CHRONIC BELL ' S PALSY LITERATURE REVIEW AND CASE REPORT : ARE THERE ANY REHABILITATION STRATEGIES AVAILABLE ?

Peripheral facial nerve palsy refers to a lower motor neuron lesion of the facial nerve and is considered the most common mononeuropathy (1). In most cases (6075%) it is idiopathic and is then referred to as Bell's palsy. The remaining 25-40% of cases have a known cause such as viral aetiology, Lyme disease, postsurgical complication, nerve compression, neurological conditions, traumatic injury, or rare genetic syndromes (1).


INTRODUCTION
Peripheral facial nerve palsy refers to a lower motor neuron lesion of the facial nerve and is considered the most common mononeuropathy (1). In most cases (60-75%) it is idiopathic and is then referred to as Bell's palsy. The remaining 25-40% of cases have a known cause such as viral aetiology, Lyme disease, postsurgical complication, nerve compression, neurological conditions, traumatic injury, or rare genetic syndromes (1).
The symptoms that may range from a minimum paresis to the complete paralysis develop within few hours and are usually at their maximum within 48 to 72 hours. Most patients with Bell's palsy recover fully while approximately 30% of the patients develop long-term sequelae such as facial spasm, synkinesis, muscle contracture, tinnitus, or facial asymmetry (2,3). These long-term sequelae are linked not only to physical impairments, but also psychological and sociological difficulties resulting in the reduced quality of life (4). Therefore, the imperative in the Bell's palsy treatment is early diagnosis, intervention, and prevention of long-term sequelae.
According to the most recent clinical guidelines, the treatment for the acute Bell's palsy is well established and primarily focused on the pharmacological treatment including the corticosteroid and antiviral therapy implemented within 72 hours. Physical therapy including exercises and electrostimulation is not recommended in the acute phase due to the lack of good quality evidence. No recommendations could be made considering the effectiveness of acupuncture. Further, the facial nerve decompression is also not proven to be beneficial in the acute Bell's palsy (Table 1.) (5)(6)(7)(8).
When it comes to the chronic Bell's palsy there are no official clinical guidelines, although there are some recommendations based on the weak evidence that exercise physical therapy might be beneficial (Table 1.) (5,6). Therefore, since present scientific literature is lacking high quality evidence regarding the effectiveness of physical therapy treatment options of the chronic Bell's palsy cases, the specialists are left scares with evidencebased rehabilitation strategies. So, the treatment of the chronic Bell's palsy is based solely on the rehabilitation specialists' experience, skills, and resources, to choose and apply most suitable treatment strategies for the patient.
Considering our patient presented with symptoms of the prolonged sequelae of Bell's palsy, in which therapeutic options are limited, we decided to combine three treatment modalities (acupuncture, High Intensity Laser Therapy and mirror book therapy) each with its own possible beneficial effects in the treatment of peripheral facial paresis. We are unaware of any such therapeutic combination used in a patient with sequelae of Bell's palsy in up-to-date literature.

CASE REPORT
A 30-year-old male presented at a private rehabilitation clinic in Split, Croatia, 18 months after the first symptoms of the severe right sided Bell's Palsy. Although patient underwent corticosteroid therapy as well as multiple two-week cycles of the conventional physical therapy during one-year period, minimum recovery effect has been achieved. Physical therapy included in front of the mirror facial exercises, chewing gum and electrostimulation. Patient complained on the left side synkinesis, facial stiffness and tearing of the right eye. During the clinical examination, he could not wrinkle the right side of forehead, or raise the right eyebrow, and the right mouth corner was lowered. He could close his right eye but had a significant synkinesis in the left eye muscles, and spasm of the sternocleidomastoid muscles bilaterally, more prominent on left side (Figure 1.). Pre-treatment, House-Brackmann scale was 4/6, Sunnybrook Facial Grading System result was 24/100, and Facial Disability Index was 43/200.
Since the conventional therapy did not have any effect and the patient still had a moderate facial paresis, to diminish the long term sequalae, we have decided to apply an alternative, multimodal treatment approach which included acupuncture, HILT, and a mirror book therapy. The treatment goal was to incre-ase the facial muscle function, diminish the synkinesis and to increase the blood flow to the affected tissues, increasing the amount of oxygen available to the damaged hypoxic tissues to stimulate recovery. In this way, we tried to stimulate the recovery of the muscular and neural structures affected. The improvement of psychosocial aspects of the chronic facial palsy was also anticipated.
HILT device used in our case study was BTL-6000 HIGH INTENSITY LA-SER 12 W with following options: wavelength 1,064 nm, power 7 W, dosage 80 J/cm 2 , area 10 cm 2 . HILT laser was applied using 30 mm spacer with back-andforth skin contact along the facial nerve branches. HILT laser was used three times a week for 3 weeks, continuing with two times a week for 5 weeks.
To address a chronic case of facial palsy, we developed our version of the mirror book therapy named FACE-UP, based on the mirror box developed by Ramachandran to treat the phantom limb pain and paralysis (9). FACE-UP bi-fold mirror has following dimensions, 20x40x70 cm and it is made of a highquality acrylic. FACE-UP was placed vertically on a hard, stable surface at an angle of 90° to prevent any distortions to the reflection and allow the display of virtual images of the patient's face in the frontal and sagittal planes. In this case the damage to the lower right motoneuron has affected the right side, so we placed FACE-UP in a way that the patient sees the left side of his face duplicated symmetrically. The therapy protocol also included gentle facial facilitations based on the Bobath therapy method, buccal massage, imitation training, facial expression exercises and diction exercises. The treatment lasted for 60 minutes and has been conducted twice a week for 7 weeks. Before engaging in the exercise, the patient was asked if he could maintain focus in the double-reflected image in the sagittal part of FACE-UP. The patient was instructed to perform the movements voluntarily under the supervision of the certified mirror therapist, which allowed the patient to form the exercise in a self-disciplined manner. It is believed that while observing performance of exercises with healthy side, the activity of the patient's motor pathways stimulates neuroplasticity.
After the completion of this combined physical therapy protocol, a significant clinical improvement was noticed. Patient had a normal symmetry and a muscle tone in the resting position with mild muscle weakness and slight mouth corner asymmetry on exertion, as well as the minimal asymmetry on active wrinkling of the forehead (Figure 1.). House-Brackmann scale was 2/6, Sunnybrook Facial Grading System result was 71/100, and Facial Disability Index was graded 173/200. DISCUSSION Even though most patients with Bell's palsy recover fully, there are still many cases of patients that develop a long-term sequela. It brings about not only physical impairments, but also psychological and sociological difficulties. Incomplete recovery affects both self-esteem and life quality (10). In this case, the patient has developed a long-term Bell's palsy sequelae that has significantly affected his daily functioning and well-being. The combination of HILT, acupuncture and mirror book therapy has shown significant improvement in recovery as well as self-esteem and social functioning of our patient. Moreover, this case report has shown that this combination of methods has provided a significant improvement in a short period even though it began 18 months after the onset of symptoms.
Our Institute of Physical Medicine and Rehabilitation with Rheumatology, Clinical Hospital Centre Split has a long tradition of acute Bell's palsy treatment with conventional physical therapy modalities. Physical therapy for acute Bell's palsy is performed on daily basis in our Institution although according to the international guidelines it is not recommended due to the scarce evidence of its efficacy (Table 1.). Scarce evidence of physical therapy efficacy in the treatment of Bell's palsy can be attributed to a small sample size in RCTs and heterogenous study population due to the possibility of the inadequate diagnosis of Bell's palsy when there might be an underlying cause. Classically, electrostimulation, galvanic currents, paraffin, and mimic exercise performed in front of the mirror are applied in every acute Bell's palsy patient with mostly good results. However, the efficacy of physical therapy is difficult to assess due to a high rate of spontaneous recoveries within 6 weeks to 3 months (1). Treating chronic Bell's palsy still poses a clinical challenge. Therefore, our group of the rehabilitation specialists skilled in performing acupuncture and laser therapy, and physiotherapists skilled in performing mirror and Bobath therapy decided to take a new approach to the chronic Bell's palsy treatment.
According to the meta-analysis from 2019 that comprised randomised control trials (RCTs) regarding the effectiveness of acupuncture in comparison to other treatments, it is considered to be an effective treatment for Bell's palsy (11). Moreover, these RCTs have considered the recovery rates of early stage (within one month) Bell's palsy, and it has shown that acupuncture had better outcomes than oral medications or topical injection. However, it is important to consider the high rates of spontaneous recovery of Bell's Palsy when observing these re- *Low overall quality of guideline according to AGREE II; **High overall quality of guideline according to AGREE II; NA -Not Applicable sults. Furthermore, a systematic review from 2015 has included RCTs with a wider range of symptoms duration, from 1 day to 6 months. It has found a greater prevalence of total effective response rate in acupuncture when compared to other therapy interventions (12). Also, an RCT from a 2015 study has suggested that acupuncture is also effective in the long-term Bell's palsy cases. However, the results of these studies are to be considered carefully due to the methodological flaws, including heterogeneity of the reviewed studies in the meta-analysis and systematic review, and poor choice of control group in the RCT (11)(12)(13).
Although there is a high rate of spontaneous recovery in Bell's palsy, we believe it should be encouraged by effective physical therapy modalities. There is some evidence that adverse consequences of Bell's palsy could be preventable if the patients had received complementary treatment to conventional therapy with laser within 15 days of the diagnosis (14). Therefore, the laser provides an excellent passive addition to the therapy since it improves the recovery from facial palsy while eliminating the possibility of side effects caused by corticosteroids. Moreover, it reduces the remaining impairments which would otherwise be treated with conventional therapy. Also, this therapy modality is safe for patients who cannot be given corticosteroids and still provide similar or better results (15). Laser therapy has a favorable prognosis in the regeneration of peripheral nerves in both neurosensory and neuromotor deficits. Moreover, the High Intensity Laser Therapy (HILT) combined with massage and exercises has been proven as a more effective therapeutic modality when compared to the low level laser therapy LLLT combined with massage and exercises, and when compared to massage, exercises, and sham laser (14)(15)(16). However, the studies on the efficiency of HILT are scarce and further research is needed to confirm these findings.
Further, the mirror book therapy (referred as FACE-UP in this case report) has been suggested as an efficient addition to facial nerve palsy rehabilitation since it significantly improves outcomes in the treatment of idiopathic facial palsy.
It was proven to affect the improvement of resting posture, voluntary movement, and synkinesis in Bell's palsy. Moreover, the mirror book therapy has shown to provide a positive psychological support and additional motivation to perform the exercises at home (17). The most recent study on the effectiveness of the mirror book therapy from 2020 observed the comparison between the group with included mirror book therapy within conventional rehabilitation and the group with conventional therapy only. In the mirror book therapy group, the average period between appearance of facial palsy and initiation of the physical therapy treatment was 21.5 months. Therefore, this study has shown that the mirror book therapy does improve the results of conventional rehabilitation for a longterm Bell's Palsy (17). The results of this study can be confirmed by a previously undertaken systematic review from 2011 that included RCTs that observed the effectiveness of the use of mirror feedback (regular mirror, not bifold) while undertaking physical therapy exercises. It observed both studies with acute and chronic Bell's palsy (18). When compared to previous applications of mirror book therapy for facial palsy, our version has combined the facilitations based on the Bobath method and the buccal massage combined with exercises and diction exercises when compared to exercises alone. Also, when compared to the previous mirror designs, our mirror is larger to avoid the need to hold the mirror by hands or by putting it on a taller table, so it is more stable and appropriate for the patients irrelevant of their height. However, the studies on the efficiency of mirror book therapy for Bell's palsy are scarce and further research in a form of RCT is needed to confirm these findings.
Since there are no clinical guidelines for the treatment of chronic Bell's palsy nor high-quality evidence of physical therapy efficacy, when choosing proper treatment strategies, we still must rely on our knowledge, skills, and clinical experience as well as the needs of the patients. We strongly believe that the individually tailored physical therapy comprised of acupuncture, HILT, and mirror book therapy (FACE UP) could make a difference. However, to prove the efficacy of these methods, the high quality RCTs are necessary. CONCLUSION Based on the outcomes observed in this case report, a combined physical therapy protocol including acupuncture, HILT, and mirror book therapy, has shown to be an effective treatment for the chronic Bell's palsy sequelae in this case. Further RCTs with large sample size for each method or their combinations are needed to confirm the efficacy of presented therapy modalities in the treatment of chronic Bell's palsy.