ABSTRACT
The cardiovascular autonomic neuropathy (CAN) is a known complication of long standing diabetes. In the present study, the prevalence of sympathetic and parasympathetic abnormalities in diabetic patients was evaluated on retrospective analysis of standard tests done for the assessment of CAN. Three different scoring systems were utilized for assessment of CAN namely, Ewing’s crtieria, Bellavere’s criteria and the criteria followed at the Autonomic Function Test laboratory. All the three criteria use different set of tests for classification. A total of 124 patients’ laboratory data was analysed. The abnormality of single test ranged from 6.49% in Valsalva Maneuver to 47.41% in cold pressor test. When Bellavere’s criteria was used only 53 patients had evidence of CAN while Ewing’s criteria revealed that 100 patients had CAN however 69 of these patients could not be categorized. The criteria used by AFT laboratory revealed that isolated sympathetic (49 patients) and paraysmpathetic (10 patients) abnormality can be seen in CAN along with those with combined deficits (42 patients). If the Bellavere’s criteria is used then patients with dominant sympathetic neuropathy are likely to be missed during testing. High prevalence of CAN in tertiary care referral centre suggests that the testing of autonomic functions in diabetics should be done routinely. It is recommended that full battery of test to evaluate both the arms of autonomic drive namely sympathetic and parasympathetic should be done and reported as such.
ABSTRACT
Background & objectives: Patients of orthostatic hypotension may or may not have symptoms of the cerebral hypoperfusion despite fall in the blood pressure. The present study was done to quantify autonomic functions and cerebral autoregulation in patients of orthostatic hypotension with or without symptoms. Methods: The study was conducted in 15 patients of orthostatic hypotension and 15 age, sex matched control subjects. The sympathetic reactivity was measured by diastolic blood pressure response to handgrip test (ΔDBP in HGT) and cold pressor test (ΔDBP in CPT). The parasympathetic reactivity was measured by E:I ratio during deep breathing test (DBT) and Valsalva ratio (VR) during Valsalva maneuver. The cerebral autoregulation was computed from the changes in the cerebral blood flow, cerebrovascular conductance and blood pressure measured during different time points during head-up tilt (HUT). Results: The sympathetic reactivity was lower in patients as compared to controls [ΔDBP in HGT: 10 (4 - 16) vs 18 (12 - 22) mmHg, P<0.01; ΔDBP in CPT : 10 (4-12) vs 16 (10-20) mmHg, P<0.01]. The parasympathetic reactivity was also lower in patients as compared to controls. The sympathetic and parasympathetic reactivity was comparable in the symptomatic and asymptomatic patients. The maximum fall in blood pressure during HUT was comparable between symptomatic and asymptomatic patients (29.14 ± 10.94 vs 29.50 ± 6.39 mmHg), however, the percentage fall in the cerebral blood flow was significantly higher in the symptomatic (P<0.05) compared to asymptomatics. Interpretation & conclusions: Patients with orthostatic hypotension had deficits in sympathetic and parasympathetic control of cardiovascular system. Cerebral autoregulation was present in asymptomatic patients (increase in cerebrovascular conductance) during HUT while it was lost in symptomatic patients.