Evolution of EEG Findings in Pontocerebellar Hypoplasia Type 2A: Normal EEG in the First Few Months followed by Abnormal Tracing over the Years.

Pontocerebellar hypoplasia (PCH) is an autosomal recessive neurodevelopmental and neurodegenerative disorder characterized by cerebellar and pontine hypoplasia, progressive microcephaly, and developmental delay. Ten types of PCH have been described; PCH type 2A (PCH2A) due to a mutation in TSEN54 is the most frequent. Seizures have been reported in the large majority of patients. The probability of epilepsy developing increases with age, along with difficulties in differentiating seizures from dyskinetic movements. The aim of the present report was to describe the clinical symptoms and electroencephalogram (EEG) changes over time in three patients of Israeli Arab origin with PCH2A. All three, including two siblings and their first cousin, were homozygous for the TSEN54 p.A304S mutation. The patients demonstrated profound psychomotor retardation, severe spasticity and contractures, choreoathetoid movements, and seizures. The magnetic resonance imaging (MRI) scans and EEGs were reviewed by an experienced neuroradiologist and epileptologist, respectively. The MRI scans revealed a dragonfly-like cerebellar pattern in all patients. Despite the normal early EEG findings, all patients had characteristic features of epilepsy, with tonic seizures starting in the first days to months followed by focal to bilateral tonic-clonic seizures in early childhood which continued to adolescence. In conclusion, patients with PCH2A due to the missense mutation p.A304S in TSEN54 exhibit profound psychomotor delay, movement disorders, and intractable epilepsy. An evolution of EEG abnormalities and seizure semiology occurs over time. Similar to several other genetic epileptic encephalopathies, the normal early EEG tracing does not rule out the later occurrence of epilepsy.

Extension of the phenotype of biallelic loss-of-function mutations in SLC25A46 to the severe form of pontocerebellar hypoplasia type I.

Biallelic mutations in SLC25A46, encoding a modified solute transporter involved in mitochondrial dynamics, have been identified in a wide range of conditions such as hereditary motor and sensory neuropathy with optic atrophy type VIB (OMIM: *610826) and congenital lethal pontocerebellar hypoplasia (PCH). To date, 18 patients from 13 families have been reported, presenting with the key clinical features of optic atrophy, peripheral neuropathy, and cerebellar atrophy. The course of the disease was highly variable ranging from severe muscular hypotonia at birth and early death to first manifestations in late childhood and survival into the fifties. Here we report on 4 patients from 2 families diagnosed with PCH who died within the first month of life from respiratory insufficiency. Patients from 1 family had pathoanatomically proven spinal motor neuron degeneration (PCH1). Using exome sequencing, we identified biallelic disease-segregating loss-of-function mutations in SLC25A46 in both families. Our study adds to the definition of the SLC25A46-associated phenotypic spectrum that includes neonatal fatalities due to PCH as the severe extreme.

Glutamate receptor block in Lurcher mutant mice during ontogeny and its effect on hippocampal long-term potentiation.

Basic evaluation of the effect of chronic NMDA glutamate receptor (NMDAR) blockade on the hippocampal long-term potentiation (LTP) was performed in an animal model of inborn olivo-cerebellar degeneration (Lurcher mutant mice, LMM). NMDA receptor antagonist MK-801 was administered to mice in the dose 0.2 mg/kg of body weight, daily during two periods of their ontogeny: D5-D26 and D91-D111. In the consecutive 15 days some behavioral characteristics were studied using special methods for physical activity testing. Then LTP was investigated in LMM and also in their healthy littermates which served as controls (wild-type, WT). LTP in animals pre-treated with MK-801 showed significant long-term suppression of NMDAR activity, in both WT and LMM despite certain small differences between them. Our results show that cerebellar pathology on one hand and a physical activity on the other hand can influence the LTP in hippocampal region. It can be concluded that the results support the ideas of close functional cooperation between the brain structures which are involved in mechanisms of learning and memory.

A patient with pontocerebellar hypoplasia type 6: Novel RARS2 mutations, comparison to previously published patients and clinical distinction from PEHO syndrome.

Pontocerebellar hypoplasia type 6 (PCH6) is a rare infantile-onset progressive encephalopathy caused by biallelic mutations in RARS2 that encodes the mitochondrial arginine-tRNA synthetase enzyme (mtArgRS). The clinical presentation overlaps that of PEHO syndrome (Progressive Encephalopathy with edema, Hypsarrhythmia and Optic atrophy). The proband presented with severe intellectual disability, epilepsy with varying seizure types, optic atrophy, axial hypotonia, acquired microcephaly, dysmorphic features and progressive cerebral and cerebellar atrophy and delayed myelination on MRI. The presentation had resemblance to PEHO syndrome but sequencing of ZNHIT3 did not identify pathogenic variants. Subsequent whole genome sequencing revealed novel compound heterozygous variants in RARS2, a missense variant affecting a highly conserved amino acid and a frameshift variant with consequent degradation of the transcript resulting in decreased mtArgRS protein level confirming the diagnosis of PCH6. Features distinguishing the proband's phenotype from PEHO syndrome were later appearance of hypotonia and elevated lactate levels in blood and cerebrospinal fluid. On MRI the proband presented with more severe supratentorial atrophy and lesser degree of abnormal myelination than PEHO syndrome patients. The study highlights the challenges in clinical diagnosis of patients with neonatal and early infantile encephalopathies with overlapping clinical features and brain MRI findings.

Rhabdomyolysis in pontocerebellar hypoplasia type 2 (PCH-2).

Pontocerebellar hypoplasia type 2, an autosomal recessive neurodegeneration with prenatal onset, is characterised by progressive microcephaly and chorea/dystonia and has not previously been associated with muscular involvement. The gene associated with PCH-2 is unknown. An episode of rhabdomyolysis is reported in two non-related children with PCH-2, fatal in one, precipitated by intercurrent disease. Muscle biopsies in two other PCH-2 patients, and in one rhabdomyolysis patient whose biopsy antedated this complication showed areas of myofibrillar disruption or necrosis. Postmortem muscle sampled in another case without neuromuscular symptoms revealed focal necrosis, regenerating small fibres and upregulation of HLA-ABC. Random serum creatine kinase values in six other PCH-2 patients without clinical signs of neuromuscular involvement were increased in four. Collected data provide preliminary evidence of a subclinical myopathy associated with PCH-2.

Sporadic ataxias in Japan--a population-based epidemiological study.

Sporadic spinocerebellar ataxias (SCAs) comprise heterogeneous diseases with poorly understood epidemiologies and etiologies. A population-based epidemiological analysis of sporadic ataxias in the Japanese population was described. The prevalence rate of SCAs in the Japanese population is estimated to be 18.5/100,000. Sporadic SCAs account for 67.2% of total SCAs including hereditary SCAs, with olivopontocerebellar atrophy (OPCA) being the most common form sporadic ataxia (64.7%). The natural history analysis conducted on the basis of International Cooperative Ataxia Rating Scale (ICARS) showed that only 33% of patients with OPCA were able to walk at least with one stick 4-5 years after the onset of OPCA, which is much less than that of patients with cortical cerebellar atrophy (CCA). Similarly, 43% of patients with OPCA were able to stand alone 4-5 years after the onset, while 76% of patients with CCA were able to stand alone at the same disease duration. A population-based epidemiological analysis should provide essential information on the natural history of SCAs.

The effect of repeated rotarod training on motor skills and spatial learning ability in Lurcher mutant mice.

Lurcher mutant mice represent a model of olivocerebellar degeneration. Due to loss of Purkinje cells, they suffer from functional cerebellar decortication resulting in ataxia and deterioration of cognitive functions. The aim of the work was to assess the effect of enforced physical activity represented by rotarod training on motor skills and spatial learning in young and adult B6CBA Lurcher mice. These functions were compared with those in untrained wild type mice of the same age. We examined motor skills using bar, ladder and rotarod tests. Spatial learning was tested in the Morris water maze. Motor skills of Lurchers were found to be worse than in wild type mice, but they showed motor learning in the course of training. The training did not significantly influence the results on the bar and ladder. In the rotarod test, young trained Lurchers achieved only slightly better results than untrained ones. In adult mice, the improvement was insignificant. Lurchers failed in spatial learning test compared to the wild type mice. In the wild type mice there was no difference in learning between young and adult individuals, while young Lurchers learned better than older ones. Enforced motor activity led to spatial learning improvement in older Lurchers, but not in young ones. The experiments showed that effects of enforced physical activity in Lurcher mice mitigated the deficit in the water maze task related to age so that trained older Lurchers showed as good performance as younger ones but still worse than the wild type mice.

The effect of nitric oxide synthase inhibitors nitro-L-arginine and 7-nitroindazole on spatial learning and motor functions in Lurcher mutant and wild type mice.

Nitric oxide (NO) is an intercellular messenger that, among other things, plays an important role in the nervous system as a gaseous neurotransmitter, modulating long-term potentiation (LTP) induction of synaptic transmission. LTP has been suggested to be the basis of memory formation. On the other hand NO also participates in excitotoxic processes which play an important role in many neuropathological states. The aim of this work was to observe the effect of two NO synthase (NOS) inhibitors (N omega-Nitro-L-arginine, NA; 7-nitroindazole, NI) on spontaneous behaviour, spatial learning and motor functions in Lurcher (+/Lc) and wild type (+/+) mice, derived from the B6CBA strain. Heterozygous Lurcher mutant mice represent a natural model of the olivocerebellar degeneration. They suffer from postnatal, practically total, extinction of cerebellar Purkinje cells (due to the excitotoxic apoptosis) and a partial decrease of granule cells and inferior olive neurons (ION) because of the lost target of their axons. +/+ animals are healthy littermates of +/Lc. NA is a nonselective NOS inhibitor which influences, except neuronal (n), also endothelial (e) NOS with an impact on blood pressure, NI is a selective nNOS inhibitor without any circulatory effect. The adult animals of both types (+/Lc; +/+) were influenced by acute administration of both inhibitors (25 mg/kg i.p. 30 min. before experiments) and newborns only by both acute and long-term administration of NI (1 month, starting from postnatal day 2, P2). Control solutions - saline or solvents of both NA and NI inhibitors--diluted 1M HCl and dimethyl sulfoxide (DMSO) respectively, were given at a relevant volume in the same way. The effect of both inhibitors and control solutions on motor functions was tested using four standard procedures (horizontal wire, slanting ladder, rotating cylinder, foot-bridge); in newborns at the age of 14 days. Spatial learning ability was examined in five-day long procedure in the Morris water maze (MWM) (in newborns started on P21). Spontaneous behaviour was studied only in adult animals (after acutely influencing them) employing the open field method. The results showed, that neither the Lurcher mutant, nor wild type mice derived from the B6CBA strain were significantly affected by NOS inhibitors NA and NI in spatial learning after both the acute and long-term application. Only significant decrease of swimming speed was found in both types of mice after the acute administration of NI and in the wild type animals after the acute administration of NA. Motor functions were significantly negatively affected only in the Lurcher mutants after both the acute and chronic application of NI.

Topographic brain mapping of the international cooperative ataxia rating scale. A positron emission tomography study.

The International Cooperative Ataxia Rating Scale (ICARS) is a 100-point semiquantitative scale designed primarily to assess cerebellar dysfunction. However, little is known of the metric properties of this scale. We assessed the ICARS by rating the severity of cerebellar dysfunction in 27 patients with spinocerebellar ataxias (SCA), three patients with sporadic olivopontocerebellar ataxia and 24 healthy control subjects. [(18)F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) study was also performed on each subject. The statistical parametric mapping analyses revealed a significant correlation between the ICARS scores and functional impairment of the frontal regions within SCA patients. The glucose metabolism in the cerebellum, thalamus and caudate nucleus had significant differences between SCA patients and healthy control subjects. The results suggested that the clinical severity of SCA patients correlated with the functional impairment in the frontal regions, the targets of cerebellar efferent projections.

Motor and visuospatial abilities in a model of olivocerebellar and retinal degeneration--Lurcher mutant mice of C3H strain.

Lurcher mutant mice represent a natural model of olivocerebellar degeneration. They suffer from loss of Purkinje cells and decreased number of granule cells and inferior olive neurons. The degeneration leads to cerebellar ataxia and deterioration of cognitive functions. Some animals of the C3H strain have also the retinal degeneration. The aim of the study was to analyze the morphology of cerebellar and retinal degeneration and to evaluate the ability of motor coordination and visuospatial orientation in C3H Lurcher mutant mice. Cerebella of Lurcher mutant and wild type mice were examined with several histological, histochemical and immunohistochemical methods. Motor coordination was tested on a bar, ladder and rotarod. Spatial orientation and learning were tested in the Morris water maze with visible or hidden platform. Histological examinations showed decreased numbers of Purkinje cell in Lurchers. Various histological methods brought different information about the course or stage of the cerebellar degeneration. Retinal degeneration was identified with hematoxyline-eosine staining very well. Lurchers performed worse in motor coordination tests and in both the spatial orientation and learning test. Retinal degeneration influenced negatively both the spatial learning and orientation. Motor tests were influenced by retinal degeneration only in the wild type mice. Wild type mice showed some ability of idiothetic navigation, which was not found in Lurchers.

The time-dependent block of NMDA glutamate receptor influences hippocampal LTP in inborn cerebellar degeneration mouse model.

The effect of single dose of NMDA glutamate receptor blockage administration on the hippocampal LTP was evaluated in animal model of inborn cerebellar degeneration. We compared the level of possible LTP blockade in two groups of animals, Lurcher mutant mice and their healthy littermates which served as controls. In the second part of the study we tested group of mice which were influenced repeatedly by the same NMDA blocker (MK-801) during behavioral experiments. Our results suggest a similar effect of blockade either after single or chronic MK-801 administration; both of them practically disrupted LTP generation with differences between healthy and neurodegenerative animals.

Does transplantation of cerebellar embryonic tissue influence hippocampal LTP in adult Lurcher mutant mice?

Possible influence of embryonic cerebellar graft transplanted into the adult neurodegenerative brain in Lurcher mutant mice on long-term potentiation (LTP) in hippocampus was investigated. Evaluation of LTP ability and comparison with the tests of motor learning suggests similarities between magnitude of LTP and criteria of motor learning. Also interstrain differences were described. Our results support ideas about tight cooperation among brain structures which are involved in mechanisms of learning and memory.

Neural functional and morphological consequences of retinal degeneration in C3H Lurcher mutant and wild type mice.

Lurcher mutant mice represent a model of olivocerebellar degeneration associated with the total functional elimination of the cerebellar cortex. The affected animals suffer from cerebellar ataxia and worsening of cognitive functions. Healthy littermates of Lurchers-wild type mice serve as controls. Except mentioned patterns some animals derived from the C3H strain exhibit signs of a hereditary retinal degeneration. The impact of the retinal degeneration on visuospatial abilities and on the neuronal morphology in visual projection of both C3H Lurcher mutant and wild type mice has been studied in this work. The Morrris water maze was used for examination of spatial learning when the animals learned to find a platform hidden under the water surface. Time of reaching the platform (escape latency) in individual experimental days as well as the swimming velocity was measured and the strategy of maze exploration was assessed. The presence of the retinal degeneration was proved histologically by means of classical hematoxillin-eosin method. The neurohistological examination of the superior colliculus and visual cortex was performed using a Ramón-Moliner modification of the Golgi method. The results obtained showed that retinal degeneration influenced the strategy of the maze exploration and caused generally worse results. The histological examination of eyes in animals with bad results confirmed presence of the retinal degeneration. The neurohistological examination of the brain visual projections of animals affected with the retinal defect showed most detectable changes in dendritic spines of the V1 cortex (lower density in general and less immature types).

Autonomic nervous evaluation in the early stages of olivopontocerebellar atrophy.

The clinical significance of evaluating autonomic nervous system functions in the early stages of olivopontocerebellar atrophy (OPCA) has been investigated in 13 OPCA out-patients (7 males and 6 females, mean age: 51.0 years). We have employed measurements of blood pressure, plasma norepinephrine (NE), CVR-R, low-frequency power/high-frequency power ratio (L/H), high-frequency power (HF) score and heart rate (HR) monitoring using Holter ECG recording for evaluation of CVR-R. We have also carried out urodynamic examinations, focusing on the possible existence of bladder dysfunction. Although no significant changes were noted between control and OPCA groups concerning HR, CVR-R, L/H, plasma levels of norepinephrine and systolic blood pressure, HF (high-frequency power) (ms(2)), especially at night time, invariably showed a significant decline in OPCA groups. All OPCA patients who showed a decreased circadian HF also exhibited a tendency towards urinary bladder dysfunction. The present results appear to relate to disorder of the parasympathetic autonomic nervous system and neuromuscular dysfunction in the lower urinary tract. In conclusion, HRV (heart rate variability) analysis is a useful and safe tool and a keen predictor for evaluating functional states of autonomic nervous activity, especially in the early stages of OPCA. This study has also suggested the possible efficacy of urodynamic measurements in OPCA patients as an indicator of neuromuscular dysfunction in the lower urinary tract and of parasympathetic malfunction.

[Spinal muscular atrophy associated with olivopontocerebellar hypoplasia. A case report]. / Atrofia muscular espinal asociada a hipoplasia olivopontocerebelosa. Informe de un caso.

INTRODUCTION: Spinal muscular atrophy is a frequent neurodegenerative disease in infancy. Nevertheless, its association with olivopontocerebellar hypoplasia is rare. CASE REPORT: We describe a case displaying clinical symptoms that included respiratory failure, dysmorphias, hypotonia, deep tendon areflexia and respiratory complications, like the cases described in the literature. In the genetic study it was not possible to find the motor neuron gene surviving from the infantile muscular atrophy. The neuropathological disorders found in the necropsy study were olivopontocerebellar hypoplasia with intense neuronal loss (fundamentally from Purkinje cells and from the granular layer of the cerebellum, olivary nuclei and pons), replacement gliosis and degeneration of the motor cells in the anterior horn of the spinal cord. Death occurred due to a respiratory complication in the 11th postnatal month. CONCLUSIONS: The paper describes the clinical-pathological study and the genetic study of a female patient who died at the age of 11 months after being diagnosed as presumably suffering from Werdnig-Hoffman disease. The autopsy revealed an olivopontocerebellar hypoplasia, which is a morphological trait that is not associated with the above-mentioned entity. The microscopic study revealed extensive areas of gliosis and neuronal loss. We conclude with the diagnosis of spinal muscular atrophy associated with olivopontocerebellar hypoplasia, which is a rare clinical entity with very few case reports and whose genetic defect is still unknown. We also review the extant literature related to this case.

Functional consequences of retinal degeneration in spatial orientation in C3H wild type and Lurcher mutant mice.

Lurcher mutant mice represent a model of genetically determined olivocerebellar degeneration. In the C3H strain there is also hereditary retinal degeneration. The aim of this work was to assess, whether the retinal degeneration influences spatial orientation and results of the spatial learning tasks. Two experiments in the Morris water maze were arranged. First, mice learned to find a platform position, which was linked to two labels on the periphery of the maze. In the second experiment the platform was removed and swimming velocity and preference of central or peripheral zone of the maze were assessed. Presence of the retinal degeneration was detected histologically. Both Lurcher mutant and wild type mice that exhibited long latencies in the first experiment were affected with the retinal degeneration, while animals that performed the trial well, had normal retina. Swimming velocity was not changed substantially. The maze exploration strategy was different in mice with and without the retinal degeneration.

Effect of whole-body exposure to high-frequency electromagnetic field on the brain electrogeny in neurodefective and healthy mice.

A direct registration of brain cortical and hippocampal activity during a high-frequency electromagnetic field (HF EMF) exposure was performed. All experimental procedures were done under urethane anaesthesia (20%, 2 g/kg i.p.) in Lurcher mutant mice, wild type (healthy littermates) were used as controls. Experimental animals were exposed to the HF EMF with frequency corresponding to cellular phones. Our method is based on the use of gel electrodes (silicon tubes or glass microcapillaries filled with agar) where the connection with classical electrodes is located out of HF EMF space. ECoG evaluation showed a distinct shift to lower frequency components but clear effect has been observed only in wild type (healthy) mice whereas in Lurcher mutant mice only gentle differences between frequency spectra were found. Measurement of hippocampal rhythmicity showed gentle changes with increase of higher frequencies (i.e. opposite effect than in cortex) and changes in theta oscillations registered from a dentate gyrus and CA1 area in both types of animals (healthy and mutant). These findings support the idea about possible influencing the central nervous system by HF EMF exposure and support also some recent results about possible health risks resulting from cellular phones use.

[Analysis of brain images in patients with spinocerebellar degeneration; using statistical parametric mapping (SPM) and easy Z score imaging system (eZIS)].

In order to investigate the cerebral blood flow objectively, the easy Z score imaging system (eZIS), was developed, and has been applied in clinical practice. SPECT with 99mTc-ethyl cysteinate dimer (99mTc-ECD) was performed, and the images were analyzed using the SPM97 and the eZIS Ver. 2 to investigate cerebral blood flow in patients with two types of spino-cerebellar degeneration. We compared the distribution of cerebral blood flow between 13 patients with cortical cerebellar atrophy (CCA) and 26 patients with olivopontocerebellar atrophy (OPCA). In the both groups, cerebellar blood flow was decreased generally. In our evaluation using the eZIS Z score, the scores for the brain stem and cerebellar nucleus in the OPCA group were lower than those in the CCA group. This method facilitates the objective evaluation of cerebral blood flow in patients with spinocerebellar degeneration, and may be useful for analyzing the condition of these disease.

The hereditary ataxias.

Efforts to classify the hereditary ataxias by their clinical and neuropathological phenotypes are troubled by excessive heterogeneity. Linkage analysis opened the door to a new approach with the methods of molecular biology. The classic form of autosomal recessive ataxia, Friedreich's ataxia (FA), is now known to be due to an intronic expansion of a guanine-adenine-adenine (GAA)-trinucleotide repeat. The autosomal dominant ataxias such as olivopontocerebellar atrophy (OPCA), familial cortical cerebellar atrophy (FCCA), and Machado-Joseph disease (MJD) have been renamed the spinocerebellar ataxias (SCA). Specific gene loci are indicated as SCA-1, SCA-2, SCA-3, SCA-4, SCA-5, SCA-6, and SCA-7. In 5 of them (SCA-1, SCA-2, SCA-3, SCA-6, and SCA-7), expanded cytosine-adenine-guanine (CAG)-trinucleotide repeats and their abnormal gene products cause the ataxic condition. The most common underlying loci for olivopontocerebellar atrophy (OPCA) are SCA-1 and SCA-2, although other genotypes may be added in the future. A major recent advance was the identification of the gene for SCA-3 and MJD, and the high prevalence of this form of autosomal dominant ataxia. In FA and the SCA with expanded CAG-trinucleotide repeats, clinical and neuropathological severity are inversely correlated with the lengths of the repeats. Anticipation in the dominant ataxias can now be explained by lengthening of the repeats in successive generations. Progress is being made in the understanding of the pathogenesis of FA and SCA as the absent or mutated gene products are studied by immunocytochemistry in human and transgenic murine brain tissue. In FA, frataxin is diminished or absent, and an excess of mitochondrial iron may cause the illness of the nervous system and the heart. In SCA-3, abnormal ataxin-3 is aggregated in neuronal nuclei, and in SCA-6, a mutated alpha1A-calcium channel protein is the likely cause of abnormal calcium channel function in Purkinje cells and in the death of these neurons.

Depression in multiple system atrophy and in idiopathic Parkinson's disease: a pilot comparative study.

Multiple system atrophy (MSA) is a disease causing parkinsonism in which response to levodopa is classically absent, poor, or transient. Idiopathic Parkinson's disease (IPD) itself, which responds favorably to levodopa, has been associated with the development of disease-related depression. Over and above the clinical and pathological characteristics of IPD, MSA causes additional, more widespread, clinical and pathological deficits. We have compared motor disability and mood in 12 patients with MSA and 12 with IPD. There was more severe motor disability, but no clinical evidence of depression among the MSA patients studied, and their Beck Depression Inventory scores did not differ significantly from the group with IPD. We conclude that depression does not appear to be more common in MSA than in IPD.