Electrophysiological investigation for autonomic dysfunction in patients with myasthenia gravis: A prospective study.

BACKGROUND AND PURPOSE: Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. Autonomic dysfunction is not a commonly known association with MG. We conducted this study to evaluate autonomic functions in MG & subgroups and to investigate the effects of acetylcholinesterase inhibitors. METHODS: This study comprised 30 autoimmune MG patients and 30 healthy volunteers. Autonomic tests including sympathetic skin response (SSR) and R-R interval variation analysis (RRIV) was carried out. The tests were performed two times for patients who were under acetylcholinesterase inhibitors during the current assessment. RESULTS: The RRIV rise during hyperventilation was better (p=0.006) and Valsalva ratio (p=0.039) was lower in control group. The SSR amplitudes were lower thereafter drug intake (p=0.030). As much as time went by after drug administration prolonged SSR latencies were obtained (p=0.043).Valsalva ratio was lower in the AchR antibody negative group (p=0.033). CONCLUSION: The findings showed that both ocular/generalized MG patients have a subclinical parasympathetic abnormality prominent in the AchR antibody negative group and pyridostigmine has a peripheral sympathetic cholinergic noncumulative effect.

Autonomic dysfunction in patients with essential tremor.

The aim of this study was to evaluate the autonomic function in patients with essential tremor (ET). Thirty-one adult patients with ET and 26 healthy controls were enrolled in the study. The electrophysiological evaluations of the autonomic nervous system function were performed by sympathetic skin response (SSR) and R-R interval variation (RRIV) tests. The mean latency of SSR in ET patients was significantly delayed compared with the controls (P = 0.01). The mean amplitude of sympathetic skin response was significantly lower in ET patients in comparison to the controls (P = 0.001). No differences were found in mean RRIV values in both group subjects. Sympathetic dysfunction may occur in patients with ET. This may be easily demonstrated by SSR tests.

Evaluation of interictal autonomic function during attack and remission periods in cluster headaches.

OBJECTIVE: To investigate which part of the autonomic system is mainly involved and assess the sensitivity of face sympathetic skin response in cluster headache. MATERIAL AND METHODS: The study sample consisted of 19 drug-free cluster headache patients (16 males, three females) and 19 healthy volunteers. Demographic features and pain characteristics were thoroughly identified. Dysautonomic symptoms were evaluated during attack and remission periods of cluster headache patients. Orthostatic hypotension, R-R interval variation and sympathetic skin responses obtained from the face and four extremities were evaluated and the sensitivity of face sympathetic skin responses was assessed in contrast to extremity sympathetic skin responses. RESULTS: All sympathetic skin responses of face and extremities could be obtained during attack and remission periods. On the symptomatic side, mean latency of face sympathetic skin responses was longer compared to the asymptomatic side and controls (p = 0.02, p = 0.004). There were no differences in latency or amplitude of extremity sympathetic skin responses between symptomatic and asymptomatic sides and controls. No significant relationship was determined between sympathetic skin responses, R-R interval variation, orthostatic hypotension and cluster headache clinical features. CONCLUSION: Sympathetic hypoactivity of the face seems to predominate the pathophysiology of cluster headache. Face sympathetic skin responses might be more sensitive compared to extremity sympathetic skin response in demonstrating dysautonomic symptoms in cluster headache patients.

Prediction of bortezomib-induced peripheral neuropathy with the R-R interval variation of the electrocardiogram in plasma cell myeloma: a retrospective study.

Bortezomib-induced peripheral neuropathy (BIPN) is a key dose-limiting toxicity in patients with plasma cell myeloma (PCM). This study examined 56 patients with PCM treated with bortezomib to determine the possible predisposing factors to BIPN with the R-R interval variation (RRIV) of the electrocardiogram (ECG). Of all, 17 patients developed Clinically obvious BIPN, grades 2-4 or grade worsening from the baseline neuropathy per the National Cancer Institute's Common Terminology Criteria for Adverse Events (v5.0). In the receiver operating characteristic curve analysis, the optimal RRIV cutoff value to distinguish patients with and without risk to develop BIPN was 1.391. A lower RRIV before bortezomib treatment independently correlated with the onset of Clinically obvious BIPN (p = .002) and the time to the onset of Clinically obvious BIPN (p < 0.001). A lower RRIV of the ECG before the bortezomib treatment is a predictive factor for BIPN in PCM.

Autonomic dysfunction in patients with polycystic ovary syndrome.

OBJECTIVE: To assess the autonomic system in patients with polycystic ovary syndrome (PCOS). MATERIALS AND METHODS: Thirty-seven adult patients with PCOS and 33 healthy controls were enrolled in the study. The electrophysiological assessments of the autonomic nervous system function were performed using sympathetic skin response and R-R interval variation tests. RESULTS: The mean latency of sympathetic skin response in PCOS patients was significantly delayed compared with the controls (p = 0.001). The mean amplitude of sympathetic skin response was significantly lower in comparison with the controls (p = 0.01). Mean R-R interval variation during deep breathing was also significantly delayed (p = 0.04). CONCLUSION: There are parasympathetic dysfunction and sympathetic dysfunction in patients with PCOS. This may be easily demonstrated with sympathetic skin response and R-R interval variation tests.

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.

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.