Cognitive changes in spinocerebellar ataxia type 2

OBJECTIVES

Cognitive disorders and dementia occur in 19 to 42% of patients with spinocerebellar ataxia type 2 (SCA2). Neuropsychological tests can reveal executive dysfunction, impaired visual and verbal memory, tongue and speech impairment, attention disorders and impaired verbal fluency.

METHODS

We performed psychiatric and neuropsychological examinations in 12 patients diagnosed with genetically confirmed SCA2 and 12 healthy volunteers matching the patients in age, gender, and length of education. The level of motor impairment was determined using the brief ataxia rating scale (BARS). The neuropsychological examination focused on testing executive functions, short-term visual and verbal memory, attention, psychomotor tempo, visual motor coordination, learning ability and comprehension ability. The tests were divided into two subgroups according to the difficulty of motor tasks. The cognitive abilities composite score (CACS) was determined by calculating the arithmetic mean of T scores of the respective tests.

RESULTS

Patients with SCA2 had significantly lower CACSs (p=0.00005) compared to the healthy volunteers. Patients exhibited impaired performance in both difficult and simple motor tests. The severity of cognitive impairment was related to the age at the onset of the disease (p=0.002) but not to the duration or to the overall BARS score.

CONCLUSIONS

Compared to healthy volunteers, patients with SCA2 exhibited significantly worse cognitive performance in all areas tested, including the tests of simple motor tasks. Moreover, the cognitive performance of patients worsened as the difficulty of the motor tasks increased.

Nonlinear analysis of the sleep EEG in children with pervasive developmental disorder

OBJECTIVES

Autism is a severe neurodevelopmental disorder with a high rate of epilepsy and subclinical epileptiform activity. High physical connectivity on a microcolumnar level leading to epileptiform activity and low functional informational connectivity are assumed in autism. The aim of this study was to investigate nonlinear EEG brain dynamics in terms of synchronization in a group of children with autism spectrum disorders compared to a control group. We expected a lower degree of synchronization in autistic subjects.

METHODS

The autistic group consisted of 27 patients with autism spectrum disorders diagnosed according to ICD-10. The mean age of the sample was 7.1 (SD 3.6) years, 14 of them were mentally retarded. Normal EEG was found in 9 patients, epileptiform EEG in 18 autistic patients. Four patients had a history of epileptic seizures, fully compensated in long term. The control group consisted of 20 children (mean age of 8.4, SD 2.3 years) with normal intelligence, without an epileptic history, investigated within the frame of the research program for cochlear implantation. They had normal neurological examination and suffered from perceptive deafness. Normal EEG was found in 17 of the control subjects, epileptiform EEG was in 3 control subjects. We analyzed night sleep EEG recordings from 10 channels (F3, F4, F7, F8, C3, C4, T3, T4, P3 and P4) with the inclusion of sleep stages NREM 2, 3 and 4 in the subsequent analyses. Coarse-grained entropy information rates between neighbouring electrodes were computed, expressing the synchronization between 11 selected electrode couples.

RESULTS

Synchronization was significantly lower in the autistic group in all three examined NREM stages even when age and intelligence were taken into account as covariates.

CONCLUSIONS

The results of the study confirmed the validity of the underconnectivity model in autism.

Prader-Willi syndrome due to uniparental disomy in a patient with a balanced chromosomal translocation

OBJECTIVES

In contrast to most human autosomal genes which are expressed biallelically, the expression of imprinted genes depends on the parental origin of the allele. Prader-Willi syndrome is a neurobehavioral disorder in which the expression of active paternal alleles of imprinted genes from chromosomal region 15q11-q13 is abolished by deletions, maternal uniparental disomy or imprinting defects. We report an unusual case of maternal uniparental disomy of chromosome 15 due to a balanced translocation t(8;15)(q24.1;q21.2) leading to Prader-Willi syndrome in a 3-year-old girl.

METHODS AND RESULTS

Cytogenetic investigation revealed a balanced translocation t(8;15)(q24.1;q21.2) in the patient and subsequently also in her unaffected mother. Fluorescence in situ hybridization analysis did not reveal any deletion of the PWS critical region, but methylation analysis of the SNRPN gene showed an abnormal methylation pattern indicating the absence of paternal chromosome 15. Microsatellite analysis of multiple loci and methylation-specific MLPA analysis confirmed maternal uniparental heterodisomy of chromosome 15 as the cause of PWS in the patient.

CONCLUSIONS

This example emphasizes the importance of uniparental disomy testing in pregnancies of carriers of chromosomal aberrations with participation of chromosomes carrying imprinted genes involved in human diseases.

First cases in the Czech Republic of the Hallervorden-Spatz disease resulting from mutation in the pantothenate kinase 2 gene

Hallervorden-Spatz disease (HSD) was and is known as a rare disorder primarily characterized by progressive extrapyramidal dysfunction and dementia alongside optic nerve atrophy or retinal degeneration and pyramidal signs. The rate of occurence of HSD is thus far unknown. Progress in DNA diagnostics stirred up a nomenclature and from HSD, or, perhaps better put, the Hallervorden-Spatz syndrome, crystallized the pantothenate kinase-associated neurodegeneration (PKAN) as a clearly defined entity on the level of DNA. In this paper, we present our first results and experience in the diagnosis of PKAN in the Czech Republic and discuss questions related to differential diagnosis.

Problems and possibilities in the differential diagnosis of Syndrome Spinocerebellar Ataxia

Differential diagnosis in neurologic patients with spinocerebellar syndrome is complex as a result of the great degree of variability in phenotypic and genetic aspects of more than 200 nosological entities. In the past decade, genetic etiology has been discovered in part of the diseases and the term ''spinocerebellar ataxia'' has become, from a neurologic point of view, a loose definition applied to a group of autosomal dominant diseases. Topical extensive literature about differential diagnoses of ataxias usually refers to genetics classification or is produced by a group of radiologists, elektrophysiologists and biologists as well as others in the field. A further problem is that the majority of studies do not take into account other acquired illnesses and diseases which may fundamentally alter the symptomology and course of a primary disease, not to mention the possibility of concomitancy in hereditary diseases. The following article was prompted by daily contact with ataxic patients and related issues raised by colleagues; its goal is to clarify problems faced by child neurologists and neurologists in clinical practice.

Concomitancy of mutation in FRDA gene and FMR1 premutation in 58 year-old woman

DNA testing broadens diagnostic tools available for hereditary ataxias. However, together with current knowledge of genes and their mutations crop up new phenotype figures of diseases already well known. Diagnostic problems in practice can consist in part due to the very similar symptoms of hereditary ataxias and acquaintance in or availability of new techniques such as DNA testing and result in misdiagnosis. We present a case study of a 57 year-old woman with both expansion of the triplet repetitive sequence of FRDA gene and a premutation in FMR1 gene. At present we diagnose her with Very Late Onset Friedreich s ataxia, but we advise of possible combinations or aggravations of her symptoms due to manifestation of Fragile X premutation tremor/ataxia syndrome. In nontypical phenotypes of DNA verifying hereditary ataxias we recommend searching of comorbidity, specifically from a range of hereditary ataxias with very similar spectra of symptoms.