Möbius sequence, hypogenitalism, cerebral, and skeletal malformations in two brothers

Moebius Syndrome: What We Know So Far

Moebius syndrome (MBS) is a rare congenital cranial nerve disorder characterized by unilateral, bilateral symmetrical, or asymmetrical facial (VII) and abducens (VI) nerve palsies. Genetics and rhombencephalon vascular disturbances from intrauterine environmental exposures have been attributed to its development. It can present with various orofacial abnormalities. Although the diagnosis is purely clinical, certain characteristic features are present in the brain's images. With no cure, it is essential to devise management on a personalized basis. We discuss etiology, presentation, diagnostic approaches, and effective management in the existing literature. This comprehensive review examines the clinic-pathological aspects of Moebius syndrome. The authors employed the PUBMED base index to identify pertinent literature and reference it according to research keywords. Findings suggest the most popular etiology is the theory of intrauterine vascular disruption to the brainstem during embryogenesis, followed by the genetic hypothesis. Intrauterine environmental exposures have been implicated as potential risk factors. Facial and abducens nerve palsies are the most common presenting features. However, clinical manifestations of lower cranial nerves (IX, X, XI, XII) may be present with orthopedic anomalies and intellectual deficiencies. The diagnosis is clinical with minimal defined diagnostic criteria. Characteristic radiological manifestations involving the brainstem and cerebellum can be observed in imaging studies. With no definitive treatment options, a multidisciplinary approach is employed to provide supportive care. Despite radiological manifestations, Moebius syndrome is diagnosed clinically. Although incurable, a multidisciplinary approach, with personalized rehabilitative measures, can manage physical and psychological deficits; however, standard guidelines need to be established.

Mobius Syndrome: A 35-Year Single Institution Experience

BACKGROUND

Mobius syndrome is a rare syndrome that is known to be associated with a variety of orthopaedic conditions including scoliosis, clubfoot, transverse limb deficiencies, Poland syndrome, and a myriad of hand conditions. To date, no large series exist to characterize the orthopaedic manifestations of Mobius syndrome.

METHODS

Medical records at a single tertiary pediatric institution were reviewed for all patients diagnosed with Mobius syndrome from January 1, 1980 to December 31, 2015. Records and radiographs were reviewed for associated orthopaedic conditions and their management.

RESULTS

In total, 44 patients with Mobius syndrome were identified. Age at presentation ranged from 6 days to 14 years. When compared with the general population, patients with Mobius syndrome had an increased incidence of clubfoot (41%), Poland syndrome (20%), and scoliosis (14%). Clubfoot treated both before and after the institution of Ponseti casting had a high rate of requiring posteromedial release, with a significant rate of subsequent revision. Hip dysplasia was noted in 1 patient and required surgical correction. Other associated syndromes included arthrogryposis, Pierre Robin syndrome, and chromosome 10 defect.

CONCLUSIONS

Mobius syndrome is accompanied by an increased rate of several orthopaedic problems; most notably clubfoot, scoliosis, and upper extremity differences that often require surgical treatment. The management of clubfoot in the setting of Mobius syndrome often requires surgical intervention due to failure of casting, and seems to have a higher rate of need for revision. Early involvement of orthopaedists in the care of patients with Mobius syndrome is often necessary. Orthopaedist should counsel families that treatment may be more complex than that of idiopathic disease.

LEVEL OF EVIDENCE

Level IV-case series.

Orthopedic Manifestations of Mobius Syndrome: Case Series and Survey Study

Background. Mobius Syndrome is a rare disease defined by bilateral congenital 7th nerve palsy. We focus on reporting the prevalence of orthopedic disease in this population. Methods. Twenty-three individuals with Mobius Syndrome underwent orthopedic physical examination, and additional 96 patients filled out a survey for self-reported orthopedic diagnoses. Results. Clubfoot was present in 60% of individuals in the physical exam series and 42% of those in the survey. Scoliosis was present in 26% and 28%, respectively. Poland's Syndrome was present in 17% and 30%. In addition to these findings, 27% of patients reported having difficulty with anesthesia, including difficulty in intubation and airway problems. Conclusion. An increased prevalence of scoliosis, clubfoot, transverse limb deficiencies, and Poland's Syndrome is identified in the setting of Mobius Syndrome. In the setting of several deformities often requiring surgical correction, a high incidence of anesthetic difficulty is noted and should be discussed with patients and other providers during surgical planning.

Isolated Asymptomatic Short Sternum in a Healthy Young Girl

Congenital sternal defects are rare deformities frequently associated with other anomalies of the chest wall and other organ systems. Although pectus excavatum, pectus carinatum, and cleft sternum can present as isolated deformity, in most cases they are associated with heart and inner organs anomalies and described as symptoms of syndromes like Marfan syndrome, Noonan syndrome, Poland anomaly, and Cantrell pentalogy. In contrast, the etiology of an isolated defect is not well understood. We observed a short sternum (dysmorphic manubrium, hypoplastic body, and complete absence of the xiphoid process) in a completely asymptomatic 13-year-old woman. A comprehensive instrumental exams panel was performed to exclude associated anomalies of the heart and of the other organ systems. The patient was completely asymptomatic and she did not need any medical or surgical treatment. To our knowledge, this is the first case of isolated short sternum reported in literature.

[Etiology and genetic aspects of Möbius sequence]

Möbius sequence is a rare congenital disorder defined by partial or complete agenesis of the 6th and 7th cranial nerves, which control eye movement and facial expression. The etiology is unclear but genetic and teratogenic factors are thought to be involved. Ischemia affecting the cranial nerve nuclei is a possible pathomechanism of Möbius sequence. Most cases of Möbius sequence are sporadic but some familial cases are also known. The inheritance patterns of Möbius sequence are heterogeneous and can be autosomal recessive, autosomal dominant or even X-linked. Some candidate regions and candidate genes have been described but no causative gene has yet been confirmed.

[Möbius syndrome and an apparently life-threatening event]

Möbius syndrome is characterized by congenital facial weakness with impairment of ocular abduction. A subgroup of these patients have associated apneas because of involvement of brainstem respiratory centers located slightly lateral to the abducens nuclei. We report a 7-month old infant admitted to the pediatric intensive care unit because of an episode of cyanosis, hypotonia and unresponsiveness. The patient then became respirator dependent afterwards. On examination, facial diplegia, impairment of ocular abduction and hypotonia were evident. Magnetic resonance imaging (MRI) revealed abnormal signal intensity in brainstem tegmentum. At the age of 11 months he was discharged but required a home ventilator. He died 5 months later due to an infection. Möbius syndrome is associated with central respiratory dysfunction. The finding of abnormal signal intensity in brainstem tegmentum on MRI is a possible predictor of apnea in these patients.

The spectrum of Möbius syndrome: an electrophysiological study

We studied the nature and extent of facial muscle innervation and the involvement of the motor and sensory long tracts in Möbius syndrome, in order to shed light on the pathophysiological mechanism of the syndrome. Standardized blink reflexes, direct responses of the facial nerves to the orbicularis oculi muscles and concentric needle electrode electromyography in orbicularis oculi and/or oris muscles were measured in 11 patients with Möbius syndrome, of whom six participated in MRI studies, all showing absent facial nerves. We performed motor- and somatosensory-evoked potentials in seven Möbius patients. We demonstrated three distinct patterns of abnormalities suggesting different sites of the primary lesion in different patients. (i) Presence of normal blink reflexes and facial compound motor action potentials, normal habituation tests, a reduced recruitment in the facial muscles and an aberrant 'blink reflex-like' response of the orbicularis oculi muscle upon stimulation of the facial nerve region, which suggests a supranuclear origin of the defect. (ii) Absent blink reflexes, absent direct responses of the facial nerves and absent motor activity on needle electromyography, indicating a defect at the facial nuclear level. However, the nuclear defect might mask an additional supranuclear defect, which cannot, therefore, be excluded in these patients. (iii) A disperse pattern of facial compound action potentials combined with long latencies that were recorded with concentric needle electrodes, indicating involvement of motor axons in the facial nerve, possibly secondary to nuclear involvement. An additional supranuclear defect cannot be excluded in these cases. All evoked potentials studied were normal. The electrophysiological findings of the facial muscles show a spectrum of disturbances varying in degree of severity and diverse in the extent of structures involved, in 11 Möbius patients. At one end of the spectrum are patients with completely immobile faces in whom electrophysiological testing shows no signs of involvement of the facial nuclei, nerves or muscles, suggestive of a dysfunction at the supranuclear level. At the other extreme of the spectrum are patients with complete absence of responses upon facial nerve stimulation and absence of motor unit activity. This is at least indicative of a defect at the facial nuclear level. While a supranuclear defect is compatible with the concept that Möbius syndrome is a developmental disorder of the lower brainstem, intact facial nuclei as part of the syndrome has not been suggested before. The findings corroborate the concept of the Möbius syndrome being a complex regional developmental disorder of the brainstem.