Autonomic dysfunction in multiple sclerosis presenting with postural orthostatic tachycardia
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- Adamec, I., Ozretić, D. & Habek, M. Acta Neurol Belg (2013) 113: 337. doi:10.1007/s13760-012-0158-2
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Postural orthostatic tachycardia syndrome (POTS) is an autonomic disorder characterized by an exaggerated increase in heart rate that occurs during standing, without orthostatic hypotension.
We report a patient with postural orthostatic tachycardia in a context of multiple sclerosis (MS).
Laboratory tests including serum and CSF serology for Borrelia burgdorferi and Syphilis, and serum serology for viruses (HBV, HCV and HIV) were all negative. Immunological tests (antistreptolysin titer, rheumatoid factor, anti-DNA antibody, antinuclear antibody, antineutrophil cytoplasmic antibody, angiotensin-converting enzyme) and thyroid function tests were all within normal range.
We repeated intravenous methylprednisolone (1,000 mg through 5 days) with no improvement. We then proceeded to plasma exchange, five cycles. This therapy lead to marked improvement, neurological examination now showed muscle strength in the left forearm and left leg 4/5, and she was able to walk without help for 100 m.
Follow-up tilt-table test showed increase in heart rate of <30 beats/min, with no change in blood pressure without syncope. Average heart rate in the lying position was 64.4 beats/min and in the upright position 89.8 beats/min (Fig. 1).
Three months later the patient developed right hand weakness. Repeated brain MRI showed three new demyelinating lesions. At this point she fulfilled the revised McDonald’s criteria for multiple sclerosis .
Pathological response to orthostatic provocation is frequent in MS, occurring in up to 63 % of patients . Despite this, POTS has rarely been reported in MS [2, 3] One series described nine MS patients with POTS, two patients developed MS after the diagnosis of POTS, and seven patients developed POTS sometime after the diagnosis of MS . Authors of this study did not find any correlation between MS symptoms or relapses with POTS. On the other hand, we have recently reported that POTS frequently occurs MS and showed that it is associated with an MS relapse .
Postural orthostatic tachycardia syndrome can be divided into two categories: neuropathic POTS and central hyperadrenergic POTS . Underlying mechanism of central hyperadrenergic POTS is excessive sympathetic nervous outflow from the brain, so it can be presumed that this type of POTS is found in MS patients, as MS is a disease of the central nervous system. Different central nervous system parts (parabrachial nucleus in the pons, thalamus, hypothalamus, amygdala, insula) are involved in the autonomic functions such as heart rate. Tachycardia may be produced by either increased sympathetic activity or decreased parasympathetic activity. Tachycardic response is mediated via sympathetic outflow from the rostral ventrolateral medulla that is modulated by excitatory and inhibitory, more central inputs . Specifically, a positive correlation was found in the left hypothalamus, left amygdala, right anterior hippocampus, and right dorsomedial and dorsolateral prefrontal cortex, while a negative correlation was found in the right parabrachial nucleus/locus ceruleus, left periaqueductal gray matter, right posterior hippocampus, right mediodorsal thalamus, left caudate and right septal nuclei, left posterior insula, and right medial temporal gyrus . Therefore, the probable mechanism of postural orthostatic tachycardia in our patient is thalamic lesion, which by inhibition of negative effect of right mediodorsal thalamic nucleus on heart rate could produce tachycardia. Another supportive finding for this association is reversal of tachycardia after MS relapse treatment.
In conclusion, autonomic dysfunction in MS is not rare and should be actively searched for. Early recognition and proper management may help to improve the symptoms and patients quality of life.
Conflict of interest
There is no conflict of interest.