New subform of the late infantile form of neuronal ceroid lipofuscinosis

Expanding the Neuroimaging Phenotype of Neuronal Ceroid Lipofuscinoses

BACKGROUND AND PURPOSE

Neuronal ceroid lipofuscinoses are a group of neurodegenerative disorders characterized by the accumulation of autofluorescent lipopigments in neuronal cells. As a result of storage material in the brain and retina, clinical manifestations include speech delay, cognitive dysfunction, motor regression, epilepsy, vision loss, and early death. At present, 14 different ceroid lipofuscinosis (CLN) genes are known. Recently, the FDA approved the use of recombinant human proenzyme of tripeptidyl-peptidase 1 for CLN2 disease, while phase I/IIa clinical trials for gene therapy in CLN3 and CLN6 are ongoing. Early diagnosis is, therefore, key to initiating treatment and arresting disease progression. Neuroimaging features of CLN1, CLN2, CLN3, and CLN5 diseases are well-described, with sparse literature on other subtypes. We aimed to investigate and expand the MR imaging features of genetically proved neuronal ceroid lipofuscinoses subtypes at our institution and also to report the time interval between the age of disease onset and the diagnosis of neuronal ceroid lipofuscinoses.

MATERIALS AND METHODS

We investigated and analyzed the age of disease onset and neuroimaging findings (signal intensity in periventricular, deep, and subcortical white matter, thalami, basal ganglia, posterior limb of the internal capsule, insular/subinsular regions, and ventral pons; and the presence or absence of supratentorial and/or infratentorial atrophy) of patients with genetically proved neuronal ceroid lipofuscinoses at our institution. This group consisted of 24 patients who underwent 40 brain MR imaging investigations between 1993 and 2019, with a male preponderance (male/female ratio = 15:9).

RESULTS

The mean ages of disease onset, first brain MR imaging, and diagnosis of neuronal ceroid lipofuscinoses were 4.70 ± 3.48 years, 6.76 ± 4.49 years, and 7.27 ± 4.78 years, respectively. Findings on initial brain MR imaging included T2/FLAIR hypointensity in the thalami (n = 22); T2/FLAIR hyperintensity in the periventricular and deep white matter (n = 22), posterior limb of the internal capsule (n = 22), ventral pons (n = 19), and insular/subinsular region (n = 18); supratentorial (n = 21) and infratentorial atrophy (n = 20). Eight of 9 patients who had follow-up neuroimaging showed progressive changes.

CONCLUSIONS

We identified reported classic neuroimaging features in all except 1 patient with neuronal ceroid lipofuscinoses in our study. CLN2, CLN5, and CLN7 diseases showed predominant cerebellar-over-cerebral atrophy. We demonstrate that abnormal signal intensity in the deep white matter, posterior limb of the internal capsule, and ventral pons is more common than previously reported in the literature. We report abnormal signal intensity in the insular/subinsular region for the first time. The difference in the median time from disease onset and diagnosis was 1.5 years.

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.

Functions and biosynthesis of plasmalogens in health and disease

Plasmalogens (1-O-alk-1'-enyl-2-acyl glycerophospholipids) constitute a special class of phospholipids characterized by the presence of a vinyl-ether bond at the sn-1 position. Although long considered as biological peculiarities, interest in this group of phospholipids has grown in recent years, thanks to the realization that plasmalogens are involved in different human diseases. In this review, we summarize the current state of knowledge with respect to the enzymatic synthesis of plasmalogens, the characteristic topology of the enzymes involved and the biological roles that have been assigned to plasmalogens.

Enlarged SI and SII somatosensory evoked responses in the CLN5 form of neuronal ceroid lipofuscinosis

OBJECTIVES

To examine in detail the activation of the primary (SI) and secondary (SII) somatosensory cortex in CLN5, the Finnish variant of late infantile neuronal ceroid lipofuscinoses (NCL).

METHODS

Somatory evoked magnetic fields were recorded with a 122-channel planar gradiometer in response to median nerve stimulation in 5 CLN5 patients (aged 8.8-16.7 years) and in 10 healthy age-matched controls.

RESULTS

The first two responses from contralateral SI, N20m and P35m, were 6-20 times stronger in the patients than in the controls. The morphology of the subsequent deflections from SI was abnormal in the patients: a prominent N45m was detected, while the normally present P60m deflection was missing. In 4 patients the contra- and in two patients the ipsilateral SII responses were also enlarged. Furthermore, the SII activation was detected at shorter latency in patients than in controls.

CONCLUSIONS

At SI, CLN5 is associated with a selective enhancement of the early cortical responses. We propose that the enlargement of N20m most likely reflects increased synchronous input from thalamus, whereas the altered morphology of the following responses may reflect defective interneuronal inhibition at the cortex. The enlargement of SII responses shows that the imbalance between excitation and inhibition in CLN5 extends outside the primary somatosensory areas.

Cellular pathology and pathogenic aspects of neuronal ceroid lipofuscinoses

Lysosomal accumulation of autofluorescent, ceroid lipopigment material in various tissues and organs is a common feature of the neuronal ceroid lipofuscinoses (NCLs). However, recent clinicopathologic and genetic studies have evidenced that NCLs encompass a group of highly heterogeneous disorders. In five of the eight NCL variants distinguished at present, genes associated with the disease process have been isolated and characterized (CLN1, CLN2, CLN3, CLN5, CLN8). Only products of two of these genes, CLN 1 and CLN2, have structural and functional properties of lysosomal enzymes. Nevertheless, according to the nature of the material accumulated in the lysosomes, NCLs in humans as well as natural animal models of these disorders can be divided into two major groups: those characterized by the prominent storage of saposins A and D, and those showing the predominance of subunit c of mitochondrial ATP synthase accumulation. Thus, taking into account the chemical character of the major component of the storage material, NCLs can be classified currently as proteinoses. Of importance, although lysosomal storage material accumulates in NCL subjects in various organs, only brain tissue shows severe dysfunction and cell death, another common feature of the NCL disease process. However, the relation between the genetic defects associated with the NCL forms, the accumulation of storage material, and tissue damage is still unknown. This chapter introduces the reader to the complex pathogenesis of NCLs and summarizes our current knowledge of the potential consequences of the genetic defects of NCL-associated proteins on the biology of the cell.

Pathological study on sibling autopsy cases of the late infantile form of neuronal ceroid lipofuscinosis

We report autopsy cases of two brothers with the late infantile form of neuronal ceroid lipofuscinosis (LINCL) and examine apoptotic cell death in autopsied brains. Both patients showed psychomotor developmental delay, cerebellar ataxia, convulsions, visual disturbance and myoclonus, and they became bedridden around the age of 6-7 years. Macular changes, mimicking cherry-red spots, were observed on funduscopy, but conjunctival biopsy failed to disclose storage materials. In these cases, the autopsies demonstrated severe atrophy with neuronal loss and gliosis throughout the brain and spinal cord, except the hypothalamic neurons and motor neurons in the brain-stem and spinal cord, and autofluorescent lipofuscin-like materials of two types, fine granular deposits and coarse round bodies, were stored in the remaining neurons and glial cells, and in the epithelial cells of various visceral organs. Immunostaining for mitochondrial subunit C visualized the fine granular deposits but not the coarse round bodies. The nuclei of neurons and glia cells were stained by in situ nick end labeling, which was more pronounced in the younger case, although the expression of both bcl-2 and bcl-x was not significantly altered in these cases. It is suggested that immunohistochemistry for subunit C may be useful for diagnosis of NCL, and further investigations are necessary to clarify the relationship between LINCL and apoptosis, especially in severely affected cases.

Neuronal ceroid lipofuscinoses: a review

Neuronal ceroid lipofuscinoses (NCLs) are among the most common neurodegenerative diseases in childhood but rarely present in adulthood. The main symptoms are psychomotor deterioration, visual failure, epilepsy and motor disturbances. The NCLs are morphologically characterized by the accumulation of lipopigments within numerous cell types and loss of neurons. Pathogenesis is unknown. The current clinical classification recognizes six classic types of NCL and several atypical forms. Electrophysiological and neuroradiological findings may be of diagnostic significance, but disease recognition rests on the demonstration of a typical ultrastructural pattern. Genetic studies have demonstrated that several different genetic loci are involved in the pathogenesis of NCL, but the molecular mechanisms underlying neuronal death and lipopigment accumulation are not understood.

Palmitoyl-protein thioesterase deficiency in a novel granular variant of LINCL

Typically, late infantile neuronal ceroid-lipofuscinosis (LINCL) patients present between the ages of 2 and 4 years with progressive dementia, blindness, seizures, and motor dysfunction. Curvilinear profiles are seen on electron microscopic examination of tissues derived from those patients. Data were collected on 122 LINCL cases, representing 81 independent families, diagnosed on the basis of age of onset, clinical symptomatology, and pathologic findings. Careful analysis of our data has revealed that 20% of these cases (24 of 122) show either an atypical clinical course or atypical pathologic findings and may represent variants of LINCL. Recent progress in the biochemistry and molecular genetics of NCL has led us to reevaluate these atypical cases. Five atypical LINCL cases (representing three independent families) manifested granular inclusions when examined by electron microscopy, a finding normally associated with the infantile form of NCL. In addition, these five cases did not show elevated subunit c levels in urine (typically seen in LINCL). In these five cases, palmitoyl-protein thioesterase activity was found to be deficient (less than 10% normal activity), suggesting that these cases represent INCL, presenting at a later age of onset. These findings suggest that palmitoyl-protein thioesterase deficiency is not restricted to infantile onset cases, and they raise the possibility that milder forms of INCL may result from less deleterious mutations.

Myoclonus and epilepsies

The possible associations of myoclonic phenomenae, progressive or non-progressive encephalopathies and epileptic features are reviewed, with special emphasis on pediatric age. This leads to recognize the following five groups of conditions: (1) Myoclonus without encephalopathy and without epilepsy; (2) Encephalopathies with non-epileptic myoclonus; (3) Progressive encephalopathies presenting myoclonus seizures of epileptic syndromes (Progressive myoclonus epilepsies); (4) Epileptic encephalopathies with myoclonic seizures; (5) Myoclonic epilepsies. Within the first group, which also includes physiologic myoclonus, a more thorough description of "Benign sleep myoclonus of newborn" and "Benign myoclonus of early infancy" is given. Characteristics of group 2 are "Kinsbourne Syndrome" and certain types of "Hyperekplexia" which pose interesting differential diagnosis with stimulus-sensitive epilepsies. In group 3, the concept of progressive encephalopathies is stressed. The fourth group refers to severe epilepsies, mainly on infancy and childhood, which lead to mental retardation irrespective of their aetiology. Group 5 comprises the true myoclonic epilepsies, differentiating syndromes recognized as idiopathic--such as "Benign myoclonic epilepsy of infancy" and "Juvenile myoclonic epilepsy"--from those which are cryptogenic and carry a more cautious prognosis--as "Cryptogenic myoclonic and myoclonoastatic epilepsies" and "Severe myoclonic epilepsy of infancy". Other epileptic syndromes not usually considered as myoclonic epilepsies, but presenting sometimes as myoclonic seizures, are finally referred.

Neuroradiological findings in classical late infantile neuronal ceroid-lipofuscinosis

We describe a girl aged 5 years, 6 months who began to have seizures at the age of 3 years, 9 months. A cranial CT scan revealed mild, generalized cerebral atrophy. During the next year, she gradually developed ataxia, myoclonic jerks, and bilateral optic nerve atrophy and lost motor skills. A second CT scan performed 12 months after the onset of first symptoms revealed marked progression of cerebral atrophy, especially in the infratentorial area. MRI demonstrated bilateral, periventricular hyperintensities in the T2-weighted images but no changes in the basal ganglia. Electron microscopic investigations of skin biopsies demonstrated curvilinear bodies, confirming the suspected diagnosis of late infantile neuronal ceroid-lipofuscinosis (LINCL). Predominance of cerebral atrophy in the infratentorial area is typical of LINCL. Periventricular white matter lesions may be evident on MRI scans of patients with classical and LINCL-variant disease. In contrast to neuroradiological findings in patients with LINCL-variant disease, findings in patients with classical LINCL revealed no changes in the basal ganglia.

MRI of neuronal ceroid lipofuscinosis. I. Cranial MRI of 30 patients with juvenile neuronal ceroid lipofuscinosis

We studied 30 patients with juvenile neuronal ceroid lipofuscinosis (JNCL). The patients (aged 6-25 years) and 43 age-matched healthy volunteers underwent MRI. After visual assessment, the signal intensity was measured on T2-weighted images in numerous locations. The thickness of the cortex and corpus callosum and the dimensions of the brain stem were measured. Mild to moderate cerebral atrophy was found in 14 of 30 patients, most of them over 14 years of age; 5 older patients had mild to moderate cerebellar atrophy. There was reduction in the size of the corpus callosum and brain stem. The thalamus, caudate nucleus and putamen appeared to give low signal in patients from the ages of 7, 11 and 11 years, respectively. In contrast, the signal intensity measured from the thalamus in these patients showed only a slight (insignificant) decrease compared with controls. The most significant alteration, an increase in measured signal intensity, was found in the white matter (P < 0.0001), even in the youngest patients. The MRI findings correlated significantly with decreased intelligence, speech disturbances and motor problems. Although MRI findings in JNCL do not appear very specific and the visual changes develop relatively late, the absence of pathological MRI findings in the very early stage of the disease may play a part in differential diagnosis of the different types of NCL. Furthermore, the MRI findings may be used in assessing severity and prognosis, particularly in young patients.

MRI evaluation of the brain in infantile neuronal ceroid-lipofuscinosis. Part 2: MRI findings in 21 patients

The purpose of this study was to demonstrate the course of infantile neuronal ceroid-lipofuscinosis with brain magnetic resonance imaging (MRI) in children aged 3 months to 11 years. Twenty-one patients and 46 neurologically normal controls of the same age were examined. The images were evaluated visually; then signal intensities were measured and related to those of references. MRI abnormalities were detectable before clinical symptoms. The radiologic picture of the brain varied with the duration of the disease. Pathognomonic MRI findings in the early stage of the disease were generalized cerebral atrophy, strong thalamic hypointensity to the white matter and to the basal ganglia, and thin periventricular high-signal rims from 13 months onward on T2-weighted images. In patients over 4 years old, cerebral atrophy was extreme, and the signal intensity of the entire white matter was higher than that of the gray matter, which is the reverse of normal. This study showed that the abnormalities seen on MRI progress rapidly during the first 4 years of life, then stabilize, in conformity with the clinical and histopathologic pictures of infantile neuronal ceroid-lipofuscinosis.

Classification of the neuronal ceroid-lipofuscinoses: expansion of the atypical forms

The neuronal ceroid-lipofuscinoses (NCL) are a group of different genetic diseases. The major types of NCL are expressed by six forms which represent different clinicopathologic and genetic forms. These are CLN-1, Infantile; CLN-2, Late Infantile; CLN-3, Juvenile; CLN-4, Adult-Recessive; CLN-5, Adult-Dominant; and CLN-6, Early Juvenile. The distinction between CLN-4 and CLN-5 is still disputatious. CLN-6 has been called CLN-5. A seventh classification of NCL represents from 12 to 20% of those afflicted. This group consists of an extensive array of atypical types of ceroid-lipofuscin accumulation in the secondary lysosomes of neurons and cells of other tissues (e.g., skin, conjunctiva, and lymphocytes) or by presumed clinical and genetic relationships. The authors have identified 15 atypical subtypes of NCL. These as a group are here described as a seventh form. Further biochemical, molecular, and genetic studies will identify more precisely the phenotypic and genotypic expression of these "minor" forms of NCL.

Topographic variabilities of immunoreactivity to subunit c of mitochondrial ATP synthase and lectin binding in late infantile neuronal ceroid-lipofuscinosis

A subset of lipophilic neurons in the brain tissue of late infantile neuronal ceroid lipofuscinosis (LINCL) cases shows in addition to finely granular storage lipopigment, larger spheroidal lysosomal inclusions, so called protein-type myoclonus bodies. Their incidence, significance, and biochemical composition have not been determined. To further characterize this type of lysosomal storage material, immunocytochemistry to subunit c of mitochondrial ATP synthase at the light and electron microscopy level, electron microscopy, and lectin histochemistry were applied. The majority of spheroidal inclusions were nonreactive to subunit c, the main protein component of the storage material in LINCL. These inclusions also showed no binding sites for the eight lectins examined, although six of the lectins used labeled finely granular storage material. According to electron and immunoelectron microscopy, spheroidal inclusions were composed of more homogeneous and more densely arranged material than typical curvilinear profiles, with shorter membranous profiles and sometime filamentous structures. The dissimilarities disclosed between finely granular lipopigment with curvilinear profiles and spheroidal inclusions in LINCL brain tissue suggest that either protein(s) other than subunit c are present in spheroidal inclusions, or subunit c in these sites undergoes conformational or proteolytic changes. These changes require further biochemical evaluations.

Neuronal ceroid-lipofuscinosis: a clinical and morphological study of 19 patients

We report on clinical, electrophysiological, neuroradiological, and morphological data from 19 patients with different types (late infantile, juvenile, and adult) of neuronal ceroid-lipofuscinosis (NCL), observed in the last 10 years at the Neurological Institute of Milan. Late Infantile NCL (LINCL) (8 patients, 4m/4f). Age at onset: 2-4 1/2 years. Seizures (6 patients) or decline of mental capacities (2 patients) were the presenting symptoms, followed by myoclonus and ataxia; visual loss and optic atrophy occurred in 6 patients within 3 years. All but 2 children became bedridden within 3 1/2 years. CT and MRI demonstrated different degrees of cerebral and cerebellar atrophy within 3 years from onset of the disease. Ultrastructural studies showed fingerprint profiles (FP) and osmiophilic bodies (OB) in circulating lymphocytes; curvilinear bodies (CB) and FP were detected in eccrine secretory cells. Juvenile NCL (JNCL) (7 patients, 4m/3f). Age at onset: 6-9 years. Visual loss with retinal degeneration was the presenting symptoms, accompanied in all but 2 patients by slight mental impairment. Seizures occurred within 2-4 years. CT and MRI detected cerebral or cerebellar atrophy in those patients (5 patients) with a clinical follow-up longer than 4 years. Electron microscopy showed FP on circulating lymphocytes, and both FP and CB on skin biopsy specimens. Adult NCL (ANCL) (4 patients, 3 m/1f). Age at onset: 12-50 years. Progressive myoclonus epilepsy (1 patient) or dementia with motor disturbances (3 patients) were the clinical phenotypes of the disease. MRI demonstrated cerebral and cerebellar atrophy within 6 years from onset. Electron microscopy disclosed FP in cytoplasmic vacuoles inside eccrine secretory cells.