Moebius syndrome: manifestations in children and treatment

Möbius syndrome is a rare, congenital, non-progressive disorder of cranial nerve development characterized by weakness of facial muscles and limited abduction of one or both eyes. In modern literature, it is considered a congenital disorder of cranial innervation rather than a classic "muscle disease." Prevalence estimates vary widely between registries, reflecting the rarity of the syndrome and historical diagnostic difficulties. [1]

The minimum diagnostic criteria adopted after the 2007 Bethesda conference are formulated very clearly: congenital, non-progressive facial weakness plus congenital ocular abduction deficit. All other features are additional characteristics that may or may not be present. It is this formulation that today helps distinguish Möbius syndrome from other causes of congenital facial weakness. [2]

The clinical significance of the syndrome extends beyond the inability to smile or frown. In early childhood, problems with feeding, swallowing, airway protection, incomplete eyelid closure, strabismus, and poor weight gain are far more significant. Later, speech, chewing, dental problems, motor skills, school adaptation, and psychosocial stress become more prominent. [3]

The syndrome is not considered progressive, but this does not mean it has a "mild" course. Its non-progressive nature means that the disease does not destroy the nervous system over time as a degenerative process. However, the initial innervation disorder can seriously impact a child's development for many years if early multidisciplinary support is not provided. [4]

In practice, this condition requires the participation of not just one doctor, but a team. This team typically includes a pediatrician, a pediatric neurologist, an ophthalmologist, a feeding and swallowing specialist, a speech therapist, a dentist, an orthodontist, an orthopedist, a geneticist, a physical therapist, and, if necessary, a plastic surgeon and psychologist. This approach is now considered the foundation of quality care. [5]

Table 1. What is considered the basis of the diagnosis and what are additional signs

Feature level	What's included
Minimum criteria	Congenital non-progressive facial weakness
Minimum criteria	Congenital abduction deficiency of 1 or 2 eyes
Frequent additional symptoms	Strabismus, incomplete closure of the eyelids, difficulty sucking and swallowing
Frequent additional symptoms	Damage to other cranial nerves
Frequent additional symptoms	Anomalies of the limbs, feet, jaw, and dental system
Long-term significant signs	Speech, motor, learning and psychosocial difficulties

The table is compiled based on modern diagnostic criteria and interdisciplinary reviews. [6]

Why does Moebius syndrome occur?

The exact cause of Möbius syndrome remains unknown. Most cases are sporadic, meaning they occur for the first time in a family. A large phenotypic and genetic study conducted in 2025 found no strong, single hereditary cause, confirming the heterogeneity of the disease and the need to carefully explain to families that in most children, a single "master gene" cannot be identified. [7]

One of the most well-known hypotheses is the vascular one. It suggests a disruption of the blood supply to the developing brainstem and associated structures during the early stages of embryogenesis. This hypothesis has been used for a long time and explains well the combination of cranial nerve damage with limb and chest wall anomalies in some children. [8]

Along with the vascular theory, genetic causes are discussed. Pathogenic variants have been described in the literature, particularly in the PLXND1 and REV3L genes, but their contribution remains limited and does not explain the majority of cases. Therefore, genetic testing is important primarily for clarifying atypical cases, family observations, and ruling out similar syndromes, rather than as a way to "confirm" the diagnosis in every child. [9]

Potential teratogenic effects have also been described historically. Reviews discuss associations with early vascular and toxic effects, including misoprostol and thalidomide, but such data do not mean that the cause is known or proven in each individual child. It is more accurate to speak of associations and hypotheses rather than a rigidly established cause-and-effect relationship. [10]

For families, this means two important practical implications. First, in most cases, the cause is not a parental error during pregnancy. Second, genetic counseling is helpful, especially in cases of an atypical phenotype, family history, multiple malformations, or planning future pregnancies, but a negative genetic test result does not rule out the syndrome. [11]

Table 2. What is known today about the origin of the syndrome

Direction	What is known now
Sporadic cases	They make up the majority
A single genetic cause	For most patients it is not confirmed
Genetic associations	Variants in PLXND1 and REV3L have been described in a minority of patients
Vascular hypothesis	Remains one of the main working models
Teratogenic effects	They are discussed as associations, but do not explain all cases.
Genetic testing	Useful for clarifying and excluding similar syndromes

The table is based on 2023 reviews, clinical resources, and a 2025 genetic study.[12]

How does the syndrome manifest itself in children?

In a newborn, the first signs often include poor facial expressions, weak sucking, choking, an inability to close the lips tightly, and incomplete eye closure. Parents often describe the baby as "too calm in appearance," not smiling, and not changing facial expression when crying. At this age, feeding, body weight, breathing, and corneal condition are especially important for the physician. [13]

Ophthalmologic manifestations are a central component of the syndrome. They are characterized by limited abduction, convergent strabismus, incomplete blinking, and the risk of exposure keratopathy due to facial weakness. According to clinical series, strabismus is common, and the goal of ocular treatment is not to "restore normal motility," but to protect the cornea, prevent amblyopia, and improve the position of the eyes in the primary position. [14]

In addition to the sixth and seventh pairs, some children also experience damage to other cranial nerves, particularly the ninth through twelfth. This explains the chewing and swallowing disturbances, dysarthria, tongue weakness, salivation, and increased risk of aspiration. In interdisciplinary series, lower cranial nerve involvement is estimated to occur in approximately 40-50% of cases, and micrognathia is frequently mentioned. [15]

The syndrome is often accompanied by extracranial anomalies. The most commonly described abnormalities include clubfoot, symbrachydactyly, finger hypoplasia, chest wall abnormalities, micrognathia, high palate, and orthodontic problems. According to clinical reviews, clubfoot occurs in approximately 32-40% of patients, hand hypoplasia in approximately 20%, and hypotonia can reach 75% in some series. [16]

Many children have normal intelligence, but this does not preclude significant functional difficulties. Children may have speech delays, motor developmental difficulties, social communication difficulties, sleep disturbances, increased anxiety, and others may mistakenly assume "low intelligence" simply because of their mask-like facial features and dysarthria. Psychosocial stress is a real part of the syndrome, not a secondary factor. [17]

Dental and maxillofacial consequences must be considered separately. Due to poor lip closure, viscous saliva, dry mouth, dental hypoplasia, and abnormal jaw growth, children are at higher risk for dental caries, malocclusion, and oral hygiene difficulties. Therefore, dental care should begin early rather than be delayed until school age. [18]

Table 3. Main manifestations of Moebius syndrome by system

System	Frequent manifestations
Face	Mask-like face, weak facial expressions, inability to smile, incomplete lip closure
Eyes	Limited abduction, strabismus, incomplete blinking, risk of corneal damage
Feeding and swallowing	Weak sucking, choking, aspiration, poor weight gain
Speech	Dysarthria, speech delay, articulation difficulties
Musculoskeletal system	Clubfoot, hand and foot anomalies, hypotonia, scoliosis
Maxillofacial region	Micrognathia, high palate, malocclusion, dental problems
Development and behavior	Motor and learning difficulties, sleep disturbances, psychosocial difficulties

The table is compiled from ophthalmological, neurological and interdisciplinary reviews. [19]

How is the diagnosis confirmed and what needs to be checked first?

The diagnosis of Möbius syndrome remains primarily clinical. If a child has non-progressive weakness of the facial muscles and abduction deficits in one or both eyes from birth, the diagnosis becomes highly probable. This is an important practical point: the absence of a "confirmatory blood test" does not render the diagnosis questionable if the clinical picture is typical. [20]

After clinical recognition, it's important not only to "confirm the syndrome" but also to assess its severity and systemic consequences. Current protocols recommend initially assessing ophthalmologic status, feeding and swallowing safety, respiratory risks, hearing, development, and associated congenital anomalies. Some centers recommend echocardiography from the outset, as cardiac defects have also been reported in some patients. [21]

Magnetic resonance imaging of the brain and brainstem can be very useful, especially in cases of atypical phenotype or diagnostic doubt. It can reveal brainstem hypoplasia, absent or hypoplastic facial and abducens nerves, and other abnormalities. However, a normal MRI does not rule out the syndrome, so it cannot be used as the sole criterion. [22]

Electromyography and nerve conduction studies can be helpful in complex cases where it is necessary to differentiate Möbius syndrome from congenital myopathies, neuropathies, myasthenic syndromes, and other causes of congenital facial weakness. This is especially important in children with atypical muscle weakness, contractures, unusual muscle tone, or additional neurological signs. [23]

The differential diagnosis is broad. It includes congenital traumatic facial nerve weakness, Duane syndrome, congenital fibrosis of the extraocular muscles, CHARGE syndrome, hereditary congenital facial paresis, congenital myotonic dystrophy, myasthenia gravis, and several other rare neuromuscular conditions. Therefore, atypical cases should be evaluated by a pediatric neurologist and geneticist, not just a single specialist. [24]

Genetic testing makes sense, especially if the phenotype is incomplete, there is a family history, multiple defects, or doubts about the difference between Möbius syndrome and similar conditions. However, when discussing with the family, it is important to explain in advance that a negative result does not invalidate the clinical diagnosis and that the detection of causal variants is currently limited. [25]

Table 4. What is usually included in a child's initial examination

Stage	Why is it needed?
Neurologist examination	Confirmation of clinical criteria and assessment of other cranial nerves
Ophthalmologist examination	Assessment of eye aversion, strabismus, cornea, and risk of amblyopia
Feeding and swallowing assessment	Identification of aspiration, poor weight gain, and need for tube feeding
Respiratory risk assessment	Exclusion of apnea and airway protection disorders
Hearing test	Early detection of hearing loss and impact on speech
Magnetic resonance imaging as indicated	Clarification of the structure of the trunk and cranial nerves, exclusion of other causes
Genetic counseling	Clarification of atypical cases and familial risk
Orthopedic and dental examination	Detection of anomalies of the limbs, jaws and teeth

The table is based on modern protocols for interdisciplinary management. [26]

Table 5. What is most often needed to differentiate Moebius syndrome?

State	What helps to distinguish
Birth injury of the facial nerve	There is no typical eye abduction deficit, there is a connection with birth trauma
Duane syndrome	The main problem is oculomotor, without typical congenital facial weakness
Congenital fibrosis of the extraocular muscles	Different ophthalmological picture and different genetic group
Hereditary congenital facial paresis	May affect the face without the characteristic combination with the VI pair
Congenital myopathies	There are usually more generalized muscle symptoms.
Congenital myasthenic syndromes	Fatigue and other electrophysiological changes may occur.
CHARGE syndrome and other syndromic forms	There are additional typical congenital anomalies

The table is compiled from clinical reviews and ophthalmological materials. [27]

How is Moebius syndrome treated?

There is currently no etiotropic treatment, that is, therapy that eliminates the underlying cause of the syndrome. Therefore, all care is focused on function, safety, and quality of life. In practice, this means early stabilization of feeding and breathing, eye protection, and subsequent work on speech, motor skills, the dental system, orthopedic issues, and psychosocial adaptation. [28]

In the neonatal period, feeding and swallowing become the primary focus. Children with poor breast or bottle latching, lip leakage, coughing, and aspiration require early evaluation by a speech therapist regarding feeding, selection of bottles and nipples, occasional modification of feeding consistency, and, if necessary, video swallowing. If insufficient weight gain persists despite conservative measures, tube feeding is used. [29]

Ophthalmological protection is equally important. Facial weakness can cause a child to blink poorly and not close their eyelids completely, causing the cornea to dry out. Therefore, artificial tears, nighttime eye ointments, sometimes protective cameras, and, in severe cases, surgical measures are used. Strabismus is treated according to general pediatric ophthalmological principles—glasses, observation, sometimes botulinum toxin, and oculomotor muscle surgery. However, the goal here is usually to improve eye position rather than fully restore movement. [30]

Early rehabilitation includes speech therapy, physical therapy, and occupational therapy. A speech therapist is needed not only for speech, but also for feeding, oral motor skills, and, in some children, alternative communication. Physical therapy and occupational therapy help with hypotonia, motor clumsiness, limb abnormalities, and limitations in daily activities. Modern protocols even outline age-specific stages for assessing speech, development, hearing, and psychology. [31]

Dental and orthodontic care should begin early, practically from the moment the first teeth emerge. Children are at higher risk for dental caries, malocclusion, and hygiene problems, so a preventative program, orthodontic monitoring, and sometimes subsequent orthognathic correction are essential. This is not a cosmetic detail, but rather part of basic functional treatment. [32]

A separate area is surgical reconstruction of the smile and face. According to a large surgical series conducted in 2025, free functional muscle transfer is considered the standard for smile reconstruction in Möbius syndrome and produces good or excellent functional and aesthetic results in most patients. In clinical protocols, the issue of reconstruction is often discussed starting at approximately 6 years of age, when the child is better able to participate in postoperative care. [33]

Psychological and social support are just as important as surgery and rehabilitation. A lack of facial expression can interfere with interaction with others, and others often mistakenly perceive the child as "unemotional" or "less intelligent." Parents, teachers, and the child themselves need explanatory work and, if necessary, the help of a psychologist or psychiatrist. [34]

Table 6. Main directions of treatment and support

Direction	What do they usually do?
Feeding and swallowing	Assessing swallowing safety, selecting feeding methods, changing food consistency, tube insertion as indicated
Eye protection	Artificial tears, ointments, corneal monitoring, strabismus treatment
Speech and communication	Speech therapist, oral motor skills development, alternative communication if necessary
Motor sphere	Physiotherapy, occupational therapy, orthopedic correction
Dentistry and bite	Early prevention, treatment of caries, orthodontic monitoring
Sleep and breathing	Assessment of apnea and airway disorders
Psychological help	Support for the family, school, and the child
Smile reconstruction	Free functional muscle transfer in suitable patients

The table is based on interdisciplinary and surgical publications of recent years. [35]

Prognosis and long-term follow-up

Möbius syndrome does not progress, and this is one of the most important prognostic factors. The child is not expected to experience progressive destruction of the nervous system, as with a neurodegenerative disease. However, the severity of functional limitations is highly individual and depends on the severity of cranial nerve damage, nutrition, eye condition, the presence of limb anomalies, hearing, and the quality of early rehabilitation. [36]

In the long term, it is especially important to address five risk areas: nutrition and growth, cornea and vision, hearing and speech, the maxillofacial system, and psychosocial adaptation. This is why modern protocols offer an age-specific monitoring plan: early ophthalmological assessment and nutrition, followed by speech, development, hearing, psychology, and, if indicated, reconstructive surgery. [37]

The prognosis for most children is good, provided severe neonatal airway and aspiration complications are avoided. Clinical resources at major centers emphasize that with appropriate treatment and support, life expectancy is usually not shortened. However, this should not create the false impression that the syndrome "does not require intervention": without support, a child may face significant functional and social difficulties. [38]

Working with the family and school is crucial. A child with Möbius syndrome may experience emotions as deeply as other children, but may express them differently or not at all. A lack of a smile or familiar facial expressions should not be interpreted as a lack of interest, empathy, or intelligence. The sooner adults around the child understand this, the lower the risk of social isolation and secondary psychological problems. [39]

Early rehabilitation does indeed impact outcomes. Even earlier reviews and modern protocols agree that timely assistance with feeding, speech, vision, motor skills, and emotional adjustment improves a child's participation in family and school life. For this disease, the rule is particularly true: the earlier support is initiated, the greater the functional gain in the future. [40]

FAQ

Is this a hereditary disease?
Not always. Most cases are sporadic, meaning they occur for the first time in a family. Genetic causes have been described, but for most patients, a strong, single hereditary cause has not yet been confirmed. [41]

Does Möbius syndrome progress with age?
No, the syndrome is considered non-progressive. However, its effects can have varying impacts on a child's development, so without monitoring, problems with speech, feeding, eyes, teeth, and social adaptation may become more noticeable. [42]

Can a diagnosis be made based solely on facial appearance?
It's not enough. A diagnosis requires a combination of congenital, non-progressive facial weakness and ocular abduction deficit. Additional features are helpful, but they alone do not replace the minimum criteria. [43]

Will a child always have decreased intelligence?
No. Many children have normal intelligence. However, speech, motor, learning, and social-communication difficulties may occur, requiring early support. [44]

Why does a child have difficulty eating and gaining weight?
The cause is usually a combination of poor lip closure, tongue weakness, swallowing difficulties, and sometimes breathing problems. Therefore, the child may need special bottles, changes in feeding consistency, or temporary tube feeding. [45]

Does all children need magnetic resonance imaging?
Not necessarily all, but it is very useful in cases of atypical phenotype, questionable diagnosis, or the need to exclude other causes. A normal magnetic resonance imaging does not rule out Möbius syndrome. [46]

Is it possible to help a child smile?
Yes, reconstructive treatment is possible in appropriate cases. According to modern surgical data, free functional muscle transfer is considered the standard for smile reconstruction and produces good results in many children. [47]

Why is it important to see a dentist so early?
Because children are at higher risk for tooth decay, dry mouth, poor hygiene, and malocclusion. A preventative dental program is recommended to begin as soon as the first teeth appear. [48]

Why might a child have sleep and behavioral problems?
Some of these problems may be related to the damage to the brainstem structures themselves, while others may be due to the accumulated burden of speech, facial expressions, social difficulties, and chronic functional limitations. Therefore, monitoring involves not only a neurologist and ophthalmologist but also psychological support. [49]

When is an infant particularly urgently needed for medical evaluation?
When there is choking, episodes of blueness, poor weight gain, frequent aspiration, severe feeding difficulties, signs of dry eyes, or episodes of breathing during sleep. These are the problems that are most clinically significant in early life. [50]

Conclusion

Möbius syndrome is a rare, congenital, non-progressive disorder of cranial innervation characterized by congenital facial weakness and ocular abduction deficits. However, clinically, this disorder is always more widespread than simply "no smile": it affects feeding, breathing, eyes, speech, dentition, limbs, and social interaction. [51]

Modern tactics are based on early interdisciplinary support. The first stage prioritizes feeding safety, corneal protection, and eliminating respiratory risks. Then come speech, hearing, dentistry, orthopedics, psychology, and, if necessary, smile reconstruction. This approach today provides the best functional prognosis for the child and family. [52]