Department of Neurosurgery, Inselspital, Bern University Hospital, Bern, Switzerland.
Department of Neurology, Inselspital, Bern University Hospital, Bern, Switzerland.
Clin Auton Res. 2021 Dec;31(6):719-727. doi: 10.1007/s10286-021-00830-5. Epub 2021 Oct 21.
In neuropathic postural tachycardia syndrome, peripheral sympathetic dysfunction leads to excessive venous blood pooling during orthostasis. Up to 84% of patients report leg pain and weakness in the upright position. To explore possible pathophysiological processes underlying these symptoms, the present study examined muscle excitability depending on body position in patients with neuropathic postural tachycardia syndrome and healthy subjects.
In ten patients with neuropathic postural tachycardia syndrome and ten healthy subjects, muscle excitability measurements were performed repeatedly: in the supine position, during 10 min of head-up tilt and during 6 min thereafter. Additionally, lower leg circumference was measured and subjective leg pain levels were assessed.
In patients with neuropathic postural tachycardia syndrome, muscle excitability was increased in the supine position, decreased progressively during tilt, continued to decrease after being returned to the supine position, and did not completely recover to baseline values after 6 min of supine rest. The reduction in muscle excitability during tilt was paralleled by an increase in lower leg circumference as well as leg pain levels. No such changes were observed in healthy subjects.
This study provides evidence for the occurrence of orthostatic changes in muscle excitability in patients with neuropathic postural tachycardia syndrome and that these may be associated with inadequate perfusion of the lower extremities. Insufficient perfusion as a consequence of blood stasis may cause misery perfusion of the muscles, which could explain the occurrence of orthostatic leg pain in neuropathic postural tachycardia syndrome.
在神经源性直立性心动过速综合征中，外周交感神经功能障碍导致直立位时静脉血液过度积聚。多达 84%的患者报告在直立位时有腿部疼痛和无力。为了探讨这些症状的可能病理生理过程，本研究检查了神经源性直立性心动过速综合征患者和健康受试者的体位依赖性肌肉兴奋性。
在 10 例神经源性直立性心动过速综合征患者和 10 例健康受试者中，重复进行肌肉兴奋性测量：仰卧位、10 分钟头高位倾斜和随后 6 分钟。此外，还测量了小腿周长并评估了主观腿部疼痛程度。
在神经源性直立性心动过速综合征患者中，仰卧位时肌肉兴奋性增加，倾斜时逐渐降低，返回仰卧位后继续降低，6 分钟仰卧休息后仍未完全恢复到基线值。倾斜时肌肉兴奋性的降低与小腿周长的增加以及腿部疼痛程度的增加相平行。在健康受试者中未观察到这种变化。
本研究为神经源性直立性心动过速综合征患者肌肉兴奋性发生直立性变化提供了证据，并且这些变化可能与下肢灌注不足有关。由于血液淤滞导致的灌注不足可能导致肌肉的悲惨灌注，这可以解释神经源性直立性心动过速综合征中直立性腿部疼痛的发生。
