Abstract
Abstract: :
Purpose:The exact cause of increased choroidal hyperpermeability remains conjectural with type A personality being a well accepted risk factor. Since stress response is related to autonomic nervous system (ANS )activity, it is possible that CSCR is also related to abnormal responsiveness of the ANS regulating choroidal blood flow. In this case–control study we evaluated the autonomic activity and reactivity [both sympathetic (SNS ) and parasympathetic (PNS)] in patients with CSCR. Methods:Autonomic function tests (AFT) in the form of SNS and PNS activity (tone) and reactivity to various stimuli were evaluated in 28 patients (mean age 36±5 yrs) with active CSCR and compared with 18 healthy controls (33± 4 yrs). Resting PNS and SNS activity was evaluated by heart rate variability (HRV) analysis. Reactivity was studied using standard AFT protocols (Deep breathing test DBT, Cold pressure test CPT, Head up tilt test HUT, Cold face test CFT, Hand grip test HGT). Results:Parameters denoting PNS activity derived from HRV were decreased while that denoting SNS activity elevated, in patients with CSCR. Comparative values for CSCR vs controls respectively including p–value are given below. For PNS activity the values were HF (36±17 vs. 50±17; p= 0.01), range (median 187{80–2388} vs. 360{138–3200}; p= 0.002), coefficient of variance (median 3.8{1.8–15.5} vs. 6.07{3.0–25.6}; p = 0.01), and SDSD (median 19.1{7.3–122.6} vs. 35.5{19.5–194.4}; p = 0.001), NN50 (median 3{0–69} vs. 16{4–120}; p = 0.0004). Increased SNS activity in CSCR was evident by their high LF value (mean 54±16 vs. 45±16; p = 0.06) and increased resting diastolic BP (mm Hg) (mean 83.6±9.7 vs. 76.8±9.8; p=0.02). PNS reactivity was decreased in CSCR patients as evidenced by their lower E:I ratio (R–R interval in expiration : inspiration in DBT) (mean 1.33±0.16 vs. 1.40±0.16; p = 0.001). SNS reactivity also showed lower rise of both systolic (median 9.0 {2–20} vs. 14 {6–24}; p = 0.004) and diastolic BP (median10{0–26} vs 18{0–40} p = 0.0009) in CPT. The LF/HF ratio, which denotes sympathetic–parasympathetic balance, also revealed significantly higher values (median 1.61{1.6–9.17} vs. 0.99{0.2–2.8}; p = 0.03). Conclusions:Patients with CSCR have higher resting sympathetic tone and lower parasympathetic tone. In addition, both their sympathetic and parasympathetic reactivity is low. Such autonomic imbalances may explain the increased predisposition to choroidal hyperpermeability and neurosensory detachment in these patients.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • macula/fovea • stress response