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 .