Facial animation in patients with Moebius and Moebius-like syndromes

Post-surgery Rehabilitative Intervention Based on Imitation Therapy and Mouth-Hand Motor Synergies Provides Better Outcomes in Smile Production in Children and Adults With Long Term Facial Paralysis

Rehabilitation after free gracilis muscle transfer (smile surgery, SS) is crucial for a functional recovery of the smiling skill, mitigating social and psychological problems resulting from facial paralysis. We compared two post-SS rehabilitation treatments: the traditional based on teeth clenching exercises and the FIT-SAT (facial imitation and synergistic activity treatment). FIT-SAT, based on observation/imitation therapy and on hand-mouth motor synergies would facilitate neuronal activity in the facial motor cortex avoiding unwanted contractions of the jaw, implementing muscle control. We measured the smile symmetry on 30 patients, half of whom after SS underwent traditional treatment (control group, CG meanage = 20 ± 9) while the other half FIT-SAT (experimental group, EG meanage= 21 ± 14). We compared pictures of participants while holding two postures: maximum and gentle smile. The former corresponds to the maximal muscle contraction, whereas the latter is strongly linked to the control of muscle strength during voluntary movements. No differences were observed between the two groups in the maximum smile, whereas in the gentle smile the EG obtained a better symmetry than the CG. These results support the efficacy of FIT-SAT in modulating the smile allowing patients to adapt their smile to the various social contexts, aspect which is crucial during reciprocal interactions.

A New Neurorehabilitative Postsurgery Intervention for Facial Palsy Based on Smile Observation and Hand-Mouth Motor Synergies

Objective

To perform a preliminary test of a new rehabilitation treatment (FIT-SAT), based on mirror mechanisms, for gracile muscles after smile surgery.

Method

A pre- and postsurgery longitudinal design was adopted to study the efficacy of FIT-SAT. Four patients with bilateral facial nerve paralysis (Moebius syndrome) were included. They underwent two surgeries with free muscle transfers, one year apart from each other. The side of the face first operated on was rehabilitated with the traditional treatment, while the second side was rehabilitated with FIT-SAT. The FIT-SAT treatment includes video clips of an actor performing a unilateral or a bilateral smile to be imitated (FIT condition). In addition to this, while smiling, the participants close their hand in order to exploit the overlapped cortical motor representation of the hand and the mouth, which may facilitate the synergistic activity of the two effectors during the early phases of recruitment of the transplanted muscles (SAT). The treatment was also aimed at avoiding undesired movements such as teeth grinding. Discussion. Results support FIT-SAT as a viable alternative for smile rehabilitation after free muscle transfer. We propose that the treatment potentiates the effect of smile observation by activating the same neural structures responsible for the execution of the smile and therefore by facilitating its production. Closing of the hand induces cortical recruitment of hand motor neurons, recruiting the transplanted muscles, and reducing the risk of associating other unwanted movements such as teeth clenching to the smile movements.

Workhorse Free Functional Muscle Transfer Techniques for Smile Reanimation in Children with Congenital Facial Palsy: Case Report and Systematic Review of the Literature

BACKGROUND

Pediatric facial palsy represents a rare multifactorial entity. Facial reanimation restores smiling, thus boosting self-confidence and social integration of the affected children. The purpose of this paper is to present a systematic review of microsurgical workhorse free functional muscle transfer procedures with emphasis on the long-term functional, aesthetic, and psychosocial outcomes.

MATERIALS AND METHODS

We performed a literature search of the PubMed database from 1995 to 2019 using the following search strategy: "facial paralysis"[Title/Abstract] OR "facial palsy"[Title]. We used as limits: full text, English language, age younger than 18 years, and humans. Two independent reviewers performed the online screening process using Covidence. Forty articles met the inclusion criteria. The protocol was aligned with the PRISMA statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and was registered at the International Prospective Register of Systematic Reviews (PROSPERO, CRD42019150112) of the National Institute for Health Research.

RESULTS

Free functional muscle transfer procedures include mainly segmental gracilis, latissimus dorsi, and pectoralis minor muscle transfer. Facial reanimation procedures with the use of the cross-face nerve graft (CFNG) or masseteric nerve result in almost symmetric smiles. The transplanted muscle grows harmoniously along with the craniofacial skeleton. Muscle function and aesthetic outcomes improve over time. All children presented improved self-esteem, oral commissure opening, facial animation, and speech.

CONCLUSIONS

A two-stage CFNG plus an FFMT may restore a spontaneous emotive smile in pediatric facial palsy patients. Superior results of children FFMT compared to adults FFMT are probably attributed to greater brain plasticity.

Long-term results of facial animation surgery in patients with Moebius syndrome

Gracilis neuromuscular transplant is considered the gold standard for facial animation in Moebius syndrome patients. However, long-term evaluation of the results has not been critically examined in the international literature. Thus, it remains unknown how the transplanted flap changes with facial growth, and whether contraction (smiling) is maintained. Pediatric patients with Moebius syndrome who underwent facial animation surgery with at least 5 years of follow-up were retrospectively examined. Photographs taken at the 1-year and most recent follow-up visits were analyzed and compared using Emotrics software. Analyses focused on the rest position, and on gentle and maximum smiles. Eighteen patients were enrolled. Seven patients had bilateral and 11 unilateral Moebius syndrome; therefore, 25 gracilis transplants were analyzed. The latest follow-ups ranged from 5 to 13.2 years (mean 7.6 years). The three principal facial expressions that were examined did not differ significantly between 1 year and a mean of 7.6 years after surgery, but tended to improve in most patients. Commissure excursion and smile angle for the maximum smile did improve significantly (p = 0.002 and 0.029, respectively). The series examined in this study supports the limited literature regarding the long-term stability of gracilis transplantation to animate the faces of Moebius syndrome children.

Evaluation of a Pediatric Facial Paralysis Education and Family Support Day

INTRODUCTION

Facial paralysis impairs the mimetic functions of the facial musculature. In pediatric patients, free functioning muscle transfer neurotized with an intact contralateral facial nerve is the gold standard for smile reanimation. In response to requests from families of children with facial paralysis, the Division of Plastic and Reconstructive Surgery at the Hospital for Sick Children hosted an inaugural "Facial Paralysis Family Day." The objective was to create an opportunity for families to meet, exchange stories, and build support networks.

METHODS

This study was a quality improvement project to conduct a needs assessment and evaluate the feasibility and satisfaction of implementing a family support intervention for individuals living with facial paralysis.

RESULTS

The needs assessment demonstrated that families were most interested in advances in medicine, therapy and coping sessions and meeting other families. The post-event evaluation questionnaire indicated that attendees enjoyed the event, would attend again and found it highly valuable connecting and networking other families. It also indicated that key needs identified were addressed, with excellent ratings for the presentation discussing advances in medicine (100% rated "good" or "very good"), the therapy sessions (92% rated "good" or "very good") and the presentations by patients and their families (100% rated "good" or "very good.") DISCUSSION:: Two areas of improvement highlighted were elaborating further on medical advances and facilitating interactions between families. Overall, this event was well regarded and will likely be repeated at our institution and serve as a valuable resource for other hospitals planning to organize a similar event.

Head magnetomyography (hMMG): A novel approach to monitor face and whole head muscular activity

Muscular activity recording is of high basic science and clinical relevance and is typically achieved using electromyography (EMG). While providing detailed information about the state of a specific muscle, this technique has limitations such as the need for a priori assumptions about electrode placement and difficulty with recording muscular activity patterns from extended body areas at once. For head and face muscle activity, the present work aimed to overcome these restrictions by exploiting magnetoencephalography (MEG) as a whole head myographic recorder (head magnetomyography, hMMG). This is in contrast to common MEG studies, which treat muscular activity as artifact in electromagnetic brain activity. In a first proof‐of‐concept step, participants imitated emotional facial expressions performed by a model. Exploiting source projection algorithms, we were able to reconstruct muscular activity, showing spatial activation patterns in accord with the hypothesized muscular contractions. Going one step further, participants passively observed affective pictures with negative, neutral, or positive valence. Applying multivariate pattern analysis to the reconstructed hMMG signal, we were able to decode above chance the valence category of the presented pictures. Underlining the potential of hMMG, a searchlight analysis revealed that generally neglected neck muscles exhibit information on stimulus valence. Results confirm the utility of hMMG as a whole head electromyographic recorder to quantify muscular activation patterns including muscular regions that are typically not recorded with EMG. This key advantage beyond conventional EMG has substantial scientific and clinical potential.

We present an innovative method called head magnetomyography (hMMG), which exploits magnetoencephalography (MEG) as a whole head electromyographic (EMG) recorder. Differently from the typical EMG recording, which needs an a priori selection of the placement of the electrodes, hMMG is able to detect muscular activity from many regions of the face and head simultaneously, including typically overlooked muscles. Our data show that hMMG can readily serve researchers in the emotion field and hold further scientific as well as clinical promise.

Children with facial paralysis due to Moebius syndrome exhibit reduced autonomic modulation during emotion processing

BACKGROUND

Facial mimicry is crucial in the recognition of others' emotional state. Thus, the observation of others' facial expressions activates the same neural representation of that affective state in the observer, along with related autonomic and somatic responses. What happens, therefore, when someone cannot mimic others' facial expressions?

METHODS

We investigated whether psychophysiological emotional responses to others' facial expressions were impaired in 13 children (9 years) with Moebius syndrome (MBS), an extremely rare neurological disorder (1/250,000 live births) characterized by congenital facial paralysis. We inspected autonomic responses and vagal regulation through facial cutaneous thermal variations and by the computation of respiratory sinus arrhythmia (RSA). These parameters provide measures of emotional arousal and show the autonomic adaptation to others' social cues. Physiological responses in children with MBS were recorded during dynamic facial expression observation and were compared to those of a control group (16 non-affected children, 9 years).

RESULTS

There were significant group effects on thermal patterns and RSA, with lower values in children with MBS. We also observed a mild deficit in emotion recognition in these patients.

CONCLUSION

Results support "embodied" theory, whereby the congenital inability to produce facial expressions induces alterations in the processing of facial expression of emotions. Such alterations may constitute a risk for emotion dysregulation.

Effectiveness and safety of the use of gracilis muscle for dynamic smile restoration in facial paralysis: A systematic review and meta-analysis

BACKGROUND

Smiling is a fundamental component of social interactions. Significant challenges arise for patients with facial palsy. One of the key procedures for dynamic smile restoration is the microneurovascular transfer of a gracilis muscle. We aimed to assess the effectiveness and safety of dynamic smile reanimation surgery using the free gracilis muscle unit in patients with facial palsy.

METHODS

We conducted a systematic review and meta-analysis of studies reporting surgical outcomes of dynamic smile restoration using free gracilis muscles identified from EMBASE, Medline, and Web of Science databases from their inception to March 15, 2018. Two-stage screening and data extraction were performed by two independent reviewers. Pooled proportions were calculated using random-effects models.

RESULTS

Thirty-one studies including 1647 patients who underwent 1739 free gracilis flaps were included. Twelve (38.7%) studies measured perioperative smile excursion change using six different tools. Six of these studies were homogeneous and were used in meta-analyses of smile excursion improvement, which revealed a mean change of 7.5 mm (95% CI 6.0-9.0 mm, I² 86.7%) perioperatively. Twenty (64.5%) studies reported perioperative complications, and pooled proportions of flap failures were of 2.9% (95% CI 1.3-4.5%, I² 47.7%).

CONCLUSIONS

Dynamic smile restoration using a free gracilis muscle may represent an effective procedure to regain oral commissure motion and is associated with an approximately 3% rate of flap failure. Masseteric nerve coaptations lead to larger improvements in perioperative smile excursion (10 mm) than cross-facial nerve grafts (6.8 mm). Future studies with homogeneous reporting of smile excursion and patient-reported outcome measures are needed.

Congenital facial palsy and emotion processing: The case of Moebius syndrome

According to the Darwinian perspective, facial expressions of emotions evolved to quickly communicate emotional states and would serve adaptive functions that promote social interactions. Embodied cognition theories suggest that we understand others' emotions by reproducing the perceived expression in our own facial musculature (facial mimicry) and the mere observation of a facial expression can evoke the corresponding emotion in the perceivers. Consequently, the inability to form facial expressions would affect the experience of emotional understanding. In this review, we aimed at providing account on the link between the lack of emotion production and the mechanisms of emotion processing. We address this issue by taking into account Moebius syndrome, a rare neurological disorder that primarily affects the muscles controlling facial expressions. Individuals with Moebius syndrome are born with facial paralysis and inability to form facial expressions. This makes them the ideal population to study whether facial mimicry is necessary for emotion understanding. Here, we discuss behavioral ambiguous/mixed results on emotion recognition deficits in Moebius syndrome suggesting the need to investigate further aspects of emotional processing such as the physiological responses associated with the emotional experience during developmental age.

Update on 13 Syndromes Affecting Craniofacial and Dental Structures

Care of individuals with syndromes affecting craniofacial and dental structures are mostly treated by an interdisciplinary team from early childhood on. In addition to medical and dental specialists that have a vivid interest in these syndromes and for whom these syndromes are of evident interest, experts of scientific background-like molecular and developmental geneticists, but also computational biologists and bioinformaticians-, become more frequently involved in the refined diagnostic and etiological processes of these patients. Early diagnosis is often crucial for the effective treatment of functional and developmental aspects. However, not all syndromes can be clinically identified early, especially in cases of absence of known family history. Moreover, the treatment of these patients is often complicated because of insufficient medical knowledge, and because of the dental and craniofacial developmental variations. The role of the team is crucial for the prevention, proper function, and craniofacial development which is often combined with orthognathic surgery. Although the existing literature does not provide considerable insight into this topic, this descriptive review aims to provide tools for the interdisciplinary team by giving an update on the genetics and general features, and the oral and craniofacial manifestations for early diagnosis. Clinical phenotyping together with genetic data and pathway information will ultimately pave the way for preventive strategies and therapeutic options in the future. This will improve the prognosis for better functional and aesthetic outcome for these patients and lead to a better quality of life, not only for the patients themselves but also for their families. The aim of this review is to promote interdisciplinary interaction and mutual understanding among all specialists involved in the diagnosis and therapeutic guidance of patients with these syndromal conditions in order to provide optimal personalized care in an integrated approach.

A proposal for new neurorehabilitative intervention on Moebius Syndrome patients after 'smile surgery'. Proof of concept based on mirror neuron system properties and hand-mouth synergistic activity

Studies of the last twenty years on the motor and premotor cortices of primates demonstrated that the motor system is involved in the control and initiation of movements, and in higher cognitive processes, such as action understanding, imitation, and empathy. Mirror neurons are only one example of such theoretical shift. Their properties demonstrate that motor and sensory processing are coupled in the brain. Such knowledge has been also central for designing new neurorehabilitative therapies for patients suffering from brain injuries and consequent motor deficits. Moebius Syndrome patients, for example, are incapable of moving their facial muscles, which are fundamental for affective communication. These patients face an important challenge after having undergone a corrective surgery: reanimating the transplanted muscles to achieve a voluntarily control of smiling. We propose two new complementary rehabilitative approaches on MBS patients based on observation/imitation therapy (Facial Imitation Therapy, FIT) and on hand-mouth motor synergies (Synergistic Activity Therapy, SAT). Preliminary results show that our intervention protocol is a promising approach for neurorehabilitation of patients with facial palsy.

Enhancing surgical outcomes: The effects of speech therapy on a school-aged girl with Moebius Syndrome

PURPOSE

Moebius Syndrome is a rare congenital neurological condition often characterized by multiple cranial nerve involvement. This case study presents an eight-year old girl with Moebius Syndrome (MC) who received 30 sessions of speech therapy. This occurred after presenting to clinic 11 months after left facial reanimation with gracilis thigh muscle transfer surgery. On examination, only flickers of left facial movement were observed. There was no movement on the right side of the face. As a consequence of the minimal movement, MC presented with drooling and unintelligible speech. The purpose of speech therapy was three fold: minimise the pooling of saliva, improve the placement of the articulators so that articulation of speech sounds would be more accurate, and gain advances in overall intelligibility.

METHODS

Therapy focussed on speech, facial movement and saliva management using a combination of speech drills, evidence-based articulation therapies, facial exercises with surface electromyography biofeedback, self-awareness training and compensatory saliva management strategies.

RESULTS

After a course of 30 one-hour speech therapy sessions, substantial improvements were seen in speech sound accuracy, overall intelligibility, facial movement and saliva control.

CONCLUSIONS

The combination of surgery and speech therapy led to functional gains that surgery alone did not achieve. The impact of speech therapy on surgical outcomes in individuals with Moebius syndrome deserves further investigation.

Facial Nerve Rehabilitation

Facial nerve paralysis, although uncommon in the pediatric population, occurs from several causes, including congenital deformities, infection, trauma, and neoplasms. Similar to the adult population, management of facial nerve disorders in children includes treatment for eye exposure, nasal obstruction/deviation, smile asymmetry, drooling, lack of labial function, and synkinesis. Free tissue transfer dynamic restoration is the preferred method for smile restoration in this population, with outcomes exceeding those of similar procedures in adults.

Examining the genetics of congenital facial paralysis--a closer look at Moebius syndrome

OBJECTIVES

The molecular underpinnings of Moebius syndrome (MBS) are diverse. This article provides a comprehensive summation of the genetic and etiologic literature underlying this disorder. Elucidating the genetic causes of the disorder can aid in earlier detection and treatment planning.

DESIGN

Articles from 1880-2013 were selected and reviewed by six researchers to understand all of the molecular theories and chronicity of advancements in the literature.

RESULTS

Mutations in the MBS1, MBS2, and MBS3 gene loci all have contributed to the development of MBS through various pathways. HOX family genes coding for homeobox domains, also, have been implicated in the abnormal development of the human brain. These are among the numerous genes that have been linked to the development of MBS.

CONCLUSION

Our study codified nascent findings of the molecular determinants of MBS. These findings add to a growing database of MBS-associated mutations and can be used to diagnose MBS and clarify pathogenesis.

The masseteric nerve: a versatile power source in facial animation techniques

The masseteric nerve has many advantages including low morbidity, its proximity to the facial nerve, the strong motor impulse, its reliability, and the fast reinnervation that is achievable in most patients. Reinnervation of a neuromuscular transplant is the main indication for its use, but it has been used for the treatment of recent facial palsies with satisfactory results. We have retrospectively evaluated 60 patients who had facial animation procedures using the masseteric nerve during the last 10 years. The patients included those with recent, and established or congenital, unilateral and bilateral palsies. The masseteric nerve was used for coaptation of the facial nerve either alone or in association with crossfacial nerve grafting, or for the reinnervation of gracilis neuromuscular transplants. Reinnervation was successful in all cases, the mean (range) time being 4 (2-5) months for facial nerve coaptation and 4 (3-7) months for neuromuscular transplants. Cosmesis was evaluated (moderate, n=10, good, n=30, and excellent, n=20) as was functional outcome (no case of impairment of masticatory function, all patients able to smile, and achievement of a smile independent from biting). The masseteric nerve has many uses, including in both recent, and established or congenital, cases. In some conditions it is the first line of treatment. The combination of combined techniques gives excellent results in unilateral palsies and should therefore be considered a valid option.

Facelift approach for mandibular resection and reconstruction

BACKGROUND

Mandibular resection is the mainstay in the treatment of several pathologies involving the jaw. When benign lesions are approached, a limited exposure and less invasive access considering the cosmetic outcome is desirable to reduce morbidity and increase patient's quality of life after surgery. The facelift approach is widely used for rhytidectomy, parotidectomy, and facial animation procedures, whereas its use for mandibular resection and reconstruction is not described yet.

METHODS

Six patients underwent mandibular resection and reconstruction with free flaps or bone grafts via the facelift approach were retrospectively evaluated with regard to function and cosmesis.

RESULTS

No impairment of occlusion or facial nerve occurred; mouth opening was normal in 4 patient and partially limited in 2. Cosmesis was assessed as excellent by 3 patients and good in 3.

CONCLUSION

The facelift approach is a valid option for resecting and reconstructing benign lesions involving the mandibular ramus, angle, and posterior body.

Oral motor assessment in individuals with Moebius syndrome

BACKGROUND

Moebius syndrome (MS) is a rare congenital condition that is characterised by facial hypomimia and congenital strabismus caused by complete or partial impairment of the 6th and 7th cranial nerves. MS may be further associated with other nerves or malformations, mainly involving the extremities. The objective of this study was to quantify the decrease in oral motor performance in people with MS compared with normoreactive individuals using the Oral Motor Assessment Scale (OMAS).

METHODS

The study group comprised 33 subjects between the ages of 2 and 20 years (average age: 10 ± 5 years) with MS along with 46 age- and gender-matched control subjects.

RESULTS

The study group displayed a lower average functional score than the control group (P < 0.0001). A significant lack of lip closure (P = 0.03) and anterior lingual seal during swallowing (P = 0.03) occurred in the study group; in most cases, the individuals with MS were classified as 'subfunctional'. In addition, individuals with MS in the older age group displayed better functional scores than those in the younger group (P = 0.05).

CONCLUSIONS

Functional damage to oral motor function in individuals with MS is evident, but differs among patients with respect to severity and the movements that are compromised. However, overall, improvements in the functional patterns of these individuals can be observed as they mature in age.

Dynamic reanimation for facial palsy: an overview

Facial paralysis can have a profound effect on the patient from both an aesthetic and functional point of view. The symptoms depend on which branch of the nerve has been damaged and the severity of the injury. The purpose of this paper is to review currently available treatments for dynamic reanimation of a damaged facial nerve, and the goals are a symmetrical and coordinated smile. Careful selection of patients and use of the appropriate surgical technique can have excellent results.

Orthognathic surgery for the complete rehabilitation of Moebius patients: principles, timing and our experience

Moebius syndrome is a rare disorder found in approximately 1/100,000 neonates and the treatment of facial palsy is now well established worldwide and consists of free-muscle transplants reinnervated with motor nerves. Dentofacial deformities are often detected in Moebius patients, and different degrees of micrognathia are often present, particularly in patients with complete expressions of Moebius syndrome. However only two published reports have described the surgical treatment of such anomalies in these patients; in both cases, the suggested approach consisted of orthognathic surgery followed by soft-tissue management. In this paper we discuss the indications and correct timing of orthognathic surgery and suggest to perform facial animation at an early age and then to wait for the completion of maxillofacial skeletal growth before performing orthognathic surgery. Finally, facial animation should precede orthognathic surgery in adult patients to prevent lower lip deformities and to ensure more predictable and satisfactory results.

Novel FGF8 mutations associated with recessive holoprosencephaly, craniofacial defects, and hypothalamo-pituitary dysfunction

CONTEXT

Fibroblast growth factor (FGF) 8 is important for GnRH neuronal development with human mutations resulting in Kallmann syndrome. Murine data suggest a role for Fgf8 in hypothalamo-pituitary development; however, its role in the etiology of wider hypothalamo-pituitary dysfunction in humans is unknown.

OBJECTIVE

The objective of this study was to screen for FGF8 mutations in patients with septo-optic dysplasia (n = 374) or holoprosencephaly (HPE)/midline clefts (n = 47).

METHODS

FGF8 was analyzed by PCR and direct sequencing. Ethnically matched controls were then screened for mutated alleles (n = 480-686). Localization of Fgf8/FGF8 expression was analyzed by in situ hybridization in developing murine and human embryos. Finally, Fgf8 hypomorphic mice (Fgf8(loxPNeo/-)) were analyzed for the presence of forebrain and hypothalamo-pituitary defects.

RESULTS

A homozygous p.R189H mutation was identified in a female patient of consanguineous parentage with semilobar HPE, diabetes insipidus, and TSH and ACTH insufficiency. Second, a heterozygous p.Q216E mutation was identified in a female patient with an absent corpus callosum, hypoplastic optic nerves, and Moebius syndrome. FGF8 was expressed in the ventral diencephalon and anterior commissural plate but not in Rathke's pouch, strongly suggesting early onset hypothalamic and corpus callosal defects in these patients. This was consolidated by significantly reduced vasopressin and oxytocin staining neurons in the hypothalamus of Fgf8 hypomorphic mice compared with controls along with variable hypothalamo-pituitary defects and HPE.

CONCLUSION

We implicate FGF8 in the etiology of recessive HPE and potentially septo-optic dysplasia/Moebius syndrome for the first time to our knowledge. Furthermore, FGF8 is important for the development of the ventral diencephalon, hypothalamus, and pituitary.

Ophthalmologic and systemic features in möbius syndrome an italian case series

PURPOSE

To describe clinical features in a large series of Möbius syndrome (MBS) cases, investigating whether specific neuro-ophthalmologic patterns of disease may provide further insight into MBS pathogenesis.

DESIGN

Observational, prospective study.

PARTICIPANTS

Fifty-five affected subjects.

METHODS

To make an MBS diagnosis, the criteria recommended in the First Scientific Conference on Möbius Syndrome were followed. Patients who did not meet the minimal criteria were classified as Möbius-like cases and were considered separately. Complete ophthalmologic evaluation, eyelid measurements, presence of abnormal tearing, and ocular motility also were assessed.

MAIN OUTCOME MEASURES

Pattern of ocular motility alteration, visual function disturbances, and eyelid and tearing defect.

RESULTS

Forty-six sporadic cases of true MBS were identified, with 3 specific patterns of ocular motility alterations. Pattern A, consisting of orthotopia in primary position with a complete defect in both abduction and adduction ocular movements, was found in 41% of cases. Pattern B, with large-angle esotropia, crossed fixation, and a relative sparing of convergence and adduction, was documented in 50% of cases. Pattern C, characterized by a large-angle exotropia in primary position with torticollis, absence of convergence, and vertical eye misalignment, was present in the minority of the patients (9%). Bilateral complete facial nerve palsy with lagophthalmos was present in 83% of patients; lacrimation showed abnormalities in 33% of cases. Visual acuity was good or impaired only moderately in all tested patients. Binocular function was testable in 31 of 46 patients, and all of them showed a complete absence of stereopsis with suppressive scotoma.

CONCLUSIONS

Based on the observed 3 different ocular motility defect patterns, the most compatible site and extension of the brainstem damage was inferred. Each pattern may reflect a different type of injury likely occurred during embryogenesis. The comparison of the characteristics of this series with those reported in different geographic areas supports the evidence that MBS does not differ phenotypically worldwide.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.