Sympathetic skin response (SSR) is abnormal in multiple sclerosis

Peripheral nervous system electrodiagnostic abnormalities in predominantly Hispanic Multiple Sclerosis patients

BACKGROUND

Peripheral nervous system (PNS) abnormalities in Multiple Sclerosis (MS) have been reported in case reports and small case series over the past several decades. Little is known, however, about the prevalence of electrodiagnostic abnormalities in patients with MS, including not only demyelinating neuropathies such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but also axonal peripheral neuropathy and sympathetic dysfunction.

METHODS

This is an observational, cross-sectional study with the objective of identifying the prevalence of the electrodiagnostic abnormalities in predominantly Hispanic MS patients in Miami, Florida. Electrodiagnostic data including nerve conduction study (NCS), electromyography (EMG) and sympathetic skin response (SSR) information was prospectively collected in 18 patients (16 females; 43.7±15.2 years) with a diagnosis of MS compared to 18 healthy (16 females; 39.9±11 years), age- and height-matched controls. The study was offered to all-comers in the MS Clinic over a period of 3 months, regardless of clinical suspicion for an underlying neuropathic process, in an effort to estimate the prevalence of abnormalities. Demographic data including age, sex, race/ethnicity was evaluated in addition to MS-specific characteristics including MS subtype, duration of disease, duration of therapy, clinical symptoms and laboratory data.

RESULTS

There were no significant differences in baseline characteristics of patients and controls for age (p=0.4) and height (164.0±6.4 vs 162.3±4.6 centimeters; p=0.3). The mean disease duration was 106±27 months (median 107 months; range 5-336 months). The mean Expanded Disability Status Scale (EDSS) was 2.4±1.87 (median: 2.5; range 1.0-6.5). The ethnicity of patients (15 Hispanic, 3 non-Hispanic) and controls (13 Hispanic, 5 non-Hispanic; p=0.56) was similar. The frequency of electrophysiological axonal polyneuropathy (PN) was 77.8% (14/18 patients), and 85.6% of these patients had clinical sensory symptoms. Interestingly, 1 patient had previously unrecognized CIDP. All 18 patients displayed prolonged SSR latencies consistent with autonomic dysfunction. Thirteen patients (72.2%) reported autonomic symptoms such as bladder abnormalities and blood pressure fluctuations.

CONCLUSION

The prevalence of electrodiagnostic abnormalities, especially axonal polyneuropathy, in the MS population may be higher than traditionally considered. The relationship between axonal polyneuropathy and central axonopathy in the context of neurodegeneration in MS should be further explored. Analytic studies may identify common symptomatic and pathophysiologic etiologies to further understanding and potentially guide treatment of MS subtypes with PNS involvement.

Sudomotor Dysfunction

Disorders of sudomotor function are common and diverse in their presentations. Hyperhidrosis or hypohidrosis in generalized or regional neuroanatomical patterns can provide clues to neurologic localization and inform neurologic diagnosis. Conditions that impair sudomotor function include small fiber peripheral neuropathy, sudomotor neuropathy, myelopathy, α-synucleinopathies, autoimmune autonomic ganglionopathy, antibody-mediated hyperexcitability syndromes, and a host of medications. Particularly relevant to neurologic practice is the detection of postganglionic sudomotor deficits as a diagnostic marker of small fiber neuropathies. Extensive anhidrosis is important to recognize, as it not only correlates with symptoms of heat intolerance but may also place the patient at risk for heat stroke when under conditions of heat stress. Methods for assessing sudomotor dysfunction include the thermoregulatory sweat test, the quantitative sudomotor axon reflex test, silicone impressions, and the sympathetic skin response.

Immune and autonomic nervous system interactions in multiple sclerosis: clinical implications

Multiple sclerosis is characterized by a wide spectrum of clinical manifestations, among which dysfunction of the autonomic nervous system represents an important cause of multiple sclerosis-related disability. The aim of this review is to provide an overview of autonomic dysfunction in people with multiple sclerosis, and to discuss the interactions between the immune and autonomic nervous systems and the effects of these interactions on various aspects of multiple sclerosis. Autonomic dysfunction in people with multiple sclerosis can be demonstrated clinically and on a molecular level. Clinically, it can be demonstrated by measuring autonomic symptoms with the Composite Autonomic Symptom Score (COMPASS-31), and neurophysiologically, with different autonomic nervous system tests. Both symptomatic and objectively determined autonomic dysfunction can be associated with increased risk of multiple sclerosis disease activity. Further supporting these clinical observations are molecular changes in immune cells. Changes in the sympathetic autonomic system, such as different expression of dopaminergic and adrenergic receptors on immune cells, or modulation of the cholinergic anti-inflammatory pathway over different subunits of the nicotinic acetylcholine receptor in the peripheral immune system, may mediate different effects on multiple sclerosis disease activity.

Sympathetic skin response in multiple sclerosis: a meta-analysis of case-control studies

The usefulness of sympathetic skin responses (SSR) in multiple sclerosis (MS) has been advocated by several studies in the last 20 years; however, due to a great heterogeneity of findings, a comprehensive meta-analysis of case-control studies is in order to pinpoint consistencies and investigate the causes of discrepancies. We searched MEDLINE, EMBASE and Cochrane databases for case-control studies comparing SSR absence frequency and latency between patients with MS and healthy controls. Thirteen eligible studies including 415 MS patients and 331 healthy controls were identified. The pooled analysis showed that SSR can be always obtained in healthy controls while 34% of patients had absent SSRs in at least one limb (95% CI 22-47%; p < 0.0001) but with considerable heterogeneity across studies (I 2 = 90.3%). Patients' age explained 22% of the overall variability and positive correlations were found with Expanded Disability Status Scale and disease duration. The pooled mean difference of SSR latency showed a significant increase in patients on both upper (193 ms; 95% CI 120-270 ms) and lower (350 ms; 95% CI 190-510 ms) extremities. We tested the discriminatory value of SSR latency thresholds defined as the 95% confidence interval (CI) upper bound of the healthy controls, and validated the results on a new dataset. The lower limb threshold of 1.964 s produces the best results in terms of sensitivity 0.86, specificity 0.67, positive predicted value 0.75 and negative predicted value 0.80. Despite a considerable heterogeneity of findings, there is evidence that SSR is a useful tool in MS.

Autonomic Dysregulation in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, progressive central neurological disease characterized by inflammation and demyelination. In patients with MS, dysregulation of the autonomic nervous system may present with various clinical symptoms including sweating abnormalities, urinary dysfunction, orthostatic dysregulation, gastrointestinal symptoms, and sexual dysfunction. These autonomic disturbances reduce the quality of life of affected patients and constitute a clinical challenge to the physician due to variability of clinical presentation and inconsistent data on diagnosis and treatment. Early diagnosis and initiation of individualized interdisciplinary and multimodal strategies is beneficial in the management of autonomic dysfunction in MS. This review summarizes the current literature on the most prevalent aspects of autonomic dysfunction in MS and provides reference to underlying pathophysiological mechanisms as well as means of diagnosis and treatment.

Association of a deficit of arousal with fatigue in multiple sclerosis: effect of modafinil

Multiple sclerosis (MS) is a multifocal demyelinating disease of the central nervous system, leading to chronic disability. Fatigue is a common and distressing symptom of MS which is unrelated to its clinical form, stage of development, the degree of disability, or the lesion load on magnetic resonance imaging. Fatigue in MS is associated with excessive daytime sleepiness and autonomic dysfunction. Recently it has been reported that the wakefulness-promoting drug modafinil may relieve fatigue in MS patients and ameliorate the associated cognitive difficulties. However, it is not clear to what extent the anti-fatigue effect of modafinil may be related to its alerting and sympathetic activating effects. We addressed this question by comparing three groups of subjects, MS patients with fatigue, MS patients without fatigue and healthy controls, matched for age and sex, on measures of alertness (self-ratings on the Epworth and Stanford Sleepiness Scales and on a battery of visual analogue scales; critical flicker fusion frequency; Pupillographic Sleepiness Test; choice reaction time) and autonomic function (systolic and diastolic blood pressure, heart rate, pupil diameter), and by examining the effect of a single dose (200 mg) of modafinil on these measures. MS patients with fatigue, compared with healthy controls, had reduced level of alertness on all the tests used; MS patients without fatigue did not differ from healthy controls. MS patients with fatigue had a reduced level of cardiovascular sympathetic activation compared to the other two groups. Modafinil displayed alerting and sympathomimetic effects in all three groups of subjects. As fatigue in MS is associated with reduced levels of alertness and sympathetic activity, modafinil may exert its anti-fatigue effect in MS by correcting these deficiencies. The anti-fatigue effect of modafinil may reflect the activation of the noradrenergic locus coeruleus (LC), since there is evidence that this wakefulness-promoting nucleus is damaged in MS, and that modafinil, probably via the dopaminergic system, can stimulate the LC. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

The effects of heat and massage application on autonomic nervous system

PURPOSE

The objective of this study is to evaluate the effects of heat and massage application on autonomic nervous system.

MATERIALS AND METHODS

One hundred thirty-nine subjects volunteered and completed this study. Heat and massage was daily applied for 40 minutes, 5 days a week for 2 weeks. Primary-dependent measures included heart rate variability, sympathetic skin response, and serum cortisol and norepinephrine levels.

RESULTS

Serum cortisol levels were significantly decreased at 2 weeks compared to baseline (p=0.003). Plasma norepinephrine levels at 4 weeks were significantly decreased compared to baseline (p=0.010). Heart rate, using the power spectra, increased significantly after 2 weeks compared to baseline. Of autonomic nerve conduction measures, latency was significantly increased at 2 and 4 weeks compared to baseline (p=0.023, 0.012), and amplitude was significantly decreased at 4 weeks compared to baseline (p=0.008). There were no serious adverse events such as burns or other major complications.

CONCLUSION

The results of this study suggest that heat and massage applications provide relaxation to the autonomic nervous system without serious adverse events.

Autonomic disorders in multiple sclerosis

Multiple sclerosis is an inflammatory disease leading to disseminated lesions of the central nervous system resulting in both somatomotor and autonomic disturbances. These involve the central centers of the autonomic nervous system, as well as the automatic control and pathway systems. All autonomic functions may be disordered individually or in combined form. There is no other disease with a clinical picture so multifaceted. Besides cardiovascular dysfunctions disorders of bladder and rectum have become apparent. Somatomotor and autonomic disturbances occur with similar frequency; however the focused exam often heavily favors somatomotor symptoms. Autonomic disturbances should primarily be taken into account on history taking and clinical examination. Individual diagnosis and treatment is a secondary feature. Impairments of the autonomic nervous systems in multiple sclerosis are frequently overlooked.

Sudomotor dysfunction in patients with optic neuritis

OBJECTIVES

Optic neuritis (ON) is a frequent initial manifestation of multiple sclerosis (MS). Autonomic failure affecting the pupillary function is known to exist in ON patients, and patients with MS are known to have more widespread autonomic dysfunction. For example, sudomotor dysfunction is well known in MS. We carried out a study investigating sudomotor abnormalities in ON patients, and later followed these patients at risk of developing MS.

METHODS

Firstly, sudomotor function was measured by sympathetic skin responses (SSRs) in 13 ON patients and in 22 healthy controls. Secondly, thermoregulatory sweating was measured by an evaporimeter after a heating stimulus in 13 ON patients and in 14 healthy control subjects.

RESULTS

The SSR latencies to electrical stimuli in the ON patients were significantly prolonged in the upper and lower extremities (p = 0.013-0.002), indicating sudomotor dysfunction. No statistically significant thermoregulatory sweating dysfunction could be found in the ON patients compared to the controls. All ON patients underwent a follow-up (mean duration 12.5 years) during which eight ON patients (62%) converted to clinically definite MS. It seemed that SSRs had no value for identifying patients who later developed MS.

INTERPRETATION

Our results enlarge the knowledge of autonomic disorders in ON patients, showing that sudomotor function may also be involved.

Assessment of autonomic nervous system dysfunction in multiple sclerosis and association with clinical disability

Recent studies have reported autonomic dysfunction (AD) in multiple sclerosis (MS), and bladder and/or bowel dysfunction, orthostatic hypotension, and cardiac adaptation disorders have been observed in a wide range of patients (15-80%). The primary aim of this study is to investigate the frequency and association of AD in MS patients, assessed by sympathetic skin response (SSR) and a symptoms questionnaire. The secondary aims are to study the association of AD and disease disability assessed by expanded disability status scale (EDSS), as well as disease duration. One hundred clinically definite MS (CDMS) patients were evaluated for autonomic nervous system (ANS) dysfunction by use of an autonomic symptoms questionnaire and SSR testing. The relationship between these methods, AD and disease-related parameters, such as the expanded disability status scale (EDSS) and disease duration were all evaluated. Sixty-five per cent of the patients presented with AD and 29% of these patients had abnormal SSR results. MS patients with high EDSS values (EDSS>4) and longer disease duration were more likely to have ANS dysfunction (p<0.0001). ANS dysfunction is not uncommon in CDMS patients and thus non-invasive investigations of AD are warranted to optimize AD evaluation and disease management.

Sexual dysfunction and sympathetic skin response recorded from the genital region in women with multiple sclerosis

Multiple Sclerosis is known to cause autonomic and sexual dysfunction. However, genitourinary and sexual problems in female multiple sclerosis patients are difficult to analyse. Therefore, it is an understudied field. As an attempt to fill this gap, we evaluated genital region autonomic dysfunction of female multiple sclerosis patients by using genital sympathetic skin response. Forty female patients with definite multiple sclerosis and twenty healthy female controls were included in the study. We examined hand, foot and genital sympathetic skin responses. Some genitourinary parameters were questioned by and results were compared with genital sympathetic skin response results. Among multiple sclerosis patients 42.5% of them had genitourinary and 75% had sexual problems clinically. Sympathetic skin response pathologies were distributed as following: 22.5% in hand, 20% in the foot, and 50% in genital region in the patient group. A statistically significant correlation between sexual dysfunction and genital sympathetic skin response could not been found. It is found that patients with multiple sclerosis have higher genital sympathetic skin response abnormalities than foot and hand sympathetic skin response abnormalities. This might be the early sign of autonomic dysfuntion in multiple sclerosis patients. Genital sympathetic skin response may be an easy and objective method to apply and helpful to evaluate genitourinary dysfunction in women in conjunction with female sexual dysfuntion index. Multiple Sclerosis 2007; 13: 742-748. http://msj.sagepub.com

Autonomic dysfunction in multiple sclerosis

Multiple sclerosis (MS) is the most frequent chronic neurological disease affecting young persons in developed countries. MS is, however, considered as a secondary cause, of central origin, for autonomic dysfunction. The most common autonomic symptoms in MS are disorders of micturation, impotence, sudomotor and gastrointestinal disturbances, orthostatic intolerance as well as sleep disorders. The majority of the patients suffer at some period of the disease from lower urinary tract symptoms and sexual dysfunction. Awareness and treatment of these conditions is vital to improving health and quality of life in patients with MS. The increased understanding of the pathophysiological mechanisms in autonomic dysfunction in MS, along with technological and pharmaceutical developments has advanced our ability to treat the multiple aspects complicating autonomic failure in MS.

Measurement of autonomic dysregulation in multiple sclerosis

OBJECTIVE

Patients with definite multiple sclerosis (MS) were tested for autonomic nervous system (ANS) dysfunction using clinical symptomatology criteria and non-invasive laboratory testing. Exactly 45.45% of patients exhibited subjective symptoms of autonomic dysfunction and 42.42% of patients had abnormal laboratory tests results.

METHODS

The sympathetic ANS tests were abnormal in 30.3% of MS patients and the parasympathetic ANS tests were abnormal in 18.18% of MS patients. The most sensitive test for the presence of autonomic dysfunction was the sympathetic skin response.

CONCLUSION

Autonomic dysfunction was often subclinical and we conclude that it is preferable to combine several tests for a more thorough and accurate evaluation of the ANS impairment in MS.

Time and frequency domain analyses of heart rate variability in patients with epilepsy

Heart rate variability (HRV) is a useful tool for the detection of sympathetic-parasympathetic balance of autonomic nervous system in patients at risk of sudden death (SD). SD is more common in patients with epilepsy and the exact mechanisms of SD are unknown. Autonomic nervous system involvement in patients with epilepsy has rarely been studied and has shown conflicting results. Our purpose was to determine if HRV showed any changes in patients with epilepsy in comparison with normal population. A short period analysis of HRV was performed for both the frequency and time domain in 43 epilepsy patients who had generalized tonic-clonic seizures (GTCS) and who were not taking any medications and also in 43 age and sex matched controls. In the time domain analysis, patients displayed higher SDNN (standard deviation of all R-R intervals), SDANN (standard deviation of mean NN intervals in 5 min recordings) and HRV triangular index than did healthy subjects (p < 0.0001). Patients tended to display higher pNN50 (number of R-R intervals differed by > 50 ms from adjacent interval divided by the total number of all R-R intervals) and RMSSD (root-mean-square of successive differences) values than did healthy subjects, but the differences were not statistically significant (p > 0.05). In the frequency domain analysis, the spectral measures of HRV showed a reduction of high frequency (HF) values (is a marker of parasympathetic activity) and an increase of low frequency (LF) values (is a measure of sympathetic activity); as a result, the ratio between low and high frequencies (LF/HF) was significantly increased (p < 0.0001, p < 0.0001 and p < 0.001, respectively). Our data suggests an increase in the sympathetic control of the heart rate in epilepsy patients who have GTCS. This increased sympathetic activity could play a key role in the development of ventricular tachyarrhythmias in patients with epilepsy and may be related to the higher incidence of sudden death in this disorder as compared to controls.

Cardiovascular autonomic dysfunction correlates with brain MRI lesion load in MS

OBJECTIVE

The aim of the present study was to investigate the cardiovascular autonomic control in clinically definite multiple sclerosis (MS) patients with a standardised battery of cardiovascular tests and to correlate these findings with the brain magnetic resonance imaging (MRI) lesion load.

METHODS

Fifty-one patients with MS and 50 healthy controls were studied. Brain MRI was performed in all patients showing typical MS lesions. The cardiovascular tests were carried out using a standardised battery.

RESULTS

Heart rate (HR) responses to deep breathing (P < 0.05) and tilt table testing (P < 0.001) were significantly decreased in MS patients when compared to those of the controls. Blood pressure (BP) responses in the tilt table test were also impaired in MS patients (diastolic P < 0.001, systolic P < 0.05). Of the different brain areas investigated the total volume of the midbrain MRI lesions (P < 0.05) was the one most clearly associated with the impaired BP responses.

CONCLUSIONS

MS results in both reduced HR variation and decreased BP reactions indicating disturbed cardiovascular regulation. In particular, the midbrain lesions found in MS are associated with cardiovascular dysfunction.

Autonomic nervous system function in multiple sclerosis

Autonomic dysfunction causes significant disability in patients with multiple sclerosis (MS). Abnormalities of bladder, bowel and sexual function have been well documented in previous studies but cardiovascular and sudomotor autonomic changes have been less frequently reported. The present study has documented autonomic symptoms and results of cardiovascular and sudomotor autonomic function tests in 63 MS patients and correlated these changes with the clinical features of MS.Autonomic symptoms were common in MS patients, the most common being disorders of micturition, impotence, sudomotor and gastrointestinal disturbances, which were associated with increased MS severity. There was no significant association between autonomic symptoms and abnormalities of autonomic investigations. Abnormalities of one or more autonomic function tests, not including those of bladder, gastrointestinal or sexual dysfunction, were present in more than one half of the MS patients. Autonomic dysfunction, defined as abnormalities in two or more tests, was found in 18% of patients and was associated with increased MS severity. Postural hypotension was very uncommon. Parasympathetic cardiovascular autonomic abnormalities occurred in 16% of patients and were associated with increased MS severity. Sympathetic cardiovascular abnormalities were present in 13% of patients and showed no significant association with MS severity. The sympathetic skin response(SSR) was abnormal in nearly one half of the patients and also showed no significant association with MS severity. There was a variable and heterogenous pattern of autonomic test abnormalities found in the MS patients, which were of minor clinical significance except for postural hypotension. Cardiovascular and sudomotor autonomic abnormalities in MS patients are likely to be due to plaques distributed throughout the brainstem and spinal cord affecting anatomically widespread autonomic regulatory areas and their connections.

The roles of blink reflex and sympathetic skin response in multiple sclerosis diagnosis

The neurological history and examination are important in multiple sclerosis (MS) diagnosis, but early and accurate diagnosis of MS often requires judicious use of paraclinical information. Electrophysiologic techniques have an important role in demonstrating lesions that are clincally silent but magnetic resonance imaging (MRI) is accepted as the most sensitive paraclincal test for detecting asymptomatic dissemination in space for MS patients. In order to test the sensitivity of electrophysiologic techniques in diagnosing asymptomatic MS lesions, we performed blink reflex (BR) and sympathetic skin response (SSR) studies on 13 female (mean age 39 -/+ 9 years) and 8 male (mean age 35 -/+ 14 years) patients with a diagnosis of definite MS who do not have any clinical symptoms nor signs referable to brainstem or autonomic system dysfunction. Forty three percent of patients on SSR testing and 40% of patients on BR testing demonstrated abnormal results. In countries with unfavorable economic conditions, diagnosis, especially the follow-up evaluation of MS patients, poses a major dilemma. The role of diagnostic techniques in MS diagnosis when MRI is available is an economic problem. Diagnostic evaluation adds to the cost of health expenses. We usually choose to perform MRI only at the initial diagnosis of MS and perform follow-up evaluations during remissions and exacerbations with the aid of electrophysiologic techniques. We stress the importance of electrophysiologic screenings in MS patients because they provide data that cannot be obtained through clinical evaluations only with a little cost.

Power spectrum analysis of heart rate variability for cerebral palsy patients

OBJECTIVE

The prevalence of bowel and bladder dysfunction, hyperhidrosis, and poor cardiopulmonary endurance is higher for children with cerebral palsy than for the general population. The purpose of this study was to investigate the autonomic function for patients with cerebral palsy.

DESIGN

Thirty patients with cerebral palsy and 30 control subjects were enrolled in this study. Power spectrum analysis of heart rate variability was performed under standardized conditions.

RESULTS

In both the supine and head-up positions for test subjects, there was no significant difference for the low frequency component of heart rate variability, high frequency component of heart rate variability, or the low frequency/high frequency ratio between the study and control groups. A significantly greater low frequency component of heart rate variability, smaller high frequency component of heart rate variability, and greater low frequency/high frequency ratio while in the head-up position compared with the supine position was noted for the control group, which implies normal sympathovagal balance. A similar phenomenon was not observed for the study group.

CONCLUSIONS

The disturbed balance of activity between the sympathetic and parasympathetic nervous system observed in the study might result from the loss of hemispheric influence in patients with cerebral palsy; however, further investigation is clearly necessary.

Abnormalities of cardiac repolarization in multiple sclerosis: relationship with a model of allergic encephalomyelitis in rat

Ventricular repolarization was investigated for the first time in 48 multiple sclerosis (MS) patients using measurement of QTc interval on standard electrocardiographic recordings. The repolarization process was prolonged significantly in MS compared to control subjects (P = 0.0001). This result was confirmed with an animal model of MS, i.e., the experimental allergic encephalomyelitis in rat. The contribution of prolonged QT to syncopal attack or sudden cardiac death in MS patients need further investigation.

Autonomic involvement in multiple sclerosis: a pupillometric study

To study pupillary autonomic function in multiple sclerosis (MS), we examined 36 subjects with low disability, preserved visual acuity and no recent history (2 years) of optic neuritis or actual visual complaints. Compared to controls, MS patients showed a greater dilatator reaction with darkness and, for the light reflex, a lower amplitude and contraction rate and a greater recovery of pupillary diameter 5 s after the stimulus. Within the MS group, no difference was found comparing patients with or without the following characteristics: nuclear magnetic resonance imaging evidence of midbrain lesions; increased visual evoked potential P100 latency; and a previous history of optic neuritis. No correlation was found between P100 latency, duration of disease and pupillometric parameters. Our results indicate that in MS patients there is autonomic dysfunction with a reduction of parasympathetic tone and a relative increase in sympathetic dilatator tone to the pupils. We suggest that pupillary abnormalities could be due to non-specific impairment of the central pathways subserving pupil functions.

Electrophysiologic evaluation of autonomic function in cerebral palsy

The presence of clinical autonomic dysfunction in patients with neurologic diseases, such as multiple sclerosis, Parkinson's disease, and cerebrovascular accident, has become increasingly recognized in the past decade. Very few autonomic tests have been done on pediatric patients thus far. The purpose of this study was to investigate the autonomic function in patients with cerebral palsy using two noninvasive tests: sympathetic skin response (SSR) and R-R interval variation (RRIV). Twenty-four patients with cerebral palsy and 24 control subjects between the ages of 4 and 12 yr were enrolled in this study. There was no significant difference of mean latency, amplitude, or amplitude ratio of SSR between the two groups under electric stimulus, startling stimulus, and deep breathing conditions. No significant difference in frequency of absent response and asymmetric response was also noted. Mean heart rate under relaxed sitting condition was significantly higher in the study group. Significant negative correlation between heart rate and age was noted in the control group but was not present in the study group. Also, there was no statistical difference of mean RRIV between the two groups. No objective evidence of autonomic disturbance in patients with cerebral palsy was found in this study.

Autonomic evaluation by means of standard tests and power spectral analysis in multiple sclerosis

Standard autonomic tests [heart rate response to deep breathing (HRDB), change in systolic blood pressure due to tilt], and spectral analysis of heart rate (HR), arterial blood pressure (ABP), and the associated transfer function analysis (gains and phases) were performed in 20 patients with multiple sclerosis to determine their diagnostic value. Transfer function analysis suggested impairment of baroreflex function in 7 patients and an alteration of cardiorespiratory coupling on a brain stem level in 4 patients. In addition, sympathetic vasomotor outflow was reduced in 2 patients (spectral ABP measures in the mid frequency band) and a decrease of vagal outflow was suggested by abnormal respiratory HR parameters in another 2 patients. An abnormal HRDB was present in 5 patients and was probably due to a central alteration (cardiorespiratory coupling) in 2 patients and due to diminished respiratory effort in 1 patient. Spectral analysis of both HR and ABP oscillations and their transfer function may considerably improve the pathophysiological interpretation of cardiovascular autonomic dysfunction in patients with central nervous system disease.

Significance of sympathetic skin response in the assessment of autonomic failure in patients with spinal cord injury

As a result of spinal cord injury (SCI) descending spinal sympathetic pathways can be severed. Because of its clinical significance, the aim of this study was to assess the disturbance of the spinal sympathetic pathway by clinical and electrophysiological examinations. The sympathetic skin response (SSR) due to electrical stimulation of median nerve and transcranial magnetic stimulation was examined in 70 patients with complete and incomplete spinal cord injury. Clinical and neurological examinations were performed in these patients according to the protocol of the American Spinal Injury Association (ASIA). The SSR can be used to assess the integrity of the spinal sympathetic nervous system. In patients with complete tetraplegia and paraplegics with high thoracical lesions (up to level T3) SSRs of the hands and feet were absent. In patients with complete paraplegia and thoroacic lesions from level T4 up to T8 the SSRs could be evoked in the hands but not in the feet. However, in paraplegics with lumbal and thoracic lesions below level T8 SSRs of the hands and feet could be recorded. In about 50% of the patients with clinically incomplete SCI lesions SSR potentials were abolished, indicating that the spinal sympathetic system was severely affected. There was no patient with preserved SSR potentials who developed symptoms of autonomic dysreflexia (AD). However, all patients with episodes of AD showed abolished SSR at the hands and feet even in incomplete SCI patients. The results of the SSR recordings in SCI patients fit with the assumption that the development of AD is related to the disconnection of the spinal sympathetic centers from supraspinal control.

Abolition of sympathetic skin responses following endoscopic thoracic sympathectomy

The recording of sympathetic skin responses (SSRs) is a simple, electrophysiological method to assess sympathetic nerve function. Within the last 10 years, SSRs have mainly been applied to delineate peripheral and central nervous system diseases, although the sympathetic nature of these responses was not fully documented, e.g., by a study of sympathectomy. We therefore recorded SSRs before and after 30 cases of endoscopic thoracic sympathectomy. The main indication was palmar hyperhidrosis, in which we found two types of SSR abnormalities. Most patients exhibited normal SSR waveforms but with increased amplitudes. The other patients exhibited abnormal SSRs which did not occur as single responses but as several consecutive waves. Thoracic sympathectomy always led to significant clinical improvement and to the abolition of ipsilateral palmar SSRs, demonstrating the sympathetic origin of these responses. We suggest that the assessment of sympathetic nerve activity by SSR recordings may be useful in sympathectomy.

Impact of aerobic training on fitness and quality of life in multiple sclerosis

Fifty-four multiple sclerosis (MS) patients were randomly assigned to exercise (EX) or nonexercise (NEX) groups. Before and after 15 weeks of aerobic training, aspects of fitness including maximal aerobic capacity (VO2max), isometric strength, body composition, and blood lipids were measured. Daily activities, mood, fatigue, and disease status were measured by the Profile of Mood States (POMS), Sickness Impact Profile (SIP), Fatigue Severity Scale (FSS), and neurological examination. Training consisted of 3 x 40-minute sessions per week of combined arm and leg ergometry. Expanded Disability Status Scale (EDSS) scores were unchanged, except for improved bowel and bladder function in the EX group. Compared with baseline, the EX group demonstrated significant increases in VO2max, upper and lower extremity strength, and significant decreases in skinfolds, triglyceride, and very-low-density lipoprotein (VLDL). For the EX group, POMS depression and anger scores were significantly reduced at weeks 5 and 10, and fatigue was reduced at week 10. The EX group improved significantly on all components of the physical dimension of the SIP and showed significant improvements for social interaction, emotional behavior, home management, total SIP score, and recreation and past times. No changes were observed for EX or NEX groups on the FSS. Exercise training resulted in improved fitness and had a positive impact on factors related to quality of life.

Tests of autonomic dysfunction in patients with multiple sclerosis

Autonomic dysfunction is frequent in patients with multiple sclerosis (MS). The sympathetic skin response (SSR) and the R-R interval variation (RRIV) are simple electrophysiologic tests for the assessment of central and peripheral autonomic disturbances. Both tests were performed in 60 patients with clinically definite MS and 30 controls. The SSR was recorded simultaneously from both upper and both lower limbs. In all volunteers normal responses were recorded from the four limbs, but 39 patients (65%) showed abnormal responses in at least one limb. The reduction in amplitude of the response was correlated with patients' EDSS. In individual limbs, the SSR amplitude correlated with weakness, spasticity and cerebellar dysfunction, but was not sufficiently related to the deep sensory loss. The RRIV was abnormal in 48 MS patients (80%), as compared to the controls, but showed no significant relationship either to the EDSS or to the SSR. The sensitivity of SSR and RRIV is high and compatible with that of visual and somatosensory evoked potentials.