upon reviewing the literature , it was found that nasopharyngeal angiofibroma and meningo - ophthalmic artery ( m - oa ) anomaly are relatively rare phenomena . in denmark , the incidence of nasopharyngeal angiofibroma is reported to be 3.7 per million males per year . tumor extirpation is the mainstay treatment , but the recurrence rate ( 20% , ranging between 5 and 50% ) remains a challenge for the surgeon . in the case of m - oa anomalies , the ophthalmic artery ( oa ) variant may supply the orbit completely or partially , in the absence or presence of a normal oa with internal carotid artery ( ica ) origin , respectively . retinal supply from the middle meningeal artery ( mma ) was also encountered . the following incidences for oa origin from the mma have been reported : 1.18% among 170 specimens , based on dissection studies in the usa ; and 1.45% among 1652 oas , based on magnetic resonance imaging ( mri ) studies in japan . to the best of our knowledge , an m - oa anomaly has not been previously reported in a patient with nasopharyngeal angiofibroma . awareness of vascular collateral routes with routine angiography can effectively contribute to strategic planning and surgical interventions for tumor extirpations . embolization of the external carotid artery ( eca ) is a useful tool in the devascularization of nasopharyngeal angiofibroma and in the treatment of epistaxis . however , the surgical interventionist needs to be aware of dangerous eca  ica connections to avoid neurological complications such as embolic stroke and palsies . among the potential orbital collateral routes the m - oa is the most frequent followed by a route from the anterior branch of the mma . and a route from the anterior branch of the mma . for embolization procedures , it is imperative to identify the source of the retinal supply to avoid visual complications . this paper reports on unilateral m - oa and mma orbital collateral routes as the sole supply of the left orbit in a patient with nasopharyngeal angiofibroma . questions pertaining to the orbital collateral routes are the following : why do they exist ? a 12-year - old boy was admitted to our academic hospital and diagnosed with nasopharyngeal angiofibroma . computed tomography ( ct ) scanning revealed a midline nasopharyngeal angiofibroma with prominent right - side infratemporal fossa infiltration [ figure 1 ] . magnetic resonance imaging ( mri ) confirmed exclusion of intra - orbital infiltrations [ figure 2 ] . a lateral rhinotomy to remove the tumor was required . access to the right common transfemoral artery was gained with a 22 g jelco , and a micro - puncture guide wire was advanced into the right common femoral artery . a 4 f pediatric sheath was advanced over the micro - puncture guide wire into the right common femoral artery . a headhunter catheter was used and 50 ml of jopamiron 300 was administered intra - arterially without any side effects . a six - vessel study , i.e. eca , ica , and vertebral artery ( va ) on both sides , was selected to determine the blood flow routes of the angiofibroma for optimal tumor extirpation . dangerous eca  ica connections rendered embolization of prominent feeder arteries unsafe , but super - selective fibrin glue embolization of both sphenopalatine arteries with a micro - catheter was performed in an attempt to control epistaxis . post - operatively , the child still suffered from epistaxis because of the extensive nasal anastomotic networks encountered . the child had a difficult recovery , but was eventually discharged and scheduled for follow - up visits . twelve - year - old boy presented with nasopharyngeal angiofi broma diagnosed with unilateral meningo - ophthalmic artery anomaly . computed tomography scan shows midline nasopharyngeal angiofi broma ( black arrow ) , with prominent right - side infiltration into the infratemporal fossa ( white arrow ) . twelve - year - old boy presented with nasopharyngeal angiofibroma diagnosed with unilateral meningo - ophthalmic artery anomaly . the pre - operative angiographic study revealed the following prominent feeder arteries : ascending pharyngeal artery with multiple pharyngeal branches from the pharyngeal trunkus ( bilateral ) , proximal maxillary artery ( ma ) with branches from the stem of the m - oa ( left side ) and the mma and accessory meningeal artery ( ama ) ( right side ) , distal ma with sphenopalatine artery ( i.e. the nasopharyngeal artery ) ( bilateral ) , and distal facial artery with nasal branches ( bilateral ) . according to expectation , ethmoidal and nasal branches via the oa ( i.e. the left oa variant and the right oa with ica origin ) and nasal branches via the distal facial artery ( unilateral ) nourished the midline nasopharyngeal angiofibroma . for the purpose of this paper , prominent feeder arteries and two major vascular networks are given in table 1 . tumor feeder arteries , branches , and vascular networks twelve - year - old boy presented with nasopharyngeal angiofibroma diagnosed with unilateral meningo - ophthalmic artery anomaly . right lateral view angiograms of head show a ) pre - embolization of tumor vessels and b ) post - embolization of tumor vessels . left lateral view angiograms of head show c ) pre - embolization of tumor vessels and d ) post - embolization of tumor vessels . left angiograms revealed no oa with ica origin , and an m - oa anomaly that originated from the ma of the eca with an oa variant and mma branch variations [ figures 46 ] . of particular interest in this case was that the oa variant had two intra - orbital parts , namely an orbital division with a distinct branching pattern to supply the nasal cavity and nose ( i.e. ethmoidal and nasal branches ) and an ocular division with a distinct branching pattern to supply the eyeball ( i.e. ciliary and muscular branches ) and the retina ( i.e. the central retinal artery as witnessed by choroidal blush ) . the orbital and ocular divisions coursed through the superior orbital fissure and optic foramen , respectively , according to expectation . the mma presented with two branch variations that originated from the anterior branch of the mma , namely a lacrimal branch that coursed through a cranio - orbital foramen and a meningeal branch that remained outside the orbit . twelve - year - old boy presented with nasopharyngeal angiofibroma diagnosed with unilateral meningo - ophthalmic artery anomaly . left lateral view angiogram of the head shows internal carotid artery ( black arrow ) with no ophthalmic artery . twelve - year - old boy presented with nasopharyngeal angiofi broma diagnosed with unilateral meningo - ophthalmic artery anomaly . left anteroposterior view angiogram of head shows meningo - ophthalmic artery anomaly ( black arrow ) . ( 1 : ophthalmic artery variant ; 2 : ocular division ; 3 : orbital division ; 4 : middle meningeal artery ; 5 : anterior branch ; 6 : meningeal branch ; 7 : lacrimal branch ) . twelve - year - old boy presented with nasopharyngeal angiofibroma diagnosed with unilateral meningo - ophthalmic artery anomaly . left view angiogram of head shows meningo - ophthalmic artery anomaly ( black arrow ) . ( 1 : ophthalmic artery variant ; 2 : middle meningeal artery ; 3 : anterior branch ; 4 : meningeal branch ; 5 : lacrimal branch ) . nasopharyngeal angiofibroma often originates in the vicinity of the sphenopalatine foramen and epistaxis is a symptom to be reckoned with . severe intra - operative bleeding in the current case is attributed to the presence of a rare vidian artery that is often encountered in nasopharyngeal angiofibroma . a vidian artery ( i.e. the artery of the pterygoid canal ) usually arises from the distal ma , or may have origin from the petrous ica ( 30% incidence ) , or may serve as anastomosis between the eca and the ica . regardless of origin , a vidian artery participates in two major vascular networks through anastomoses in the pterygopalatine fossa ( with pharyngeal , ethmoidal , and sphenopalatine arteries ) and on the pharyngeal mucosa ( with ascending pharyngeal and meningeal arteries ) , as witnessed in this patient . the presence of an inferolateral trunkus ( ilt ) with origin from the cavernous ica ( c4 segment ) and its anastomotic connections with the ma , mma , and oa must also be taken into consideration . an ilt is often identifiable in the dissection specimen , but is less frequently seen on imaging and was not witnessed in this case . embryological explanations for m - oa and mma orbital routes are fetal anastomotic connections between the ica and eca and enlargement of fetal anastomosis between branches of the mma and oa , respectively . in principle , the stapedial system plays a pivotal role in the development of m - oa and mma orbital routes . suggested embryonic evolutionary changes for the orbital collateral routes ( m - oa and mma ) encountered in this case are as follows : regression of the proximal parts of the stapedial artery ( sa ) ( origin : ica ) and primitive ophthalmic artery ( poa ) ( origin : ica ) occurred , and an annex between the distal parts of the sa and poa formed , whereby the m - oa gained eca origin . ( 1 : internal carotid artery ; 2 : ophthalmic artery ; 3 : external carotid artery ; 4 : middle meningeal artery ; 5 : orbital branch ; 6 : stapedial artery ; 7 : maxillary artery ; 8 : meningo - ophthalmic artery ; 9 : meningeal branch ; 10 : lacrimal branch ) . upon decision - making whether the m - oa and mma routes were tumor - related or incidental , it was evident that the latter was applicable in this case . in favor of the incidental presence of the m - oa and mma routes were their unilateral ( left side ) presence , the prominent right - side occurrence of the tumor , and no intra - orbital infiltrations . of clinical significance is that in cases where the m - oa is the sole supply to the eye , proximal embolization of the ma or mma carries a high risk of visual impairment and must be avoided . a pre - operative routine angiographic study in a patient who presented with a nasopharyngeal angiofibroma revealed an m - oa anomaly . the m - oa anomaly followed distinct patterns of orbital supply and was the sole supply to the eye . in this particular case , the m - oa anomaly was not tumor related and was considered incidental . proximal embolization of the ma was considered unsafe for tumor extirpation , but embolization of both sphenopalatine arteries was a useful tool in the management of epistaxis . documentation of this tumor entity and m - oa anomaly , both relatively rare , remains a valuable contribution to the literature .
a 12-year - old boy with epistaxis presented with a rare midline nasopharyngeal angiofibroma that extended lateral into the pterygoid and infratemporal fossae . 
 pre - operative angiography revealed bilateral prominent feeder arteries and two major anastomotic connections , and a rare left meningo - ophthalmic artery ( m - oa ) anomaly that was the sole path of supply to the eye . a literature search using pubmed and medline was conducted . for imaging , a six - vessel study ( i.e. external and internal carotid and vertebral arteries on both sides ) was selected . 
 embolization of prominent tumor feeder arteries was unsafe for tumor extirpation , but super - selective embolization of both sphenopalatine arteries was performed to control epistaxis . 
 the m - oa anomaly that originated from the maxillary artery ( ma ) was marked by an ophthalmic artery ( oa ) variant with orbital and ocular divisions that coursed through the superior orbital fissure and optic foramen , respectively , each with distinct branching patterns , a middle meningeal artery ( mma ) with normal branches ( i.e. anterior and posterior branches ) , and two branch variations ( i.e. lacrimal and meningeal branches ) that originated from the anterior branch of the mma . 
 the lacrimal branch coursed through a cranio - orbital foramen , but the meningeal branch remained outside the orbit . 
 the anatomy of the right oa was normal . 
 the left m - oa anomaly was considered incidental and not tumor - related since the tumor was more prominent on the right side , and no intra - orbital infiltrations occurred . of clinical significance is that proximal embolization of ma or mma carries a high risk of visual impairment in cases where m - oa anomalies are the sole mode of supply to the eye .