Facial palsy results in functional and social dysfunction, which is related to the inability to control the muscles of facial expression[1–3]. In all types of facial paralysis, Bell’s palsy is the most common acute disorder affecting a single nerve, and the cause is unknown. The condition affects 11–40 people per 100,000 in the population each year, most commonly in the age group 30–45[4]. Compared with Bell’s palsy, facial palsy caused by Varicella Zoster Virus(VZV), which is best known as the Ramsay Hunt syndrome has a lower incidence but more severe symptoms at onset, and it is less likely to ensure full recovery[5]. Besides, a risk of 10% -18% of a common complication of Ramsay Hunt syndrome may develop, which is known as postherpetic neuralgia (PHN), a chronic pain condition[6].
Typically, facial paralysis is self-limited, but long-term poor outcomes do occur when it is under a severe condition at onset. Although the detailed pathological changes of the facial nerve in the infratemporal remains unclear[7], the swelling of facial nerve segments was identified in all patients through enhanced MRI[8]. Thus, the use of corticosteroids can help attenuate disease progression by decompressing the swelling caused by inflammation of the facial nerve canal[9], and the use of oral steroids within 72 hours of symptom onset is recommended[10]. When it comes to Ramsay Hunt syndromes, the inflammation is due to Varicella-Zoster Virus(VZV), so the anti-viral drugs such as famciclovir or acyclovir should be given to patients with a 7–10 days course[5], and an early combined acyclovir-corticosteroid therapy displays a better result exclusive usage of corticosteroid or antiviral therapy[9]. Moreover, over 80% of the patients who received antiviral therapy within 72 h from onset obtained good recovery.[11].That is to say, a timely diagnosis and treatment are crucial, otherwise, sequelae such as round eye or synkinesis may appear over time[12, 13].
Acupuncture was defined as inserting fine needles into specific locations in the body[14]. As an invasive treatment, injury is inevitable. Inflammation usually results from infection or tissue injury[15]. Thus, there are concerns that acupuncture therapy would have some side effects such as increasing the grade of facial nerve swelling and causing a delay in instituting steroid therapy[10]. In the acute phase of facial paralysis, facial nerve edema more or less exists, if a strong stimulation of acupuncture therapy is performed at that local area, side effects or aggravation would appear eventually. Acupuncture therapy is not a simple procedure by choosing some local points near the lesion, but a purposeful and targeted operation under the guidance of traditional Chinese medicine theory.
For acupoints, both horizontal and vertical levels should be considered. Specifically, it involves the locus and nature of the disease, as well as the different symptoms a disease reflected. Thus, we have different ways to select acupoints such as from the near part (of locus) or the distant part (of locus) based on syndrome differentiation or based on symptoms". These are choices from a "horizontal" perspective. On this basis, the depth of needling varies for each acupoint which is based on the depth of the disease locus. "skin" "veins" "flesh" "tendons" and "bones",which corresponds roughly to the concept of "pi" "mai" "rou" "jin" and "gu”, is a transition from the surface of the body to the deeper layers of the body, choosing the most appropriate depth to operate is about the "vertical" perspective. Just as a location is determined by latitude and longitude in a map, the exact location of the needle puncture can only be determined when both horizontal and vertical aspects are identified. Also, when necessary, time of the day, season, age, the structure of different people and other factors will be taken into account in the depth of needling. By combining all these factors, the selection of acupoints and the method of acupuncture manipulation have greater flexibility and consequent precision, similar to the precision medicine that modern medicine is beginning to approach[16]. According to the theory of traditional Chinese medicine, the evil qi in the acute phase of facial paralysis is still shallow and deepens inward as the condition progresses. As it is said in the classics of Chinese medicine, "The shallow focus means the shallow acupuncture depth, and the deep focus means the deep acupuncture depth". Therefore, during the acute phase of facial palsy, the clinical selection of acupuncture points is mainly from distal acupuncture points with local superficial acupuncture for treatment(Figure 1A-B), when the disease progresses to the recovery period, deep puncture and penetrating puncture are adopted (Fig. 2A-B). After understanding these characteristics of acupuncture, it is clear that the idea of acupuncture performed in early facial palsy could aggravate local edema is a limited understanding of acupuncture therapy, which is formed in the absence of relevant elements.
Traditional Chinese medicine believes that the main cause of facial paralysis is the emptiness of the meridian and the invasion of external evils. When the body is tired and the immune system is weakened, the wind pathogens would take advantage of the void. Or it could be caused by bad emotional conditions such as anxiety and tension. Among them, damp-heat of liver and gallbladder or hyperactivity of liver yang are the most common syndromes of Ramsay Hunt syndrome [17]. Bad emotions can be the trigger of this disease, and the potentially devastating disorder may result in extensive functional or psychosocial sequelae for patients which will enhance the depression in affected individuals [18, 19]. There is an old saying in Chinese medicine, Righteousness is inside, evil cannot be done. Acupuncture can regulate the qi and blood of the whole body to a balanced condition by tonifying qi, activating blood, dredging collaterals, etc. According to the patient's facial function damage, selecting different meridian points can purposely affect the facial meridians. Modern studies have also suggested that the occurrence of facial paralysis may be related to weakened immunity[13, 20]. Although the onset is regardless of age and gender, a North American study suggests that children have a higher incidence of Bell’s palsy[21]. Acupuncture has a certain effect in the treatment of autoimmune diseases and neurological diseases, and can better regulate emotions[22–24], so it has the basis for lightening the causes of facial paralysis.
In the setting of no treatment, 70% of the Bell’s palsy patients fully recovered, 15% progress to non-flaccid FP and 15% recover with minor deficits. For people who are unable to restore by themselves, a potentially devastating disorder may result in functional, sensuous, and psychosocial sequelae on patients[19]. Modern medicine’s understanding of this disease is to find out and treat it as soon as possible. Early diagnosis and the immediate initiation of treatment can improve the outcome. Besides,for children younger than 18 years old, the use of glucocorticoids or antiviral drugs is slightly restricted, and there are fewer clinical studies [25]. There is no age limit for acupuncture therapy, and many clinical studies have found that the intervention of early acupuncture and moxibustion programs can shorten the course of facial paralysis, reduce complications, and sequelae[26–29]. Therefore, whether acupuncture therapy should be involved in the treatment of facial paralysis patients at onset is of great significance.
Four systematic reviews have assessed the safety and effectiveness of acupuncture applying in the acute phase of facial palsy[30–33], the findings showed a beneficial effect of acupuncture therapy at the onset of the facial palsy, but still illustrate some methodological limitations of included trials, varies from study design or comparisons. Two out of four systematic reviews only searched literature from Chinese databases, and use Jadad scoring criteria to score the quality of the literature[31, 32]. JIN et al[33] selected 11 studies, in which the control group’s selection of points must involve facial points. And all of the systematic reviews only focused on the peripheral facial paralysis but did not include Hunter's facial paralysis. In addition, these studies are only general descriptions of the safety and effectiveness of acupuncture therapy and didn’t specify the most suitable point selection or manipulation in the acute phase. Thus, although several systematic reviews are suggesting that the acupuncture treatment at onset is beneficial to the recovery of facial paralysis, there is still controversy. Recently, more clinical trials have been published, but little is known about whether there is a most suitable way to perform acupuncture in the acute phase.
The objective of this systematic review is to assess whether acupuncture should be used in the acute phase of peripheral facial paralysis and whether an early acupuncture intervention can shorten the recovery time of the facial function and reduce the formation of sequelae, and find out the most suitable therapy for FP in the acute phase.