The autonomic dysfunction in patients with ankylosing spondylitis: a clinical and electrophysiological study

Heart Rate Variability in Patients of Ankylosing Spondylitis: A Systematic Review and Meta-Analysis

Patients with ankylosing spondylitis (AS) have a significantly higher risk of cardiovascular morbidities. The participation of the autonomic nervous system (ANS) in AS is still unknown and inconclusive. Heart rate variability (HRV) is defined as the variability of the time interval between two consecutive heartbeats. This meta-analysis aims to detect the association of HRV and its various parameters with AS patients by comparing them to healthy controls. Research literature was searched in PubMed, Embase, and Cochrane Library databases from inception to April 2022. The Review Manager 5 (RevMan) Version 5.4 software was used to analyze the data. In addition, the protocol of systematic review is registered in the PROSPERO database with ID CRD42022336484. This study includes a total of nine case-control studies with a total of 923 patients; 409 with AS and 514 healthy controls. The root mean square of successive differences between normal heartbeats (RMSSD) [standardized mean difference (SMD); -0.47, 95% CI: -0.69 to -0.25, p < 0.0001], proportion of NN50 (pNN50) (SMD; -0.89, 95% CI: -1.74 to -0.04, p = 0.04) and HRV (SMD; -1.11, 95% CI: -1.53 to 0.69, P < 0.00001) were significantly low in AS cases compared to healthy controls. The HRV value was also significantly low in patients with high Bath ankylosing spondylitis disease activity (BASDAI) index (SMD: -1.45, 95% CI: -2.45 to -0.36, p < 0.009). HRV (parasympathetic activity) was significantly lowered in AS patients compared to healthy controls.

Exercise capacity in axial spondyloarthritis and associated factors: A cross-sectional controlled study

OBJECTIVE

To examine the associations between exercise capacity (EC), cardiovascular (CV) risk factors and disease-related variables in axial spondyloarthritis (AxSpA) patients.

METHODS

In this cross-sectional controlled study, CV risk profile data, physical activity, 10-year CV event risk estimated by the Framingham model and Ankylosing Spondylitis Disease Activity Score - C-reactive protein were recorded. A maximal treadmill exercise test by Bruce protocol was administered. Analyses of covariance were performed with adjustments for age, smoking status and physical activity level. Linear regression analysis was performed to study the association between EC and related CV risk factors.

RESULTS

Thirty-eight patients and 38 age-gender matched controls were recruited between May and October 2014. Patients had significantly lower EC than controls (MD 2.2; metabolic equivalents 0.91-3.49; P = .001). The difference remained significant after adjustments (P = .001). There were significant correlations between EC and age, 10-year CV event risk, body mass index (BMI) and waist circumference for patients and controls (P < .001 and P < .05, respectively). There was a significant relationship between EC and total cholesterol, triglycerides and heart rate recovery (HRR) in patients (P = .04, P < .001 and P = .006, respectively). High-density lipoprotein - cholesterol was significantly higher, and BMI was significantly lower in nonradiographic AxSpA patients (P = .026 and P = .03 respectively). Age and triglyceride levels were found as the significant predictors for EC in the AxSpa group (for age β = -.105, P = .003; for triglycerides β = -.016 P = .003).

CONCLUSION

Exercise capacity was significantly lower and attenuated HRR was significantly associated with low EC and high 10-year CV event risk in AxSpA patients.

Neuropathic component of low back pain in patients with ankylosing spondylitis

OBJECTIVE

The aim of this cross sectional study was to evaluate frequency of neuropathic back pain in ankylosing spondylitis (AS) patients and to determine the relation with disease variables and occurrence of neuropathic pain.

METHODS

Fifty-eight AS patients who were not having any comorbid disease and/or using drugs that would cause neuropathy, were recruited to the study. Demographic properties and clinical characteristics (functional status and disease activity assessed by BASFI and BASDAI respectively, ESR, CRP) and quality of life determined by AS quality of life-QoL questionnaire, were recorded. The neuropathic property of back pain was assessed by both Leeds Assessment of Neuropathic symptoms and signs (LANSS) and Douleur Neuropathique 4 (DN4) scales.

RESULTS

58 AS patients (17 female, 41 male) with a mean age of 45 ± 18 years were included. 33 patients (56.9%) and 31 patients (53.4%) were defined as having neuropathic pain depending on the LANSS (scores > 12) and DN4 (scores > 4) questionnaire scores respectively. The mean score of LANSS scale was correlated with ASQoL, BASFI, BASDAI, and DN4; and the mean score of DN4 scale was correlated with ASQoL, BASFI and LANSS. The mean levels of BASFI and ASQoL scores were significantly higher in patients having neuropathic pain than in patients not having (p < .05).

CONCLUSION

Neuropathic pain is common and determined in more than half of the patients with AS and related with functional status and quality of life. Diagnosis and treatment of neuropathic pain are warranted in order to increase functional ability and quality of life in patients suffering from AS.

Evaluation of cardiac autonomic nervous system in patients with ankylosing spondylitis using 12-lead electrocardiography and Holter monitoring

OBJECTIVES

Ankylosing spondylitis (AS) is associated with increased risk of cardiovascular problems, including complications such as conduction defects and arrhythmias, which might lead to increased morbidity and/or mortality. The objective of the present study is to evaluate the electrocardiographic (ECG) parameters, including T-peak to T-end intervals (Tpe), Tpe/corrected QT (QTc) ratio, heart rate variability (HRV), and heart rate turbulence (HRT) in AS patients.

METHODS

Seventy-six AS patients and 55 control subjects were included in the study. 12-lead ECG and 24-h Holter monitoring recordings were obtained. Tpe and Tpe/QTc were measured using the 12-lead ECG and HRV and HRT parameters were assessed using 24-h Holter ECG recordings. Subjects were assigned into three groups based on their HRT parameters (Tonset (TO) and Tslope (TS)) (HRT-0, normal TO or TS; HRT-1, abnormal TO or TS; HRT-2, abnormal TO and TS).

RESULTS

Tpe was prolonged and Tpe/QTc ratio was higher in AS patients (p < 0.001 for both). Moreover, Tpe and Tpe/QTc ratio significantly correlated with disease duration. All HRV parameters (VLF, LF, HF, SDNN, SDANN, ASDNN, rMSSD, pNN50) were decreased in AS patients in comparison with those in control subjects (p < 0.05 for all parameters). Controls were significantly more likely to have normal TO and TS (82% vs 53%, p < 0.001). There was negative correlation between Holter parameters and disease duration, as well as Tpe and Tpe/QTc ratio (p < 0.05 for all parameters).

CONCLUSIONS

This study demonstrated that AS patients have disrupted ventricular repolarization (increased Tpe, Tpe/QTc ratio). Results suggest a decreased cardiac impact of the parasympathetic system in AS patients. Key Points • This study demonstrated that AS patients have disrupted ventricular repolarization. • The study also finds that heart rate turbulence and heart rate variability are impaired in AS patients. • Impaired Holter and ECG parameters may be one of the high cardiovascular risk factors in AS patients.

Systemic inflammation and arrhythmic risk: lessons from rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic immuno-mediated disease primarily affecting the joints, characterized by persistent high-grade systemic inflammation. Cardiovascular morbidity and mortality are significantly increased in RA, with >50% of premature deaths attributable to cardiovascular disease. In particular, RA patients were twice as likely to experience sudden cardiac death compared with non-RA subjects, pointing to an increased propensity to develop malignant ventricular arrhythmias. Indeed, ventricular repolarization (QT interval) abnormalities and cardiovascular autonomic nervous system dysfunction, representing two well-recognized risk factors for life-threatening ventricular arrhythmias in the general population, are commonly observed in RA. Moreover, large population-based studies seem to indicate that also the prevalence of atrial fibrillation is significantly higher in RA subjects than in the general population, thus suggesting that these patients are characterized by an abnormal diffuse myocardial electrical instability. Although the underlying mechanisms accounting for the pro-arrhythmogenic substrate in RA are probably intricate, the leading role seems to be played by chronic systemic inflammatory activation, able to promote arrhythmias both indirectly, by accelerating the development of ischaemic heart disease and congestive heart failure, and directly, by affecting cardiac electrophysiology. In this integrated mechanistic view, lowering the inflammatory burden through an increasingly tight control of disease activity may represent the most effective intervention to reduce arrhythmic risk in these patients. Intriguingly, these considerations could be more generally applicable to all the diseases characterized by chronic systemic inflammation, and could help elucidate the link between low-grade chronic inflammation and arrhythmic risk in the general population.

Biologic drugs and arrhythmic risk in chronic inflammatory arthritis: the good and the bad

Increasing evidence indicates that patients with chronic inflammatory arthritis (CIA), including rheumatoid arthritis and spondyloarthropathies, have an increased risk of arrhythmic events, significantly contributing to the higher cardiovascular disease (CVD) morbidity and mortality observed in these subjects compared to the general population. Although the mechanisms accounting for such an arrhythmogenic substrate are not fully understood, the main role is probably played by chronic systemic inflammation, able to accelerate the development of structural CVD, as well as to directly affect cardiac electrophysiology. In the past decade, biologic therapies have revolutionized the treatment of CIA by highly enhancing the probability to effectively control disease activity and its systemic consequences, including cardiovascular involvement. Accordingly, accumulating data demonstrated that by potently inhibiting systemic inflammation, biologic drugs can reduce CVD progression and ameliorate arrhythmic risk parameters, with a putative beneficial impact on arrhythmia incidence. Nevertheless, a significant number of reports from clinical trials and postmarketing experience suggest that some of these medications, particularly TNF inhibitor monoclonal antibodies and rituximab, may in some circumstances precipitate arrhythmia occurrence, probably by acutely amplifying myocardial electric instability intrinsically associated with these diseases. In this review, we analyze the intricate link between biologic drugs and arrhythmias in CIA in the effort to identify which factors are involved in the fine-tuning of antiarrhythmic/pro-arrhythmic balance, and understand how this knowledge should be translated in the clinical practice to obtain the most favorable benefit-to-risk profile when biologic drugs are used in these patients.

Evidence of reduced parasympathetic autonomic regulation in inflammatory joint disease: A meta-analyses study

BACKGROUND

Rheumatoid arthritis (RA) and spondyloarthritis (SpA) are inflammatory joint disorders (IJD) with increased risk of cardiovascular disease (CVD). Autonomic dysfunction (AD) is a risk factor for CVD, and parasympathetic AD is linked to key features of IJD such as inflammation, physical inactivity and pain. Heart-rate variability (HRV) is a marker of cardiac AD. The study objective was to compare parasympathetic cardiac AD, measured by HRV, between patients with IJD and healthy controls, using meta-analysis methodology, and to examine the impact of inflammation, physical inactivity and pain on HRV in IJD.

METHODS

Medline, Embase and Amed were searched. Inclusion criteria were adult case-control studies published in English or a Scandinavian language, presenting HRV data in IJD. Two measures of HRV and 3 from the Ewing protocol were selected: square root of mean squared difference of successive R-R intervals (RMSSD), high frequency (HF), Ewing protocol; standing (E-S), breathing (E-B) and Valsalva (E-V). Patients with RA, SpA and healthy controls were compared separately using random-effects meta-analyses of standardized mean differences (SMD).

RESULTS

In all, 35 papers were eligible for inclusion. For RMSSD the pooled SMD (95% CI) RA vs. controls was -0.90 (-1.35 to -0.44), for SpA vs. controls; -0.34 (-0.73 to 0.06). For HF pooled SMD RA vs. controls was -0.78 (-0.99 to -0.57), for SpA vs. controls; -0.04 (-0.22 to 0.13). All Ewing parameters were significantly lower in cases, except for E-V which was comparable between cases and controls in patients with RA.

CONCLUSION

Patients with IJD have cardiac parasympathetic AD which is related to inflammation.

Cardiac Autonomic Function in Patients With Ankylosing Spondylitis: A Case-Control Study

Ankylosing spondylitis (AS) is a chronic inflammatory disease involing spine and enthesis. The primary aim of this study is to investigate the autonomic nervous system (ANS) function and the association between ANS and the functional status or disease activity in AS.The study included 42 AS patients, all fulfilling the modified New York criteria. All the patients are totally symptom free for ANS involvement and had normal neurological findings. These AS patients and 230 healthy volunteers receive analysis of 5 minutes heart rate variability (HRV) in lying posture. In addition, disease activity and functional status of these AS patients are assessed by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), and Bath Ankylosing Spondylitis Global Score (BAS-G).Both groups were age and sex-matched. Although the HRV analysis indicates that the peaks of total power (TP, 0-0.5 Hz) and high-frequency power (HF, 0.15-0.40 Hz) are similar in both groups, the activities of low-frequency power (LF, 0.04-0.15 Hz), LF in normalized units (LF%), and the ratio of LF to HF (LF/HF) in AS patients are obviously lower than healthy controls. The erythrocyte sedimentation rate and C-reactive protein revealed negative relationship with HF. The AS patients without peripheral joint disease have higher LF, TP, variance, LF%, and HF than the patients with peripheral joint disease. The AS patients without uvetis have higher HF than the patients with uvetis. The total scores of BASDI, BASFI, and BAS-G do not show any association to HRV parameters.AS patients have significantly abnormal cardiac autonomic regulation. This is closely related with some inflammatory activities. Reduced autonomic function may be one of the factors of high cardiovascular risk in AS patients.

Disease-modifying antirheumatic drugs improve cardiovascular autonomic neuropathy in psoriatic arthritis

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) is a significant risk predictor for sudden cardiac death in autoimmune rheumatic diseases. As yet, there is no therapeutic treatment of CAN in psoriatic arthritis (PsA). Even now, the impact of the most commonly employed disease-modifying antirheumatic drug (DMARD) therapy on CAN in PsA is not known. Hence, we investigated the impact of DMARDs on CAN in PsA.

METHODS

In this prospective, cross-sectional study, 20 patients of PsA and 20 age- and sex-matched healthy controls were recruited. CAN was diagnosed by applying the five cardiovascular reflex tests according to Ewing. Parasympathetic dysfunction was established by performing three tests: heart-rate response to deep breathing, standing, and Valsalva tests. Sympathetic dysfunction was examined by applying two tests: blood pressure response to standing, and handgrip tests. Disease severity was assessed by the 28-joint-count disease activity score (DAS-28) and the disease activity score in psoriatic arthritis (DAPSA).

RESULTS

Cardiovascular reflex tests were impaired significantly among the PsA patients compared with well-matched healthy subjects (p < 0.05). Parasympathetic dysfunction was more prominent than sympathetic dysfunction. After 12 weeks treatment, parasympathetic dysfunction (heart rate response to deep breath and standing) significantly (p < 0.05) improved in patients with PsA, while there was no significant improvement in sympathetic function.

CONCLUSION

These study results suggests parasympathetic autonomic dysfunction is more prominent than sympathetic dysfunction in PsA. Synthetic DMARDs improved parasympathetic dysfunction in PsA.

Autonomic Dysfunction Precedes Development of Rheumatoid Arthritis: A Prospective Cohort Study

Background

Heart rate variability (HRV) is a validated method to establish autonomic nervous system (ANS) activity. Rheumatoid arthritis (RA) is accompanied by ANS imbalance. We hypothesized that ANS dysfunction may precede the development of RA, which would suggest that it plays a role in its etiopathogenesis.

Methods

First, we assessed HRV parameters in supine (resting) and upright (active) position in healthy subjects (HS, n = 20), individuals at risk of developing arthritis (AR subjects, n = 50) and RA patients (RA, n = 20). Next, we measured resting heart rate (RHR), a parasympathetic HRV parameter, in an independent prospective cohort of AR subjects (n = 45). We also evaluated expression levels of the parasympathetic nicotinic acetylcholine receptor type 7 (α7nAChR) on circulating monocytes.

Findings

Both AR subjects (68 beats per minute (bpm), interquartile range (IQR) 68–73) and RA patients (68 bpm, IQR 62–76) had a significantly higher RHR compared to HS (60 bpm, IQR 56–63). RHR was significantly higher at baseline in individuals who subsequently developed arthritis. Expression levels of α7nAChR were lower in AR subjects with RHR ≥ 70 bpm compared to those with RHR < 70 bpm, consistent with reduced activity of the parasympathetic cholinergic anti-inflammatory pathway.

Interpretation

These data support the notion that autonomic dysfunction precedes the development of RA.

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Individuals at risk of developing RA show autonomic dysfunction similar to established RA patients.

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Autonomic dysfunction is a predictor of development of arthritis in subjects at risk of RA, suggesting a role in its etiopathogenesis.

The autonomous nervous system is a neurological control system that acts largely unconsciously and regulates a variety of bodily functions. We found that dysfunction of this system may precede and predict the development of rheumatoid arthritis (RA), a chronic inflammatory disease with great unmet need. These findings provide important insights into the changes in the nervous system contributing to the development of this condition. They also open up the perspective of potential measures aimed at prevention of RA by restoring the balance in the nervous system before arthritis develops, which would have major implications for patients as well as society.

Vagus nerve stimulation: a new bioelectronics approach to treat rheumatoid arthritis?

There has been a marked improvement in the treatment of rheumatoid arthritis (RA), but most patients do not achieve disease remission. Therefore, there is still a need for new treatments. By screening an adenoviral short hairpin RNA library, we discovered that knockdown of the nicotinic acetylcholine receptor type 7 (α7nAChR) in RA fibroblast-like synoviocytes results in an increased production of mediators of inflammation and degradation. The α7nAChR is intimately involved in the cholinergic anti-inflammatory pathway (CAP). This led us to study the effects of α7nAChR activation in an animal model of RA, and we could show that this resulted in reduced arthritis activity. Accordingly, stimulation of the CAP by vagus nerve stimulation improved experimental arthritis. Conversely, we found aggravation of arthritis activity after unilateral cervical vagotomy as well as in α7nAChR-knockout mice. Together, these data provided the basis for exploration of vagus nerve stimulation in RA patients as a novel anti-inflammatory approach.

Disease-modifying anti-rheumatic drugs improve autonomic neuropathy in arthritis: DIANA study

Autonomic neuropathy (AN) is a risk predictor for sudden cardiac death in rheumatoid arthritis (RA) and ankylosing spondylitis (AS). However, the impact of most commonly employed disease-modifying anti-rheumatic drug (DMARD) therapy on autonomic neuropathy in rheumatic diseases is not known. Hence, we investigated the efficacy of DMARDs on autonomic neuropathy in RA and AS. We performed autonomic function assessment in 60 patients in this open-label, 12-week pilot study including 42 patients with RA, 18 with AS, and 30 aged-matched healthy subjects. The methodology included assessment of cardiovascular autonomic reflex tests according to Ewing. Parasympathetic dysfunction was established by performing three tests: heart rate response to deep breathing, standing, and Valsalva tests. Sympathetic dysfunction was examined by applying two tests: blood pressure response to standing and handgrip tests. Sudomotor function was assessed by Sudoscan. Cardiovascular reflex tests were impaired significantly among the patients as compared to healthy subjects (p < 0.05). Autonomic neuropathy was more pronounced in biologic-naive RA and AS patients. After treatment with combination synthetic DMARDs, parasympathetic, and sudomotor dysfunction significantly (p < 0.05) improved in RA and AS. Biologic DMARDs significantly improved parasympathetic, sympathetic and peripheral sympathetic autonomic neuropathy (p < 0.05) in biologic-naive RA and AS patients. In conclusion, synthetic DMARDs improved parasympathetic and sudomotor dysfunction in both DMARD-naive RA and AS patients. However, biologic DMARDs improved parasympathetic, sympathetic and sudomotor dysfunction to a greater extent than synthetic DMARDs in both RA and AS patients.

Abnormal heart rate recovery on exercise in ankylosing spondylitis

OBJECTIVES

This study evaluated the heart rate recovery response in ankylosing spondylitis (AS) patients and control subjects.

BACKGROUND

Delayed heart rate recovery after exercise reflects AD and independently predicts adverse cardiac outcome.

METHODS

Fifty-one patients with AS and 50 age- and matched controls received electrocardiography, echocardiography, and treadmill exercise testing. The heart rate recovery (HRR) index was calculated as the reduction in heart rate from the rate at peak exercise to the rate at the 1st (HRR1), 2nd (HRR2), 3rd (HRR3) and 5th (HRR5) minute after the cessation of exercise stress testing.

RESULTS

There were significant differences in HRR1 and HRR2 indices between patients and controls (24.8 ± 12.1 vs 34.9 ± 11.0; p<0.001 and 41.2 ± 14.2 vs 54.3 ± 11.8; p<0.001, beats/min, respectively). Similarly, HRR3 and HRR5 indices were lower in patients than controls (51.3 ± 15.1 vs 65.2 ± 14.0; p<0.001 and 61.0 ± 14.2 vs 76.1 ± 14.8; p<0.001). In addition, exercise capacity was markedly lower (8.1 ± 2.0 vs 10.5 ± 2.5 METs; p<0.001) in AS than controls.

CONCLUSION

The HRR index is impaired in AS patients, implying the occurrence of autonomic dysfunction even without active joint disease or frank cardiac involvement.

Association between high sensitivity C-reactive protein, heart rate variability and corrected QT interval in patients with chronic inflammatory arthritis

BACKGROUND

The risk of sudden cardiac death is increased in chronic inflammatory arthritis, particularly rheumatoid arthritis (RA). To evaluate the putative effect of systemic inflammation on heart rate variability (HRV) and ventricular repolarization in chronic inflammatory arthritis, we analyzed in these patients the possible relationship among HRV parameters, QT interval, and high sensitivity C-reactive protein (hsCRP).

METHODS

One hundred-one patients with chronic inflammatory arthritis underwent a 15-minute ambulatory twelve-channel electrocardiogram-recording, to evaluate HRV and QT interval, as well as a venous withdrawal for hsCRP as an estimation of ongoing systemic inflammation.

RESULTS

In patients with chronic inflammatory arthritis, hsCRP is inversely correlated with HRV and directly with QTc duration, but while hsCRP is associated with HRV independently from any other investigated factor, the association between hsCRP and QTc seems to be an indirect consequence of the autonomic dysfunction itself. Within the whole cohort of patients, those subjects having elevated hsCRP levels displayed both a significant reduction in HRV and a prolongation of QTc with respect to patients with a normal hsCRP value. A similar, although less marked, degree of HRV depression and QTc prolongation was found in RA patients when compared to subjects with spondyloarthritis (SpA) and healthy controls.

CONCLUSIONS

These data provide evidence of a link between systemic inflammation and the arrhythmic risk in patients with chronic inflammatory arthritis, also putatively explaining, at least in part, how the different inflammatory load characterizing RA and SpA parallels the different risks of cardiovascular death in these two conditions.

Autonomic dysfunction in psoriatic arthritis

Autonomic nervous system (ANS) involvement has been studied in systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, Sjogren's syndrome, and ankylosing spondylitis but still has not been studied in psoriatic arthritis (PsA). The aim of this study was to investigate the prevalence and the nature of autonomic neuropathy in patients with PsA. Sixteen patients of PsA and 15 age and sex matched control subjects were studied prospectively using a battery of noninvasive tests. Cardiovascular autonomic neuropathy (CAN) was diagnosed by applying four cardiovascular reflex tests, and peripheral sympathetic autonomic function was assessed by Sudoscan. Patients with PsA had significantly higher heart rate response to standing (p = 0.01), blood pressure response to standing (p = 0.02), and Sudoscan (p = 0.01) when compared with healthy controls. Fifty percent (n = 8) of the patients with PsA had at least two or more abnormal CAN parasympathetic dysfunction; of these, 18.75% (n = 3) of the patients had abnormal parasympathetic and sympathetic dysfunction, 68.7% (n = 11) and 25% (n = 4) of the patients had at least one abnormal parasympathetic and sympathetic parameters, respectively, and 37.5% (n = 6) of the patients had moderate sudomotor dysfunction. About 18.7% (n = 3) of our parasympathetic dysfunction patients had autonomic symptoms. None of healthy volunteers had abnormal ANS dysfunction. Heart rate response significantly correlated with erythrocyte sedimentation rate (p < 0.05) and C-reactive protein (p < 0.05) levels. In conclusion, cardiovascular autonomic and peripheral sympathetic neuropathy occurs in PsA. Parasympathetic function is more commonly found to be abnormal than sympathetic function. There is no correlation of peripheral sympathetic dysfunction with cardiovascular autonomic neuropathy.

The subclinic autonomic dysfunction in patients with Behçet disease: an electrophysiological study

Studies that have evaluated autonomic nervous system (ANS) function in Behçet disease (BD) are rare and have indicated conflicting results with different degrees of involvement. The aim of this study was to investigate ANS function by using electrophysiological tests in patients with BD and to determine the relationship between the disease activity parameters and the indicators of autonomic activity. We included 70 BD patients and 50 healthy controls. Demographic characteristics including age, sex, and disease duration were recorded. A detailed neurological examination was performed, and clinical autonomic symptoms were recorded. The Behçet Disease Current Activity Form (BDCAF) was used to determine the disease activity. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were determined for laboratory activity. The electrophysiological assessments of ANS function were performed by sympathetic skin response (SSR) and R-R interval variation (RRIV) tests. The mean values of sympathetic (SSR latency and amplitude) and parasympathetic (RRIV at rest [R%] and deep breathing [D%], D% - R%, and D%/R%) parameters were compared, and any correlations between ANS parameters and clinical disease characteristics were determined. Seventy BD patients (23 males, 47 females) with a mean age of 41.2 ± 10.01 years and 50 control subjects (18 males, 32 females) with a mean age of 39.5 ± 8.94 years were included in the study. All the subjects were totally symptom free with respect to ANS involvement, and the subjects in both groups had normal neurological examination findings. The demographic characteristics were similar between the groups. The mean latency of SSR was increased (1.4 ± 0.4 vs 0.7 ± 0.8), and R% (0.3 ± 0.3 vs 0.5 ± 0.4) and D% (0.3 ± 0.3 vs 0.6 ± 0.5) values were decreased in BD patients compared to control subjects. No correlation was found between BDCAF scores and ANS variables. However, there was a significant correlation between SSR latency and ESR and CRP values (p < 0.01, r = -0.25, r = -0.31, respectively) in the patient group, indicating a more sympathetic dysautonomia in patients with active laboratory parameters. In conclusion, our study indicates a subclinical sympathetic and parasympathetic autonomic dysfunction in patients with BD, which may be related with disease activity. As the early recognition of abnormalities in ANS may be very important in order to prevent excessive morbidity, simple electrophysiological methods are suggested to identify Behçet patients at high risk for symptomatic dysautonomia.