Publications by authors named "Tiiu Tomberg"

12 Publications

  • Page 1 of 1

Bi-allelic variants in TSPOAP1, encoding the active zone protein RIMBP1, cause autosomal recessive dystonia.

J Clin Invest 2021 Feb 4. Epub 2021 Feb 4.

Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany.

Dystonia is a debilitating hyperkinetic movement disorder, which can be transmitted as a monogenic trait. Here, we describe homozygous frameshift, nonsense and missense variants in TSPOAP1, encoding the active zone RIM-binding protein 1 (RIMBP1), as a novel genetic cause of autosomal recessive dystonia in seven subjects from three unrelated families. Subjects carrying loss-of-function variants presented with juvenile-onset progressive generalized dystonia, associated with intellectual disability and cerebellar atrophy. Conversely, subjects carrying a pathogenic missense variant (p.Gly1808Ser) presented with isolated adult-onset focal dystonia. In mice, complete loss of RIMBP1, known to reduce neurotransmission, led to motor abnormalities reminiscent of dystonia, decreased Purkinje cell dendritic arborization, and reduced numbers of cerebellar synapses. In vitro analysis of the p.Gly1808Ser variant showed larger spike-evoked calcium transients and enhanced neurotransmission, suggesting that RIMBP1-linked dystonia can be caused by either reduced or enhanced rates of spike-evoked release in relevant neural networks. Our findings establish a direct link between dysfunction of the presynaptic active zone and dystonia and highlight the critical role played by well-balanced neurotransmission in motor control and disease pathogenesis.  .
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http://dx.doi.org/10.1172/JCI140625DOI Listing
February 2021

Long-term neurodevelopmental outcome after perinatal arterial ischemic stroke and periventricular venous infarction.

Eur J Paediatr Neurol 2018 Nov 21;22(6):1006-1015. Epub 2018 Jul 21.

Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Background: Long-term follow-up data after different vascular types of ischemic perinatal stroke is sparse. Our aim was to study neurodevelopmental outcomes following neonatal and presumed perinatal ischemic middle cerebral artery territory stroke (arterial ischemic stroke, AIS) and periventricular venous infarction (PVI).

Methods: A prospective consecutive cohort of 40 term-born children with perinatal stroke (21 AIS, 19 PVI) was identified through the Estonian Paediatric Stroke Database. While 48% of the children with AIS were diagnosed during the neonatal period, all the children with PVI had presumed perinatal stroke. Outcomes based on the Paediatric Stroke Outcome Measure (PSOM) and Kaufman Assessment Battery for Children - Second Edition (K-ABC-II), in relation to extent and laterality of stroke, were defined.

Results: At a median age of 7 years 6 months (range 3.6-13y), there was a trend towards worse neurodevelopmental outcome in participants with AIS when compared to PVI (mean total PSOM scores 3.1 and 2.2, respectively; p = 0.06). Combined deficits of motor, language and cognitive/behavioural functions were significantly more common among children with AIS (90%) when compared to children with PVI (53%, p = 0.007). General cognitive ability (by K-ABC-II) was significantly lower in the AIS subgroup (mean 79.6; 95% CI 72.3-87.0), but children with PVI (91.6; 95% CI 85.5-97.8) also had poorer performance than the age-equivalent normative mean. Large extent of stroke was associated with poorer neurodevelopmental outcome and lower cognitive performance in children following AIS but not in PVI.

Conclusion: In this national cohort, poor long-term neurodevelopmental outcome after perinatal ischemic stroke was seen irrespective of the vascular type or time of diagnosis of stroke. However, the spectrum of neurological deficits is different after perinatal AIS and PVI, with combined deficits more common among children following AIS.
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http://dx.doi.org/10.1016/j.ejpn.2018.07.005DOI Listing
November 2018

Resting-State Functional Connectivity and Cognitive Impairment in Children with Perinatal Stroke.

Neural Plast 2016 15;2016:2306406. Epub 2016 Dec 15.

Department of Pediatrics, University of Tartu, Tartu, Estonia; Children's Clinic of Tartu University Hospital, Tartu, Estonia.

Perinatal stroke is a leading cause of congenital hemiparesis and neurocognitive deficits in children. Dysfunctions in the large-scale resting-state functional networks may underlie cognitive and behavioral disability in these children. We studied resting-state functional connectivity in patients with perinatal stroke collected from the Estonian Pediatric Stroke Database. Neurodevelopment of children was assessed by the Pediatric Stroke Outcome Measurement and the Kaufman Assessment Battery. The study included 36 children (age range 7.6-17.9 years): 10 with periventricular venous infarction (PVI), 7 with arterial ischemic stroke (AIS), and 19 controls. There were no differences in severity of hemiparesis between the PVI and AIS groups. A significant increase in default mode network connectivity (FDR 0.1) and lower cognitive functions ( < 0.05) were found in children with AIS compared to the controls and the PVI group. The children with PVI had no significant differences in the resting-state networks compared to the controls and their cognitive functions were normal. Our findings demonstrate impairment in cognitive functions and neural network profile in hemiparetic children with AIS compared to children with PVI and controls. Changes in the resting-state networks found in children with AIS could possibly serve as the underlying derangements of cognitive brain functions in these children.
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http://dx.doi.org/10.1155/2016/2306406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5198182PMC
October 2017

Grey matter abnormalities in methcathinone abusers with a Parkinsonian syndrome.

Brain Behav 2016 11 18;6(11):e00539. Epub 2016 Aug 18.

Department of Neurology and Neurosurgery University of Tartu Tartu Estonia.

Background: A permanent Parkinsonian syndrome occurs in intravenous abusers of the designer psychostimulant methcathinone (ephedrone). It is attributed to deposition of contaminant manganese, as reflected by characteristic globus pallidus hyperintensity on T1-weighted MRI.

Methods: We have investigated brain structure and function in methcathinone abusers ( = 12) compared to matched control subjects ( = 12) using T1-weighted structural and resting-state functional MRI.

Results: Segmentation analysis revealed significant ( < .05) subcortical grey matter atrophy in methcathinone abusers within putamen and thalamus bilaterally, and the left caudate nucleus. The volume of the caudate nuclei correlated inversely with duration of methcathinone abuse. Voxel-based morphometry showed patients to have significant grey matter loss ( < .05) bilaterally in the putamina and caudate nucleus. Surface-based analysis demonstrated nine clusters of cerebral cortical thinning in methcathinone abusers, with relative sparing of prefrontal, parieto-occipital, and temporal regions. Resting-state functional MRI analysis showed increased functional connectivity within the motor network of patients ( < .05), particularly within the right primary motor cortex.

Conclusion: Taken together, these results suggest that the manganese exposure associated with prolonged methcathinone abuse results in widespread structural and functional changes affecting both subcortical and cortical grey matter and their connections. Underlying the distinctive movement disorder caused by methcathinone abuse, there is a more widespread pattern of brain involvement than is evident from the hyperintensity restricted to the basal ganglia as shown by T1-weighted structural MRI.
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http://dx.doi.org/10.1002/brb3.539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102639PMC
November 2016

Biallelic CACNA1A mutations cause early onset epileptic encephalopathy with progressive cerebral, cerebellar, and optic nerve atrophy.

Am J Med Genet A 2016 08 2;170(8):2173-6. Epub 2016 Jun 2.

Department of Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia.

The CACNA1A gene encodes the transmembrane pore-forming alpha-1A subunit of the Cav 2.1 P/Q-type voltage-gated calcium channel. Several heterozygous mutations within this gene, including nonsense mutations, missense mutations, and expansion of cytosine-adenine-guanine repeats, are known to cause three allelic autosomal dominant conditions-episodic ataxia type 2, familial hemiplegic migraine type 1, and spinocerebellar ataxia type 6. An association with epilepsy and CACNA1A mutations has also been described. However, the link with epileptic encephalopathies has emerged only recently. Here we describe two patients, sister and brother, with compound heterozygous mutations in CACNA1A. Exome sequencing detected biallelic mutations in CACNA1A: A missense mutation c.4315T>A (p.Trp1439Arg) in exon 27, and a seven base pair deletion c.472_478delGCCTTCC (p.Ala158Thrfs*6) in exon 3. Both patients were normal at birth, but developed daily recurrent seizures in early infancy with concomitant extreme muscular hypotonia, hypokinesia, and global developmental delay. The brain MRI images showed progressive cerebral, cerebellar, and optic nerve atrophy. At the age of 5, both patients were blind and bedridden with a profound developmental delay. The elder sister died at that age. Their parents and two siblings were heterozygotes for one of those pathogenic mutations and expressed a milder phenotype. Both of them have intellectual disability and in addition the mother has adult onset cerebellar ataxia with a slowly progressive cerebellar atrophy. Compound heterozygous mutations in the CACNA1A gene presumably cause early onset epileptic encephalopathy, and progressive cerebral, cerebellar and optic nerve atrophy with reduced lifespan. © 2016 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ajmg.a.37678DOI Listing
August 2016

Presumed Perinatal Stroke: Risk Factors, Clinical and Radiological Findings.

J Child Neurol 2016 Apr 7;31(5):621-8. Epub 2015 Oct 7.

Department of Pediatrics, University of Tartu, Tartu, Estonia Children's Clinic of Tartu University Hospital, Tartu, Estonia.

It is unknown why some infants with perinatal stroke present clinical symptoms late during infancy and will be identified as infants with presumed perinatal stroke. The risk factors and clinical and radiological data of 42 infants with presumed perinatal stroke (69% with periventricular venous infarction and 31% with arterial ischemic stroke) from the Estonian Pediatric Stroke Database were reviewed. Children with presumed perinatal stroke were born at term in 95% of the cases and had had no risk factors during pregnancy in 43% of the cases. Children with periventricular venous infarction were born significantly more often (82%) vaginally (P = .0213) compared to children with arterial stroke (42%); nor did they require resuscitation (P = .0212) or had any neurological symptoms after birth (P = .0249). Periventricular venous infarction is the most common type of lesion among infants with the presumed perinatal stroke. Data suggest that the disease is of prenatal origin.
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http://dx.doi.org/10.1177/0883073815609149DOI Listing
April 2016

Monosomy 1p36 - a multifaceted and still enigmatic syndrome: four clinically diverse cases with shared white matter abnormalities.

Eur J Paediatr Neurol 2014 May 25;18(3):338-46. Epub 2014 Jan 25.

Department of Pediatrics, Faculty of Medicine, University of Tartu, Tartu, Estonia; Department of Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia.

Monosomy 1p36 is the most common subtelomeric deletion syndrome seen in humans. Uniform features of the syndrome include early developmental delay and consequent intellectual disability, muscular hypotonia, and characteristic dysmorphic facial features. The gene-rich nature of the chromosomal band, inconsistent deletion sizes and overlapping clinical features have complicated relevant genotype-phenotype correlations. We describe four patients with isolated chromosome 1p36 deletions. All patients shared white matter abnormalities, allowing us to narrow the critical region for white matter involvement to the deletion size of up to 2.5 Mb from the telomere. We hypothesise that there might be a gene(s) responsible for myelin development in the 1p36 subtelomeric region. Other significant clinical findings were progressive spastic paraparesis, epileptic encephalopathy, various skeletal anomalies, Prader-Willi-like phenotype, neoplastic changes - a haemangioma and a benign skin tumour, and in one case, sleep myoclonus, a clinical entity not previously described in association with 1p36 monosomy. Combined with prior studies, our results suggest that the clinical features seen in monosomy 1p36 have more complex causes than a classical contiguous gene deletion syndrome.
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http://dx.doi.org/10.1016/j.ejpn.2014.01.008DOI Listing
May 2014

Different plasticity patterns of language function in children with perinatal and childhood stroke.

J Child Neurol 2014 Jun 6;29(6):756-64. Epub 2013 Jun 6.

Department of Neurology and Neurorehabilitation, University of Tartu and Children's Clinic of Tartu University Hospital, Tartu, Estonia.

Plasticity of language function after brain damage can depend on maturation of the brain. Children with left-hemisphere perinatal (n = 7) or childhood stroke (n = 5) and 12 controls were investigated using functional magnetic resonance imaging. The verb generation and the sentence comprehension tasks were employed to activate the expressive and receptive language areas, respectively. Weighted laterality indices were calculated and correlated with results assessed by neuropsychological test battery. Compared to controls, children with childhood stroke showed significantly lower mean scores for the expressive (P < .05) and receptive (P = .05) language tests. On functional magnetic resonance imaging they showed left-side cortical activation, as did controls. Perinatal stroke patients showed atypical right-side or bilateral language lateralization during both tasks. Negative correlation for stroke patients was found between scores for expressive language tests and laterality index during the verb generation task. (Re)organization of language function differs in children with perinatal and childhood stroke and correlates with neurocognitive performance.
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http://dx.doi.org/10.1177/0883073813489350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4230975PMC
June 2014

Epidemiology of childhood stroke in Estonia.

Pediatr Neurol 2010 Feb;42(2):93-100

Department of Pediatrics, University of Tartu, Tartu, Estonia.

We investigated the incidence and 30-day case-fatality of childhood stroke in Estonia, and clinical signs and risk factors of childhood stroke. A retrospective (1995-2003) and prospective study (2004-2006) of childhood stroke (arterial ischemic, hemorrhagic, and sinovenous thrombosis) and transient ischemic attack was conducted. Stroke-incidence calculation was based on the prospective study. Clinical diagnoses of stroke were confirmed by neuroradiology. The incidence rate of childhood stroke in Estonia was 2.73/100,000 person-years for children aged 30 days to 18 years: 1.61/100,000 for arterial ischemic stroke, 0.87/100,000 for hemorrhagic stroke, 0.25/100,000 for sinovenous thrombosis, and 0.37/100,000 for transient ischemic attack. No arterial ischemic stroke patients died within 30 days, but case-fatality for intracerebral hemorrhage was 46%. Focal signs occurred in 100% of arterial ischemic strokes and 64% of intracerebral hemorrhage cases. Risk factors were identified in 35/48 (73%) children with cerebrovascular attacks. Six children with arterial ischemic stroke (6/24, 25%) manifested more than one risk factor. The incidence rate of childhood stroke in Estonia is similar to that in earlier data.
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http://dx.doi.org/10.1016/j.pediatrneurol.2009.08.009DOI Listing
February 2010

Magnetic resonance imaging in children with bilateral spastic forms of cerebral palsy.

Pediatr Neurol 2008 May;38(5):321-8

Department of Pediatrics, University of Tartu, Tartu, Estonia.

We analyzed the relationship between magnetic resonance image findings in children with bilateral spastic cerebral palsy and its stages of severity in term and preterm children. Magnetic resonance image findings of 102 children (66 male and 36 female) with bilateral spastic cerebral palsy (median age, 2.5 years; range, 3 months to 15 years) were reevaluated. The study group consisted of children with confirmed perinatal asphyxia. Hypoxic-ischemic events were diagnosed in 64% of the children. Significant abnormalities relevant to cerebral palsy were evident on imaging in 85/102 (83%) children (in 77% of term and 93% of preterm children). Enlargement of the ventricles alone (48%) or accompanied by periventricular white-matter damage (25%) was the most frequent finding in term and preterm children, but was more highly expressed in preterm children (P < 0.05). White-matter damage was more often found in preterm children (P < 0.05). Enlargement of the lateral ventricles and periventricular leukomalacia may be attributable to ischemic damage to the neonatal brain. Significant correlations were found between magnetic resonance image findings and severity of cerebral palsy (P < 0.05). Detection of brain abnormalities in children with cerebral palsy may prove useful in prognoses as well as in medical consultations and management.
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http://dx.doi.org/10.1016/j.pediatrneurol.2007.12.011DOI Listing
May 2008

Acutely and retrospectively diagnosed perinatal stroke: a population-based study.

Stroke 2007 Aug 21;38(8):2234-40. Epub 2007 Jun 21.

Children's Clinic of Tartu University Hospital, Tartu, Estonia.

Background And Purpose: There are not very many epidemiological studies on perinatal stroke, and many authors suggest that this may be an underdiagnosed condition. The aim of the study was to estimate the incidence of perinatal arterial ischemic and hemorrhagic stroke in Estonia, to study the first clinical signs and to identify possible differences in predisposing factors and outcome between acutely and retrospectively diagnosed cases of perinatal stroke.

Methods: A retro- and prospective study of acutely (within the first month) and retrospectively diagnosed ischemic and hemorrhagic cases of perinatal stroke was conducted in a children population born in the eastern and southern regions of Estonia during the years 1994 to 2003. Patients were identified from a pilot study, hospital records, and an inquiry of child neurologists and general practitioners. The diagnosis was confirmed in 38 (12 were diagnosed acutely and 26 retrospectively) cases by neuroradiology (MRI or CT).

Results: The incidence rate of perinatal stroke in Estonia is 63 per 100,000 live births. Main clinical findings in the neonatal period were seizures, abnormalities of muscular tone, and disturbed level of alertness. Previously identified risk factors occurred in 32% of cases. Children with early diagnosis had more often adverse events during pregnancy and delivery (P<0.05) and developed more severe stage of hemiparesis compared with children with late diagnosis (P<0.05).

Conclusions: The incidence rate of 63 per 100,000 live birth is higher than previously reported. Detailed analysis of the first signs of perinatal stroke may improve the early diagnostics of perinatal stroke.
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http://dx.doi.org/10.1161/STROKEAHA.107.483743DOI Listing
August 2007

Possible interpretation of subjective complaints in patients with spontaneous subarachnoid haemorrhage.

J Rehabil Med 2004 Mar;36(2):63-9

Department of Special Education, School of Teacher Education, University of Tartu, Estonia.

Objective: To analyse factors related to subjective non-cognitive and cognitive complaints in patients with spontaneous subarachnoid haemorrhage.

Subjects: Twenty-seven patients with subarachnoid haemorrhage and 27 age-, sex- and education-matched healthy controls.

Methods: A battery of cognitive tests measuring visuo-spatial abilities, verbal abilities, and fine-motor skill, Brief Social Support Questionnaire, and Life Orientation Scale were individually presented to all participants.

Results: Cognitive complaints were related to low social support but not to cognitive performance. Complaints about headaches and dizziness were also related to decreased cognitive performance. Above-normal optimistic life-orientation was related to the absence of complaints in patients with subarachnoid haemorrhage. Healthy participants were best discriminated from patients with subarachnoid haemorrhage by less satisfactory social support system and decreased fine motor skills in the latter group.

Conclusion: Change in social support network may be an important resource for increasing quality of life in patients with subarachnoid haemorrhage not only through help provided by supporters but also indirectly, through increasing subjective well-being. The absence of subjective complaints in patients with subarachnoid haemorrhage is not necessarily related to better objective condition but rather to inadequately optimistic life orientation.
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http://dx.doi.org/10.1080/16501970310017414DOI Listing
March 2004