Sympathetic skin response and heart rate variability in patients with Huntington disease.

OBJECTIVE: To examine the autonomic nervous system functions in patients with Huntington disease. BACKGROUND: Although patients with Huntington disease frequently experience vegetative symptoms, it is not clear if there is dysfunction of the autonomic nervous system. METHODS: Sympathetic skin response (SSR) latency and amplitude from both palms and soles and R-R (heart rate) interval variation (RRIV) at rest and during the Valsalva maneuver were examined in 22 patients and 21 age-matched controls. Unified Huntington's Disease Rating Scale scores were determined in all the patients. RESULTS: Our data are reported as means +/- SEMs. The SSR latencies in patients (mean palm latency, 1835.8+/-110.7 milliseconds; mean sole latency, 2625.3+/-226.9 milliseconds) were prolonged compared with controls (mean palm latency, 1359.5+/-28 milliseconds [P<.01]); mean sole latency, 2038.1+/-44.9 milliseconds [P<.01]) and amplitudes in patients (mean amplitude, 1063.1+/-237.7 microV) were smaller compared with controls (mean amplitude, 1846.3+/-251.2 microV [P<.05]). The RRIV in patients both at rest (mean RRIV in patients, 3.7%+/-0.4% vs. controls, 9.7%+/-0.6% [P<.01]) and during the Valsalva maneuver (mean RRIV in patients, 6.3%+/-1.6% vs. controls, 14.5%+/-1.2% [P<.01]) was lower compared with controls. Furthermore, the prolonged SSR latencies, smaller amplitudes, and lower RRIV in patients compared with controls closely correlated with the various components of the Unified Huntington's Disease Rating Scale scores (total behavior score and SSR latency, R = 0.6 [P<.01]; total behavior score and SSR amplitude, R = -0.5 [P<.05]; total behavior score and RRIV, R = -0.4 [P<.05]; verbal fluency and SSR latency, R = -0.5 [P<.05]; verbal fluency and SSR amplitude, R = 0.5 [P<.05], verbal fluency and RRIV, R = 0.5 [P<.05]; total functional capacity and SSR latency, R = -0.6 [P<.01]; total functional capacity and SSR amplitude, R = 0.5 [P<.05]). CONCLUSION: These results suggest that there is autonomic nervous system dysfunction in patients with Huntington disease.     

Supression of cardiac parasympathetic functions in patients with right hemispheric stroke

OBJECTIVES: The aim of this study was to investigate the relationship between sympathetic and cardiac parasympathetic function and the side of the lesion in stroke patients. METHODS: Thirty-two patients with stroke and 29 healthy age-matched control subjects were studied. Sympathetic skin responses (SSR) and RR interval variations (RRIV) during rest and deep breathing were recorded for the assessment of sympathetic and vagal parasympathetic function, respectively. RESULTS: The mean SSR amplitude values in patients compared with controls were 337 +/- 244 versus 1897 +/- 848 (P < 0.0001) for right hemispheric lesions and 466 +/- 398 versus 1873 +/- 843 (P < 0.0001) for left hemispheric lesions. The mean SSR latencies in patients compared with controls were 1526 +/- 163 versus 1395 +/- 109 (P < 0.05) for right hemispheric lesions and 1490 +/- 125 versus 1423 +/- 112 (P < 0.05) for left hemispheric lesions. RRIV (during deep breathing)/RRIV (at rest) ratios in patients compared with controls were 1.20 +/- 0.25 versus 1.84 +/- 0. 52 (P < 0.0001), and 1.55 +/- 0.88 versus 1.84 +/- 0.52 (P < 0.05) for right and left hemispheric lesions, respectively. CONCLUSION: Supression of vagal parasympathetic activity was more apparent in stroke patients with right hemispheric lesions in our series. Therefore, the right hemisphere seems to have a greater effect upon parasympathetic activity.     

Effects of epilepsy on autonomic nervous system and respiratory function tests

We have investigated autonomic nervous system function during the interictal period in epileptic patients and the possible effects of autonomic dysfunction on respiratory functions. A total of 32 epileptic patients (23 generalized, 9 partial epilepsy) and 32 healthy volunteers were involved. Sympathetic skin response (SSR), for evaluating the sympathetic nervous system, and RR interval variation (RRIV) were measured at the beginning and third month of antiepileptic treatment, and respiratory function tests (RFTs) were performed. In patients with partial epilepsy, SSR latency in the upper extremity (1.3+/-0.2 s) was longer than that of controls (1.2+/-0.3 s) at baseline (P=0.05), and was significantly reduced (1.1+/-0.3 s) after treatment (P<0.05). RRIV values of patients with generalized epilepsy were statistically significantly lower than those of controls (P<0.01). However, deep breathing RRIV values (32.6+/-15.3%) of patients were lower than those (43.0+/-18.2%) of controls (P<0.05). Sympathetic dysfunction was determined in patients with partial epilepsy and parasympathetic dysfunction in patients with generalized epilepsy. No abnormality was observed on RFTs for both patients with partial epilepsy and patients with generalized epilepsy.     

Normative data of sympathetic skin response and RR interval variation in Turkish children

Sympathetic skin response (SSR) and RR interval variation (RRIV) are used commonly for the assessment of sympathetic and parasympathetic nervous system function, respectively. We determined the normal values of SSR and RRIV in 23 (14 females, nine males) Turkish children aged 5 to 14 (mean 9.86, SD 2.48) years. SSR was recorded on the hands and feet during the electrical stimulation of both median and posterior tibial nerves, respectively. Similar response was elicited on both feet during the stimulation of the right median nerve. RRIV testing was performed during rest on the supine position and deep inspiration at a frequency of 6 times/min. The SSR was elicited in all children. The mean SSR latencies recorded on the feet during the stimulation of median or posterior tibial nerve were significantly more prolonged than those recorded at the hands (P < 0.001). There was no significant difference between the mean latencies of SSR recorded at the ipsilateral and contralateral palms or soles. The mean latencies recorded at the sole during stimulation of the median nerve were not significantly different compared to those that recorded at the sole during the posterior tibial nerve (P > 0.05). The SSR amplitudes were not assessed because of great variability and rapid habituation. The mean RRIV (46.54+/-11.29%) during deep breathing was significantly increased as compared to that (35.90+/-10.63%) during rest (P < 0.003). As a result, SSR and RRIV are preferred non-invasive tests for evaluation of autonomic nervous system in children. The SSR is useful and reliable if it is obtained in the optimum technical conditions. Further research is necessary to establish strict criteria for abnormality.     

Sympathetic skin response in monomelic amyotrophy

OBJECTIVES: Monomelic amyotrophy (MMA) a variant of motor neuron disease, has the characteristic features of wasting and weakness usually confined to a single upper or lower limb occurring predominantly in young males and a benign outcome. Symptoms of increased sweating, coldness and cyanosis have been observed in a few patients. The objective was to evaluate the involvement of the sympathetic nervous system in MMA by measuring sympathetic skin response. METHODS: Electromyography, motor and sensory nerve conduction studies were done in all the four limbs of 9 patients with atrophy of one upper limb. Stimulation at Erb's point, and above and below elbow was done to look for evidence of conduction block. The sympathetic skin response (SSR) was recorded in all the limbs of these patients. Wasting and weakness of right upper limb in 7 patients and left upper limb in 2 patients was seen. The mean age was 28.3+/-10.1 years. Twenty-five age matched (24.8+/-4.8 years) healthy subjects served as controls. RESULTS: The mean SSR latency in the affected upper limbs of 9 patients was prolonged compared to the 25 control subjects (1.51+/-0.07 s vs 1.42+/-0.19 s, P=0.03). The mean value of SSR latency in 18 upper limbs of the 9 patients which included atrophied and unatrophied limbs was also prolonged compared to the controls (1.50+/-0.08 s vs 1.42+/-0.19 s, P=0.05). There was no significant difference of the mean latency of SSR between the atrophied upper limbs and the clinically normal upper limbs (1.51+/-0.07 s vs 1.49+/-0.09 s, P=0.51). The mean SSR latency in the lower limbs of the patients (2.09+/-0.09 s) did not significantly differ from the control subjects (1.97+/-0.28 s, P=0.09). Motor and sensory nerve conduction was normal and there was no evidence of conduction block. CONCLUSION: In MMA the sympathetic nervous system is involved in the atrophic upper limb and also in the clinically unaffected upper limb but not in the lower limbs.     

Comparative neurophysiological study for the diagnosis of mild polyneuropathy in patients with diabetes mellitus and glucose intolerance

This article evaluates diagnostic sensitivity of minimal F-wave latency, sural/radial amplitude ratio (SRAR), dorsal sural/radial amplitude ratio (DSRAR), sympathetic skin response (SSR), and R-R interval variability (RRIV) for detecting early polyneuropathy in patients with glucose intolerance and diabetic patients. F-wave latencies were more prolonged in diabetic patients with normal and abnormal nerve conduction studies than control subjects (p < .001). SRAR was lower, SSR latency was more prolonged, and RRIV was lower in diabetic patients with abnormal nerve conduction studies than healty controls (p < .001). SSR latency was more prolonged and RRIV was lower in diabetic patients with normal nerve conduction studies than healty controls (p < .01, p < .05, respectively). DSRAR was lower in diabetic patients with normal and abnormal nerve conduction studies than control subjects (p < .001). DSRAR was also lower in patients with glucose intolerance than control subjects (p < .01). DSRAR was the most sensitive and specific test in either of diabetic patients with normal nerve conduction studies (sensitivity 66%, specificity 90%) and diabetic patients with abnormal nerve conduction studies (sensitivity 100%, specificity 90%). DSRAR is the most reliable method for detection of early nerve pathology. Patients with glucose intolerance might have subclinical neuropathy that can be demonstrated with DSRAR analysis.     

Diagnostic role of deep tendon reflex latency measurement in small-fiber neuropathy

Small-fiber neuropathy (SFN) is diagnosed on the basis of clinical features and specialized tests of small-fiber function because standard nerve conduction studies are normal. Thus, the objective of this study was to determine the value of deep tendon reflex (DTR) latency measurement in the diagnosis of SFN in patients with preserved DTR on clinical examination. We prospectively examined electromyographic reflexes from the biceps brachii [biceps brachii reflex (BR)], patellar [patellar reflex (PR)], and ankle [ankle reflex (AR)] using a manually operated electronic reflex hammer attached to electromyography machine and recorded by means of surface electrodes in 18 patients with SFN and 38 controls. Intra- and inter-evaluator reliability was good (intraclass correlation coefficient: 0.80-0.91, p < 0.01). In controls, the latencies at all sites were correlated to the height (R= 0.6, p < 0.01). Compared with controls, in patients with SFN, the mean latency in milliseconds was prolonged at all sites (BR: 12.8 +/- 1.6 vs. 8.9 +/- 1.9, p < 0.01; PR: 23.0 +/- 5.8 vs. 17.4 +/- 2.4, p < 0.01; and AR: 34.5 +/- 4.8 vs. 30.0 +/- 2.4, p < 0.01). The sensitivity [61.1% (95% CI: 51-94.9)] and specificity [92% (95% CI: 73-97.3)] of BR latency were roughly equal to those of PR and AR. We conclude that DTR latencies were significantly abnormal in the majority of the patients with SFN, suggestive of subclinical involvement of large myelinated fibers. DTR latency measurement is a reproducible, valuable, sensitive tool in the evaluation of mild subclinical involvement of large fibers.     

Clinical versus electrophysiological assessment of dysautonomia in obstructive sleep apnea syndrome.

To assess the autonomic system in obstructive sleep apnea syndrome (OSAS), the sympathetic skin response (SSR) and the R-R interval variation (RRIV) tests were studied in 34 OSAS patients and in 32 healthy controls. The aim of the study was to evaluate the sympathetic and parasympathetic system function in OSAS, to define the pattern of autonomic abnormalities found in SSR and RRIV in patients, and to analyze the usefulness of both tests in paraclinical assessment of the dysautonomia, compared with clinical symptoms and signs of autonomic nervous system involvement. The correlations between both autonomic tests results were also studied. In OSAS patients, SSR test results were abnormal in about 44% and RRIV results were abnormal in about 21% of patients. The mean values of parameters studied in SSR were significantly different in OSAS patients and controls (P < 0.05), whereas the differences between RRIV results were less important. The SSR and RRIV results in patients with mild apnea (Apnea/ Hypopnea Index (AHI) < 15) were more frequently within normal limits if compared with those of patients with severe apnea, but without reaching statistical significance. The clinical studies results (according to the Autonomic Symptoms Questionnaire) were related to the SSR results (p < 0.05 on chi and Fisher exact test). According to these results, SSR and RRIV are simple paraclinical electrophysiologic tests that confirm clinical dysautonomia. They may be useful as screening tests for assessment of dysautonomia in OSAS.     

Electrophysiological evaluation of peripheral and autonomic involvement in leprosy

OBJECTIVE: Motor and sensory nerve conductions, F responses, sympathetic skin responses and R-R interval variations (RRIV) were studied to determine the type of peripheral neuropathy among patients with leprosy. METHODS: Twenty-nine consecutive patients with leprosy (25 male, 4 female) hospitalized in the "Istanbul Leprosy Hospital" between January - December, 1999 were included in this study. Ten patients had borderline lepromatous leprosy, and 19 had lepromatous leprosy. None of the patients studied had the tuberculoid form. The mean age was 55 +/- 12 years. The control group consisted of 30 (26 male, 4 female) healthy volunteers (mean age: 58.1 +/- 7.8 years). All subjects included in the study underwent neurological examination and electrophysiological evaluation. Standard procedures were performed for evaluating sensory and motor conduction studies. Motor studies were carried out on both left and right median, ulnar, tibial and common peroneal nerves while median, ulnar, sural and superficial peroneal nerves were examined for sensory studies. Sympathetic skin response recordings on both hands and RRIV recordings on precordial region were done in order to evaluate the autonomic involvement. RESULTS: The lower extremity was found to be more severely affected than the upper, and sensory impairment predominated over motor. Of 58 upper limbs examined, no sympathetic skin responses was recorded in 46 (79.3%). Compared with the controls, the RRIVs of the leprosy patients were found to be reduced during both resting and deep forced hyperventilation. CONCLUSION: Our results indicate that leprosy causes a predominantly axonal polyneuropathy that is more severe in the lower extremities. Sensory nerve damage is accompanied by autonomic involvement.     

Pattern electroretinography and visual evoked potentials in optic nerve diseases.

BACKGROUND: To evaluate transient pattern electroretinography (PERG) and pattern visual evoked potential (VEP) for the diagnosis, differential diagnosis and follow-up of optic nerve diseases. METHODS: Twenty-nine consecutive patients (14 female, 15 male) with the diagnosis of ischaemic optic neuropathy (n=14) and optic neuritis (n=15) were included in this study. Mean age of the patients with ischaemic optic neuropathy was 63.3+/-3.3 (60-78) years and the mean age of the patients with optic neuritis was 28.3+/-8.4 (19-43) years. In each patient ophthalmological examination and systemic evaluation were done and VEP and PERG were recorded. As a control group, VEP recordings of 35 healthy subjects were included. RESULTS: In the ischaemic optic neuropathy group (group 1), mean VEP amplitude (+/-SD) (1.96+/-0.95 microV) was found to be decreased significantly in the affected eyes in comparison to the control group and the unaffected eyes. The delay in latency (116.3+/-20.14 msec in the affected eyes compared with 101.31+/-6.19 msec in unaffected eyes) was statistically significant when compared with the healthy subjects. In the optic neuritis group (group 2), VEP amplitude was decreased (4.13+/-4.04 microV vs 6.97+/-3.35 microV and 6.97+/-4.43 microV) and latency was increased (122.59+/-20.09 msec vs 101.31+/-6.19 msec and 108.76+/-13.57 msec) in affected eyes significantly in comparison to the unaffected eyes and control group, respectively. Even though there were no significant differences for P50 latency and N95/P50 ratios between affected and unaffected eyes in both groups, N95 amplitude decreased significantly in the affected eyes of the ischaemic optic neuropathy patients and N95 latency was found to be decreased in optic neuritis patients. There was no correlation between VEP and PERG findings in both groups. CONCLUSION: VEP amplitude decreased significantly in ischaemic optic neuropathies while latency delay was more significant in patients with optic neuritis. PERG findings showed decreased N95 amplitude in ischemic optic neuropathy without associated latency changes.     

COMPARATIVE NEUROPHYSIOLOGICAL STUDY FOR THE DIAGNOSIS OF MILD POLYNEUROPATHY IN PATIENTS WITH DIABETES MELLITUS AND GLUCOSE INTOLERANCE

This article evaluates diagnostic sensitivity of minimal F-wave latency, sural/radial amplitude ratio (SRAR), dorsal sural/radial amplitude ratio (DSRAR), sympathetic skin response (SSR), and R-R interval variability (RRIV) for detecting early polyneuropathy in patients with glucose intolerance and diabetic patients. F-wave latencies were more prolonged in diabetic patients with normal and abnormal nerve conduction studies than control subjects (p < .001). SRAR was lower, SSR latency was more prolonged, and RRIV was lower in diabetic patients with abnormal nerve conduction studies than healty controls (p < .001). SSR latency was more prolonged and RRIV was lower in diabetic patients with normal nerve conduction studies than healty controls (p < .01, p < .05, respectively). DSRAR was lower in diabetic patients with normal and abnormal nerve conduction studies than control subjects (p < .001). DSRAR was also lower in patients with glucose intolerance than control subjects (p < .01). DSRAR was the most sensitive and specific test in either of diabetic patients with normal nerve conduction studies (sensitivity 66%, specificity 90%) and diabetic patients with abnormal nerve conduction studies (sensitivity 100%, specificity 90%). DSRAR is the most reliable method for detection of early nerve pathology. Patients with glucose intolerance might have subclinical neuropathy that can be demonstrated with DSRAR analysis.     

Nerve conduction studies,electromyography and sympathetic skin response in Fabry's disease

We prospectively performed neurophysiologic studies in nine Fabry's Disease (FD) patients (8 male and 1 female) in order to describe the results of nerve conduction studies (NCS) and electromyography (EMG) and to verify whether the sympathetic skin response (SSR) is impaired in these patients. The investigation protocol included SSR, sensory and motor NCS and EMG. SSR was performed not only in FD patients, but also in 18 normal controls. All FD patients had normal nerve conduction studies and electromyography. SSR was present in all controls with a mean amplitude of 1453.6+/-682.3 microV. However, the SSR was absent in six and lower than 500 microV in the remaining FD patients. All patients had normal sensory and motor NCS and EMG. SSR, on the other hand, was significantly altered in all patients and this test could, therefore, be useful in the diagnostic evaluation of FD patients.     

Study of visual evoked potentials in the assessment of the central optic pathways in leprosy patients

Abstract. We evaluated the possible involvement of central optic pathways (COP) in leprosy patients with visual evoked potentials, an easy, sensitive and reliable noninvasive method for evaluation of COP. In 37 patients with lepromatous leprosy and in 37 age-matched controls, we measured reversal pattern visual evoked potentials (RP-VEP) and nerve conduction parameters. The mean latency value of positive peak P100 in leprosy patients was significantly delayed compared to that of controls (patients, 108.02±9.61 ms in left eye and 108.23±8.51 ms in right eye; controls, 96.22±4.20 ms in left eye and 95.75±4.03 ms in right eye; p<0.05). Abnormally delayed P100 latency was recorded in 5 of 37 leprosy patients (13.5%). The mean amplitude of P100 latency in leprosy patients was smaller than that of controls (patients, 8.7±5.6 µV in left eye and 9.5±4.8 µV in right eye; controls, 10.7±4.6 µV in left eye and 10.5±5.1 µV in right eye), but this difference was not significant. No correlation was observed between abnormalities of RP-VEP and sensorimotor nerve conduction parameters. This study suggests that involvement of COP may develop in patients with lepromatous leprosy. RP-VEP measurement, which can be easily and rapidly performed in an EMG laboratory using standard equipment, can show these alterations.     

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.     

帕金森病交感神经皮肤反应的临床研究

目的 探讨交感神经皮肤反应(SSR)对帕金森病自主神经功能障碍的诊断价值.方法 对解放军第一○二医院神经内科自2006年7月至2008年8月门诊或住院的47例帕金森病患者及与之相匹配的20例健康人进行SSR检测,并对其中有自主神经功能障碍患者与无自主神经功能障碍患者的结果进行对比分析. 结果帕金森病患者与健康人相比,上肢潜伏期明显延长(1.55±0.18 vs 1.42±0.29),波幅明显降低(1.87±0.26 vs 2.56±1.47);下肢潜伏期明显延长(2.13±0.16vs 2.04±0.27),波幅明显降低(0.49±0.21 vs 0.76±0.39),差异均有统计学意义(P<0.05).有自主神经功能障碍患者与无自主神经功能障碍患者相比,上肢潜伏期明显延长(1.56 ± 0.17 vs 1.53 ± 0.15),波幅明显降低(1.75±0.21 vs 1.89±0.33);下肢潜伏期明显延长(2.17 ± 0.18 vs 2.08±0.24),波幅明显降低(0.46±0.20 vs 0.51±0.17),差异均有统计学意义(P<0.05). 结论 SSR检测结果与患者临床表现相一致,其对帕金森病患者的自主神经功能障碍有诊断价值.     

Sympathetic skin response and R–R interval variation in chronic uremic patients

Sympathetic skin response (SSR) and R–R interval variation (RRIV) were studied in 36 chronic, nondiabetic uremics to compare with their nerve conduction studies (NCS) and clinical dysautonomia. Abnormal SSR was noted in 5 (13.9%) patients, abnormal RRIV in 14 (38.9%), and abnormal NCS in 26 (72.2%). The patients were classified into three groups: group (GP) 1: “normal,” n = 21 (58.3%), normal RRIV and SSR; GP 2: “isolated parasympathetic dysfunction,” n = 10 (27.8%), abnormal RRIV and normal SSR; and GP 3: “sympathetic sudomotor dysfunction,” n = 5 (13.9%), abnormal SSR. A significant difference in age was found among the three groups (GP 3 > GP 2 > GP 1; P < 0.0001, ANOVA). After controlling the age factor, we still noted a tendency toward increasing NCS disturbances (distal latency and nerve conduction velocity of peroneal nerve; P < 0.05, multiple regression analysis) and frequencies of clinical autonomic symptoms (postural dizziness and impotence; P < 0.05, Mantel–Hanszel test) from GP 1 to GP 3. Patients with abnormal SSR (GP 3) displayed significantly higher frequencies of postural dizziness and impotence, indicating the relationship between an absence of SSR and clinical dysautonomia. © 1994 John Wiley & Sons, Inc.     

Influence of nocturnal hypoxemia on the function of the visual tract in the course of the obstructive sleep apnea syndrome

BACKGROUND AND PURPOSE: In patients with obstructive sleep apnea (OSA) syndrome the episodes of upper airway obstruction lead to hypoxemia during sleep. The aim of the study was to establish the influence of sleep hypoxemia on the function of the visual tract in OSA patients. MATERIAL AND METHODS: The latency and amplitude of wave P100 of visual evoked potentials have been studied in 35 patients with OSA syndrome (mean apnea index 48+/-19). The diagnosis of OSA was established on the basis of continuous recordings of the respiratory function during sleep with additional full polysomnography in 17 patients. RESULTS: Mean absolute latency of P100 was longer in OSA patients than in healthy controls (117.0+/-8.8 ms vs. 104.3+/-4.6 ms, p<0.001). The differences in the amplitude of P100 were not significant (5.9+/-2.6 mV in OSA patients and 7.62+/-3.04 mV in healthy persons). In 60% of patients the latency of P100 exceeded 118 ms; in this group of patients the mean SaO2 during sleep apneas was lower than in patients with normal P100 latency (46+/-15% vs. 69+/-10%, p<0.05). Full polysomnographic studies revealed that in patients with prolonged latencies as compared with patients with normal P100 latencies there were lower: minimal SaO2 during NREM sleep (63+/-12% vs. 78+/-8%, p<0.05), as well as mean and minimal SaO2 during REM sleep (53+/-15% vs. 80+/-5% and 46+/-15% vs. 69+/-10%, p<0.05), without differences in apnea index or apnea duration. CONCLUSIONS: In patients with OSA syndrome the electrophysiological abnormalities suggesting damage of the optical tract may develop probably as a consequence of profound sleep hypoxemia.     

Abnormal cerebral processing of oesophageal stimuli in patients with noncardiac chest pain (NCCP)

In noncardiac chest pain (NCCP), altered visceral perception may result from abnormal cerebral processing of sensory input rather than abnormalities of afferent pathways. However, the interactions between symptoms, autonomic function and oesophageal stimuli are poorly studied. Oesophageal stimulation elicits reproducible cortical evoked potentials [CEP] and modulates heart rate variability via vagal pathways, as visible on power spectrum analysis of heart rate variability [PS-HRV]. These methods are increasingly used to study the function of visceral afferent neural pathways in human. The aim of this study was to compare EP and PS-HRV during oesophageal stimuli in NCCP and controls. Twelve healthy volunteers (one female, 11 male; aged 24-51 years; mean 32 +/- 8 years), and eight NCCP patients (three female, five male; age range 26-58, mean 40.5 +/- 10 years) were studied. Electrical oesophageal stimulation (EOS; 200 microseconds, 0.2 Hz, 25 stimuli) was applied to the oesophageal wall 5 cm above the lower oesophageal sphincter (LOS), and perception thresholds (measured in mA) determined. EP responses were recorded using 22 standard electroencephalogram scalp electrodes. Autonomic activity was assessed using PS-HRV, before, during, and after oesophageal stimulation. Measured PS-HRV indices included high frequency (HF; 0. 15-0.5 Hz) and low frequency (LF; 0.06-0.15 Hz) power, respectively, assessing vagal and sympathetic activity, and the LF/HF ratio. EOS perception occurred at lower thresholds in NCCP than in controls (3. 6 +/- 1 vs. 7.8 +/- 2 mA, P < 0.05). EP amplitude was greater (13 +/- 2 vs. 6 +/- 1 microV, P < 0.0001), and latency longer in controls vs. NCCP (191 +/- 7 ms vs. 219 +/- 6 ms, P < 0.001). In NCCP, EOS decreased sympathetic outflow (low frequency peak on PS-HRV) and increased cardiovagal activity (high frequency peak, P < 0.02) to a significantly higher degree in comparison with controls. During EOS, heart rate decreased in NCCP from 68 vs. 62 beats min-1 (P < 0.003) but not in controls. In NCCP patients, EOS was perceived at lower intensities and was associated with a greater cardiovagal reflex response. EP responses associated with EOS were smaller in NCCP than in controls, suggesting that an increased perception of oesophageal stimuli results from an enhanced cerebral processing of visceral sensory input in NCCP, rather than from hyperalgesic responses in visceral afferent pathways.     

Peripheral autonomic surface potential. A quantitative technique for recording sympathetic conduction in man

Using EMG equipment with time locked recording and standard averaging facilities we were able to record a previously poorly defined skin potential. The potential, termed by us the peripheral autonomic surface potential (PASP), was recorded from the palmar surface of the hand and the plantar surface of the foot in 30 normal subjects. The PASP usually consisted of a biphasic potential with an initial negative and a later positive peak. It was elicited by randomly timed electrical stimuli over the median nerve at the wrist. The mean palmar PASP latency was 1.52 +/- 0.13 s and the mean plantar PASP latency was 2.07 +/- 0.16 s. The mean palmar and plantar PASP amplitudes were 479 +/- 105 microV and 101 +/- 40 microV, respectively. A mean sympathetic conduction velocity was calculated to be 1.28 +/- 0.18 m/s. In 5 normal subjects a similar technique was used to record a PASP from the volar surface of the left middle finger. Iontophoresis of atropine into the skin under the recording site abolished the PASP in all subjects. Palmar and plantar PASPs were recorded in 10 diabetic patients. The amplitudes (palmar 179 +/- 158 microV, plantar 17 +/- 16 microV) were significantly reduced compared to normals (P less than 0.001). Five patients with unilateral lumbar or cervical sympathectomy were studied. The PASP was absent or markedly reduced on the side of the sympathectomy in all patients.     

Are electrophysiological autonomic tests useful in the assessment of dysautonomia in Parkinson's disease?

To assess the autonomic system in Parkinson's disease (PD), the sympathetic skin response (SSR) and the R-R interval variation (RRIV) tests were studied in 26 PD patients and in 24 healthy controls. The aim of the study was to evaluate the sympathetic and parasympathetic system function in PD, to define the pattern of autonomic abnormalities found in SSR and RRIV in parkinsonian patients as well as to analyze the usefulness of both tests in paraclinical assessment of the dysautonomia, compared with clinical symptoms and signs of the autonomic nervous system involvement. The corrrelations between both autonomic tests results were also studied. In PD patients SSR test was abnormal in about 35% and RRIV was abnormal in about 54% of patients. SSR and RRIV were both abnormal in about 27% of PD patients whereas at least one of electrophysiological autonomic tests was abnormal in about 62% of PD patients. Clinical and paraclinical signs of dysautonomia occurred in a similar proportion of patients (i.e. in about 62%). A weak correlation was found between the latency of SSR from upper limbs and the value of RRIV during deep breathing (p=0.063). Our results show that SSR and RRIV are non-invasive paraclinical electrophysiological tests that confirm clinical dysautonomia in PD and can supplement the clinical differentiation of Parkinsonian syndromes.