Conditions associated with nausea and vomiting, such as motion sickness or side effects of medications, are commonly associated with a clinical picture consistent with parasympathetic activation and sympathetic withdrawal. It can be postulated, therefore, that vestibular stimulation contributes to sympathetic withdrawal. To test this hypothesis five normal volunteers, 24-33 years old, were studied during caloric vestibular stimulation while monitoring muscle sympathetic nerve activity directly through a needle electrode placed in a peroneal nerve. The ear was irrigated with water at a flow rate of 450 ml/min and 37 degrees C. The water temperature was sequentially lowered by 7 degree C intervals until intolerable side effects developed or a temperature of 16 degrees C was reached. Nystagmus was induced in all subjects, but heart rate, blood pressure, muscle sympathetic nerve activity and plasma norepinephrine levels did not change significantly during or after caloric stimulation, even when the subjects felt dizzy and nauseated. No evidence of sympathetic withdrawal was observed in any subject either by muscle sympathetic nerve activity or plasma norepinephrine measurements. In conclusion, we have found that selective vestibular stimulation is not accompanied by significant changes in the sympathetic nervous system function. In particular, no sympathetic withdrawal was observed. It could be argued that lack of sympathetic stimulation is an inadequate response to the symptoms associated with caloric stimulation.
Climacteric and menopause are two terms that are indistinctly used to name clinical expected events related to the decline in ovarian function. Thus, in the literature and in clinical settings we read and hear 'menopausal symptoms' or 'climacterics symptoms'. Globally, the term menopause is much more frequently used than climacteric but, before we use either one, we should consider that 'menopause' is referring to a specific event, the cessation of menses, and 'climacteric' to gradual changes of ovarian function that start before the menopause and continue thereafter for a while. In the premenopause period, hormonal changes will take place that are associated with symptoms, which deteriorate the quality of life, and with metabolic changes which increase the risk of chronic diseases. Therefore, the word climacteric ('steps' in Greek) seems more adequate to refer to the symptoms and chronic diseases associated with the gradual decrease of ovarian function, and we should leave the term 'menopause' only for naming the event of cessation of menstruation that will happen later as the consequence of the decline in ovarian activity. This differentiation has clinical importance, because it implies that, during the premenopausal period, the impact that the decrease in estrogen has on the health status of women must be assessed and, if it is pertinent, we should indicate lifestyle changes, hormonal therapy, hypolipidemic drugs, etc. It does not seem proper to wait for the cessation of menstrual bleeding before some intervention is started. The decay of women's health starts many years before menopause and prevention of its consequences is a must for us, the clinicians.
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