The localization of facial motor impairment in sporadic Mobius syndrome

Autonomic Responses to Emotional Stimuli in Children Affected by Facial Palsy: The Case of Moebius Syndrome

According to embodied simulation theories, others' emotions are recognized by the unconscious mimicking of observed facial expressions, which requires the implicit activation of the motor programs that produce a specific expression. Motor responses performed during the expression of a given emotion are hypothesized to be directly linked to autonomic responses associated with that emotional behavior. We tested this hypothesis in 9 children (M_age = 5.66) affected by Moebius syndrome (MBS) and 15 control children (M_age = 6.6). MBS is a neurological congenital disorder characterized by underdevelopment of the VI and VII cranial nerves, which results in paralysis of the face. Moebius patients' inability to produce facial expressions impairs their capacity to communicate emotions through the face. We therefore assessed Moebius children's autonomic response to emotional stimuli (video cartoons) by means of functional infrared thermal (fIRT) imaging. Patients showed weaker temperature changes compared to controls, suggesting impaired autonomic activity. They also showed difficulties in recognizing facial emotions from static illustrations. These findings reveal that the impairment of facial movement attenuates the intensity of emotional experience, probably through the diminished activation of autonomic responses associated with emotional stimuli. The current study is the first to investigate emotional responses in MBS children, providing important insights into the role of facial expressions in emotional processing during early development.

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.

Pathogenesis of cranial neuropathies in Moebius syndrome: Electrodiagnostic orofacial studies

INTRODUCTION

We designed a retrospective study of 59 patients with congenital sporadic nonprogressive bilateral facial and abducens palsies.

METHODS

Examinations included needle electromyography (EMG) of facial and oral muscles, facial nerve motor latency and conduction velocity (FNCV), and blink responses (BR).

RESULTS

Neurogenic EMG changes were found in 1 or more muscles in 55 of 59 patients, with no abnormal spontaneous activity. EMG changes were homogeneously neurogenic in 17 patients, homogeneously myopathic in 1 patient, and heterogeneous in 41 of 59 patients. Motor latency was increased according to recordings from 52 of 137 facial muscles. An increase of motor latency was not associated with neurogenic EMG (Fischer's test: right, P = 1; left, P = 0.76). FNCV was slowed in 19 of 36 patients. BR was absent bilaterally in 35 of 58 patients; when present, R1 and R2 latencies were normal.

DISCUSSION

Our results support the hypothesis of an early developmental defect localized in motor cranial nerves with spared V-VII internuclear pathways. Muscle Nerve, 2018.

Managing the child with a diagnosis of Moebius syndrome: more than meets the eye

Moebius syndrome (MBS) is a congenital, non-progressive facial and abducens nerve palsy in the presence of full vertical gaze and may be associated with limb abnormalities and craniofacial dysmorphisms. MBS is now defined as a disorder of rhombencephalic maldevelopment and recent gene discoveries have shown this to be a dominant disorder in a subset of patients. Accurate diagnosis and management by a multidisciplinary team with expertise in congenital facial palsy is paramount.

Moebius syndrome: clinical features, diagnosis, management and early intervention

Background

Moebius syndrome (MBS) is rare disease characterized by nonprogressive congenital uni- or bi-lateral facial (i. e. VII cranial nerve) and abducens (i. e. VI cranial nerve) palsy. Although the neurological and ophthalmological findings are quite well-known, data concerning the attendant functional difficulties and their changes over time are seldom addressed.

In this study we attempt to estimate the prevalence of clinical and functional data in an Italian cohort affected by MBS.

Methods

The study included 50 children, 21 males and 29 females, aged 1 month to 14 years. The patients entered into a multidisciplinary diagnostic and follow-up protocol that had the specific purpose of detecting clinical and developmental deficits related to MBS.

Results

Involvement of the VII cranial nerve (total/partial, bilateral or unilateral) was present in 96 % of patients, and of the VI nerve in 85 %. Two patients were without impairment of the VII nerve and seven patients had no involvement of the VI nerve and were thus classified as Moebius-like because of the involvement of other CNs. Additional affected CNs were numbers III-IV in 16 %, V in 11 %, VIII and X each in 8 %, the XI in 6 %, the IX, most often partially, in 22 %, and the XII in 48 % of cases. Their development was characterized by global delay at one year of age, motor, emotional and speech difficulties at two years of age, a trend toward normalization at three years of age but with weakness in hand-eye coordination, and achieving average results at five years of age. Overall 90 % of children had a normal developmental quotient whereas only 10 % manifested cognitive deficits.

Conclusion

Early rehabilitation may enhance the recovery of normal function, particularly in vulnerable areas of development. It is possible that early intervention that integrates sensory and visual information with emotional difficulties can improve the prognosis of the child with MBS.

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.

[A case of Möbius syndrome with congenital facial palsy and supranuclear oculomotor palsy]

An 18-year-old man with congenital weakness in the facial and mastication muscles was referred to us. His facial senses were intact; however, the bilateral massetter and facial muscles were extremely weak and atrophic. He presented lagophthalmos and had difficulty in closing his mouth. The voluntary movements of his left eye, such as abduction, adduction, and elevation, were partially impaired, without the impairment of the Bell phenomenon. Nerve conduction studies of the facial nerves revealed normal distal latencies for bilateral orbicularis oculi. Blink reflexes were not evoked on both sides. Needle electromyography showed a chronic neurogenic change in the tongue. A biopsy of the biceps brachii and skin did not show abnormality. We diagnosed his condition as Möbius syndrome with congenital facial palsy and supranuclear oculomotor palsy. Möbius syndrome, which manifests itself as congenital and non-progressing facial and abducens palsy, is associated with many clinical symptoms and is probably heterogenous nosological entity. Although several cases of Möbius syndrome with supranuclear binocular elevation palsy were previously known, this is the first case of Möbius syndrome presenting supranuclear monocular elevation palsy.

Clinical characteristics and outcomes of Möbius syndrome in a children's hospital

BACKGROUND

Möbius syndrome is a congenital disorder with facial and abducens palsy. Although a few case series studies have examined comorbid conditions in Möbius syndrome, follow-up and outcome data are sparse.

OBJECTIVES

To examine the clinical characteristics and outcomes of Möbius syndrome.

METHODS

Clinical data were reviewed for 10 patients. Neonatal history, neurological examination, comorbid anomalies, medical home care, outcomes, and neuroimaging were summarized.

RESULTS

The patients' mean age was 7.3 ± 6.2 years. On neurological examination, absent blink reflex, jaw ankylosis, absent gag reflex, and tongue atrophy were frequently observed. Poland anomaly and clubfoot were present in three and six patients, respectively. Specific therapies required for patients included medical home care (six patients), suction apparatus (six), tube feeding (five), gastrostomy (two), tracheostomy (three), oxygen therapy (three), and home ventilator (two). Punctate calcification in the brainstem was observed in four patients. Pontine and medulla hypoplasia were detected on the basis of anteroposterior diameter in four and seven patients, respectively. Two patients had congenital hydrocephalus with aqueductal stenosis. Global developmental delay occurred in five patients. Three patients died.

CONCLUSION

The rate of both the use of home medical devices and death was high in our patients. Möbius syndrome is extremely diverse, not only in clinical manifestation, but also outcome. Early multidisciplinary intervention is important to ensure an optimal outcome. Aqueductal stenosis is an occasional comorbid anomaly resulting from midbrain abnormality.

Unilateral Möbius syndrome: two cases and a review of the literature

IMPORTANCE

The Möbius sequence is a rare condition defined by the combination of congenital non-progressive facial and abducens nerve palsies. The etiology of the sequence is still unknown, but likely encompasses a group of heterogeneous disorders involving genetic maldevelopment of the brainstem, a fetal vascular insult and/or teratogen exposure. The clinical phenotype reported has expanded over the years, and may be associated with more extensive cranial nerve and oropharyngeal involvement, as well as limb defects.

OBSERVATIONS

We describe two cases of children presenting with unilateral Möbius syndrome associated with ipsilateral unilateral palatal weakness. Investigations failed to identified a clear underlying etiology, but both cases shared phenotypic features of other more common cranial facial disorders such as craniofacial microsomia and the velocardiofacial syndrome.

CONCLUSION AND RELEVANCE

These two cases highlight the clinical heterogeneity of the Möbius sequence. Although asymmetries are not uncommon, cases with strictly unilateral features are extremely rare, and as such these may represent a distinct subgroup that may pertain to a specific etiology. Although in many cases, evidence of an intrauterine vascular insult may be identified, a contributing genetic etiology should be considered, even in cases with strictly unilateral features. As such genes expressed in the developing rhombencephalon and its vasculature represent good candidates for future investigation.

The facial motor system

Facial movements support a variety of functions in human behavior. They participate in automatic somatic and visceral motor programs, they are essential in producing communicative displays of affective states and they are also subject to voluntary control. The multiplicity of functions of facial muscles, compared to limb muscles, is reflected in the heterogeneity of their anatomical and histological characteristics that goes well beyond the conventional classification in single facial muscles. Such parcellation in different functional muscular units is maintained throughout the central representation of facial movements from the brainstem up to the neocortex. Facial movements peculiarly lack a conventional proprioceptive feedback system, which is only in part vicariated by cutaneous or auditory afferents. Facial motor activity is the main marker of endogenous affective states and of the affective valence of external stimuli. At the cortical level, a complex network of specialized motor areas supports voluntary facial movements and, differently from upper limb movements, in such network there does not seem to be a prime actor in the primary motor cortex.

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.

[Diagnosis and treatment of oculomotor deficits in Möbius sequence]

This article reviews the spectrum of possible motility disorders and ocular misalignment in patients with Möbius sequence. The various options for strabismus surgery are discussed and a stepwise algorithm is presented.

Soft tissue facial morphometry in subjects with Moebius syndrome

Moebius syndrome is a congenital facial palsy associated with the impairment of ocular abduction. The three-dimensional characteristics of the facial soft tissues of 12 male and 14 female subjects [3-52 yr of age (mean age + standard deviation: 17 + 14 yr)] were measured using a non-invasive, computerized system; facial volumes, areas, angles, and distances were computed and compared with those obtained in reference subjects of the same age and gender. When compared with reference subjects, patients with Moebius syndrome had a more prominent and hyperdivergent face in the sagittal plane, a smaller and more prominent upper facial third; a smaller middle facial width; a smaller nose; smaller mandibular volume, depth, corpus length, and ramus height; and a more posterior positioned mandible, with a less prominent chin. In conclusion, patients with Moebius syndrome had a tendency towards a skeletal Class II pattern. These morphological variations may be the combined effect of a general alteration of the motor and sensitive facial nerves, including the trigeminal nerve, and of a maldevelopment of the brainstem.

Facial animation in children with Moebius and Moebius-like syndromes

BACKGROUND

Moebius syndrome, a rare congenital disorder of varying severity, involves multiple cranial nerves and is characterized predominantly by bilateral or unilateral paralysis of the facial and abducens nerves. The paralysis of the VI and VII cranial nerves leads to a lack of function in the muscles they supply. Facial paralysis often causes bilabial incompetence with speech difficulties, oral incompetence, problems with eating and drinking, including pocketing of food in the cheek and dribbling, as well as severe drooling.

METHODS

In this study, we report on pediatric patients with Moebius and Moebius-like syndromes seen and treated surgically from 2003 to September 2007 at the Operative Unit of Maxillofacial Surgery, Head and Neck Department, University of Parma, Italy.

RESULTS

Twelve patients underwent microsurgical reconstruction for restoration of facial movement. The contralateral facial nerve was used as a motor donor nerve in 4 procedures, the motor nerve to the masseter muscle was used in 8 patients, and the gracilis muscle was used in all operations, with a total of 17 free-muscle transplantations. All free-muscle transplantations survived transfer, and no flap was lost. We observed a significant improvement in drooling, drinking, speech, and facial animation with a high degree of patient satisfaction.

CONCLUSIONS

The gracilis muscle free transfer is a surgical procedure well tolerated by the young patients and well accepted by their families. We consider it a safe and reliable technique for facial reanimation with good aesthetical and functional results in children with Moebius and Moebius-like syndromes.

Möbius syndrome as a syndrome of rhombencephalic maldevelopment: a case report

Möbius syndrome is a rare congenital disorder characterized by congenital facial weakness with impairment of ocular abduction. It is considered as a rhombencephalic disorder, and is often accompanied with hypoplasia of the pons and cerebellum. Here we report a male infant who had congenital facial asymmetry with absence of right-sided expression. Evident developmental delay was also found. The bilateral auditory brain stem response showed no response at 85dB. A reconstructive brain magnetic resonance imaging (MRI) revealed the absence of the right facial nerve as well as hypoplasia of the pons and cerebellum of the same side. Some voluntary contraction over the patient's right lower face was noted after facial muscle electrical stimulation.

Inhibitory reflexes in human perioral facial muscles: A single-motor unit study

OBJECTIVE

To describe the reflex responses evoked by trigeminal stimulation in perioral facial motor units (MUs) in humans.

METHODS

We recorded single motor units (MUs) from perioral muscles performing three movements: elevation of the upper lip (levator labii superioris muscle--LLS), protrusion of the lips (orbicularis oris muscle--OOr) and depression of the lower lip (depressor anguli oris and depressor labii inferioris muscles--DAO/DLI) with concentric needle electrodes. MUs were tested during constant voluntary activation with non-painful cutaneous electrical stimuli applied to the mental or supraorbital nerves and intraorally. Analysis was performed with peristimulus histograms and cumulative sum.

RESULTS

Eighty MUs were sampled from 17 subjects. Cutaneous stimulation induced inhibition of discharge in 100% of the lip-depressor MUs, inhibition in 65-70% of LLS MUs and in 25% of OOr MUs. Mean latency of inhibition was of 35+/-12ms. Intraoral stimulation produced an equivalent percentage of inhibitory or facilitatory effects with no difference among the three muscles.

CONCLUSIONS

Reflex responses to cutaneous stimulation identify a completely inhibitory (DAO/DLI), a mainly inhibitory (LLS) and a mixed (OOr) pattern in perioral muscles.

SIGNIFICANCE

A purely inhibitory trigemino-facial reflex is present in lip-lowering muscles with potential use in clinical practice.