三叉神经鞘瘤影像学特点和分型与手术入路的关系

Imaging features of trigeminal schwannoma and the relationship between its classification and surgical approaches

目的探讨三叉神经鞘瘤影像学特点和分型与手术入路的关系。方法对15例经手术病理证实的三叉神经鞘瘤影像学特点、分型及手术入路作回顾性分析。结果 15例三叉神经鞘瘤位于中颅窝3例,后颅窝2例,中后颅窝7例,颞下窝1例,翼腭窝1例和眼眶1例。影像学特点如下:①肿瘤位于岩尖,Mechel腔扩大,岩尖骨质吸收;②肿瘤位于桥小脑角池,与三叉神经根相连;③肿瘤沿三叉神经跨中后颅窝呈"哑铃状"生长;④颞下窝、翼腭窝肿瘤向中颅窝生长,卵圆孔、圆孔扩大;⑤肿瘤位于上直肌与眼眶之间,眶上裂增宽;⑥肿瘤边界清楚,CT呈不均匀等低密度,T1WI呈不均匀等低信号,T2WI呈不均匀等高信号,增强不均匀强化。15例三叉神经鞘瘤分为6型:中颅窝型3例、后颅窝型2例、中后颅窝型7例、颞下窝型1例、翼腭窝型1例和眼眶型1例。依据肿瘤类型采取不同的手术入路,额颞断颧弓入路3例、乙状窦后入路2例、扩大中颅窝底入路4例、颞下经小脑幕入路2例、乙状窦后和颞下经小脑幕联合入路1例、颞下窝入路1例、翼腭窝入路1例和额眶硬膜外入路1例。结论 CT和MRI是诊断三叉神经鞘瘤的理想方法,依据三叉神经鞘瘤影像学特点和分型,为外科手术入路的选择提供可靠依据。

Objective To explore the imaging features of trigeminal schwannoma and the relationship between its classifi- cation and surgical approaches. Methods The imaging features and the classification and the surgical approaches of tri- geminal schwannoma confirmed by pathology in 15 cases were analyzed retrospectively. Results In 15 cases, the tumors located in middle cranial fossa in 3 cases, in posterior cranial fossa in 2 cases, in middle and posterior cranial fossa in 7 ca- ses, in infratemporal fossa in 1 case, in pterygopalatine fossa in 1 case and in orbita in 1 case. The imaging features were as following： The tumors located in petrous apex, Meckel＇s cave enlarged and petrous bone absorbed The tumors located in the cistern of pontocerebellar trigone and connected with the root of trigeminal nerve The tumors grew along trigeminal nerve and acrossed middle and posterior cranial fossa with dumbbell appearance The tumors of infratemporal fossa and pterygopalatine fossa grew up to middle cranial fossa, foramen ovale and foramen rotundum enlarged~ @ The tumor was between rectus superior and orbita, superior orbital fissure expended; The tumors showed inhomogeneous e- qual and low density on CT, inhomogeneous hypo-intense and iso-intense signal on T1 WI , inhomogeneous iso-intense and hyper-intense signal on T2WI and inhomogeneous enhancement with clear edge. These cases were divided into six types： type of middle cranial fossa in 3 cases, type of posterior cranial fossa in 2 cases, type of middle and posterior cranial fossa in 7 cases, type of infratemporal fossa in 1 case, type of pterygopalatine fossa in 1 case, and type of orbita in 1 case. The different approaches were used to remove the tumors according to the type of tumor. 3 cases were through frontotemporal with zygomatic osteomy approach, 2 cases through sigmoid sinus approach, 4 cases through extended middle cranial fossa approach, 2 cases through temproromandibular cerebelli tentorium approach, 1 case through sigmoid sinus approach and temproromandibular cerebelli tentorium approach, and 1 case through infratemporal fossa approach, 1 case through ptery- gopalatine fossa approach, 1 case through frontoorbito extradural approach. Conclusion CT and MRI are ideal methods in diagnosis of trigeminal schwannoma, and provide reliable evidence in the selection of surgical approaches according to the imaging features and the classification of trigeminal schwannoma.