Tag: CNS deficits

Variability of postural orthostatic tachycardia in patients with myalgic encephalomyelitis and orthostatic intolerance

Abstract:

Central nervous system dysfunction with myalgic encephalomyelitis (ME) has been suggested as the main cause of chronic fatigue syndrome. Fluctuation of the symptom severity and hierarchy is a characteristic feature in ME patients. The characteristics of the sympathetic activation may differ between the “good days” and “bad days” in them.

Twenty-four ME patients with orthostatic intolerance underwent a conventional 10-min active standing test and echocardiography both on a “good day” and a “bad day”, defined according to the severity of their symptoms. The mean heart rate at rest was significantly higher on the “bad days” than on the “good days”. During the standing test on a “bad day”, 5 patients (21 %) failed to maintain an upright posture for 10 min, whereas on a “good day” all the 24 patients maintained it.

Postural orthostatic tachycardia (POT) (increase in heart rate ≥30 beats/min) or severe POT (heart rate ≥120 beats/min) was observed on the “bad days” in 10 patients (43 %) who did not suffer from the severe tachycardia on the “good days”, suggesting the exaggerated sympathetic nervous activation.

In contrast, POT did not occur or severe POT was attenuated on the “bad days” in 5 patients (21 %) who developed POT or severe POT on the “good days”, suggesting the impaired sympathetic activation. Echocardiography revealed significantly lower mean values of both the left ventricular end-diastolic diameter and stroke volume index on the “bad days” compared with the “good days”.

In conclusion, in ME patients with orthostatic intolerance, the exaggerated activation of the sympathetic nervous system while standing appears to switch to the impaired sympathetic activation after the system is loaded with the additional accentuated stimuli associated with the preload reduction.

 

Source: Miwa K. Variability of postural orthostatic tachycardia in patients with myalgic encephalomyelitis and orthostatic intolerance. Heart Vessels. 2016 Sep;31(9):1522-8. doi: 10.1007/s00380-015-0744-3. Epub 2015 Sep 15. https://www.ncbi.nlm.nih.gov/pubmed/26374335

 

Postural orthostatic tachycardia syndrome as a clinically important subgroup of chronic fatigue syndrome: further evidence for central nervous system dysfunctioning

In this issue of the Journal of Internal Medicine, Lewis and colleagues [1] provide compelling data for a novel subgroup within the chronic fatigue syndrome (CFS) population. They show that approximately 13% (24/179) of CFS patients have postural orthostatic tachycardia syndrome (POTS), a form of dysautonomia implying that when patients change their body position from supine to upright, their heart rate will increase abnormally (tachycardia). POTS is associated with several symptoms often seen in CFS patients: fatigue, lightheadedness, dizziness, neurocognitive deficits and exercise intolerance. Importantly, this was a confirmatory study of a previously published pilot study that found a prevalence rate for POTS of 29% in a smaller sample (n = 63) of CFS patients [2]. Another significant finding is the differences in fatigue severity, depressive thoughts and daytime hypersomnolence between CFS patients with and without POTS, providing evidence for the clinical importance of POTS in CFS.

You can read the full comment here: http://onlinelibrary.wiley.com/doi/10.1111/joim.12034/full

Comment on: Clinical characteristics of a novel subgroup of chronic fatigue syndrome patients with postural orthostatic tachycardia syndrome. [J Intern Med. 2013]

 

Source: Nijs J, Ickmans K. Postural orthostatic tachycardia syndrome as a clinically important subgroup of chronic fatigue syndrome: further evidence for central nervous system dysfunctioning. J Intern Med. 2013 May;273(5):498-500. doi: 10.1111/joim.12034. Epub 2013 Feb 8. http://onlinelibrary.wiley.com/doi/10.1111/joim.12034/full (Full article)

 

Vestibular function test anomalies in patients with chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is distinguished by the new onset of debilitating fatigue that lasts at least 6 months, concomitant with other symptoms to be described later. Many CFS patients complain of disequilibrium, yet the exact type of the balance dysfunction and its function and its location (peripheral vs. central) have not been described.

Herein we report results of vestibular function testing performed on 11 CFS patients. These results revealed no predominant pattern of abnormalities. Patients typically performed below average in dynamic posturography testing, with a significant number of falls in the tests requiring subjects to depend heavily on the vestibular system. One patient had abnormal caloric testing, while 3 had abnormally low earth vertical axis rotation (EVA) gains at the higher frequencies tested.

As a group, the average gain of EVA was significantly lower than normals in the 0.1 – 1.0 Hz range (p < 0.05). In earth horizontal axis rotation, the CFS group had a higher than normal bias value for the optokinetic (OKN) and eyes open in the dark conditions (p < 0.05), but had normal scores during visual vestibular reflex testing. Five of the 11 subjects had an abnormal OKN bias build up over the course of the run, equal to or actually exceeding the 60 degrees/s target velocity by as much as 14 degrees/s.

Altogether, these results are more suggestive of central nervous system deficits than of peripheral vestibular disfunction.

 

Source: Ash-Bernal R, Wall C 3rd, Komaroff AL, Bell D, Oas JG, Payman RN, Fagioli LR. Vestibular function test anomalies in patients with chronic fatigue syndrome. Acta Otolaryngol. 1995 Jan;115(1):9-17. http://www.ncbi.nlm.nih.gov/pubmed/7762393