Effects of Laser Acupuncture Therapy for Patients With Inadequate Recovery From Bell's Palsy: Preliminary Results From Randomized, Double-Blind, Sham-Controlled Study

Peripheral facial palsy, known as Bell's palsy, is a condition that suddenly affects the muscles of the face, causing functional difficulties and significant emotional distress. Although most patients recover spontaneously — with more than 70% regaining normal function of the facial muscles — about one-third of cases show inadequate recovery, resulting in persistent complications such as muscle weakness, involuntary contractions, and spasms. These chronic sequelae generate not only physical limitations but also important social impacts, since the face plays a fundamental role in human interactions. Conventional treatment options for chronic cases are limited and controversial, including physical therapy, botulinum toxin injections, and surgical procedures, which can have considerable adverse effects.

Acupuncture has shown promising results in the treatment of Bell's palsy, both in acute and chronic cases, and is widely used in Asian countries. Different acupuncture modalities, including electroacupuncture and manual acupuncture, have shown benefits when compared with standard treatment. In parallel, low-level laser therapy has been gaining recognition for its potential for peripheral nerve regeneration, demonstrated in both laboratory and clinical studies. Laser acupuncture therapy combines the traditional principles of acupuncture with photonic stimulation of specific points, offering a noninvasive and painless approach.

Despite promising results of this technique in other conditions, its effects in chronic Bell's palsy remained unexplored.

This pioneering study investigated the efficacy of laser acupuncture therapy in the treatment of patients with inadequate recovery from Bell's palsy. The researchers conducted a randomized, controlled, double-blind pilot trial at China Medical University Hospital in Taiwan, between May 2018 and July 2020. Seventeen eligible patients were randomly divided into two groups: eight received active laser treatment and nine received sham (placebo) treatment. All participants had a confirmed diagnosis of Bell's palsy for more than three months and had significant functional limitations.

The protocol consisted of 18 treatment sessions over six weeks, three times per week. Nine acupuncture points were stimulated with low-level infrared laser, with seven points located on the affected face and two distal points on the limbs. The device used emitted infrared light at 810 nanometers with a power of 150 milliwatts per square centimeter, applied for 40 to 80 seconds at each point. The control group received an identical procedure, but with inactive equipment that maintained the same visual and auditory characteristics, ensuring blinding of participants and researchers.

The results showed encouraging trends of improvement in the group that received active laser treatment. After three weeks of treatment, a statistically significant difference was observed on the House-Brackmann scale, a system widely used to assess facial function in patients with palsy. At week 6, two other measurements — the Sunnybrook system and the facial stiffness scale — showed results close to statistical significance, suggesting relevant clinical benefits. Although the primary outcome of the study, related to the social impact of the condition, did not show a significant difference between the groups, this may be related to the small sample size.

It is important to note that no participant in the treatment group experienced worsening of symptoms, while one case in the control group showed deterioration. Throughout the study period, no adverse events were reported, confirming the safety of the technique.

For patients with chronic Bell's palsy, these results represent a promising treatment perspective. Laser acupuncture therapy offers a noninvasive, painless, and safe alternative to conventional therapeutic options, which often have limitations and risks of side effects. For health care professionals, the study provides specific technical parameters on how to apply this therapeutic modality, including acupuncture point locations, laser power, and treatment duration. The technique can be considered both as primary treatment and as complementary therapy for cases of persistent facial palsy.

The findings also suggest that laser stimulation may aid in nerve regeneration and improvement of local blood circulation, fundamental processes for the functional recovery of facial muscles.

It is important to recognize the limitations of this preliminary study. The final number of participants was small due to restrictions imposed by the COVID-19 pandemic, which significantly affected volunteer recruitment. This limitation may have influenced the ability to detect statistically significant differences in all evaluated outcomes. In addition, the study did not include more objective electrophysiological assessments of nerve function, focusing on clinical assessment scales.

Despite these limitations, this is the first clinical trial to systematically investigate laser acupuncture for chronic Bell's palsy, providing important preliminary evidence that justifies future studies with larger samples and long-term follow-up. The encouraging results, combined with the excellent safety profile of the technique, open the way for a new therapeutic option for patients facing the persistent consequences of this challenging condition.