osteopetrosis ( op ) has also called with its historical names as a albers - schnberg disease , which was firstly described by a german radiologist [ 1 , 2 ] .
the main cause of the disease is osteoclastic activity defect , which results hypersclerotic fragile bone [ 3 , 4 ] .
autosomal recessive op ( aro ) has a two subtype , which are infantile malignant op and intermediate type .
infantile malignant aro has diagnosed within the first year of the life that has fatal clinical progression due to the bone marrow deficiency and infection .
important neurological symptoms are cranial verve palsies due to the obliteration of cranial nerve foramina such as vision loss , deafness , and facial paralysis .
the most common neurological finding is visual loss due to the optic nerve compression within the optic channel .
in contrast to the aro , autosomal dominant op ( ado ) is described as adult benign type due to the normal life expectancy [ 2 , 3 , 7 ] .
ado diagnosis is given easily by recurrent bone fracture history , osteomyelitis , radiologic and laboratory findings , and genetic examination .
the typical signs are bone within the bone on the end bones , sclerotic appearances on the long bone and multiple previous fracture lines .
other radiological findings are hypoplastic maxillary sinus , teeth deformity and multiple carious . the genetic mutation in the chloride channel 7 ( clcn7 ) gene has been shown .
clcn7 gene mutations are heterogeneous , but the result is osteoclastic activity failure [ 4 , 6 ] .
she was evaluated with magnetic resonance imaging ( mri ) , which showed chiari i malformation with a 7 mm descent of cerebellar tonsils ( fig .  1 a and b ) .
computed tomography demonstrated diffuse calvarial thickening and loss of the medullary space ( fig .  2 ) .
her past medical history was consistent with left eye surgery due to amblyopia when she was a child and she was blind in her left eye .
radioactive i treatment had been given due to the graves disease and hyperthyroidism ; therefore , she was hypothyroidic and was using levothyroxine daily .
her physical examination revealed prominent occipital area and midfacial hypoplasia . increased cortical thickness in her long bones
c ) . there were no abnormal findings on neurological examination except of left eye amorozis .
large enough posterior fossa craniectomy with c1 laminectomy was performed with ssep and mep monitoring .
she developed superficial wound infection , which was treated with simple washout and antibiotics . 

figure  1:(a ) sagittal t2-weighted image showing cerebellar tonsillar herniation and diffuse thickening of the occipital bone .
( b ) axial t1-weighted image showing compression on the upper cervical spinal cord ( green arrow ) and cerebellar tonsillar herniation ( red arrow ) . 

figure  2:axial ct image ( bone window ) showing diffuse calvarial thickening and loss of the medullary space . 

figure  3:patients ' picture showing midfacial hypoplasia on the face ( a ) , x - ray graphy of the right femur ( b ) and x - ray of left femur ( c ) showing diffuse cortical thickening .
( a ) sagittal t2-weighted image showing cerebellar tonsillar herniation and diffuse thickening of the occipital bone .
( b ) axial t1-weighted image showing compression on the upper cervical spinal cord ( green arrow ) and cerebellar tonsillar herniation ( red arrow ) .
axial ct image ( bone window ) showing diffuse calvarial thickening and loss of the medullary space .
patients ' picture showing midfacial hypoplasia on the face ( a ) , x - ray graphy of the right femur ( b ) and x - ray of left femur ( c ) showing diffuse cortical thickening .
op is a rare and hereditary skeletal disease , which resulting from destructive or absence of osteoclastic activity . over
this case is the second ado case associated with chiari type i , which presented with hindbrain headache and numbness on the upper extremity without other cranial nerve compression sign .
mri revealed brain stem compression , tonsillar herniation , occipital bone thickening and shallow posterior fossa .
the first diagnosis was chiari type i , but detailed history , endocrinologic and radiologic work - up yielded as an ado , which was a final diagnosis .
reported that untreated aro patients died by the age of 4 years because of the pancytopenia and recurrent infection , which had a 75% rate .
there are two type describe , which have different clinical , biochemical and histological manifestation .
type i has osteosclerosis on the cranial vault , while type ii has end - plate thickening of vertebral body ( rugger jersey spine ) and end bones in the pelvis . both the types are strictly family related and seen in late childhood [ 3 , 10 ] .
the fracture frequency is increased in type ii and normal type i [ 1 , 2 , 4 , 8 , 10 ] .
de oliveira et al .   reported that there is no need to perform genetic study to confirm the disease .
tohidi and bagherpour   suggest that ado is rare condition , which can be asymptomatic .
therefore , accurate diagnosis can be achieved with the proper clinical , endocrinologic and radiologic investigation .
calcium , phosphorus and alkaline phosphatase levels are usually within the normal limits in the benign op [ 7 , 10 ] .
dlouhy and menezes   proposed in their report that even if their report is the first case ado with chiari , further study is needed . in their report , the cause of the chiari malformation in the op explained as unclear .
moreover , the absence of the osteoclastic activity leads to underdeveloped occipital bone , and this results in a smaller posterior fossa . in conclusion ,
however , patients can present with only chiari symptoms without other cranial nerves compression symptoms ; therefore , ado can be overlooked for differential diagnosis .
symptomatic chiari malformation needs surgical intervention , but it should be kept in mind that the patients with chiari malformation should investigate differential diagnosis for ado .
whole skeletal survey must be done , whether there are sclerotic chances , thickening skull base , bone within the bone appearance , rugger jersey spine , erlenmeyer flask deformity on the long bone and fracture line on the bone .
 osteopetrosis ( op ) is hereditary x - linked , autosomal recessive ( aro ) , or autosomal dominant ( ado ) skeletal disease . 
 aro has two subtypes , which are infantile malignant and intermediate type . 
 aro and x - linked op have poor clinical outcome . 
 ado is called adult benign type because of the normal life expectancy , which has type i and type ii . here , the authors present an ado patient with chiari type i. concomitant ado with chiari type i malformation is an extremely rare condition . 
 literature research yielded only one case report to date . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONFLICT OF INTEREST STATEMENT