Epileptic seizures and electroencephalographic evolution in genetic leukodystrophies

Consensus guidelines for the monitoring and management of metachromatic leukodystrophy in the United States

Metachromatic leukodystrophy (MLD) is a fatal, progressive neurodegenerative disorder caused by biallelic pathogenic mutations in the ARSA (Arylsulfatase A) gene. With the advent of presymptomatic diagnosis and the availability of therapies with a narrow window for intervention, it is critical to define a standardized approach to diagnosis, presymptomatic monitoring, and clinical care. To meet the needs of the MLD community, a panel of MLD experts was established to develop disease-specific guidelines based on healthcare resources in the United States. This group developed a consensus opinion for best-practice recommendations, as follows: (i) Diagnosis should include both genetic and biochemical testing; (ii) Early diagnosis and treatment for MLD is associated with improved clinical outcomes; (iii) The panel supported the development of newborn screening to accelerate the time to diagnosis and treatment; (iv) Clinical management of MLD should include specialists familiar with the disease who are able to follow patients longitudinally; (v) In early onset MLD, including late infantile and early juvenile subtypes, ex vivo gene therapy should be considered for presymptomatic patients where available; (vi) In late-onset MLD, including late juvenile and adult subtypes, hematopoietic cell transplant (HCT) should be considered for patients with no or minimal disease involvement. This document summarizes current guidance on the presymptomatic monitoring of children affected by MLD as well as the clinical management of symptomatic patients. Future data-driven evidence and evolution of these recommendations will be important to stratify clinical treatment options and improve clinical care.

Clinical and biochemical footprints of inherited metabolic diseases. XV. Epilepsies

We provide a comprehensive overview of inherited metabolic disorders (IMDs) in which epilepsy is a prominent manifestation. Our unique database search has identified 256 IMDs associated with various types of epilepsies, which we classified according to the classic pathophysiology-based classification of IMDs, and according to selected seizure-related factors (neonatal seizures, infantile spasms, myoclonic seizures, and characteristic EEG patterns) and treatability for the underlying metabolic defect. Our findings indicate that inherited metabolic epilepsies are more likely to present in the neonatal period, with infantile spasms or myoclonic seizures. Additionally, the ∼20% of treatable inherited metabolic epilepsies found by our search were mainly associated with the IMD groups of "cofactor and mineral metabolism" and "Intermediary nutrient metabolism." The information provided by this study, including a comprehensive list of IMDs with epilepsy stratified according to age of onset, and seizure type and characteristics, along with an overview of the key clinical features and proposed diagnostic and therapeutic approaches, may benefit any epileptologist and healthcare provider caring for individuals with metabolic conditions.

A hypomyelinating leukodystrophy in German Shepherd dogs

BACKGROUND

Shaking puppy syndrome is commonly attributed to abnormal myelination of the central nervous system.

HYPOTHESIS/OBJECTIVES

To report the long-term clinical course and the imaging characteristics of hypomyelinating leukodystrophy in German Shepherd dogs.

ANIMALS AND METHODS

Three related litters with 11 affected dogs.

RESULTS

The 11 affected dogs experienced coarse, side-to-side tremors of the head and trunk, which interfered with normal goal-oriented movements and disappeared at rest. Signs were noticed shortly after birth. Nine dogs were euthanized, 3 dogs underwent pathological examination, and 2 littermates were raised by their breeder. Tremors improved gradually until 6 to 7 months of age. Adult dogs walked with severe residual pelvic limb ataxia. One dog developed epilepsy with tonic-clonic seizures at 15 months of age. Conventional magnetic resonance imaging (MRI) disclosed homogenous hyperintense signal of the entire subcortical white matter in 3 affected 7-week-old dogs and a hypointense signal in a presumably unaffected littermate. Subcortical white matter appeared isointense to gray matter at 15 and 27 weeks of age on repeated MRI. Abnormal white matter signal with failure to display normal gray-white matter contrast persisted into adulthood. Cerebellar arbor vitae was not visible at any time point. Clinical signs, MRI findings, and pathological examinations were indicative of a hypomyelinating leukodystrophy. All parents of the affected litters shared a common ancestor and relatedness of the puppies suggested an autosomal recessive mode of inheritance.

CONCLUSION

We describe a novel hypomyelinating leukodystrophy in German Shepherd dogs with a suspected inherited origin.

General Anesthesia for a Patient With Pelizaeus-Merzbacher Disease

We report the successful management of general anesthesia for a patient with Pelizaeus-Merzbacher disease (PMD). PMD is one of a group of progressive, degenerative disorders of the cerebral white matter. The typical clinical manifestations of PMD include psychomotor retardation, nystagmus, abnormal muscle tone, seizures, and cognitive impairment. General anesthesia for a patient with PMD may be difficult mainly because of seizures and airway complications related to poor pharyngeal muscle control. In addition, the possibility of exacerbation of spasticity should be considered. A 20-year-old man with PMD required removal of impacted wisdom teeth under general anesthesia. General anesthesia was induced with thiamylal, fentanyl, and desflurane. Anesthesia was maintained with desflurane and continuous intravenous remifentanil under bispectral index and train-of-4 monitoring. Anesthesia lasted 1 hour 20 minutes and was completed uneventfully. Airway complications, seizures, and exacerbation of spasticity did not occur postoperatively. Preoperatively, our patient had no history of epilepsy attacks or aspiration pneumonia, and no clinical symptoms of gastroesophageal reflux disease. Therefore, exacerbation of spasticity was one of the most likely potential complications. Identification of these associated conditions and evaluation of risk factors during preoperative examination is important for performing safe anesthesia in these patients.

A Novel Catastrophic Presentation of X-Linked Adrenoleukodystrophy

OBJECTIVE

We report a novel presentation of childhood cerebral X-linked adrenoleukodystrophy: status epilepticus followed by abrupt and catastrophic neurologic deterioration.

METHODS

A description of the clinical presentation, laboratory evaluation, and imaging findings leading to a diagnosis of X-linked adrenoleukodystrophy.

RESULTS

A 3-year-old male with prior history of autism presented with fever, diarrhea, and status epilepticus requiring a pentobarbital coma. Admission labs were notable only for a glucose level of 22 mg/dL, which stabilized after correction. The child never returned to his prior neurologic baseline, with complete loss of gross motor, fine motor, and speech skills. Serial brain magnetic resonance imaging (MRI)/magnetic resonance spectroscopy (MRS) was notable for progressive diffuse cortical signal changes with swelling, diffusion restriction, and ultimately laminar necrosis. Nine months after presentation, CSF (cerebrospinal fluid) protein and MRS lactate were persistently elevated, concerning for a neurodegenerative disorder. This led to testing for mitochondrial disease, followed by lysosomal and peroxisomal disorders. Very long-chain fatty acids were elevated. Identification of a pathogenic ABCD1 mutation confirmed the diagnosis of X-linked adrenoleukodystrophy.

CONCLUSIONS

Boys with childhood cerebral X-linked adrenoleukodystrophy typically present with gradual behavioral changes. Rare reports of boys presenting with transient altered mental status or status epilepticus describe a recovery to their pre-presentation baseline. To our knowledge this is the first X-ALD patient to present with status epilepticus with abrupt and catastrophic loss of neurologic function. X-linked adrenoleukodystrophy should be suspected in young males presenting with seizures, acute decline in neurologic function, with persistently elevated CSF protein and MRS lactate.

Epilepsy in Aicardi-Goutières syndrome

BACKGROUND

Aicardi-Goutières syndrome (AGS) is a genetically determined early-onset encephalopathy with variable phenotype, including neurologic manifestations such as dystonia, spasticity, epileptic seizures, progressive microcephaly, and severe developmental delay. The aim of our study was the characterization of epilepsy, one of the most frequent and severe AGS manifestations, in molecularly confirmed patients.

METHODS

We reviewed the medical records, EEG, and CT/MRI findings in 16 patients aged 1-22 years that carried AGS1-5 mutations.

RESULTS

Epilepsy manifested in 12 (75%) patients and took a refractory course in 9 (56%). 4 (25%) patients presented with seizures in the first four weeks and 11 (69%) altogether in the first year of life. Spasms were reported in 3 (19%) patients, focal seizures in 4 (25%), myoclonic in 5 (31%), symmetric or asymmetric tonic in 11 (69%), generalized tonic-clonic in 3 (19%) and status epilepticus in 4 (25%). EEG recordings initially showed a slow and disorganized background, followed by a regional intermittent theta/delta slow, while obvious multifocal or generalized epileptic discharges were only observed at follow-up. None of these EEG features were specific of AGS. There was no discernible correlation between the genotype and epilepsy onset, seizure types and epilepsy evolution. Epilepsy severity did not correspond to neuroimaging pathology.

DISCUSSION

Epilepsy constitutes a cardinal feature of AGS, characterized by early onset, predominantly tonic semiology and a refractory course. The early discrimination of epileptic seizures from paroxysmal dystonia poses a challenge for neuropaediatricians, considering the initially inconspicuous or non-specific EEG findings. This study underlines the necessity of a more systematic serial evaluation of AGS patients using long-term video-EEG recordings.

Lamin B1 mediates cell-autonomous neuropathology in a leukodystrophy mouse model

Adult-onset autosomal-dominant leukodystrophy (ADLD) is a progressive and fatal neurological disorder characterized by early autonomic dysfunction, cognitive impairment, pyramidal tract and cerebellar dysfunction, and white matter loss in the central nervous system. ADLD is caused by duplication of the LMNB1 gene, which results in increased lamin B1 transcripts and protein expression. How duplication of LMNB1 leads to myelin defects is unknown. To address this question, we developed a mouse model of ADLD that overexpresses lamin B1. These mice exhibited cognitive impairment and epilepsy, followed by age-dependent motor deficits. Selective overexpression of lamin B1 in oligodendrocytes also resulted in marked motor deficits and myelin defects, suggesting these deficits are cell autonomous. Proteomic and genome-wide transcriptome studies indicated that lamin B1 overexpression is associated with downregulation of proteolipid protein, a highly abundant myelin sheath component that was previously linked to another myelin-related disorder, Pelizaeus-Merzbacher disease. Furthermore, we found that lamin B1 overexpression leads to reduced occupancy of Yin Yang 1 transcription factor at the promoter region of proteolipid protein. These studies identify a mechanism by which lamin B1 overexpression mediates oligodendrocyte cell-autonomous neuropathology in ADLD and implicate lamin B1 as an important regulator of myelin formation and maintenance during aging.

Leukodystrophies

Leukodystrophies comprise a broad group of progressive, inherited disorders affecting mainly myelin. They often present after a variable period of normalcy with a variety of neurologic problems. Though the ultimate diagnosis is not found in many patients with leukodystrophies, distinctive features unique to them aid in diagnosis, treatment and prognostication. The clinical characteristics, etiologies, diagnostic testing and treatment options are reviewed in detail for some of the major leukodystrophies: X-linked adrenoleukodystrophy, Krabbe disease, metachromatic leukodystrophy, Pelizaeus-Merzbacher disease, Alexander disease, Canavan disease, megalencephalic leukoencephalopathy with subcortical cysts and vanishing white matter disease.

Peroxisomal disorders with infantile seizures

Peroxisomes are organelles responsible for multiple metabolic pathways including the biosynthesis of plasmalogens and the oxidation of branched-chain as well as very-long-chain fatty acids (VLCFAs). Peroxisomal disorders (PDs) are heterogeneous groups of diseases and affect many organs with varying degrees of involvement. Even pathogenetically distinct PDs share some common symptoms. However, several PDs have uniquely characteristic clinical findings. The durations of survival in PDs are also variable. Infants with PDs are usually presented with developmental delay, visual and hearing impairment. Generalized hypotonia is present in severe cases. Epileptic seizures are also a common characteristic of patients with certain PDs. Nonetheless, the classification and evolution of epilepsy in PDs have not been elucidated in detail. Here, we review the relevant literatures and provide an overview of PDs with particular emphasis on the characteristics of seizures in infants.

An unusual homozygous arylsulfatase: a pseudodeficiency in a metachromatic leukodystrophy Tunisian patient

Metachromatic leukodystrophy is an autosomal recessive neurodegenerative lysosomal disease characterized by a deficiency of the lysosomal enzyme arylsulfatase A and the subsequent accumulation of sulfatide in neuronal and visceral tissues. Clinical diagnosis is usually confirmed by in vitro analysis of arylsulfatase A activity but may be complicated in cases of arylsulfatase A pseudodeficiency and sphingolipid activators protein deficiency. We report the case of a 3-year-old boy who presented a severe form of late infantile metachromatic leukodystrophy. This patient was found to be homozygous for the arylsulfatase A pseudodeficiency. This condition is rare and can lead to a severe disease. Prenatal diagnosis was performed in this family, and the fetus was healthy.

Epilepsy in inherited metabolic disorders

INTRODUCTION

The study of neurometabolic diseases is still in a prolonged preliminary stage. The catalogue of these diseases continues to grow; some known clinical syndromes have been subdivided into a number of variants once the genes that cause them have been identified, and at the same time new metabolic disorders have been discovered that aggravate or contribute to forms of epilepsy not previously classified as cerebral metabolic disorders.

RESULTS

This review presents the basic principles underlying the recognition and treatment of epilepsy caused by neurometabolic diseases. These disorders are divided (purely for the sake of convenience) into epilepsy presenting in newborn infants, children, and adolescents and adults, recognizing that there is a significant degree of overlap between these chronological stages. Current analytical methods and therapeutic approaches are summarized both from a general point of view and within the context of each clinical syndrome, acknowledging that each patient presents specific peculiarities and that, in general, antiepileptic drugs provide few benefits compared with more specific types of therapy (eg, special diets or vitamins) when indicated. We also include therapeutic recommendations and a general approach to fulminant epilepsies of neurometabolic origin, emphasizing the importance of identifying all of the proband's relatives who may be potential carriers of a genetic disorder during the diagnostic and genetic counselling process. Particular emphasis is placed on disorders for which there is curative treatment and on the importance of follow-up by expert professionals.

CONCLUSION

It is expected that in a few years' time it will be possible to know the metabolomic profile of these diseases (possibly by non-invasive methods), thus facilitating accurate diagnosis and making it possible to establish the response to treatment and to identify all individuals who are carriers or remain minimally symptomatic in terms of their risk of manifesting or transmitting epilepsy.

Partial trisomy 13q22-qter associated to leukoencephalopathy and late onset generalised epilepsy

The partial trisomy 13q.22 is an uncommon chromosomopathy. We present a case with a partial trisomic component 13q22 and a monosomic component 5p15 from paternal origin. This patient developed early menopause and major neurological disorders as leukoencephalopathy, late onset generalised epilepsy and stroke. She also had fatty acids disturbances and their potential relation to the neurological disorders and early menopause is discussed. The presented case illustrates the phenotype of 13q22-qter in adult age and reaffirms the importance of studying the karyotype of any patient with seizures or leukoencephalopathy particularly when there are associated other clinical features including stroke at a young age, fatty acids disturbances, microcephaly, hypotelorism, short neck, hemangiomata, short fingers or distal swell in thumbs.

Epileptic encephalopathy with bilateral continuous spike-waves during slow sleep in a child with vacuolating megalencephalic leukoencephalopathy

This case report describes the clinical evolution of a symptomatic epileptic encephalopathy with bilateral continuous spike-waves during slow wave sleep (BCSWS) in a 3-year-old girl. Her epilepsy with focal motor seizures during sleep was later complicated by myoclonic, atonic and clonic seizures culminating in BCSWS. The clinical picture, clinical course and magnetic resonance imaging findings were characterstic of primary white matter disease, probably, vacuolated megalencephalic leukoencephalopathy with subcortical cysts (MLC). To the best of our knowledge, this is the first reported case of BSCWS in a patient with leukodystrophies or MLC. This case report indicates that epileptic encephalopathy with BSCWS may be a cause of neurological or neuropsychological deterioration in MLC.

Genetic and physiological evidence that oligodendrocyte gap junctions contribute to spatial buffering of potassium released during neuronal activity

Mice lacking the K+ channel Kir4.1 or both connexin32 (Cx32) and Cx47 exhibit myelin-associated vacuoles, raising the possibility that oligodendrocytes, and the connexins they express, contribute to recycling the K+ evolved during neuronal activity. To study this possibility, we first examined the effect of neuronal activity on the appearance of vacuoles in mice lacking both Cx32 and Cx47. The size and number of myelin vacuoles was dramatically increased when axonal activity was increased, by either a natural stimulus (eye opening) or pharmacological treatment. Conversely, myelin vacuoles were dramatically reduced when axonal activity was suppressed. Second, we used genetic complementation to test for a relationship between the function of Kir4.1 and oligodendrocyte connexins. In a Cx32-null background, haploinsufficiency of either Cx47 or Kir4.1 did not affect myelin, but double heterozygotes developed vacuoles, consistent with the idea that oligodendrocyte connexins and Kir4.1 function in a common pathway. Together, these results implicate oligodendrocytes and their connexins as having critical roles in the buffering of K+ released during neuronal activity.

Leukodystrophies: clinical and genetic aspects

The leukodystrophies comprise an ever-expanding group of rare central nervous system disorders with defined clinical, pathological, and genetic characteristics. The broader term, leukoencephalopathy, is applied to all brain white matter diseases, whether their molecular cause is known. Magnetic resonance imaging has helped to elucidate new forms of leukodystrophy as well as to permit longitudinal studies of disease progression. The white matter abnormality may appear similar in different forms of leukodystrophy so that in most cases, further studies such as magnetic resonance spectroscopy, tissue biopsies, enzyme studies, and molecular DNA analyses are needed to pinpoint the specific diagnosis. The primary inherited leukoencephalopathies include dysmyelinating, hypomyelinative, and vacuolating forms. Metabolic and vascular causes account for most of the secondary forms, but other inherited syndromes are recognized that have their onset in childhood or adult life and are characterized by distinctive clinical and neuropathologic features. This review discusses some of the mechanisms that have been proposed to explain deficiencies of myelin and the molecular genetic bases underlying these disorders.

Brain-stem auditory and visual evoked potentials in children with Krabbe disease

OBJECTIVE

There are few reports in the literature detailing brain-stem auditory and visual evoked potentials (BAEP and VEP) in children with Krabbe disease (KD). The purpose of this study was to provide a descriptive analysis of the BAEP and VEP findings in these children.

METHODS

Charts of children with KD were reviewed. BAEP and VEP studies performed on these children were reviewed; findings in the early infantile and late onset KD (EIKD, LOKD, respectively) groups were also examined. Likelihood ratios (LR) for the neurophysiologic tests being abnormal in the various groups were also determined.

RESULTS

BAEP abnormalities were seen in 15/17 (88%) children with EIKD and 2/5 (40%) children with LOKD, LR statistically significant. In the EIKD group, all 13 symptomatic children had an abnormal BAEP, whereas 2/4 (50%) of the pre-symptomatic children had similar findings, LR statistically significant. VEP abnormalities were noted in 8/15 (53%) children with EIKD and none of the children with LOKD, LR statistically significant. In the EIKD group, the 8/12 (67%) symptomatic children had an abnormal VEP, whereas none of the pre-symptomatic children did, LR statistically significant. Subgroup analyses of the LOKD subgroups did not yield significant findings.

CONCLUSIONS

BAEP abnormalities are among the first objective indications of central nervous system disease in children with EIKD. VEP abnormalities occur later in the course of the illness. Both tests are less helpful in children with LOKD.

SIGNIFICANCE

BAEP and VEP testing is helpful in objective evaluation of children with KD.

Clinical findings in Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher disease is a rare X-linked disease characterized by defective central nervous system myelination owing to a mutation in the proteolipid protein 1 gene. Few studies report detailed clinical findings in children with genetic confirmation of mutations in the proteolipid protein 1 gene. We reviewed the records of 10 boys with Pelizaeus-Merzbacher disease and one symptomatic carrier girl. Their median age was 2 1/2 years (range 10 months to 20 years). Nine had proteolipid protein 1 gene duplications, one had a point mutation, and one had a single codon deletion. The families of eight patients reported perinatal complications, including maternal hypertension (three patients) and meconium aspiration (three patients). All of the patients were social and interactive, but all had difficulty with expressive speech. All patients presented with nystagmus and had hypotonia that progressed to spasticity, affecting the legs more than the arms; ataxia also contributed to motor impairment. Additional problems reported regarded feeding (eight patients) and sleep (three patients). Further work is needed to clarify the variations in disease course and the relationship of genotype to phenotype.

Epilepsy in vacuolating megalencephalic leukoencephalopathy with subcortical cysts

Vacuolating megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a disorder characterised by acquired macrocephaly, developmental motor delay of varying degrees, slowly progressive cerebellar and pyramidal signs, and initially preserved intellectual function. More than 60% of the published cases had epileptic seizures. In this study, we analysed the seizures and EEG findings of nine patients with MLC. Six patients (66.6%) with moderate to severe neurological impairment had epilepsy, four with partial and two with generalised seizures. The EEG of five epileptic patients revealed epileptogenic foci over the temporal, frontal and parietal regions with variable predominance during waking and sleep. The facilitation of spike-and-wave paroxysms by eye closure, by intermittent photic stimulation and by hyperventilation were determined in four patients. Four patients also showed abnormalities in the background activity. In conclusion, we think that epilepsy is a significant component of MLC compared to the other leukodystrophies. The elucidation of the underlying molecular defect may explain the unusual pathogenetic relation between this leukoencephalopathy and the associated seizures.