Clinical and EEG findings in 18 cases of late infantile neuronal ceroid lipofuscinosis

A Thalamocortical Perspective on Sleep Spindle Alterations in Neurodevelopmental Disorders

Purpose of Review

Neurodevelopmental disorders are a group of conditions that affect the development and function of the nervous system, typically arising early in life. These disorders can have various genetic, environmental, and/or neural underpinnings, which can impact the thalamocortical system. Sleep spindles, brief bursts of oscillatory activity that occur during NREM sleep, provide a unique in vivo measure of the thalamocortical system. In this manuscript, we review the development of the thalamocortical system and sleep spindles in rodent models and humans. We then utilize this as a foundation to discuss alterations in sleep spindle activity in four of the most pervasive neurodevelopmental disorders-intellectual disability, attention deficit hyperactivity disorder, autism, and schizophrenia.

Recent Findings

Recent work in humans has shown alterations in sleep spindles across several neurodevelopmental disorders. Simultaneously, rodent models have elucidated the mechanisms which may underlie these deficits in spindle activity. This review merges recent findings from these two separate lines of research to draw conclusions about the pathogenesis of neurodevelopmental disorders.

Summary

We speculate that deficits in the thalamocortical system associated with neurodevelopmental disorders are exquisitely reflected in sleep spindle activity. We propose that sleep spindles may represent a promising biomarker for drug discovery, risk stratification, and treatment monitoring.

Rare adult neuronal ceroid lipofuscinosis associated with CLN6 gene mutations: A case report

BACKGROUND

Adult neuronal ceroid lipofuscinosis (ANCL) can be caused by compound heterozygous recessive mutations in CLN6. The main clinical features of the disease are neurodegeneration, progressive motor dysfunction, seizures, cognitive decline, ataxia, vision loss and premature death.

CASE SUMMARY

A 37-year-old female presented to our clinic with a 3-year history of limb weakness and gradually experiencing unstable walking. The patient was diagnosed with CLN6 type ANCL after the identification of mutations in the CLN6 gene. The patient was treated with antiepileptic drugs. The patient is under ongoing follow-up. Unfortunately, the patient’s condition has deteriorated, and she is currently unable to care for herself.

CONCLUSION

There is presently no effective treatment for ANCL. However, early diagnosis and symptomatic treatment are possible.

Role of Electroencephalogram (EEG) and Magnetic Resonance Imaging (MRI) Findings in Early Recognition and Diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 Disease

Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a very rare neurodegenerative lysosomal storage disorder. Progression is rapid and irreversible, making early diagnosis crucial for timely treatment. A group of pediatric neurologists and neuroradiologists with expertise in CLN2 convened to discuss early electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings in CLN2 diagnosis. Of 18 CLN2 cases, 16 (88.9%) had background slowing and 16 (88.9%) had epileptiform discharges on initial EEG. Seven of 17 (41.2%) patients who received intermittent low-frequency photic stimulation had a photoparoxysmal response. Initial MRIs showed subtle cerebellar (n = 14, 77.8%) or cerebral (n = 9, 50.0%) atrophy, white matter abnormalities (n = 11, 61.1%), and basal ganglia T2 hypointensity (n = 6, 33.3%), which became more apparent on follow-up MRI. The recognition of even subtle cerebellar atrophy and white matter signal changes in children aged 2-5 years who present with language delay, new-onset seizures, and an EEG with epileptiform discharges and background slowing should prompt investigation for CLN2. Because these early signs are not unique to CLN2, genetic testing is essential early in the diagnostic journey.

Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses

Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs.

Application of Anticonvulsants, Antiepileptic Drugs, and Vitamin C in the Treatment and Analysis of Batten Disease

Batten disease is a rare group of neurological diseases, specifically called neuronal ceroid lipofuscinosis. This is a genetic disorder and usually manifests during childhood. Batten disease is fatal and there is currently no proven cure. However, there are certain treatment methods that show potential in mitigating the aftermath of the disease. This review will explore the application and effectiveness of antiepileptic drugs, anticonvulsants, and vitamin C in multiple scenarios to treat Batten disease. Anticonvulsants are a broad group of medications that are used to treat epileptic seizures. Epileptic seizures are a big indicator of Batten disease, making anticonvulsants a potential treatment for Batten disease patients. Antiepileptic drugs also work to stop seizures by decreasing neurological excitation, thus for the same reason are often grouped alongside anticonvulsants and are being investigated as a promising way to help Batten disease patients. Vitamin C helps maintain the integrity of several intracellular processes in the central nervous system, which makes it a possible candidate for treating Batten disease. The known effects of anticonvulsants, antiepileptic drugs, and vitamin C on Batten disease are very limited and should be considered more often by healthcare professionals because of their potential effects on patients with Batten disease.

CASK related disorder: Epilepsy and developmental outcome

OBJECTIVE

CASK pathogenic variants are associated with variable features, as intellectual disability, optic atrophy, brainstem/cerebellar hypoplasia, and epileptic encephalopathy. Few studies describe the electroclinical features of epilepsy in patients with CASK pathogenic variants and their relationship with developmental delay.

METHODS

this national multicentre cohort included genetically confirmed patients with different CASK pathogenic variants. Our findings were compared with cohorts reported in the literature.

RESULTS

we collected 34 patients (29 females) showing from moderate (4 patients) to severe (22) and profound (8) developmental delay; all showed pontine and cerebellar hypoplasia, all except three with microcephaly. Seventeen out of 34 patients (50%) suffered from epileptic seizures, including spasms (11 patients, 32.3%), generalized (5) or focal seizures (1). In 8/17 individuals (47.1%), epilepsy started at or beyond the age of 24 months. Seven (3 males) out of the 11 children with spasms showed EEG features and a course supporting the diagnosis of a developmental and epileptic encephalopathy (DEE). Drug resistance was frequent in our cohort (52.9% of patients with epilepsy). EEG abnormalities included poorly organized background activity with diffuse or multifocal epileptiform abnormalities and sleep-activation, with possible appearance over the follow-up period. Developmental delay degree was not statistically different among patients with or without seizures but feeding difficulties were more frequent in patients with epilepsy.

CONCLUSIONS

epilepsy is a frequent comorbidity with a high incidence of spasms and drug resistance. Overall developmental disability does not seem to be more severe in the group of patients with epilepsy nor to be linked to specific epilepsy/EEG characteristics. A childhood onset of epilepsy is frequent, with possible worsening over time, so that serial and systematic monitoring is mandatory.

Targeted re-sequencing for early diagnosis of genetic causes of childhood epilepsy: the Italian experience from the 'beyond epilepsy' project

Background

Childhood epilepsies are a heterogeneous group of conditions differing in diagnostic criteria, management, and outcome. Late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) is a neurodegenerative condition caused by biallelic TPP1 variants. This disorder presents with subtle and relatively non-specific symptoms, mimicking those observed in more common paediatric epilepsies and followed by rapid psychomotor deterioration and drug-resistant epilepsy. A prompt diagnosis is essential to adopt appropriate treatment and disease management strategies.

Methods

This is a prospective, multicentre study on the efficiency of targeted re-sequencing in the early identification of the genetic causes of childhood epilepsy, with particular regard to CLN2. After phenotypic characterization, a 283-gene Next Generation Sequencing panel was performed in 21 Italian children with neurodevelopmental abnormalities, aged between 24 and 60 months, experiencing first unprovoked seizure after 2 years of age.

Results

The average age at enrolment was 39.9 months, with a mean age at seizure onset of 30.9 months and a mean time interval between seizure onset and targeted resequencing of 9 months. Genetic confirmation was achieved in 4 out of 21 patients, with a diagnostic yield of 19%. In one case, the homozygous splice acceptor variant c.509-1G > C in TPP1 was identified, leading to a CLN2 diagnosis. Three pathogenic variants in MECP2 were also detected in three patients, including the frameshift variant c.1157_1186delinsA (p.Leu386Hisfs*9) in a girl with negative single gene sequencing. Variants of unknown significance (VUS) were found in 11 out of 21 (52.4%) individuals, whereas no clinically significant variants were observed in the remaining 6 subjects.

Conclusions

Our findings support the efficacy of target re-sequencing in the identification of the genetic causes of childhood epilepsy and suggest that this technique might prove successful in the early detection of CLN2 as well as other neurodevelopmental conditions.

Therapeutic landscape for Batten disease: current treatments and future prospects

Batten disease (also known as neuronal ceroid lipofuscinoses) constitutes a family of devastating lysosomal storage disorders that collectively represent the most common inherited paediatric neurodegenerative disorders worldwide. Batten disease can result from mutations in 1 of 13 genes. These mutations lead to a group of diseases with loosely overlapping symptoms and pathology. Phenotypically, patients with Batten disease have visual impairment and blindness, cognitive and motor decline, seizures and premature death. Pathologically, Batten disease is characterized by lysosomal accumulation of autofluorescent storage material, glial reactivity and neuronal loss. Substantial progress has been made towards the development of effective therapies and treatments for the multiple forms of Batten disease. In 2017, cerliponase alfa (Brineura), a tripeptidyl peptidase enzyme replacement therapy, became the first globally approved treatment for CLN2 Batten disease. Here, we provide an overview of the promising therapeutic avenues for Batten disease, highlighting current FDA-approved clinical trials and prospective future treatments.

Unique Characteristics of the Photoparoxysmal Response in Patients With Neuronal Ceroid Lipofuscinosis Type 2: Can EEG Be a Biomarker?

OBJECTIVE

The objective was to identify unique features of the photoparoxysmal response seen in patients with neuronal ceroid lipofuscinosis type 2 as compared to patients with a photoparoxysmal response associated with other epilepsy syndromes.

METHODS

Electroencephalograms from patients with neuronal ceroid lipofuscinosis type 2 seen at the authors' institution in the past 10 years as well as electroencephalograms (EEGs) reported to have a photoparoxysmal response during a single year were reviewed.

RESULTS

A photoparoxysmal response was seen in 60% of the patients with neuronal ceroid lipofuscinosis type 2. This was most commonly seen with low frequency intermittent photic stimulation (76%) which often occurred in a time-locked fashion (63%) and was seen on the patient's initial EEG (78%). A unique pattern the authors called "sentinel" discharge was identified in 30% of EEGs in patients with neuronal ceroid lipofuscinosis.

CONCLUSIONS

Photoparoxysmal responses in patients with neuronal ceroid lipofuscinosis type 2 have features which are distinguishing from photoparoxysmal responses seen in other epilepsies.

Sleep Spindle Characteristics in Children with Neurodevelopmental Disorders and Their Relation to Cognition

Empirical evidence indicates that sleep spindles facilitate neuroplasticity and “off-line” processing during sleep, which supports learning, memory consolidation, and intellectual performance. Children with neurodevelopmental disorders (NDDs) exhibit characteristics that may increase both the risk for and vulnerability to abnormal spindle generation. Despite the high prevalence of sleep problems and cognitive deficits in children with NDD, only a few studies have examined the putative association between spindle characteristics and cognitive function. This paper reviews the literature regarding sleep spindle characteristics in children with NDD and their relation to cognition in light of what is known in typically developing children and based on the available evidence regarding children with NDD. We integrate available data, identify gaps in understanding, and recommend future research directions. Collectively, studies are limited by small sample sizes, heterogeneous populations with multiple comorbidities, and nonstandardized methods for collecting and analyzing findings. These limitations notwithstanding, the evidence suggests that future studies should examine associations between sleep spindle characteristics and cognitive function in children with and without NDD, and preliminary findings raise the intriguing question of whether enhancement or manipulation of sleep spindles could improve sleep-dependent memory and other aspects of cognitive function in this population.

Further delineation of eye manifestations in homozygous 15q13.3 microdeletions including TRPM1: a differential diagnosis of ceroid lipofuscinosis

The 15q13.3 heterozygous microdeletion is a fairly common microdeletion syndrome with marked clinical variability and incomplete penetrance. The average size of the deletion, which comprises six genes including CHRNA7, is 1.5 Mb. CHRNA7 has been identified as the gene responsible for the neurological phenotype in this microdeletion syndrome. Only seven patients with a homozygous microdeletion that includes at least CHRNA7, and is inherited from both parents have been described in the literature. The aim of this study was to further describe the distinctive eye manifestations from the analysis in the three French patients diagnosed with the classical 1.5 Mb homozygous microdeletion. Patients' ages ranged from 30 months to 9 years, and included one sib pair. They all displayed a remarkably severe identifiable clinical phenotype that included congenital blindness and convulsive encephalopathy with inconstant abnormal movements. The ophthalmological examination revealed a lack of eye tracking, optic nerve pallor, an immature response with increased latencies with no response to the checkerboard stimulations at the visual evoked potential examination, and a distinctive retina dystrophy with a negative electroretinogram in which the "b" wave was smaller than the "a" wave after a dark adapted pupil and bright flash in all patients. Clear genotype-phenotype correlations emerged, showing that this eye phenotype was secondary to homozygous deletion of TRPM1, the gene responsible for autosomal recessive congenital stationary night blindness. The main differential diagnosis is ceroid lipofuscinosis.

Clinical, electrophysiological, imaging, and ultrastructural description in 68 patients with neuronal ceroid lipofuscinoses and its subtypes

PURPOSE

We evaluated the clinical, electrophysiological, imaging, and ultrastructural features of neuronal ceroid lipofuscinoses and its subtypes.

METHODS

The clinical, electrophysiological, imaging, histopathological, and ultrastructural features of 68 (age at onset: 4.3 ± 5.4 years) neuronal ceroid lipofuscinoses and its subtypes (infantile neuronal ceroid lipofuscinoses [9], late infantile neuronal ceroid lipofuscinoses [34], juvenile neuronal ceroid lipofuscinoses [23], and adult neuronal ceroid lipofuscinoses [2] were evaluated. Skin (n = 56), brain (n = 12), muscle (n = 4) and nerve (n = 1) biopsies confirmed the diagnosis.

RESULTS

Clinical manifestations were milestone regression (93%), involuntary movements (92%), seizures (89%), myoclonus (79%), and visual impairment (68%). Response to anticonvulsants was unsatisfactory. Electroencephalography (n = 59) was abnormal in 90%: background slowing (90%); epileptiform discharges (71%), and photoparoxysmal response (4/21). Visual-evoked (n = 33) and somatosensory evoked (n = 40) potentials were abnormal in 62% and 63% of patients. Cranial computed tomography (n = 33) showed diffuse cerebral (61%) and cerebellar (27%) atrophy. Magnetic resonance imaging was abnormal in all 43 patients who were scanned: diffuse atrophy (100%), cerebellar atrophy (40%), leukoencephalopathy (65%), and thalamic T2 W hypointensity (33%). Dermal inclusions such as curvilinear inclusions were the most common abnormality: late infantile neuronal ceroid lipofuscinoses (97%), juvenile neuronal ceroid lipofuscinoses (100%), and infantile neuronal ceroid lipofuscinoses (88%). Additional fingerprint inclusions were noted: juvenile neuronal ceroid lipofuscinoses (43%), late infantile neuronal ceroid lipofuscinoses (15%), and infantile neuronal ceroid lipofuscinoses (13%). Granular osmiophilic deposits were noted in 50% of infantile neuronal ceroid lipofuscinoses. In 75% of patients, there was good correlation between the clinical subtype and ultrastructural inclusion pattern. In 27% of neuronal ceroid lipofuscinoses, multiple inclusions were noted.

CONCLUSIONS

The diagnosis of neuronal ceroid lipofuscinoses should be considered in individuals with characteristic clinical presentations and characteristic ultrastructural dermal inclusions. Three fourths showed morphological correlation of the inclusions with neuronal ceroid lipofuscinoses subtype.

Late infantile neuronal ceroid lipofuscinosis: mutations in the CLN2 gene and clinical course in Spanish patients

Late infantile neuronal ceroid lipofuscinosis (Jansky-Bielchowsky disease) is a rare disease caused by mutations in the CLN2 gene. The authors report the clinical outcome and correlate with genotype in 12 Spanish patients with this disease. Psychomotor regression, epilepsy, and other clinical symptoms/signs were assessed. Age at onset of clinical symptoms ranged from 18 months to 3.7 years, and they included delayed speech and simple febrile seizures followed by epilepsy. Partial seizures and myoclonic jerks occurred at an earlier age (median 3.4 and 3.7 years, respectively) than ataxia and cognitive decline (median 4 years). Clinical regression was initiated by loss of sentences (median 3.7 years) followed by loss of walking ability and absence of language (median 4.5 years). Patients showed blindness and lost sitting ability at similar age (median 5 years). The authors report 4 novel mutations in the CLN2 gene. This study provides detailed information about the natural history of this disease.

Diagnosis of neuronal ceroid lipofuscinosis: mutation detection strategies

The neuronal ceroid lipofuscinoses (NCL) are a group of rare genetically inherited neurodegenerative disorders in children. These diseases are classified by age of onset (congenital, infantile, late-infantile, juvenile and adult-onset) and by the gene bearing mutations (CLN10/CTSD, CLN1/PPT1, CLN2/TPP1, CLN3, CLN5, CLN6, CLN7/MFSD8 and CLN8). Enzyme activity assays are helpful in identifying several of these disorders; however confirmation of the mutation in the gene causing these diseases is vital for definitive diagnosis. There exists considerable heterogeneity in the NCLs as a whole and within each type of NCL both in phenotype (disease manifestation and progression) and genotype (type of mutation), which complicates NCL diagnosis. In order to streamline the diagnostic process, the age of symptom onset, geography and/or ethnicity, and enzyme activity may be considered together. However, these ultimately serve to guide targeting the correct route to genetic confirmation of an NCL through mutational analysis. Herein, an effective protocol to diagnose NCLs using these criteria is presented.

Clinical study in Chinese patients with late-infantile form neuronal ceroid lipofuscinoses

Clinical findings, pathological features and tripeptidyl peptidase 1 (TPP1) activity and genetic mutation analysis data of nine patients affected with the late-infantile form of neuronal ceroid lipofuscinoses (LINCL) in China are systematically reviewed with long-term follow-up. The patients were enrolled if curvilinear bodies were found on lymphocyte, skin or muscle specimens' examination, and/or reduction of tripeptidyl peptidase 1 (TPP1) activity were detected. CLN2 gene mutation were tested in five patients. The patients have onset age of 2-3.5 years, and most of them initially present partial seizure, and then progressed to deteriorated mental function, refractory myoclonic seizures, impaired vision, and ataxia with cerebellar atrophy. Discrete small vacuolated lymphocytes are found in 5-10% lymphocytes in 5 patients examined. Curvilinear bodies were found in vacuolated lymphocytes, in skin and muscle tissues. Tripeptidyl peptidase 1 (TPP1) activities are reduced in 5 patients with different CLN2 gene mutation. Detection of vacuolated lymphocytes may be a screen method for LINCL, ultrastructural examination of lymphocytes, combined with TPP1 activity assay, allowing for a definite and faster diagnosis and classification with minimal invasion.

Electroencephalography in autosomal dominant adult neuronal ceroid lipofuscinosis

OBJECTIVE

To describe the findings in 59 EEGs from six patients from three generations in a family with autosomal dominant adult neuronal ceroid lipofuscinosis (Parry disease), autopsy proven, with a follow up of 9-21 years.

METHODS

Descriptive, visual EEG analysis.

RESULTS

In these patients with epilepsy, myoclonus, dementia and Parkinsonism, EEGs were all severely abnormal, with generalized or bilateral independent periodic epileptiform discharges as the most common pattern. In a few EEGs periodic discharges were seen. No alpha rhythm was present. No paroxysmal response to photic stimulation was seen. Intraindividual EEG changes in the course of the disease were modest, despite severe clinical disease progression. No cortical component linked to myoclonus could be found with a backaveraging technique.

CONCLUSIONS

EEG in autosomal dominant neuronal ceroid lipofuscinosis is dominated by generalised periodic epileptiform discharges (GPEDs, or GPD+).

SIGNIFICANCE

GPD/GPEDs in adults with myoclonus, Parkinsonism, dementia or epilepsy should raise the possibility of adult neuronal ceroid lipofuscinosis, especially with familial occurrence.

Myoclonic Status in Nonprogressive Encephalopathies: Study of 29 Cases

PURPOSE

Myoclonic status in nonprogressive encephalopaties (MSNE) is characterized by recurrence of long-lasting myoclonic status appearing in infants and young children with nonprogressive encephalopathy. Here, we describe the electroclinical features and evolution of MSNE.

METHODS

Between February 1, 1990 and July 31, 2005, 29 patients who met diagnostic criteria of MSNE were enrolled in the study at our department and have been followed up to the present time.

RESULTS

Three main subgroups could be identified. The first subgroup of 18 patients presented myoclonic absences and rhythmic myoclonias. These were followed by a brief silent period related to a subcontinuous delta-theta activity involving the central areas, and rhythmic delta waves with superimposed spikes mainly involving the parietooccipital regions and often activated by eye closure. It was found in all children with a genetic etiology. The second subgroup included five patients showing a pattern characterized by inhibitory phenomena associated with a dystonic component and sudden irregular rapid lightning-like jerks. The EEG showed subcontinuous multifocal slow spike-waves, predominating in frontocentral regions. These patients are affected by a cortical malformation or the etiology is unknown. The third subgroup included six children who initially suffered from myoclonic absences. The status was initially characterized by subcontinuous generalized spike-wave-type paroxysms related to rhythmic myoclonia of face and limbs. After 1-3 weeks, the EEG showed sharp theta waves with very slow pseudorhythmic continuous spikes in the central regions and vertex. The etiology was found to be perinatal anoxic injury.

CONCLUSION

MSNE should be considered as a new epileptic syndrome in the group of epileptic encephalopathy.

Dificuldades no diagnóstico clínico e eletrencefalográfico de lipofuscinose ceróide neuronal

Tradicionalmente, as lipofuscinoses ceróides neuronais (LCN) eram classificadas de acordo com a idade de início e características clínicas em quatro grandes grupos. Recentemente, os estudos genéticos possibilitaram uma classificação mais pormenorizada dessa entidade em oito formas, permitindo o diagnóstico mais preciso de casos previamente considerados atípicos. Por outro lado, foi demonstrado que mutações de um mesmo gene poderiam ser responsáveis por grande variedade de fenótipos clínicos. O objetivo deste estudo é apresentar dois irmãos com achados clínicos e eletrencefalográficos compatíveis com a forma juvenil de LCN mas com alterações ultra-estruturais características da forma infantil tardia dessa doença. Os achados eletrencefalográficos auxiliam no diagnóstico da LCN, mas pouco contribuem na sua classificação.