Stroke is defined as an acute focal injury of the central nervous system (CNS) arising from a vascular cause such as cerebral infarction, or intracerebral hemorrhage, or subarachnoid hemorrhage[1]. It is one of the most common causes of death and is the main cause of persistent and acquired disability in adults worldwide. The World Health Organization (WHO) refers to stroke as the incoming epidemic of the 21st century, and it is expected to increasingly affect younger patients. In Europe, stroke cause over 1 million deaths, and worldwide, stroke cause 6.5 million deaths[2]. According to a report published in The Lancet, stroke has become the leading cause of death in China since 2017, and stroke burden in China has increased over the past 30 years, especially remains particularly high in rural areas[3, 4]. However, it has been estimated that over 90% of the burden of stroke is attributable to modifiable factors[5]. Among these, interventions targeting modifiable factors have shown their significant impact in reducing the incidence and mortality of stroke[6].
Acupuncture is one of the oldest and most studied techniques in Chinese medicine, the mode of operation is insertion of a fine needle into the skin or deeper tissues at acupoints of the body, which is recommended as an alternative and complementary strategy for stroke treatment by the WHO[7, 8]. This needling involving manipulated manually, electrically, or by heat. In the CNS, endogenous opioids are the principal biological mediators of the therapeutic actions of this ancient technique[7]. Clinical trials have shown that acupuncture can enhance balance[9], reduce spasticity[10], and increase muscle strength[11]. A systematic review and meta-analysis of randomized trials conducted in 2010 has indicated that acupuncture may be effective in improving post-stroke impairment, as measured by its motor rehabilitation, increased perfusion within peri-infarcts, and the stimulation of neuronal reorganization, amongst other findings[12]. However, the poor study quality and publication bias hinder the strength of this recommendation.
Functional magnetic resonance image (fMRI) is nonpolluting, noninvasive, and has high temporal and spatial resolution, neuronal activity was measured by monitoring the hemodynamic response. It can objectively and visually evaluate different cerebral functional areas activated by acupuncture under physiological and pathological conditions[13]. It has become a reliable technique to reveal the CNS mechanism of acupuncture because of high repeatability and reliability[13, 14].
In recent years, researchers have study the CNS mechanism of acupuncture in the treatment of stroke by fMRI, and show that acupuncture can activate several relevant regions in the brain. However, the activation regions found in various studies are not completely consistent, and the exact mechanisms underlying the beneficial effects of acupuncture in the treatment of stroke remain unclear. At present, there is no systematic review to conduct statistical analysis on the studies in this area. Therefore, the aim of this study is collected clinical research with cerebral function image as primary outcome, comparison the influence of acupuncture treatment for stroke on the CNS, in order to understand the role of acupuncture in the central level, and explore the effective pathway and action mechanism of acupuncture treatment for stroke.