[Autonomic cardiovascular dysfunction in multiple sclerosis not caused solely by brain stem lesions]. / Disfunción autonómica cardiovascular en la esclerosis múltiple no provocada únicamente por lesiones troncoencefálicas.

INTRODUCTION: Multiple sclerosis (MS) can cause alterations in autonomic cardiovascular functioning. Some authors attribute these anomalies detected in MS patients to brain stem lesions, due to the fact that important autonomic nuclei are located in this region of the brain. Other studies, however, have been unable to prove such a relation. AIMS. The purpose of this study was to analyse whether these alterations had an exclusive relation with the brain stem lesions that usually appear in the course of this disease. PATIENTS AND METHODS: We compared the spectral analysis of the heart rate variability (SAHRV) in the frequency domain between a group of 34 patients with MS and another group of 14 patients with isolated brain stem lesions (IBSL) of a non inflammatory origin, which were measured using a 24 hour Holter recording. RESULTS: Heart rate, very low rates, low rates and the low rate/high rate quotient are significantly higher in the MS group than in the IBSL group, even when the former present brain stem lesions. Results in the high rate component, however, depend on the presence of brain stem lesions in the MS group. CONCLUSION: These findings suggest that autonomic cardiovascular dysfunction in MS is only related with brain stem lesions, although we obtained results that confirm the importance of this area in cardiovascular innervation.

Brainstem lesions decrease heart rate variability.

OBJECTIVE: Brainstem is an essential region in the regulation of the autonomic cardiovascular functions. Some authors have reported that medulla oblongata is very important in this regulation, but probably is not the unique because the sympathetic cardiovascular centers are spread in the brainstem. Since some years ago, we are able to measure heart rate variability which is a useful tool for assessing quantitatively both sympathetic and parasympathetic autonomic effects on the heart. The objective is to evaluate the effects of isolated brainstem lesion (IBL) on sympathetic and parasympathetic cardiovascular regulatory functions. PATIENTS AND METHODS: We analyzed the heart rate variability in time and frequency domains in 14 IBL patients and 25 age and sex matched healthy control subjects, measured from 24-h electrocardiogram. RESULTS: Low frequency power (0.001) and low frequency/high frequency power (0.05) were significantly higher in control subjects independently, all together or in subgroups (medulla oblongata affected or not). High frequency power (0.05) were higher too in control subjects. Variability in time domain (0.001 and 0.01) was lower when the medulla oblongata was affected. CONCLUSIONS: These results confirm that brainstem lesions cause cardiovascular autonomic dysregulation overall when the medulla oblongata is affected. The importance of this region in parasympathetic and sympathetic cardiovascular functions is showed. However, pontine and mesencephalic lesions seem to provoke a decrease only in sympathetic regulation.

Heart rate variability in multiple sclerosis during a stable phase.

OBJECTIVES: Multiple sclerosis (MS) frequently causes disturbances of autonomic functions. Cardiovascular dysautonomia has been studied by classic autonomic tests and, recently, by heart rate variability analysis in some isolated periods. Multiple authors recommended performing heart rate variability analysis with a 24 h ECG recording to increase its sensitivity. MATERIAL AND METHODS: We analyzed the heart rate variability in time and frequency domains in 34 MS patients and 24 age and sex-matched healthy control subjects, in order to evaluate the effects of MS on sympathetic and parasympathetic cardiovascular regulatory functions measured from 24-h electrocardiogram. RESULTS: Low frequency power (0.01) and low frequency/high frequency power (0.01) were significantly higher in multiple sclerosis patients independently, all together or in subgroups. Very low frequency (0.01) and high frequency (0.001) power were higher in less affected multiple sclerosis patients. Variability in time domain (0.05) were lower in most affected multiple sclerosis patients. CONCLUSIONS: These results suggest that multiple sclerosis causes cardiovascular autonomic dysregulation manifesting as impaired heart rate variability. This illness seems to cause an increase in sympathetic cardiovascular tone; the parasympathetic tone is most variable and depends on clinical and paraclinical findings, but the illness progression seems to provoke a decrease in it.