated prevalence, type, and etiology of epilepsy in a neurofibromatosis 1 population. A retrospective analysis of 198 patients affected by neurofibromatosis 1 was performed. Fourteen patients (7%) were found to be epileptic. Every patient underwent electroencephalographic examination and neuroimaging investigations. Thirteen were submitted to magnetic resonance imaging (MRI) study and one to computed tomographic (CT) scanning. Single-photon emission computed tomographic and positron emission tomographic studies were performed in a few selected cases. Seizures were partial in 12 of these (85%) and generalized in 2 (15%). In nine (64%), epilepsy was secondary to brain lesions: five of these had cerebral tumors (three with epilepsy as the fist symptom), three had cortical malformation, and one had mesial temporal sclerosis. Seizures were controlled rapidly in eight (57%) and drug resistant in four (29%). Two patients were lost at follow-up. All patients with uncontrolled seizures had severe mental retardation, and three of these had malformations of cortical development. Our observations and our re-evaluation of the literature indicate that patients with neurofibromatosis 1 have an increased risk of epilepsy related to intracranial masses and cytoarchitectural abnormalities, and seizures can represent the first symptom of a tumor or cortical malformation. Brain MRI and, in selected cases, functional studies appear to be useful in patients with neurofibromatosis 1 who present with seizures, especially if associated with mental retardation.

Pathologic characteristics of the cortical dysplasias

The gross and microscopic features of cortical dysplasia (malformations caused by abnormalities of cortical development) are reviewed and illustrated in this article. The pathologic associations of neurocutaneous disorders, neoplasms, and hippocampal sclerosis with cortical dysplasia also are discussed.

Recent advances in the genetics of epilepsy: insights from human and animal studies

Progress in understanding the genetics of epilepsy is proceeding at a dizzying pace. Due in large part to rapid progress in molecular genetics, gene defects underlying many of the inherited epilepsies have been mapped, and several more are likely to be added each year. In this review, we summarize the available information on the genetic basis of human epilepsies and epilepsy syndromes, and correlate these advances with rapidly expanding information about the mechanisms of epilepsy gained from both spontaneous and transgenic animal models. We also provide practical suggestions for clinicians confronted with families in which multiple members are afflicted with epilepsy.

Startle-induced epilepsy in a patient with epidermal nevus syndrome

Startle-induced epilepsy was observed in a 5-year-old boy with epidermal nevus syndrome. He manifested linear nevus on the face and neck, mild mental retardation, and right hemiparesis. Massive myoclonus, followed by tonic seizures, had been triggered by unexpected auditory stimuli since 3 years of age. The startle-induced seizures were the only epileptic manifestation. Interictal EEG occasionally depicted spontaneous focal spikes and waves in the left frontotemporal area, and ictal EEG depicted vertex spikes and then diffuse slow spike-and-wave complex bursts. Left frontal and perisylvian cortical atrophy and a white matter abnormality in the left frontal area were revealed by magnetic resonance imaging. Single photon emission computed tomography demonstrated diffuse low perfusion in the left cerebral hemisphere. Lower amplitude potentials in the left cerebral cortex were evident during somatosensory evoked potential evaluation. These results indicate that hemispheric dysfunction could cause startle-induced epilepsy in this patient.