Treatment of aberrant facial nerve regeneration with botulinum toxin A

Botulinum toxin treatment of the buccinator muscle facial synkinesis: A systematic review

BACKGROUND

The purpose of this review is to provide an overview of the available literature assessing the treatment of botulinum toxin injections for the treatment of synkinesis of the buccinator muscle in patients with peripheral facial palsy (PFP).

MATERIALS AND METHODS

A multi database search was performed, including the following databases: Pubmed, Medline, Embase, and the Cochrane Library. Each database was searched from its earliest date until 8 June 2023. The following outcome measures were extracted from the articles when available: subjective, somatic, and psychological effects on the patients and objective outcomes such as the House-Brackmann, Sunnybrook and Sydney scores. The methodological quality of the included studies was rated using the Newcastle-Ottawa scale for nonrandomised trials.

RESULTS

The primary literature search generated 37 articles. After removing duplicates, 25 articles remained for abstract appraisal, of which 20 underwent full-text appraisal, resulting in 3 studies for analysis. All of these studies showed (significant) improvement in synkinesis either measured using the Synkinesis Assessment Questionnaire or subjectively measured by asking treated patients.

CONCLUSION

The available literature supports the finding that botulinum toxin treatment of the buccinator muscle could be a welcome addition to facial synkinesis treatment and could significantly improve patient outcomes. In future studies, the efficacy of EMG-guided buccinator injections, optimal dose, and a validated measuring method could be beneficial in optimising treatment for patients with a PFP and synkinesis.

Treatment Patterns and Outcomes in Botulinum Therapy for Patients With Facial Synkinesis

Importance

In the last decade, there has been a significant increase in the number of practitioners administering botulinum toxin for facial synkinesis. However, there are few resources available to guide treatment patterns, and little is known about how these patterns are associated with functional outcomes and quality of life.

Objective

To evaluate botulinum treatment patterns, including the dosing and frequency of muscle targeting, for treatment of facial synkinesis and to quantify patient outcomes.

Design, Setting, and Participants

This prospective cohort study of 99 patients treated for facial synkinesis was conducted from January 2016 through December 2018 at the Vanderbilt Bill Wilkerson Center in Nashville, Tennessee, a tertiary referral center.

Intervention

Onabotulinum toxin A treatment of facial synkinesis.

Main Outcomes and Measures

Patient-reported outcomes on the Synkinesis Assessment Questionnaire and botulinum treatment patterns, including the dosages and frequency of injection for each facial muscle, were compared at the initiation of treatment and at the end of recorded treatment.

Results

In total, 99 patients (80 female patients [81%]) underwent botulinum injections for treatment of facial synkinesis. The median (interquartile range) age was 54.0 (43.5-61.5) years, and the median (interquartile range) follow-up was 27.1 (8.9-59.7) months. Most patients underwent injections after receiving a diagnosis of Bell palsy (41 patients, 41%) or after resection of vestibular schwannoma (36 patients [36%]). The patients received a total of 441 treatment injections, and 369 pretreatment and posttreatment Synkinesis Assessment Questionnaire scores were analyzed. The mean botulinum dose was 2 to 3 U for each facial muscle and 9 to 10 U for the platysma muscle. The dose increased over time for the majority of all muscles, with steady state achieved after a median of 3 treatments (interquartile range, 2-3). Linear regression analysis for cluster data of the mean total questionnaire score difference was -14.2 (95% CI, -17.0 to -11.5; P < .001). There was a significant association of postinjection questionnaire score with younger patients, female sex, total dose, and synkinesis severity. Oculo-oral synkinesis may respond more to treatment compared with oro-ocular synkinesis.

Conclusion and Relevance

Patients with facial synkinesis responded significantly to botulinum treatment. Treatment began with 6 core facial muscles that were injected during most treatment sessions, and dosages increased after the first injection until steady state was achieved. Those with a greater degree of morbidity, younger patients, and females showed significant improvement, and the larger the dose administered, the greater the response. Oculo-oral synkinesis may be more responsive than oro-ocular synkinesis.

Level of Evidence

3.

Too much or too little? A systematic review of postparetic synkinesis treatment

Synkinesis is a negative sequela of facial nerve recovery. Despite the need for effective treatment, controversy exists regarding optimal management and outcome reporting measures. The goals of this study were to evaluate the current synkinesis literature and compare the effectiveness of treatment modalities. A search of biomedical databases was performed in May 2019. Full-text English language articles of cohort studies or randomized controlled trials on synkinesis treatment were eligible for inclusion. Reviews, animal studies, and those without assessment of treatment effect were excluded. We found 592 unique citations; 33 articles were included in the final analyses. Nine studies focused on botulinum toxin (BTX-A), 7 on surgery, 5 on physical therapy (PT), and 12 on multimodal therapy. The Sunnybrook Facial Grading System was the most frequently used outcome measure (17 studies, 51.5%). All treatment modalities improved outcomes. Chemodenervation studies showed an average improvement of 17.8% (range 11-33.3%) in the respective outcome measures after treatment. PT improved by 29.7% (range 14.6-41.2%), surgery by 16.6% (range 4.7-41%), and combination therapy by 20.4% (range 5.13-37.5%). Only 21 studies (63.6%) provided data on adverse outcomes. There is lack of high-evidence level data for robust comparisons of postparetic synkinesis treatments; however, this condition is likely effectively treated nonsurgically and requires the support of a specialized multidisciplinary team. Adoption of standardized patient evaluation and outcome reporting methods is necessary for robust comparative effectiveness studies.

Outcomes of Buccinator Treatment With Botulinum Toxin in Facial Synkinesis

Importance

The buccinator, despite being a prominent midface muscle, has been previously overlooked as a target in the treatment of facial synkinesis with botulinum toxin.

Objective

To evaluate outcomes of patients treated with botulinum toxin to the buccinator muscle in the setting of facial synkinesis.

Design, Setting, and Participants

Prospective cohort study of patients who underwent treatment for facial synkinesis with botulinum toxin over multiple treatment cycles during a 1-year period was carried out in a tertiary referral center.

Interventions

Botulinum toxin treatment of facial musculature, including treatment cycles with and without buccinator injections.

Main Outcomes and Measures

Subjective outcomes were evaluated using the Synkinesis Assessment Questionnaire (SAQ) prior to injection of botulinum toxin and 2 weeks after treatment. Outcomes of SAQ preinjection and postinjection scores were compared in patients who had at least 1 treatment cycle with and without buccinator injections. Subanalysis was performed on SAQ questions specific to buccinator function (facial tightness and lip movement).

Results

Of 84 patients who received botulinum toxin injections for facial synkinesis, 33 received injections into the buccinator muscle. Of the 33, 23 met inclusion criteria (19 [82.6%] women; mean [SD] age, 46 [10] years). These patients presented for 82 treatment visits, of which 44 (53.6%) involved buccinator injections and 38 (46.4%) were without buccinator injections. The most common etiology of facial paralysis included vestibular schwannoma (10 [43.5%] participants) and Bell Palsy (9 [39.1%] participants). All patients had improved posttreatment SAQ scores compared with prebotulinum scores regardless of buccinator treatment. Compared with treatment cycles in which the buccinator was not addressed, buccinator injections resulted in lower total postinjection SAQ scores (45.9; 95% CI, 38.8-46.8; vs 42.8; 95% CI, 41.3-50.4; P = .43) and greater differences in prebotox and postbotox injection outcomes (18; 95% CI, 16.2-21.8; vs 19; 95% CI, 14.2-21.8; P = .73). Subanalysis of buccinator-specific scores revealed significantly improved postbotox injection scores with the addition of buccinator injections (5.7; 95% CI, 5.0-6.4; vs 4.1; 95% CI, 3.7-4.6; P = .004) and this corresponded to greater differences between prebotulinum and postbotulinum injection scores (3.3; 95% CI, 2.7-3.9; vs 2.0; 95% CI, 1.4-2.6; P = .02). The duration of botulinum toxin effect was similar both with and without buccinator treatment (66.8; 95% CI, 61.7-69.6; vs 65.7; 95% CI, 62.5-71.1; P = .72).

Conclusions and Relevance

The buccinator is a symptomatic muscle in the facial synkinesis population. Treatment with botulinum toxin is safe, effective and significantly improves patient symptoms.

Level of Evidence

3.

[Staged complex treatment of paralytic lagophthalmos (case report)]

Paralytic lagophthalmos, resulting from facial nerve palsy, is a difficult medical and social issue that requires cooperation of different specialists. Complications that arise in paralytic lagophthalmos may cause significant vision loss and even eye loss. Various techniques of paralytic lagophthalmos correction are used to protect the cornea and restore eyelid anatomy and functions. These comprise palliative (conservative), surgical, and alternative treatments (such as botulinum toxin type A therapy). Surgical treatment of paralytic lagophthalmos patients often has to be staged and complex. This article presents a clinical case of a female patient with paralytic lagophthalmos complicated by corneal perforation. Her staged complex treatment included lower eyelid surgery, chemodenervation of the upper eyelid levator and optical reconstructive surgery. The following positive results were achieved: the protective function of the eyelids was restored, residual visual functions - preserved, the risk of eye loss - eliminated, and the asymmetry between the two halves of the face - corrected.

Facial Palsy, a Disorder Belonging to Influential Neurological Dynasty: Review of Literature

Facial paralysis is one of the common problem leading to facial deformation. Bell's palsy (BP) is defined as a lower motor neuron palsy of acute onset and idiopathic origin. BP is regarded as a benign common neurological disorder of unknown cause. It has an acute onset and is almost always a mononeuritis. The facial nerve is a mixed cranial nerve with a predominant motor component, which supplies all muscles concerned with unilateral facial expression. Knowledge of its course is vital for anatomic localization and clinical correlation. BP accounts for approximately 72% of facial palsies. Almost a century later, the management and etiology of BP is still a subject of controversy. Here, we present a review of literature on this neurologically significant entity.

Botulinum Toxin in Pediatric Neurology: Switching Lanes From Death to Life

Botulinum neurotoxins are natural molecules produced by anaerobic spore-forming bacteria called Clostradium boltulinum. The toxin has a peculiar mechanism of action by preventing the release of acetylcholine from the presynaptic membrane. Consequently, it has been used in the treatment of various neurological conditions related to muscle hyperactivity and/or spasticity. Also, it has an impact on the autonomic nervous system by acting on smooth muscle, leading to its use in the management of pain syndromes. The use of botulinum toxin in children separate from adults has received very little attention in the literature. This review presents the current data on the use of botulinum neurotoxin to treat various neurological disorders in children.

Therapeutic strategies in post-facial paralysis synkinesis in pediatric patients

Synkinetic movements comprise abnormal involuntary contractions of one or more facial muscle groups which follow the desired contraction of another facial muscle group. They are frequently encountered in patients with long standing facial paralysis and seriously affect their psychological status due to the impairment of their facial appearance, function and emotional expressivity.

PATIENTS AND METHODS

Eleven pediatric patients (2 male and 9 female) presenting with post-facial paralysis synkinesis were included in the study. Mean age was 10.3±4 years and mean denervation time 72.5 months.

RESULTS

Patients underwent the following types of treatment: --Cross facial nerve grafting (CFNG) and secondary microcoaptations with botulinum toxin injection which had an improvement of 100% (3 in the 3 grade synkinesis scale) (n=2). --Cross facial nerve grafting (CFNG) and secondary microcoaptations without botulinum toxin injection which had an improvement of 66%(2 in the 3 grade synkinesis scale) (n=5). --CFNG and direct muscle neurotization with (n=2) or without (n=1) botulinum toxin injection where the improvement was 33%. --Contralateral nasalis muscle myectomy was performed in one patient along with CFNG and secondary microcoaptations which resulted in 66% synkinesis improvement. Biofeedback was invariably undertaken by all patients. Postoperative improvement in eye closure and smile was also noted in the respective cases treated for synkinesis ranging from 25 to 50%, with all patients achieving optimum functional return.

CONCLUSION

CFNG with secondary microcoaptations and botulinum toxin injections was found to be a very efficient surgical modality addressing post-facial palsy synkinesis with high improvement in facial function and symmetry. Facial neuromuscular re-education contributes considerably in the treatment.

Facial nerve palsy: providing eye comfort and cosmesis

Development of facial nerve palsy (FNP) may lead to dramatic change in the patient's facial function, expression, and emotions. The ophthalmologist may play an important role in the initial evaluation, and the long-term management of patients with new-onset of FNP. In patients with expected temporary facial weakness, no efforts should be wasted to ensure proper corneal protection. Patients with permanent functional deficit may require combination of surgical procedures tailored to the patient's clinical findings that may require good eye comfort and cosmesis.

Noncosmetic periocular therapeutic applications of botulinum toxin

Botulinum toxin blocks acetylcholine release at the neuromuscular junction. The drug which was initially found to be useful in the treatment of strabismus has been extremely effective in the treatment of variety of conditions, both cosmetic and noncosmetic. Some of the noncosmetic uses of botulinum toxin applications include treatment of spastic facial dystonias, temporary treatment of idiopathic or thyroid dysfunction-induced upper eyelid retraction, suppression of undesired hyperlacrimation, induction of temporary ptosis by chemodenervation in facial paralysis, and correction of lower eyelid spastic entropion. Additional periocular uses include control of synchronic eyelid and extraocular muscle movements after aberrant regeneration of cranial nerve palsies. Cosmetic effects of botulinum toxin were discovered accidentally during treatments of facial dystonias. Some of the emerging nonperiocular application for the drug includes treatment of hyperhidrosis, migraine, tension-type headaches, and paralytic spasticity. Some of the undesired side effects of periocular applications of botulinum toxin inlcude ecchymosis, rash, hematoma, headache, flu-like symptoms, nausea, dizziness, loss of facial expression, lower eyelid laxity, dermatochalasis, ectropion, epiphora, eyebrow and eyelid ptosis, lagophthalmos, keratitis sicca, and diplopia.

Evaluation and treatment of synkinesis with botulinum toxin following facial nerve palsy

PURPOSE

To assess the effect and efficacy of botulinum toxin type A (BTX-A) in reducing synkinesis in aberrant facial nerve regeneration (following facial paralysis).

METHOD

A total of 55 sessions of BTX-A (Botox) infiltration were performed on 30 patients (23 female) with synkinesis after facial palsy. Each subject was injected with 2.5 units of BTX-A in each injection site (the sites were chosen on a case-by-case basis). The synkinetic muscles targeted include: orbicularis oculi, zygomaticus major, depressor labii inferioris, platysma, healthy frontalis and healthy corrugator supercilii. The patients were examined using the Sunnybrook Facial Grading System, both before the BTX-A treatment and after an average of 35 days.

RESULTS

All 30 patients experienced improvement to the synkinesis after treatment. Total scores: median pre-BTX-A: 40; post 53 p = 0.004. Resting symmetry scores: mean pre-BTX-A -7.1; post: -3.5; median pre -5 [interquartile range (IQR) -10 to -5]; post: -5 (IQR -5 to 0); p = 0.0001. Symmetry of voluntary movement median pre-BTX-A: 56 post 60 p = 0.10. Synkinesis scores: median pre-BTX-A: -9 post -3 p < 0.0001. Mean duration of improvement was 4 months.

CONCLUSIONS

BTX-A injection treatment was effective in reducing facial synkinesis, thus improving facial expression symmetry both at rest and in voluntary movements.

Review and update of involuntary facial movement disorders presenting in the ophthalmological setting

We review the existing literature on the involuntary facial movement disorders-benign essential blepharospasm, apraxia of eyelid opening, hemifacial spasm, and aberrant facial nerve regeneration. The etiology of idiopathic blepharospasm, a disorder of the central nervous system, and hemifacial spasm, a condition involving the facial nerve of the peripheral nervous system, is markedly different. We discuss established methods of managing patients and highlight new approaches.

Medical and surgical management of facial nerve palsy

PURPOSE OF REVIEW

To review the results of recently published studies on the medical management of Bell's palsy and highlight strategies in the surgical management of facial nerve palsy.

RECENT FINDINGS

Although corticosteroid and antiviral therapy have been proposed for the treatment of Bell's palsy for many years, the clinical efficacy of these treatments has been debated in the literature due to the lack of conclusive evidence from large-scale clinical trials. However, recently completed randomized, controlled studies have found that the early administration of corticosteroids improves the chances of full recovery in patients with Bell's palsy. But there remains insufficient evidence supporting the routine use of antiviral medications in the treatment of Bell's palsy. In addition, improvement in surgical techniques has allowed the introduction of a number of surgical procedures for patients with permanent facial nerve palsy.

SUMMARY

On the basis of the results of several recently completed randomized, controlled studies, corticosteroid therapy has proven to be efficacious in the treatment of Bell's palsy and should be offered to patients presenting within 72 h of symptom onset with consideration to the addition of antiviral therapy for severe cases. Currently available surgical procedures can minimize the complications associated with permanent facial nerve palsy.

Sound-induced facial synkinesis following facial nerve paralysis

Facial synkinesis (or synkinesia) (FS) occurs frequently after paresis or paralysis of the facial nerve and is in most cases due to aberrant regeneration of (branches of) the facial nerve. Patients suffer from inappropriate and involuntary synchronous facial muscle contractions. Here we describe two cases of sound-induced facial synkinesis (SFS) after facial nerve injury. As far as we know, this phenomenon has not been described in the English literature before. Patient A presented with right hemifacial palsy after lesion of the facial nerve due to skull base fracture. He reported involuntary muscle activity at the right corner of the mouth, specifically on hearing ringing keys. Patient B suffered from left hemifacial palsy following otitis media and developed involuntary muscle contraction in the facial musculature specifically on hearing clapping hands or a trumpet sound. Both patients were evaluated by means of video, audio and EMG analysis. Possible mechanisms in the pathophysiology of SFS are postulated and therapeutic options are discussed.

Ophthalmic Management of Facial Nerve Palsy: A Review

Facial nerve palsy affects individuals of all ages, races, and sexes. Psychological and functional implications of the paralysis present a devastating management problem to those afflicted, as well as the carriers. Since Sir Charles Bell's original description of facial palsy in 1821, our understanding and treatment options have expanded. It is essential that a multidisciplinary approach, encompassing ophthalmologists; Ear, Nose, and Throat surgeons; plastic surgeons; and psychologists work closely to optimize patient management in a staged approach. Although the etiology remains unknown, strong histological, cerebral spinal fluid, and radiological evidence suggests a possible association with herpes simplex virus in idiopathic facial nerve palsy (Bell's palsy). The use of steroids has been suggested as a means of limiting facial nerve damage in the acute phase. Unfortunately, no single randomized control trial has achieved an unquestionable benefit with the use of oral steroid therapy and thus remains controversial. In the acute phase, ophthalmologists play a pivotal role in preventing irreversible blindness from corneal exposure. This may be successfully achieved by using intensive lubrication, medical therapy (botulinum toxin), or surgery (upper lid weighting or tarsorraphy). Once the cornea is adequately protected and recovery deemed unlikely, longer term planning for eyelid and facial reanimation may take place in an individualized manner. Onset is sudden and management potentially lengthy. Physician empathy, knowledge, and experience are essential in averting long-term lifestyle and psychological discomfort for patients.

Botulinum Toxin in Ophthalmology

Since its introduction into clinical medicine in 1980, botulinum toxin has become a major therapeutic drug with applications valuable to many medical sub-specialties. Its use was spearheaded in ophthalmology where its potential applications have expanded to cover a broad range of visually related disorders. These include dystonic movement disorders, strabismus, nystagmus, headache syndromes such as migraine, lacrimal hypersecretion syndromes, eyelid retraction, spastic entropion, compressive optic neuropathy, and, more recently, periorbital aesthetic uses. Botulinum toxin is a potent neurotoxin that blocks the release of acetylcholine at the neuromuscular junction of cholinergic nerves. When used appropriately it will weaken the force of muscular contraction, or inhibit glandular secretion. Recovery occurs over 3 to 4 months from nerve terminal sprouting and regeneration of inactivated proteins necessary for degranualtion of acetylcholine vesicles. Complications are related to chemodenervation of adjacent muscle groups, injection technique, and immunological mechanisms.

Automated Facial Image Analysis

The purpose of this study was to evaluate the ability of Automated Facial Image Analysis (AFA) to detect changes in facial motion after Botox injections in patients with facial nerve disorders accompanied by abnormal muscle activity. Eight subjects received Botox for oral to ocular synkinesis (n = 6), ocular to oral synkinesis (n = 1), and/or depressor anguli oris overactivity (n = 3). Subjects were video-recorded during 2 directed facial action tasks before and after Botox treatment. AFA measurement and Facial Grading System (FGS) scores were used to evaluate the effects of Botox. After Botox, AFA detected a decrease in abnormal movements of the eyelids in all patients with oral to ocular synkinesis, a decrease in oral commissure movement for the patients with ocular to oral synkinesis, and an increase in oral commissure movement in all patients with depressor overactivity. The FGS scores failed to demonstrate any change in facial movement for the case of ocular to oral synkinesis and for 2 cases of depressor overactivity. AFA enables recognition of subtle changes in facial movement that may not be adequately measured by observer based ratings of facial function.