Ichimura S, Kawase T, Onozuka S, Yoshida K, Ohira T
Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan.
Acta Neurochir (Wien). 2008 Jul;150(7):637-45. doi: 10.1007/s00701-008-1586-x. Epub 2008 Jun 12.
Petroclival meningiomas are vaguely defined as tumours arising from the antero-medial zone to the internal auditory meatus. This report subclassifies petroclival meningiomas based on their origin determined by using radiological and intra-operative findings.
Ninety-one patients with petroclival meningioma underwent surgery via the anterior transpetrosal approach. The Meckel's cave was routinely opened. Tumour origin was classified into four subtypes according to the main attachment and trigeminal nerve deviation into, upper clivus (UC), cavernous sinus (CS), tentorium (TE), and petrous apex (PA). Their characteristic clinical symptoms and anatomical features were investigated.
The characteristic symptom was ataxia in the UC type (37.5%), abducens nerve palsy in the CS type (64.3%) and trigeminal neuropathy, mainly neuralgia in the PA type (80.0%) with a higher statistical difference from other subtypes. The rate of tumour invasion into Meckel's cave reached 70.3% in average, with the lowest rate in the PA type (25.0%). The rate of middle fossa extension was the highest in the TE type (59.5%). The middle fossa approach was considered to be ideal for UC and TE types because of easier access to the Meckel's cave. Radical dissection without complications was difficult in the CS type. Both the anterior transpetrosal approach and the lateral suboccipital approach could be indicated in the PA type due to the rare invasion of Meckel's cave and middle fossa, and frequent extension into the internal auditory meatus.
This classification is useful to predict the relation between the tumour and the cranial nerves based on symptoms and images. The anterior transpetrosal approach could be used for all four subtypes and with an absolute indication in the UC and TE types showing middle fossa extension.
岩斜区脑膜瘤的定义较为模糊，是指起源于内听道前内侧区域的肿瘤。本报告根据影像学和术中发现确定的起源，对岩斜区脑膜瘤进行了亚分类。
91例岩斜区脑膜瘤患者接受了经岩前入路手术。常规打开Meckel腔。根据主要附着部位和三叉神经移位情况，将肿瘤起源分为四种亚型，即上斜坡（UC）、海绵窦（CS）、小脑幕（TE）和岩尖（PA）。研究了它们的特征性临床症状和解剖学特征。
UC型的特征性症状是共济失调（37.5%），CS型是展神经麻痹（64.3%），PA型是三叉神经病变，主要是神经痛（80.0%），与其他亚型相比有较高的统计学差异。肿瘤侵犯Meckel腔的平均发生率达到70.3%，PA型最低（25.0%）。中颅窝扩展率在TE型最高（59.5%）。由于更容易进入Meckel腔，中颅窝入路被认为对UC型和TE型是理想的。CS型难以进行无并发症的根治性切除。PA型由于Meckel腔和中颅窝侵犯罕见，且常延伸至内听道，经岩前入路和枕下外侧入路均可采用。
这种分类有助于根据症状和影像学预测肿瘤与颅神经之间的关系。经岩前入路可用于所有四种亚型，对于显示中颅窝扩展的UC型和TE型有绝对指征。
