Jānis Mednieks

Dr. Jānis Mednieks

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Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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VNVladimirs Naumovs
Vladimirs Naumovs
VGValerija Groma
Valerija Groma
JMJānis Mednieks
Jānis Mednieks
Nowadays, osteoarthritis (OA), a common, multifactorial musculoskeletal disease, is considered to have a low-grade inflammatory pathogenetic component. Lately, neuropsychiatric sequelae of the disease have gained recognition. However, a link between the peripheral inflammatory process of OA and the development of neuropsychiatric pathology is not completely understood. In this review, we provide a narrative that explores the development of neuropsychiatric disease in the presence of chronic peripheral low-grade inflammation with a focus on its signaling to the brain. We describe the development of a pro-inflammatory environment in the OA-affected joint. We discuss inflammation-signaling pathways that link the affected joint to the central nervous system, mainly using primary sensory afferents and blood circulation via circumventricular organs and cerebral endothelium. The review describes molecular and cellular changes in the brain, recognized in the presence of chronic peripheral inflammation. In addition, changes in the volume of gray matter and alterations of connectivity important for the assessment of the efficacy of treatment in OA are discussed in the given review. Finally, the narrative considers the importance of the use of neuropsychiatric diagnostic tools for a disease with an inflammatory component in the clinical setting.

29 May 2024 in Medicina
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AGArtūrs Garbilis
Artūrs Garbilis
JMJānis Mednieks
Jānis Mednieks
Background and Objectives: Heart rate variability (HRV) is defined as a physiological variation in duration between sinus beats. The aim of this study was to research and analyze the HRV between various groups of patients. Materials and Methods: A retrospective study was conducted in an outpatient setting. Patients who had undergone a tilt-table test were selected for this study and were divided into three groups based on their self-reported health anamnesis: group 1 (n = 84, mean age 45.8 ± 17.8) consisted of patients with no known orthostatic intolerance or neurodegenerative disease, group 2 consisted of patients with a known or suspected orthostatic intolerance (n = 50, mean age 46.5 ± 18.6), and group 3 consisted of patients with a known or suspected neurodegenerative disorder (n = 29, mean age 55.6 ± 20.4). During the tilt-table test, HRV frequency-domain parameters—normalized low frequency (LFnu) and high frequency (HFnu), absolute powers—absolute low frequency (LF-RRI), absolute high frequency (HF-RRI), and LF/HF ratio—were recorded during 5 min rest in the supine position. Results: Group 1 had a reduced LFnu at 52.93% (SD: 18.00) compared to group 2 at 58.57% (18.06) and group 3 at 61.80% (SD: 17.74), and group 1 had increased HFnu: group 1—47.08% (SD: 17.97), group 2—41.41% (SD: 18.03), and group 3—38.16% (SD: 14.7). LFnu and HFnu differences were statistically significant (p < 0.05). LF-RRI was reported as follows: group 1—531.32 ms2 (SD: 578.57), group 2—346.2 ms2 (SD: 447.96), and group 3—143.21 ms2 (SD: 166.96). HF-RRI was reported as follows: group 1—835.87 ms2 (SD: 1625.42), group 2—297.46 ms2 (SD: 507.15), and group 3—70.83 ms2 (SD: 75.67). LF-RRI and HF-RRI comparisons between groups were statistically significant (p < 0.001). LF/HF ratios were reported as follows: group 1—1.91 (SD: 2.29), group 2—2.43 (SD: 2.33), and group 3–2.54 (SD: 2.17). LF/HF ratio comparisons between groups were statistically significant at p < 0.05. Conclusions: This study shows that patients with known or suspected orthostatic intolerance and neurodegenerative disorders have reduced HRV, possibly caused by reduced parasympathetic modulation. HRV in patients with known or suspected neurodegenerative disorders is reduced more severely than in patients with orthostatic disorders. Other studies in HRV have indicated a possible increase of risk in cardiovascular disorders in patients with reduced HRV, and therefore, HRV analysis could be a potential clinical diagnostic tool. However, the lack of universally agreed upon methodology, reference values, and possible external and internal factor influence hinders the introduction of HRV examinations into wider clinical practice.

28 September 2021 in Neurology International
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NPNatalja Predkele
Natalja Predkele
JMJānis Mednieks
Jānis Mednieks
We present a case of a patient with positive N-methyl-D-aspartate receptor (NMDAR) IgG antibodies in their serum and cerebrospinal fluid (CSF) associated with neuroborreliosis. Clinically, the patient presented with symptoms of confusion, as well as behavioral and speech impairments. Regardless of antibacterial treatment, no significant improvement was achieved. Methylprednisolone provided a marked improvement in the patient’s clinical signs and CSF findings. The screening did not reveal any underlying neoplasm. Taking into account the marked clinical improvement after treatment with glucocorticosteroids, we suggest that NMDAR encephalitis is a possible autoimmune complication in neuroborreliosis patients requiring additional immunotherapy.

30 March 2026 in Diagnostics
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ASArturs Silovs
Arturs Silovs
GSGvido Karlis Skuburs
Gvido Karlis Skuburs
Nauris ZdanovskisNauris Zdanovskis
Nauris Zdanovskis
AŠAleksejs Ševčenko
Aleksejs Ševčenko
JMJānis Mednieks
Jānis Mednieks
APArdis Platkājis
Ardis Platkājis
Background: Parkinson’s disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta, accompanied by neuromelanin loss. Neuromelanin-sensitive magnetic resonance imaging (NM-MRI) enables in vivo visualization of these changes; however, its diagnostic and clinical utility remains incompletely defined. This study evaluated the feasibility, reliability, and biological sensitivity of semi-automated NM-MRI–based substantia nigra volumetry in PD. Methods: In this prospective case–control study, 50 participants (25 PD patients and 25 healthy controls) underwent 3T NM-sensitive MRI using a high-resolution T1-weighted spin-echo sequence. Semi-automated segmentation of hyperintense substantia nigra regions was performed using Mango v3.5.1, with intracranial volume normalization derived from FreeSurfer v7.3. Four participants were excluded due to motion artifacts, yielding a final cohort of 46 subjects. Clinical assessment included the Unified Parkinson’s Disease Rating Scale (UPDRS) Part III and Hoehn and Yahr (H&Y) staging. Group comparisons, receiver operating characteristic (ROC) analysis, and reliability testing using intraclass correlation coefficients (ICC) were performed. Results: Corrected substantia nigra volume was significantly reduced in PD patients compared with controls (18% reduction; p = 0.039, Mann–Whitney U test). Semi-automated measurements demonstrated excellent agreement with manual segmentation (ICC = 0.945). ROC analysis showed moderate discriminative performance for corrected volume (AUC = 0.700; sensitivity 68.4%, specificity 74.1%). No significant correlation was observed between corrected substantia nigra volume and UPDRS-III motor scores, while a trend toward lower SNc volume was observed with advancing H&Y stage. Conclusions: Semi-automated NM-MRI volumetry detects biologically meaningful substantia nigra volume loss in early-stage Parkinson’s disease with high measurement reliability. However, diagnostic performance was moderate and insufficient for standalone clinical diagnosis or motor severity prediction. These findings support the role of NM-MRI as a complementary imaging marker within multimodal diagnostic and research frameworks rather than as an independent diagnostic tool.

4 June 2023 in Medicina
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SSSintija Strautmane
Sintija Strautmane
ABArturs Balodis
Arturs Balodis
ATAgnete Teivāne
Agnete Teivāne
DGDagnija Grabovska
Dagnija Grabovska
ENEdgars Naudins
Edgars Naudins
MZMaksims Zolovs
Maksims Zolovs
Background and Objectives: We aimed to determine the link between brain volumetry results and functional disability calculated using the Expanded Disability Status Scale (EDSS) among multiple sclerosis (MS) patients in relation to the provided treatment (disease-modifying therapies (DMTs)) during a 5-year follow-up period. Materials and Methods: A retrospective cohort study was performed enrolling 66 consecutive patients with a confirmed diagnosis of MS, predominantly females (62% (n = 41)). Relapsing–remitting (RR) MS was noted in 92% (n = 61) of patients, with the rest being patients with secondary progressive (SP) MS. The mean age was 43.3 years (SD 8.3 years). All patients were evaluated clinically using the EDSS and “FreeSurfer© 7.2.0” radiologically during a 5-year follow-up. Results: A significant increase in patient functional disability was noted, calculated using the EDSS during a 5-year follow-up. The baseline EDSS ranged between 1 and 6 with a median of 1.5 (IQR 1.5–2.0), and after 5 years, the EDSS was between 1 and 7, with a median EDSS of 3.0 (IQR 2.4–3.6). Compared with RRMS patients, SPMS patients demonstrated a significant increase in EDSS score during a 5-year period, with a median EDSS of 2.5 in RRMS patients (IQR 2.0–3.3) and 7.0 (IQR 5.0–7.0) among SPMS patients. Significantly lower brain volumetry results in different brain areas were found, including cortical, total grey and white matter, p < 0.05. Statistically significant differences were observed between baseline volumetry results of the hippocampus and the middle anterior part of the corpus callosum and their volumetry results after 5 years, p < 0.001. In this study population, the thalamus did not demonstrate significant changes in volumetry results during follow-up, p > 0.05. The provided treatment (DMTs) did not demonstrate a significant impact on the brain MRI volumetry results during a 5-year follow-up, p > 0.05. Conclusions: Brain MRI volumetry seriously impacts the early detection of brain atrophic changes. In this study, significant relationship between brain magnetic resonance volumetry results and disability progression among MS patients with no important impact of the provided treatment was described. Brain MRI volumetry may aid in the identification of early disease progression among MS patients, as well as enrich the clinical evaluation of MS patients in clinical patient care.

13 August 2025 in Physiological Reports
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LSLaura Stirane
Laura Stirane
KSKarlis Stirans
Karlis Stirans
LPLeonora Pahirko
Leonora Pahirko
JMJānis Mednieks
Jānis Mednieks
KOKarina Ostrovska
Karina Ostrovska
JSJelizaveta Sokolovska
Jelizaveta Sokolovska
This post hoc analysis of the “Healthy walk” study evaluated the effect of interval walking training on cardiovascular autonomic neuropathy (CAN) in type 2 diabetes (T2D) patients. At baseline, 64 T2D patients underwent tilt table testing with autonomic reflex tests: heart rate responses to the Valsalva maneuver, deep breathing, and standing, and blood pressure responses to standing and sustained handgrip, using the Ewing score. Fifty‐six participants were allocated to an interval training (IT) group and control group. The IT group completed supervised interval walking training three times weekly for 60 min over 4 months, while the control group received physical activity education. Twenty‐four participants in the IT group and 30 in the control group completed the study. The primary endpoint of this post hoc analysis was the change in Ewing score. CAN was detected in 42 patients (66%), mean Ewing score of 2.7 ± 0.72. Those with CAN, 16 were in the IT group and 19 in the control group. Both groups showed a significant reduction in Ewing scores (IT: from 2.5 to 1.77, p = 0.003; control: from 2.72 to 1.91, p = 0.001). Interval walking training and physical activity education both reduce CAN severity in T2D patients.