Electrophysiological Characteristics of Autonomic Nervous System Function in Post-Stroke Patients

OBJECTIVE: To evaluate the autonomic nervous function in post-stroke patients. METHOD: A total of 58 subjects, 34 post-stroke patients (mean age of 61.35 years) and 24 healthy subjects (mean age of 34.42 years) were included. The sympathetic skin response (SSR), the R-R interval variation (RRIV) and orthostatic hypotension (OH) were evaluated. Bilateral sympathetic skin responses were recorded on the palm and sole with stimulation of both median and tibial nerves. The obtained SSRs were divided into normal response and abnormal response including no response. The R-R interval variations were estimated during rest, deep breathing and Valsalva maneuver respectively. RESULTS: In all healthy subjects, obtained SSRs were of normal response. Although the rate of abnormal SSR was 75.4% (205 of 272 waves) in stroke patients, the rate of abnormal SSR on affected side (81.6%, 111 of 136 waves) was significantly higher than unaffected side (69.1%, 94 of 136 waves) (p0.05). The RRIV of stroke patients with OH (1.09+/-0.06) was significantly lower than in control (1.14+/-0.05) during rest (p<0.01), and in stroke patients without OH, the RRIV (1.13+/-0.06) was also significantly lower than in control (1.27+/-0.22) during Valsalva maneuver (p<0.01). CONCLUSION: Evaluation of SSR and RRIV could be helpful in detecting dysfunction of autonomic nervous system in post-stroke patients.

R-R interval variation in healthy subjects.

This study was performed to establish normal data for R-R interval variation in order to study parasympathetic heart rate control in subject with autonomic neuropathy. R-R interval variation or heart rate change was measured in 50 healthy subjects aged 16-53 (30.52 + 8.8) years using electromyographic equipment. The studies were performed at rest and deep breathing was 19.34 + 7.26 and 39.18 + 14.14 respectively. The difference between maximal and minimal heart rate at rest and deep breathing was 14.56 + 5.38 and 29.38 + 10.06 beat per minute respectively.

Assessment of Autonomic Function in Diabetic Patients

Dysfunction of the autonomic nervous system is reported to occur at an incidence of 20% to 40% in diabetes. The clinical symptoms include orthostatic hypotension, vomiting, diarrhea, bladder dysfunction, male impotence, sweating, etc. Two simple noninvasive tests, sympathetic skin response (SSR) and R-R interval variation (RRIV), were used to assess autonomic functions. We performed SSR and RRIV on the diabetic patients and controls. The patients were classified into 4 groups (group I: without peripheral neuropathy or dysautonomia, group II: with dysautonomia only, group III: with peripheral neuropathy only, group IV: with both peripheral neuropathy and dysautonomia). We also tried to correlate their clinical dysautonomic symptoms and the results of nerve conduction studies (NCS) and of SSR and RRIV. The subjects of this study were 82 diabetic patients, 20 to 73 years old with the mean age of 53, and 12 controls. Latency, amplitude, and loss of SSR all showed a significant difference in relation to the dysautonomic symptoms. The loss of SSR in the foot showed a remarkable difference in group I. In groups III and IV, three RRIVs (Valsalva ratio, E:I ratio, 30 : 15 ratio) showed a significant decrease compared with the control group, and in group II, only the 30:15 ratio showed a statistically significant decrease. In conclusion, the changes in SSR and RRIV were significantly associated with the dysautonomia. Among these, loss of SSR in the foot and decrease in the 30 : 15 ratio were useful parameters for early detection of diabetic autonomic neuropathy without peripheral neuropathy.