the syndrome is named after french neurosurgeon octave crouzon , who described this rare genetic disorder first time in 1912 .
although it is encountered rarely , crouzon syndrome constitutes almost 5% of all craniosynostoses with an approximate birth prevalance of 1/25,000 - 1/50,000 .
the syndrome is characterized by abnormal head shape , midfacial hypoplasia , maxillary hypoplasia , mandibular prognathism , ocular hypertelorism , proptosis , and airway obstruction due to premature fusion of multiple calvarial and skull base sutures within the first year of life .
however , the clinical picture may vary greatly from mild to severe midfacial and orbital anomalies .
the relationship between craniosynostosis and chiari malformation type i ( cm - i ) has been well - documented .
cm - i has a tendency to accompany syndromic craniosynostosis more commonly than sporadic synostosis .
the incidence of cm - i in crouzon syndrome is about 70% . herein , we present a 16-year - old boy who admitted with symptoms related to cm - i and underwent suboccipital decompression . however , on physical examination his cruzonoid features drawed attention .
a 16-year - old , formerly healthy boy admitted to the outpatient clinic with occasional headache and neck pain . on physical examination
it was remarked that he had characteristic features of syndromic craniosynostoses : hypertelorism , proptosis , midfacial hypoplasia , and abnormal head shape [ figures 1a and b ] .
however , the patient and his family did not admit to a hospital for this reason before , despite prominent cruzonoid features .
the patients neurological examination revealed no abnormalities including pinprick , touch , pain , and temperature sensations in both upper extremities .
anteroposterior ( ap ) and lateral plain radiographs of head and a cranial computed tomography ( ct ) demonstrated midfacial and orbital hypoplasia , the fusion of bilateral coronal and lambdoid sutures and sagittal suture , alongside with the increase of ap diameter of the head [ figures 2a and b ] .
cranial and spinal magnetic resonance imaging ( mri ) studies were obtained and it showed a 18 mm cerebellar tonsil herniation into the foramen magnum with accompanying syringomyelia between th 4 and th 7 [ figure 3 ] .
surgery was planned in order to decompress the posterior cranial fossa . using a median incision ,
the dura was opened in y - form and after arachnoid dissection duraplasty was performed .
there were no significant events in the postoperative course and the patient was discharged from the hospital with no neurological deficits .
the patient was then referred to the genetics department for the further evaluation of the craniosynostosis .
phenotypical features like the typical dismorphic facies , ocular proptozis and hypertelorism , parrot - like nose , and frontal bossing alongside with the patients mothers history of four recurrent intrauterine fetal losses supported the diagnosis of crouzon syndrome in our patient .
regular follow - up examinations were scheduled for the observation of orbital deformities and vision .
control mri showed complete resolution of the tonsillar herniation and significant reducement of the syringomyelia both in length and thickness [ figures 4a and b ] .
four years after the operation the patient is still doing well with no neurological or ocular deficits and with the relief of his symptoms at the admission . ( a and b ) photographs show characteristic features of syndromic craniosynostoses in our patient : hypertelorism , proptosis , midfacial hypoplasia , and abnormal head shape .
( published with permission and informed consent of the patient ) ( a ) anteroposterior ( ap ) and lateral plain radiographs of head shows increase of ap diameter of the head and midfacial - orbital hypoplasia .
fusion of multiple calvarial sutures is also remerkable , ( b ) axial cranial computed tomography scan demonstrated the abnormal head shape and the fusion of bilateral coronal and lambdoid sutures alongside with sagittal suture sagittal t2-weighted magnetic resonance imaging shows a 18 mm cerebellar tonsil herniation into the foramen magnum with accompanying syringomyelia between th 4 and th 7 with the largest thickness of 11 mm ( a ) sagittal t2-weighted mri of the craniocervical junction showed complete resolution of 18 mm cerebellar tonsil herniation , ( b ) sagittal t2-weighted thoracal mri showed relative resolution of the accompanying syringomyelia between th 4 and th 7 with the largest thickness of 7 mm
the premature fusion of cerebral sutures has been postulated as the mechanism leading to the development of cm - i in patients with syndromic craniosynostosis .
especially premature fusion of the lambdoid suture has been accepted as a crucial developmental anomaly , which results in a relatively small posterior fossa .
cinalli et al . , have reported that cm - i is present in 70% of patients with crouzon syndrome . on contrary ,
they have proposed , that this relationship is due to earlier closure of sagittal and lambdoid sutures in crouzon syndrome compared to apert syndrome .
hydrocephalus , jugular venous stenosis leads to venous hypertension and associated brain malformations have been postulated as the other mechanisms leading to cm - i development .
mutations in three of four fibroblast growth factor receptor ( fgfr ) genes have been demonstrated to be responsible for various types of syndromic craniosynostoses including crouzon syndrome .
fujisawa et al . , have demonstrated that a missense mutation in fgfr2 gene ( tyr281cys ) is responsible for the development of cm - i in patients with crouzon syndrome .
, the patient or his family was never attempted to seek for professional medical help .
the syndrome was only diagnosed when the patient was admitted to our department with symptoms of cm - i .
strahle et al . , presented a series of patients with cm - i associated with craniosynostosis . in their series of 29 patients ,
however , the mean age of the whole patient group was 1.8 years ( range 2 months-9 years ) .
this data shows that both craniosynostosis or craniosynostosis related cm - i are expected to be diagnosed in early childhood .
cm - i could be diagnosed before the craniosynostosis in some instances , but the age of our patient at diagnosis was 16 . to our knowledge , this is the only case report indicating a late adolescent diagnosis of crouzon syndrome through clinical symptoms of an associated cm - i
. surgical approach to craniosynostosis related cm - i may include cranial vault remodeling with an adequate posterior fossa decompression . however , most neurosurgeons agree with the conservative follow - up of patients with cm - i unless it is not symptomatic or associated with spinal syringomyelia .
strahle et al . , reported some of his patients cm - i was resolved or regressed with cranial vault remodeling only , without posterior fossa decompression .
, we do not consider cranial vault remodeling as an option , instead we applied a classical posterior fossa decompression for cm - i .
strahle et al . , underlined the risk of venous bleeding due to abnormal venous sinuses and increased venous hypertension , therefore suggested a posterior fossa decompression without dural opening and c1 arcusectomy .
we did not encounter any venous bleeding during the surgery , where we opened dura and performed a duraplasty .
pediatric patients with cm - i should be carefully examined for the clinical signs and features of crouzon syndrome or other syndromic craniosynostosis . in mild clinical forms or in case of a late diagnosis , posterior fossa decompression without cranial remodeling should be kept in mind as a treatment option .
 chiari malformation type i ( cm - i ) related to syndromic craniosynostosis in pediatric patients has been well - studied . 
 the surgical management consists of cranial vault remodeling with or without posterior fossa decompression . 
 there were also cases , in whom cm - i was diagnosed prior to the craniosynostosis in early childhood . 
 we present a 16-year - old boy who admitted with symptoms related to cm - i . with careful examination and further genetic investigations , 
 a diagnosis of crouzon syndrome was made , of which the patient and his family was unaware before . 
 the patient underwent surgery for posterior fossa decompression and followed - up for crouzon 's syndrome . to our knowledge , this is the only case report indicating a late adolescent diagnosis of crouzon syndrome through clinical symptoms of an associated cm - i . 
Introduction
Case Report
Discussion
Conclusion