it is characterized by unilateral or bilateral paralysis of the sixth and seventh cranial nerves , manifested clinically as external ophthalmoplegia and weakness of facial muscles . even though von graaefe described a case of congenital facial diplegia in 1880 , it was paul julius mbius , a german neurologist , who drew attention to the association of congenital facial diplegia with other malformations in 1888 and 1892 . only about 300 cases have been reported in the literature , and very few cases of this syndrome have been reported in the radiology literature . a 2-year - old girl was referred to our department for plain magnetic resonance imaging ( mri ) scan of the brain . the child 's parents noticed facial asymmetry in the child with deviation of the angle of mouth to the right side on smiling , watering and incomplete closure of the left eye since birth . the child 's birth and developmental history were normal . on physical examination , facial asymmetry , bilateral convergent squint , prominent everted upper and lower lips were noted . left facial nerve paralysis and bilateral abducent nerve paralysis mild ptosis on left side is also seen ( b ) picture demonstrating left - sided facial paralysis causing deviation of angle of mouth to right side on smiling mr examination was performed using a 1.5 tesla mri scanner ( avanto ; siemens medical solutions , erlangen , germany ) . axial and sagittal t1-weighted , axial t2-weighted , fluid - attenuated inversion recovery ( flair ) , and three - dimensional ( 3d ) constructive interference in steady state ( ciss ) sequences ( 0.7-mm slice thickness ) were evaluated . mri brain showed the following findings : 
 absent cisternal and canalicular segments of left facial nerve [ figures 2 and 3]nonvisualization of cisternal segments of bilateral abducens nerves [ figures 2a and c]flattened floor of fourth ventricle with absence of bilateral facial colliculi [ figure 4 ] . absent cisternal and canalicular segments of left facial nerve [ figures 2 and 3 ] nonvisualization of cisternal segments of bilateral abducens nerves [ figures 2a and c ] flattened floor of fourth ventricle with absence of bilateral facial colliculi [ figure 4 ] . four ( a  d ) contiguous 0.7-mm thick axial 3d ciss mr images of brain showing the absence of left facial nerve in cerebellopontine angle cistern ( a and c , bent arrows ) . right facial nerve ( a , black arrow head ) and bilateral vestibulocochlear nerves ( a and c , black arrows ) are visualized . in addition , there is absence of bilateral abducens nerves ( a , b , and d , white arrows ) in prepontine cisterns , the expected position of bilateral abducens nerves ( a  d images are cranial to caudal sections ) parasagittal ciss mr image of left internal auditory canal ( iac ) showing absent facial nerve in anterosuperior part of left iac ( black arrow ) . vestibular ( thick white arrow ) and cochlear nerves ( thin white arrow ) are visualized in posterior and anteroinferior parts of left iac respectively . ( anterior is to the left of image and posterior is to the right ) axial t1w mr image at the level of middle cerebellar peduncles showing flattened floor of fourth ( black arrow ) ventricle secondary to absence of bilateral facial colliculi the left anterior inferior cerebellar artery ( aica ) flow void was absent , and mild prominence of the right aica was noted [ figure 5 ] . axial ciss mr image showing right aica ( black arrow ) and absent left aica ( white arrow ) mbius syndrome is rare disorder , which is characterized by congenital complete or partial facial nerve paralysis with or without paralysis of other cranial nerves . the definition and criteria for diagnosis of mbius syndrome vary among authors . based on previously published reviews , kumar used the following criteria for diagnosis of this syndrome : ( a ) complete or partial facial nerve paralysis is an essential criterion for the diagnosis of mbius syndrome , ( b ) limb malformations ( syndactyly , brachydactyly , absent digits , talipes ) are often present , ( c ) bilateral or unilateral cranial nerve palsies ( commonly vi , xii , also ix , x ) may be seen , ( d ) orofacial malformations , ear deformities , and musculoskeletal deformities may also be seen . recently , verzijl et al . , suggested facial palsy with impairment of ocular abduction as the primary criterion for mbius syndrome , with or without association of other cranial nerve paralysis , musculoskeletal defects , or orofacial malformations . mbius syndrome manifests soon after birth with inability to close the eyelids during sleep , drooling of saliva , difficulty in sucking , and mask - like facies . the hypoglossal nerve is the third most common nerve to be involved , causing paralysis and hypoplasia of the tongue . although neither the etiology nor the pathogenesis of mbius syndrome has yet been elucidated , verzijl et al . proposed two theories based on previous published reviews : ( a ) a developmental rhombomeric defect including facial cranial nerve nuclei due to a genetic cause , or ( b ) an interruption in the vascular supply of the brainstem secondary to an environmental , mechanical , or genetic cause resulting in ischemia in the region of facial cranial nerve nuclei . an association of absent aica with mbius syndrome is not described in the literature ; however , an association of the ischemic process resulting from an interruption of vascular supply to the brainstem in early fetal development was proposed . absent left aica with mildly prominent contralateral aica , observed in our case , may be an incidental finding and an anatomic variant . at times , either the posterior inferior cerebellar artery or the aica is absent and one artery supplies the usual territories of both arteries . however , mri is useful in demonstrating the abnormalities of the cranial nerves and orbital structures . other computed tomography ( ct ) and mr imaging findings include brainstem hypoplasia with straightening of floor of the fourth ventricle , indicating absence of the facial colliculus ; calcification in pons in the region of abducens nuclei ; absence of hypoglossal eminence at the medulla ; and cerebellar hypoplasia . based on history and clinicoradiological examinations ( 3d ciss ) , our case was diagnosed as mbius syndrome . craniofacial syndrome with asymmetric crying facies , congenital heart disease , and other factors may be confused with mbius syndrome . other neuromuscular disorders such as melkersson  rosenthal syndrome , muscular dystrophy , congenital facial muscular atrophy , cerebral palsy , and congenital myopathies may overlap with mbius syndrome . the seventh nerve palsy in mbius syndrome primarily affects the upper face , which is differentiated from other lower motor neuron palsies affecting both upper and lower portions of the face . additionally , this can also be differentiated from supranuclear lesions , which only affect the lower half of the face . since the disease is congenital and nonprogressive , no definitive and established treatment has been described . ocular care and careful monitoring of complications that might set in , patient education , and a multidisciplinary approach by health professionals help to reduce the morbidity . we herein reported a case of mbius syndrome with absent left facial and bilateral abducens nerves . it is an irreversible condition that causes not only physical abnormalities but also social and psychological disturbances . ct and mr imaging may depict abnormalities in the brainstem , extraocular muscle hypoplasia , and other associated abnormalities . mr imaging , particularly 3d ciss sequence , is very useful in evaluating cisternal and cavernous segments of the cranial nerves . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .