Tachibana S, Harada K, Abe T, Yamada H, Yokota A
Department of Neurosurgery, Kitasato University, Sagamihara, Japan.
Surg Neurol. 1995 May;43(5):470-5; discussion 475-7. doi: 10.1016/0090-3019(95)80092-u.
A number of patients diagnosed as having syringomyelia secondary to tonsillar herniation caused by posterior fossa tumors has recently been described, although the backgrounds of the affected patients were not studied. In order to determine the possible causative contribution of the tonsillar herniation, the present cooperative study was carried out.
A retrospective study was performed by five cooperating institutes. Magnetic resonance images (MRIs) of patients with posterior fossa tumors were reevaluated with particular attention to the existence of tonsillar herniation and syringomyelia.
The total number of patients with posterior fossa tumors whose MRIs were reinvestigated was 164. In 24 out of the 164 patients, tonsillar herniation was apparent in the sagittal plane of the MRI. Syringomyelia was observed in five of the 24 cases with tonsillar herniation being a consistent associated finding. None of the individuals demonstrated any sensory disturbance directly corresponding to the syrinx formation. All but one of the five patients underwent surgical removal of the tumor, but no one required surgical treatment for the syrinx itself. Disappearance or shrinkage of the syrinx could be confirmed by postoperative MRIs in three of them.
A simple mechanism of blockage of cerebrospinal fluid flow at the foramen magnum may play an important role in syrinx formation, as evidenced by the unexpectedly high incidence of cervical syrinx along with tonsillar herniation caused by posterior fossa tumors shown in the present study.
最近有报道称，一些因后颅窝肿瘤导致扁桃体疝继发脊髓空洞症的患者，但未对这些患者的背景进行研究。为了确定扁桃体疝可能的致病作用，开展了本合作研究。
由五个合作机构进行回顾性研究。对后颅窝肿瘤患者的磁共振成像（MRI）进行重新评估，特别关注扁桃体疝和脊髓空洞症的存在情况。
重新研究MRI的后颅窝肿瘤患者总数为164例。在164例患者中的24例中，MRI矢状面上可见明显的扁桃体疝。在24例有扁桃体疝的病例中，有5例观察到脊髓空洞症，扁桃体疝是一个一致的相关发现。所有患者均未表现出与空洞形成直接对应的感觉障碍。5例患者中除1例之外均接受了肿瘤手术切除，但无人需要对空洞本身进行手术治疗。其中3例患者术后MRI证实空洞消失或缩小。
本研究显示，后颅窝肿瘤导致扁桃体疝时，颈髓空洞症的发生率意外地高，这证明枕骨大孔处脑脊液流动受阻的简单机制可能在空洞形成中起重要作用。
