Biomarker-specific differences between transpulmonary and peripheral arterial–venous blood sampling in patients with pulmonary hypertension

Abstract

Purpose: Transpulmonary biomarkers may provide insight into pulmonary hypertension (PH) pathophysiology, but require cardiac catheterization. We investigated whether the peripheral arterial–venous ratio (PR) could substitute for the transpulmonary ratio (TPR).

Materials and methods: Blood from the pulmonary artery (PA), pulmonary arterial wedge (PAW), peripheral venous, and peripheral arterial positions was analysed for ET-1, NT-pro-BNP and cAMP levels in subjects with no PH (n?=?18) and PH due to left heart disease (PH-LHD), which included combined pre- and post-capillary PH (Cpc-PH; n?=?7) and isolated post-capillary PH (Ipc-PH; n?=?9). Bland–Altman comparisons were made between peripheral venous and PA samples and between peripheral arterial and PAW samples. TPR was defined as [PAW]/[PA].

Results: For ET-1, Bland–Altman analysis indicated negative bias (?24%) in peripheral arterial compared to PAW concentration and positive bias (23%) in peripheral venous compared to PA concentration. There was <10% absolute bias for NT-pro-BNP and cAMP. For ET-1, there was no difference in PR between Cpc-PH and Ipc-PH (0.87?±?0.4 vs. 0.94?±?0.6, p?=?0.8), whereas there was a difference in TPR (2.2?±?1.1 vs. 1.1?±?0.2, p?<?0.05).

Conclusions: In PH-LHD, peripheral samples may be inadequate surrogates for transpulmonary samples, particularly when measuring mediators with prominent pulmonary secretion or clearance, such as ET-1.     

Dynamic thiol/disulphide homeostasis as indicator of oxidative stress in automotive workers

Abstract

Purpose: To examine thiol-disulphide homeostasis auto painters.

Materials and methods: A total of 115 male workers, including 60 auto painters workers and 55 reference group, of the painting and assembly line units respectively, were included in the study. Thiol-disulphide parameters and ischaemia-modified albumin (IMA) of groups were determined. Urinary hippuric acid, (HA) phenol, hexanedione, trichloroacetic acid, arsenic and blood lead and manganese were analysed.

Results: The median urinary HA level was significantly higher in auto painters when compared to the reference group [(2461 (1212) vs. 520 (513) µgr/L), (p?<?0.001)] . The mean disulphide level [19.7 (4.3) vs 0.15.1(4.1) μmol/L, (p?<?0.001)], the disulphide/native thiol ratio [4.72 (1.47) vs. 3.13 (1.21, (p?<?0.001)] and the disulphide/total thiol ratio [4.31 (1.23) vs. 2.94 (1.06), (p?<?0.001)] were higher in auto painters when compared to the reference group. There was a statistically significant positive correlation between urinary HA and disulphide concentrations (r?=?0.536 and p?<?0.001), disulphide/native thiol ratio (r?=?0.564 and p?<?0.001) and the disulphide/total thiol ratio (r?=?0.564 and p?<?0.001) and IMA (r?=?0.396 and p?<?0.001).

Conclusion: The results presented in this study showed that oxidative stress can be associated with occupational exposure to toluene denoted by alteration of thiol disulphide homeostasis and ischaemia-modified albumin levels.     

Low proportions of folic acid deficiency after introduction of mandatory folic acid fortification in remote areas of northern Queensland,Australia: a secondary health data analysis

Abstract

Background: Australia implemented mandatory folic acid fortification of bread-making flour in 2009.

Objective: To assess the impact of folic acid fortification in remote vs. regional urban areas and Indigenous vs. non-Indigenous populations in northern Queensland.

Methods: Routinely collected data on folic acid measurements in remote areas and two regional urban centres in northern Queensland between 2004 and 2015 were analysed (n?=?13,929) dichotomously (folic deficient vs. non-deficient).

Results: Overall prevalence of folic acid deficiency was 3.2% (235/7282) in urban centres compared with 7.2% (480/6647) in remote areas (p?<?0.001), and 9.3% (393/4240) in the Indigenous population compared with 3.2% (273/8451) in the non-Indigenous population (p?<?0.001). Prevalence of folic acid deficiency dropped from 12.2% (n?=?481) in 2004–2008 to 1.5% (n?=?126) in 2010–2015 (p?<?0.001). This translates into a relative risk reduction (RRR) of 88%. RRR was 79% (7.2% vs. 1.5%) in urban centres, 91% (17.3% vs. 1.5%) in remote areas, 92% (20.5% vs. 1.6%) in the Indigenous population and 80% (7.4% vs. 1.5%) in the non-Indigenous population (p?<?0.001 for all).

Conclusions: Substantial declines of folic acid deficiency to low and comparable proportions in former high-risk populations indicate that mandatory folic acid fortification of flour has had a population-wide benefit in northern Queensland.     

Association between circulating irisin levels and epicardial fat in patients with treatment-naïve overt hyperthyroidism

Abstract

Background: Hyperthyroidism is associated with increased metabolic activity and thermogenesis. Irisin is a key molecule in thermogenesis and energy expenditure via adipose tissue browning. Epicardial fat was previously defined as brown-like fat. Thus, here we aimed to evaluate the association between serum irisin level and epicardial fat thickness (EFT) in patients with hyperthyroidism.

Methods: A total of 25 hyperthyroid patients and 24 age-, sex- and BMI-matched healthy controls were enrolled. Serum irisin levels, thyroid hormone levels, and body compositions were compared. EFT was measured via transthoracic echocardiography.

Results: Serum irisin level and EFT were significantly higher in the hyperthyroid group (p?<?0.001 and p?=?0.001, respectively). The distributions of fat-free mass, muscle mass and fat mass were similar between the study groups. Serum irisin level was negatively correlated with TSH (p?<?0.001) and positively correlated with fT3 (p?<?0.001), fT4 (p?<?0.001) and TSH receptor antibody (p?=?0.002) levels and EFT (p?=?0.001). In multivariate linear regression analysis, TSH (β?=??0.475, p?<?0.001) and EFT (β?=?0.290, p?=?0.023) levels were significantly associated with serum irisin levels.

Conclusions: An increased serum irisin level associated with EFT might contribute to metabolic derangement in hyperthyroidism. Further studies are needed to elucidate whether irisin levels and EFT are affected by hyperthyroidism or vice versa.     

Subjects with microvascular angina have longer GT repeats polymorphism in the haem oxygenase-1 gene promoter

Abstract

Objective: Few studies have investigated haem oxygenase-1 gene (HMOX1) promoter polymorphism in microvascular angina (MVA).

Materials and methods: HMOX1 promoter (GT)_n repeats were examined in healthy controls (N?=?220) and MVA subjects (N?=?181).

Results: The distribution of genotype of SS, SL and LL were significantly different in MVA (17%, 51%, 33%) vs. normal controls (35%, 46%, 20%) (p?<?0.001, S allele: ≤30 repeats, L allele: >30 repeats). In multivariate analysis, carrier of L allele (odds ratio 2.772, p?<?0.001) was a significant predictor for the diagnosis of MVA.

Conclusions: Subjects with MVA had longer HMOX1 promoter (GT)_n repeats than the healthy controls.

Trial registration number: NCT01198730 at https://clinicaltrials.gov     

Long-term prognostic significance of homocysteine in middle-aged and elderly

Objective: We investigated the association among increased levels of plasma homocysteine (Hcy), all-cause mortality, and cardiovascular events. Methods: Hcy was measured in 670 middle-aged and elderly subjects with no previous manifest cardiovascular disease. The follow-up period was 15 years. Results: Subjects with Hcy?≥?10.8?μmol/l (n?=?231) had a significant higher incidence of all-cause mortality (p?<?0.001) and CV events (p?<?0.001) compared with subjects with Hcy?<?10.8?μmol/l (n?=?439). However, there was no association on high levels of Hcy and VTE events or stroke. Conclusion: Increased levels of Hcy are associated with all-cause mortality and CV events.     

Characterization of soluble thrombomodulin levels in patients with stage 3–5 chronic kidney disease

Abstract

Objective: This study aims to test the serum levels of soluble thrombomodulin (TM) in patients with chronic kidney disease (CKD)3–5 and to assess their connection with the different stages and severity of disease.

Methods: Sixty-seven patients with CKD are included, disease severity was evaluated accordingly to CKD staging and clinical data is collected. Nineteen healthy volunteers served as healthy controls. Serum soluble TM is analyzed by ELISA.

Results: The levels of soluble TM in all patients with CKD were significantly higher than those of healthy controls (p?<?0.001). CKD5 patients showed higher serum levels of soluble TM, in comparison to CKD4 patients (p?=?0.001), CKD3 patients (p?<?0.001), and healthy controls (p?<?0.001). The correlation analysis revealed significant correlation between serum soluble TM and disease severity (r?=?0.714, p?<?0.001). Serum soluble TM was found to be correlated with eGFR (r?=??0.766; p?<?0.001) and serum creatinine (r?=?0.778, p?<?0.001).

Conclusion: Soluble TM concentrations significantly increase in the CKD patients and are associated with the severity of the disease. Soluble TM may play critical roles in the development of CKD, as a biomarker of endothelial cells damage, anticoagulation and anti-inflammation.     

Circulating biomarkers of hypertrophy and fibrosis in patients with hypertrophic cardiomyopathy assessed by cardiac magnetic resonance

Abstract

Background: Myocardial fibrosis in hypertrophic cardiomyopathy (HCM) is associated with worse clinical outcomes. The availability of circulating biomarkers of myocardial fibrosis and hypertrophy would be helpful in clinical practice.

Objective: The aim of this study was to evaluate usefulness of various biomarkers of myocardial fibrosis and hypertrophy in HCM.

Methods: Levels of biomarkers: soluble ST2 (sST2), galectin-3 (Gal-3), growth differentiation factor-15 (GDF-15), NT-proBNP and high-sensitivity cardiac troponin T (hs-cTnT) were measured in 60 patients with HCM. All patients underwent cardiac magnetic resonance imaging to calculate parameters of hypertrophy and fibrosis.

Results: We observed positive correlations among sST2 levels and left ventricular mass (LVM) (r?=?0.32, p?=?0.012), LV mass indexed for the body surface area (LVMI) (r?=?0.27, p?=?0.036) and maximal wall thickness (MWT) (r?=?0.31, p?=?0.015). No correlation was found between Gal-3 and GDF-15 levels and hypertrophy and fibrosis parameters. We observed positive correlations among hs-cTnT levels and LVM (r?=?0.58, p?<?0.0001), LVMI (r?=?0.48, p?=?0.0001), MWT (r?=?0.31, p?=?0.015) and late gadolinium enhancement (LGE) mass (r?=?0.37, p?=?0.003). There were positive correlations between NT-proBNP levels and LVM (r?=?0.33, p?=?0.01), LVMI (r?=?0.41, p?=?0.001), MWT (r?=?0.42, p?<?0.001) and LGE mass (r?=?0.44, p?<?0.001).

Conclusions: Although no correlation between sST2 levels and myocardial fibrosis was found, sST2 may provide some additional information about hypertrophy extension. NT-proBNP and hs-cTnT are useful biomarkers in assessment of hypertrophy and fibrosis in HCM.     

Diagnostic utility of MR-proANP and NT-proBNP in elderly outpatients with a high risk of heart failure: the Copenhagen heart failure risk study

Abstract

Background: Amino-terminal-pro-B-type-natriuretic-peptide (NT-proBNP) is a diagnostic biomarker for heart failure (HF), but plasma concentrations are influenced by numerous factors. Mid-regional-pro-atrial-natriuretic-peptide (MR-proANP) have comparable diagnostic value in acute HF. However, data are lacking in the non-acute setting. This study sought to assess the diagnostic utility of MR-proANP in outpatients with a high risk of HF.

Methods: This prospective study included 399 outpatients. Inclusion criteria were: age?≥?60?years, ≥1 risk factor for HF (diabetes, chronic kidney disease, vascular disease, atrial fibrillation, hypertension), without known or suspected HF. Unrecognized HF was diagnosed based on clinical signs, patient-reported symptoms and echocardiography. Plasma concentrations of MR-proANP and NT-proBNP were analysed.

Results: In total, 65 patients were diagnosed with HF or asymptomatic left ventricular systolic dysfunction (N?=?12 LVEF?≤?40%, N?=?7 LVEF?>?40% to ≤50%, N?=?46 LVEF?>?50%). Both MR-proANP (odds-ratio: 1.77; 95% CI:1.16–2.72; p?=?0.009) and NT-proBNP (odds-ratio: 1.49; 95% CI:1.22–1.82; p?<?0.001) were associated with HF. Area under receiver-operator characteristics curve (AUC) for the diagnosis of HF or asymptomatic left ventricular systolic dysfunction was higher for MR-proANP (AUC?=?0.886; p?<?0.001) and NT-proBNP (AUC?=?0.910; p?<?0.001) compared to patient-reported symptoms of HF (AUC?=?0.830), but NT-proBNP added more diagnostic information compared to MR-proANP (p?=?0.022).

Conclusions: Both NT-proBNP and MR-proANP are useful biomarkers in the diagnosis of HF or asymptomatic left ventricular systolic dysfunction in a non-acute setting. However, NT-proBNP added more diagnostic information compared to MR-proANP.     

Diagnostic value of exercise-induced changes in circulating high sensitive troponin T in stable chest pain patients

Abstract

Objective: We investigated the diagnostic value of exercise-induced increase in cardiac Troponin T (cTnT) in stable chest pain subjects.

Methods: CTnT was measured before and 20?h after an exercise test in 157 subjects suspected of coronary artery disease (CAD).

Results: CAD subjects (n?=?41) had higher baseline cTnT levels compared to non-CAD subjects (n?=?116), 6.39?ng/l and 3.00?ng/l, respectively, p?<?0.0001, and were more likely to increase in cTnT (70.7% versus 27.6%, p?<?0.0001). Net Reclassification Index for the combined variable was 19%, p?=?0.02.

Conclusions: Exercise-induced increase in cTnT was found to be associated with CAD and cTnT measurements improved the diagnostic evaluation.     

A novel noninvasive index for nonalcoholic steatohepatitis: a pilot study

Abstract

Objective: The potential development of a noninvasive marker predicting nonalcoholic steatohepatitis (NASH).

Methods: Thirty patients with biopsy-proven nonalcoholic fatty liver disease were evaluated by numerous anthropometric, clinical and biochemical parameters.

Results: Serum glutamic oxaloacetic transaminase (SGOT; p?=?0.027), log (erythrocyte sedimentation rate) (ESR; p?=?0.034) and homocysteine (p?=?0.041) were associated with NASH independently from gender, age and body mass index. When combined, the regression model provided R²?=?0.563 (p?=?0.001) and area under the ROC curve?=?0.873?±?0.066 (p?<?0.001).

Conclusion: This noninvasive marker, named HSENSI (acronym of homocysteine, SGOT, ESR, Nonalcoholic Steatohepatitis Index), consists of three low cost, easily measurable parameters and may accurately predict NASH.     

Neutrophil gelatinase-associated lipocalin after off pump versus on pump coronary artery surgery

Abstract

Context: Cardiac surgery.

Objective: To compare plasma and urinary neutrophil gelatinase-associated lipocalin (P-/U-NGAL) in on-pump (n?=?43) versus off-pump (n?=?40) surgery.

Materials and methods: We obtained perioperative P-/U-NGAL and outcome data.

Results: P-/U-NGAL increased after surgery. P-NGAL was higher post-surgery in on pump patients (139 versus 67?µg L^?1; p?<?0.001), but not at 24?h. There were no differences in U-NGAL. Correlation between P-/U-NGAL and plasma creatinine was weak.

Discussion: P-NGAL acts like a neutrophil activation biomarker and U-NGAL like a tubular injury marker.

Conclusion: On-pump patients had greater neutrophil activation. On- versus off-pump surgery had similar impact on tubular cells.     

Plasma levels of nesfatin-1 as a new biomarker in depression in Asians: evidence from meta-analysis

Abstract

Objective: This study aims to review the alteration of plasma nesfatin-1 levels in patients with depression.

Methods: Under the guidance of the latest PRISMA checklist, a systematic review and meta-analysis were conducted by searching English database (PubMed, Web of Science, EMDASE) and Chinese database for relevant studies up to August, 2019. Pooled standardised mean difference (SMD) with 95% confidence intervals (CI) was calculated with the random effects model.

Results: Nine studies that reported the association between plasma levels of nesfatin-1 and the risk of depression with 567 patients and 447 control participants were included in the meta-analysis. Compared with the healthy controls, depressive patients had a higher plasma level of nesfatin-1 [SMD (95% CI):1.58(0.75, 2.41), Z?=?3.74, p for Z?<?0.001; I² = 96.8%, p for I² < 0.001]. The subgroup analyses and meta-regression failed to find the source of the heterogeneity. No evidence of publication bias was found either in Begg’s test (p?=?0.348) or the Egger’s test (p?=?0.523).

Conclusion: The present meta-analysis indicated that a higher plasma level of nesfatin-1 was associated with an increased risk of depression.     

Evaluation of mediators of oxidative stress and inflammation in patients with acute appendicitis

Context: This study aims to explore the potential of new inflammatory markers for improving the challenging diagnosis of acute appendicitis (AA).

Methods: Levels of IL-1, IL-6, IL-8, IL-10, CRP, INF-γ, and TNF-α in serum were measured in 73 patients with AA. Oxidative stress and antioxidant enzymes were analyzed.

Results: Serum levels of interleukins, TNF-α, and INF-γ were significantly elevated in patients with appendicitis (p?<?0.0001), except for IL-10, which presented decreased levels. There were no significant differences in SOD (p?=?0.29), CAT (p?=?0.19), or TBARS levels (p?=?0.18), whereas protein carbonyls presented significant increase (p?<?0.0001).

Conclusion: Evaluating these biomarkers could aid in diagnosing AA.     

Visual motor imagery predominance in professional Spanish dancers

Abstract

Purpose: The main objectives of the study were to analyse the predominant motor imagery modality used by professional Spanish dancers and to compare Spanish dancers’ ability to perform mental motor imagery with that of non-dancers, and to analyse differences between male and female dancers. As a secondary aim, to compare the motor imagery ability between two styles of Spanish dance: classical Spanish dancers and Flamenco dancers.

Methods: A total of 74 participants were classified into two groups: professional Spanish dancers (n?=?37) and sedentary participants (n?=?37). The professional Spanish dancer group was composed of two dance disciplines: flamenco dancers (n?=?17), and classical dancers (n?=?20).

Results: Professional Spanish dancers used predominantly visual imagery modalities over kinesthetics to generate motor imagery, with a moderate effect size (p?<?.01, d?=?0.68). Regarding the ability to generate motor imagery, significant intergroup differences between professional Spanish dancers and sedentary participants were observed in all variables, with a large effect size (p?<?.05, d?>?0.80). Differences were obtained between men and women among non-dancers group (t?=??3.34; p?=?.03; d?=?0.5). No differences between Flamenco and classical dancers were observed.

Conclusion: Visual motor imagery modality was easier than the kinaesthetic modality in the generation of motor imagery for professional Spanish dancers regardless of the dance style. Spanish dancers had a greater ability to perform motor imagery compared with non-dancer individuals, needing less time to perform these mental tasks. Men non-dancers had a greater ability to generate motor imagery than women. Reinforcing the training of kinaesthetic motor imagery might be useful for professional Spanish dancers.     

Methylated arginines and nitric oxide in end-stage renal disease: impact of inflammation,oxidative stress and haemodialysis

Abstract

Objectives: To determine whether inflammation (C-reactive protein, CRP), oxidative stress (malondialdehyde, MDA) or haemodialysis (HD) affect associations between asymmetric (ADMA), symmetric (SDMA) dimethylarginine, NG-monomethyl-L-arginine (L-NMMA) and nitrite/nitrate (NOx) in end-stage renal disease (ESRD).

Method: Metabolites were measured pre-HD, after 1 hour and end-HD in 40 ESRD patients (age 63?±?14 years).

Results: Positive associations between NOx and ADMA (p?=?0.04), SDMA (p?<?0.001) and L-NMMA (p?=?0.04) were observed pre-HD. Associations weakened during HD but were not significantly influenced by CRP or MDA.

Conclusions: HD, oxidative stress or inflammation did not significantly affect the positive associations between methylated arginines and NOx in ESRD.     

Paraoxonase and arylesterase levels in autoimmune thyroid diseases

Objective: The aim of this study was to evaluate serum paraoxonase-1 (PON1) activity and its association with oxidative stress in autoimmune thyroid disease (AITD).

Methods: A total of 50 patients with AITD, including 25 with Hashimoto's thyroiditis and 25 with Graves’ disease were enrolled. The control group comprised 27 healthy subjects. Blood samples were obtained in the euthyroid period and 3 months after initiation of medical treatment. Serum samples from patients with AITD and the healthy control group were analyzed for basal PON1, salt-stimulated PON1, and arylesterase (ARE) activities, along with lipid hydroperoxide (LOOH) and total free sulfhydryl (–SH) levels.

Results: Serum PON1 activities and –SH levels were significantly lower (P?<?0.001, for each), whereas LOOH levels were significantly higher (P?<?0.001, for each) in patients with AITD, compared to the control group. We observed no significant differences in ARE levels between the patient and healthy control groups (P?>?0.05). PON1 activity was positively correlated with –SH (r?=?0.522, P?<?0.001) and negatively correlated with LOOH (r?=??0.487, P?<?0.001). PON1 phenotype distribution of the subjects was not significantly different among the three groups (P?=?0.961).

Conclusions: Serum PON1 activity is decreased in patients with AITD, and correlated positively with –SH, a well-known antioxidant, and negatively with LOOH, an index of lipid oxidation.     

Prognostic and diagnostic significance of mid-regional pro-atrial natriuretic peptide in acute exacerbation of chronic obstructive pulmonary disease and acute heart failure: data from the ACE 2 Study

Abstract

Purpose: To compare the diagnostic and prognostic value of mid-regional pro-ANP (MR-proANP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with acute dyspnea.

Methods: MR-proANP and NT-proBNP were measured with commercial immunoassays at hospital admission (n?=?313), on day 2 (n?=?234), and before discharge (n?=?91) and compared for diagnosing acute heart failure (HF; n?=?143) and to predict mortality among patients with acute HF and acute exacerbation of chronic obstructive pulmonary disease (AECOPD; n?=?84) separately.

Results: The correlation coefficient between MR-proANP and NT-proBNP was 0.89 (p?<?0.001) and the receiver-operating area under the curve (AUC) was 0.85 (95% CI 0.81–0.89) for MR-proANP and 0.86 (0.82–0.90) for NT-proBNP to diagnose acute HF. During a median follow-up of 816?days, mortality rates were 46% in acute HF patients and 42% in AECOPD patients. After adjustment for other risk variables by multivariate Cox regression analysis, MR-proANP and NT-proBNP concentrations were associated with mortality in patients with acute HF, but only MR-proANP were associated with mortality among patients with AECOPD: hazard ratio (_lnMR-proANP) 1.98 (95% CI 1.17–3.34).

Conclusion: MR-proANP and NT-proBNP concentrations provide similar diagnostic and prognostic information in patients with acute HF. In contrast to NT-proBNP, MR-proANP measurements also provided independent prognostic information in AECOPD patients.     

The effects of acute and prolonged muscle vibration on the function of the muscle spindle’s reflex arc

Abstract

Purpose:?Localized mechanical vibration, applied directly to a muscle, is known to have powerful, duration-dependent effects on the muscle spindle’s reflex arc. Here, the conditioning of the function of the spindle reflex arc via vibration was examined with considerations for use as a non-invasive, sensorimotor research tool.

Methods:?Muscle spindle function was examined with patellar tendon taps prior to and following exposure to muscle vibration applied to the quadriceps femoris for acute (<5?s) and prolonged (20?min) durations. Surface electromyography (sEMG), torque, and accelerometry signals were obtained during the taps to quantify various measures of reflex magnitude and latency.

Results:?Our findings suggest that acute vibration had no effect on normalized reflex torque or sEMG amplitude (p?>?0.05), but increased total reflex latency (p?=?0.022). Alternatively, prolonged vibration reduced normalized reflex torque and sEMG amplitude (p?<?0.001), and increased reflex latency (p?<?0.001).

Conclusions:?Our findings support the use of prolonged vibration as a practical means to decrease the function of the muscle spindle’s reflex arc. Overall, this suppressive effect was evident in the majority of subjects, but the extent was variable. This approach could potentially be used to help delineate the muscle spindle’s role in various sensory or motor tasks in which more direct measures are not feasible. Acute vibration, however, did not potentiate muscle spindle function as hypothesized. Rather, our results suggest that acute vibration increased total reflex latency. Accordingly, potential mechanical and neurophysiological mechanisms are discussed.     

Corticomotor correlates of somatosensory reaction time and variability in individuals with post concussion symptoms

Abstract

Persistent post concussion symptoms (PPCS) describe the condition when an individual experiences chronic symptoms, particularly fatigue, beyond the expected time of recovery. The aim of this study was to quantify the effect of fatigue and related ongoing symptoms on somatosensory and corticomotor pathways using reaction time (RT) testing, and single-pulse and paired-pulse transcranial magnetic stimulation (TMS). Eighty-three participants (nine female, mean age 37.9?±?11.5?years) were divided into two groups (persistent symptoms versus asymptomatic) following self-report based upon previously published clinical symptom scores. All participants completed somatosensory and visuomotor RT testing, as well as corticomotor excitability and inhibition measurements via TMS. Participants in the persistent symptom group (n?=?38) reported greater number of previous concussions (t?=?2.81, p?=?0.006) and significantly higher levels of fatigue and related symptoms in the asymptomatic group (n?=?45; t?=?11.32, p?<?0.006). Somatosensory RT showed significant slowing and increased variability in the persistent symptoms group (p?<?0.001), however no significant differences were observed between groups for visuomotor RTs. Transcranial magnetic stimulation revealed differences between groups for intracortical inhibition at all stimulus intensities and paired pulse measures. The results indicate that somatosensory and corticomotor systems reflect on-going fatigue. From a practical perspective, objective and simplistic measures such as somatosensory and corticomotor measures can be used in the assessment of PPCS and gauging the efficacy of post concussion rehabilitation programmes.