a 75-year - old asian female without systemic disease initially presented with nasal congestion , mucous rhinorrhea and progressively decreasing sense of smell .
she was treated as allergic rhinitis with oral antihistamine and nasal steroid spray , but no obvious improvement .
one month after the symptoms , paranasal sinus computed tomography ( ct ) showed heterogeneous soft tissue densities in the left maxillary , frontal , bilateral ethmoid , and sphenoid sinuses , with extensive bony destruction [ fig . 1 ] .
paranasal sinus ct ( a : coronal view , b : axial view ) shows sinusitis with bony erosion over left maxillary , frontal , bilateral ethmoid and sphenoid however , 6 months later , the patient was referred to our clinic with a 2 weeks history of declining vision in one eye ( oculus sinister [ os ] ) .
examination disclosed no light perception and revealed a relative afferent pupillary defect , but normal fundus appearance [ os ; fig .
2a ] . visual field testing ( oculus dexter ) showed a temporal defect with moderate constriction [ fig .
the diagnosis was not confirmed with suspicion of central retinal artery occlusion or optic neuropathy .
orbital magnetic resonance imaging ( mri ) was suggested and indicated multiple sinusitis with bone erosion and intracranial extension .
furthermore , encasement of the right optic nerve and infiltration of the left optic nerve near the optic chiasm were noted without abnormal optic nerve enhancement after contrast [ fig . 4 ] . due to the finding of the intracranial lesion ,
surgical debridement for sinusitis with suspected optic neuropathy was suggested by the ophthalmologist but not performed immediately .
fundus appearance reveals no obvious abnormality , including disc , macula and vessels initially 2 weeks after left visual loss ( a ) .
six months later with bilateral visual loss , disc does not reveal pale appearance ( b ) ( poor quality due to loss of fixation ) visual field ( vf ) .
vf ( oculus dexter ) shows temporal defect with moderate constriction while visual loss optic nerve in orbital magnetic resonance imaging .
encasement of the right optic nerve ( marked as  r  ) by the fluid - filled onodi cell ( * ) and the fluid - filled anterior clinoid process ( + ) is suspected on t2-weighted image ( a ) ; left optic nerve ( l ) is infiltrated by the anterior cranial fossa lesion ( # ) ( b , t1 with enhancement and fat suppression ) , which are indicated in coronal view ( c , t1 with enhancement and fat suppression , right optic nerve marked as 
 ,  left optic nerve marked as    ) moreover , 3 weeks after the first episode of vision loss ( os ) , vision loss suddenly occurred in the other eye . under the impression of optic neuropathy associated with presumed sinusitis ( oculus uterque [ ou ] )
, the patient received mega - dose steroids ( methylprednisolone 250 mg q6 h for 5 days ) and emergent bilateral sinusectomy . because of unusual clinical course ,
the findings were highly suggestive of sinonasal undifferentiated carcinoma ( snuc)-related retrobulbar infiltrative optic neuropathy ( ou ) ; therefore , the patient underwent concurrent radiochemotherapy as malignancy therapy .
three months after the first episode of visual loss , ocular examination still showed no light perception ( ou ) .
the pattern visual evoked potential ( vep ) failed to perform due to poor vision and flash vep [ fig .
6 ] . at the final visit ( 6 months after the first visual loss episode ) , no light perception ( ou ) persisted even though the disc appeared pinkish [ fig .
two months after visual loss ( oculus dexter [ od ] ) and 3 months after visual loss ( oculus sinister [ os ] ) , pattern vep fails due to tracing inability with no light perception ; flash vep reveals delayed latency ( od : 120 ms , os : 140 ms ) and decreased amplitude ( od : 11 uv , os : 7.5 uv ) electroretinography ( erg ) , erg reveals no obvious abnormal amplitude both in rod and cone function
rhinogenic optic neuropathy is characterized by optic nerve damage secondary to the sinonasal lesion , and includes various sinonasal diseases such as sinusitis , mucocele , and sinus surgery , with the main mechanism being compression and inflammatory changes .
in addition to optic neuropathy , orbital invasion is a common manifestation with ocular findings such as lid edema , blepharoptosis , conjunctival chemosis , conjunctival injection , diplopia , limitation of ocular motility , globe displacement , epiphora , anisocoria , eye pain , and photophobia .
the efficacy of steroid therapy for rhinogenic optic neuropathy has not been elucidated , possibly due to the limited number of cases .
surgical intervention in the form of orbital or optic nerve decompression accompanied by systemic steroids resulted in favorable visual outcome ; however , poor prognosis was still mentioned in case reports of sphenoid sinus mucocele and eosinophilic chronic rhinosinusitis .
preoperative visual acuity tended to correlate with prognosis ; therefore , patients with severely impaired vision should be given more attention and treated aggressively .
snuc , a rare and aggressive malignancy , was first described in 1986 as a highly aggressive neoplasm arising from the nasal cavity and paranasal sinuses .
the most common locations of snuc are the nasal cavity and ethmoid sinus ; in addition , orbital and intracranial invasion and distant metastasis are frequent findings .
bone destruction and invasion of adjacent structures such as the orbit , cranial vault , and skull base is frequently seen .
in addition to retrobulbar optic neuropathy , other ophthalmic symptoms of the oculomotor nerve palsy , optic atrophy , and proptosis are possible manifestations . due to the frequent cranial invasion ,
there are several possible mechanisms to explain the sudden visual loss with intracranial mass lesions , including ischemia due to vascular compression of the visual pathways or demyelination secondary to compression . in all previous cases of snuc
related optic neuropathy , one eye is affected more than the other eye , or just only one eye affected , while this case is totally blindness in both eyes .
the cause of bilateral visual loss was possibly ischemia , originating from a compromised visual pathway vascular system caused by the snuc , which could not be excluded even though no optic disc pale was noted 3 months after first visual loss ( os ) . distinguishing mucosal inflammatory and neoplastic lesions of the paranasal sinuses by medical imaging modalities may be appropriate but difficult , as seen in our patient .
snucs have typical but nonspecific imaging characters , such as a large , expansile , and aggressive lesion with bone destruction and invasion of adjacent structures , including the anterior cranial fossa , adjacent paranasal sinuses , and orbits . on ct scans ,
the lesions are typically isointense to muscle on t1-weighted scans , iso - to hyperintense to muscle on t2-weighted scans , and heterogeneous on enhancement with gadolinium [ fig .
these imaging findings could not provide much advantage in differentiating snuc from other pathological entities in this region .
sinonasal undifferentiated carcinoma ( snuc ) in different magnetic resonance imaging modalities . to differentiate snuc by different modalities
, the lesion reveals isointense to muscle on t1-weighted image ( a , marked as 
  ) and heterogeneous appearance after enhancement ( c , marked as    ) overall survival of patients with snuc is poor in most reported series , especially for those presenting with brain parenchymal invasion .
the visual outcome is not available in the literature owing to the limited number of cases ; however , surgical decompression with steroid therapy did not results in any improvement in our patient .
no clear consensus exists regarding treatment for snuc , but a combination of operation , chemotherapy , and radiotherapy may be suggested . to the best of our knowledge ,
this is the first report of bilateral sequential total blindness induced by snuc - related rhinogenic optic neuropathy . because of aggressive optic neuropathy and poor survivor in snuc , it is important to differentiate between chronic sinusitis and snuc , or other sinonasal malignancies , based on clinical presentation and image study of mri .
atypical clinical presentation includes poor response to medication , such as antihistamine and antibiotics , ocular and visual symptoms ; furthermore , imaging suggests sinus wall bony erosion , multiple invasion , and obvious intralesional necrosis .
more attention and aggressive surveillance , such as early biopsy , should be given to the patients mentioned above .
however , in our experience , surgical decompression by sinusectomy with systemic steroids and antibiotics did not improve the visual outcome , which emphasizes the rapid disease progression and importance of early diagnosis and treatment .
 sinonasal undifferentiated carcinoma - related rhinogenic optic neuropathy is rare and may lead to visual loss . to the best of our knowledge , 
 this is the first report of bilateral sequential visual loss induced by this etiology . 
 it is important to differentiate between chronic sinusitis and malignancy on the basis of specific findings on magnetic resonance images . 
 surgical decompression with multidisciplinary therapy , including steroids , chemotherapy , and radiotherapy , is indicated . 
 however , no visual improvement was noted in this case , emphasizing the rapid disease progression and importance of early diagnosis and treatment . 
Case Report
Discussion